DNV-RP-E403: Hyperbaric Evacuation Systems · DNV-RP-E403 HYPERBARIC EVACUATION SYSTEMS ......

RECOMMENDED PRACTICE

DET NORSKE VERITAS

DNV-RP-E403

HYPERBARIC EVACUATION SYSTEMS

OCTOBER 2010

FOREWORD

DET NORSKE VERITAS (DNV) is an autonomous and independent foundation with the objectives of safeguarding life,property and the environment, at sea and onshore. DNV undertakes classification, certification, and other verification andconsultancy services relating to quality of ships, offshore units and installations, and onshore industries worldwide, and carriesout research in relation to these functions.

DNV service documents consist of amongst other the following types of documents:— Service Specifications. Procedual requirements.— Standards. Technical requirements.— Recommended Practices. Guidance.

The Standards and Recommended Practices are offered within the following areas:A) Qualification, Quality and Safety MethodologyB) Materials TechnologyC) StructuresD) SystemsE) Special FacilitiesF) Pipelines and RisersG) Asset OperationH) Marine OperationsJ) Cleaner Energy

O) Subsea Systems

The electronic pdf version of this document found through http://www.dnv.com is the officially binding version© Det Norske Veritas

Any comments may be sent by e-mail to [email protected] subscription orders or information about subscription terms, please use [email protected] Typesetting (Adobe Frame Maker) by Det Norske Veritas

If any person suffers loss or damage which is proved to have been caused by any negligent act or omission of Det Norske Veritas, then Det Norske Veritas shall pay compensation to such personfor his proved direct loss or damage. However, the compensation shall not exceed an amount equal to ten times the fee charged for the service in question, provided that the maximum compen-sation shall never exceed USD 2 million.In this provision "Det Norske Veritas" shall mean the Foundation Det Norske Veritas as well as all its subsidiaries, directors, officers, employees, agents and any other acting on behalf of DetNorske Veritas.

Recommended Practice DNV-RP-E403, October 2010Changes –

CHANGES

• General

As of October 2010 all DNV service documents are primarilypublished electronically.

In order to ensure a practical transition from the “print” schemeto the “electronic” scheme, all documents having incorporatedamendments and corrections more recent than the date of thelatest printed issue, have been given the date October 2010.

An overview of DNV service documents, their update statusand historical “amendments and corrections” may be foundthrough http://www.dnv.com/resources/rules_standards/.

• Main changes

Since the previous edition (December 2006), this documenthas been amended, most recently in October 2009. All changeshave been incorporated and a new date (October 2010) hasbeen given as explained under “General”.

DET NORSKE VERITAS

Recommended Practice DNV-RP-E403, October 2010 – Changes

DET NORSKE VERITAS

Recommended Practice DNV-RP-E403, October 2010 Contents –

CONTENTS

Sec. 1 General................................................................... 9

A. General....................................................................................9A 100 Objectives .........................................................................9A 200 Application, scope and assumptions.................................9A 300 Documentation..................................................................9A 400 Other codes .....................................................................10A 500 Exemptions and deviations ............................................. 10A 600 Hyperbaric evacuation methods......................................10A 700 Contingency planning and emergency instructions .......10A 800 Rescue treatment facilities .............................................. 11

B. Normative References ..........................................................11B 100 Service specifications .....................................................11B 200 Standards.........................................................................11B 300 Recommended practices .................................................11B 400 Rules and regulations...................................................... 11B 500 Standards for Certification.............................................. 11B 600 Guidelines and Classification Notes ...............................11

C. Informative References......................................................... 11C 100 General............................................................................11

D. Verbal Forms and Definitions .............................................. 13D 100 Auxiliary verbal forms.................................................... 13D 200 Definitions ...................................................................... 13D 300 Definitions (continued) ...................................................16

E. Abbreviations and Symbols (Guidance)............................... 16E 100 Abbreviations.................................................................. 16E 200 Symbols .......................................................................... 17

Sec. 2 Design Philosophy and Premises ....................... 18

A. General..................................................................................18A 100 Objectives .......................................................................18A 200 Application and scope.....................................................18A 300 Documentation................................................................18A 400 Units................................................................................18

B. Safety Philosophy .................................................................18B 100 General............................................................................18B 200 Safety objective............................................................... 18B 300 Systematic review........................................................... 18

C. Environmental Conditions.................................................... 19C 100 General............................................................................19C 200 External operational conditions and outer area............... 19C 300 Submerged components.................................................. 19C 400 Internal conditions ..........................................................19C 500 Corrosive operational conditions .................................... 20C 600 Collection of environmental data (Guidance)................. 20

D. Premises ............................................................................... 20D 100 Concept development .................................................... 20D 200 Execution plan ................................................................21D 300 Plan for manufacture, installation and operation ............ 21

E. System Design Principles ..................................................... 21E 100 System integrity ..............................................................21E 200 Design and construction principles.................................21E 300 Self-Propelled Hyperbaric Lifeboat (SPHL) ..................22E 400 Crew facilities ................................................................. 22E 500 Pressure control system .................................................. 22

F. Arrangement Layout and Location of the Hyperbaric Evacuation System ...............................................................22

F 100 General............................................................................22F 200 Stability and floatation of support vessel

(for installations on ships and mobile offshore units)..... 22F 300 Location of the hyperbaric evacuation system ............... 22F 400 Layout of the hyperbaric evacuation system ..................23F 500 Avoidance of contaminants ............................................23F 600 Entry and egress..............................................................23F 700 Mechanical equipment.................................................... 23

G. Materials and Structures .......................................................23G 100 Materials ......................................................................... 23G 200 Supports and foundations for the hyperbaric

evacuation system .......................................................... 23G 300 Supports and foundations for handling systems and

lifting appliances............................................................. 23G 400 Supports and foundations for other equipment............... 24

H. Documentation......................................................................24H 100 General............................................................................ 24H 200 Documentation of arrangement ...................................... 24H 300 Documentation for systems in operation ........................ 24H 400 Filing of documentation.................................................. 24

I. Inspection, Surveys, Testing and Drills ................................25I 100 General............................................................................ 25I 200 Testing at the manufacturers........................................... 25I 300 Testing after completed installation................................ 25I 400 Surveys and testing during operations............................ 26I 500 Maintenance.................................................................... 26I 600 Drills ............................................................................... 27

J. Marking and Signboards.......................................................27J 100 General............................................................................ 27J 200 Gas containers................................................................. 27J 300 Other pressure vessels than gas containers ..................... 28J 400 Launch and recovery system .......................................... 28

Sec. 3 Pressure Vessels for Human Occupancy, Gas Storage and Other Purposes ...................... 29

A. General..................................................................................29A 100 Objectives ....................................................................... 29A 200 Application and scope..................................................... 29A 300 Documentation................................................................ 29A 400 Testing and marking after completion............................ 29A 500 Material protection.......................................................... 29A 600 Design loads.................................................................... 30

B. Design of Chambers .............................................................30B 100 Chambers ........................................................................ 30B 200 Doors, hatches, windows, branches, etc. ........................ 31

C. Materials and Fabrication of Pressure Vessels .....................32C 100 Materials and components .............................................. 32C 200 Fabrication ...................................................................... 32C 300 Fabrication tolerances..................................................... 32

D. Strength of Hulls and Pressure Vessels ................................33D 100 Structural analysis........................................................... 33D 200 Vessels subjected to external pressure............................ 33D 300 Flanges for windows....................................................... 33

E. Gas Cylinders........................................................................33E 100 General............................................................................ 33E 200 Heat treatment................................................................. 33E 300 Tolerances and surface conditions.................................. 33E 400 Production tests............................................................... 34

F. Acrylic Plastic Windows ......................................................34F 100 General............................................................................ 34F 200 Materials ......................................................................... 34F 300 Manufacturers of cast material ....................................... 34F 400 Certification of cast material .......................................... 34F 500 Certification of windows ................................................ 34F 600 Geometry and thickness.................................................. 34F 700 Fabrication ...................................................................... 34F 800 In service inspection ....................................................... 34

Sec. 4 Life Support Systems ......................................... 35

A. General..................................................................................35A 100 Objectives ....................................................................... 35A 200 Application and scope..................................................... 35A 300 Documentation................................................................ 35

DET NORSKE VERITAS

Recommended Practice DNV-RP-E403, October 2010 – Contents

B. Gas Storage........................................................................... 35B 100 Capacity ..........................................................................35B 200 Shut-off, pressure relief and drainage .............................36

C. Gas distribution..................................................................... 36C 100 General ............................................................................36C 200 Built in Breathing Systems (BIBS).................................36C 300 Life Support Package (LSP) and equipment for

connection to support and rescue vessels........................37C 400 Stand-by facility at surface .............................................37

D. Oxygen Systems ................................................................... 37D 100 General ............................................................................37

E. Piping Systems ..................................................................... 37E 100 General ............................................................................37E 200 Hyperbaric evacuation chambers ....................................38

F. Environmental Conditioning in Hyperbaric Evacuation Chambers and Adjoining Decompression Chambers and Tunnels ................................................................................. 38

F 100 Thermal control of hyperbaric evacuation units .............38F 200 Humidity reduction in chambers.....................................38F 300 Noise reduction ...............................................................38F 400 Gas circulation systems for chambers.............................38F 500 Removal of carbon dioxide .............................................38F 600 Regeneration of gas (if applicable) .................................38

G. Gas Control Systems ............................................................ 39G 100 Control stands .................................................................39G 200 Helium and oxygen mixing systems for direct supply for

breathing (if fitted) ..........................................................39

H. Closed Circuit Breathing Systems (CCBS) (if fitted) .......... 39H 100 General ............................................................................39

I. Facilities, Food and First Aid ............................................... 39I 100 General ............................................................................39I 200 Hyperbaric evacuation units used as decompression

chambers during normal operations ................................39

Sec. 5 Electrical, Instrumentation, Communication and Navigation Systems ..................................... 41

A. General.................................................................................. 41A 100 Objective .........................................................................41A 200 Application and scope.....................................................41A 300 Documentation ................................................................41A 400 Codes and standards........................................................41A 500 Service definitions...........................................................41

B. System Design ...................................................................... 42B 100 System voltages and distribution systems types .............42B 200 Power supply systems .....................................................42B 300 Distribution systems........................................................42B 400 Capacity ..........................................................................43B 500 Environmental requirements ...........................................43B 600 Inspection and testing requirements................................43

C. Equipment Selection and Installation ................................... 43C 100 General ............................................................................43C 200 Enclosures .......................................................................43C 300 Earthing...........................................................................44C 400 Batteries ..........................................................................44C 500 Cables and penetrators ....................................................44C 600 Lighting, inner area .........................................................44

D. Communication .................................................................... 45D 100 General ............................................................................45D 200 Location systems.............................................................45D 300 Surface radio communication .........................................45D 400 Hardwire telephone communication ...............................45D 500 Visual observation of evacuees.......................................45D 600 Other voice communication systems ..............................45

E. Instrumentation..................................................................... 45E 100 General ............................................................................45E 200 Control stands (including pilot's compartment in

SPHLs) ............................................................................46E 300 Pressure indicators in hyperbaric evacuation chambers

compartments ..................................................................46E 400 Oxygen analysing systems ..............................................46E 500 Carbon dioxide analysing systems..................................46E 600 Other gases......................................................................46E 700 Contaminants ..................................................................47E 800 Automatic environmental control systems......................47

F. Navigation (SPHL) ...............................................................47F 100 Visibility..........................................................................47F 200 Orientation ......................................................................47F 300 Positioning ......................................................................47F 400 Speed...............................................................................47F 500 Lights and reflectors........................................................47F 600 Radiotelegraphy and radiotelephony ..............................47

Sec. 6 Fire Prevention, Detection and Extinction ...... 48

A. General..................................................................................48A 100 Objective .........................................................................48A 200 Application and scope.....................................................48A 300 Documentation ................................................................48A 400 Control stands .................................................................48

B. Fire Protection ......................................................................48B 100 Materials..........................................................................48

C. Fire Detection and Alarm System.........................................49C 100 Outer area........................................................................49C 200 Inner area.........................................................................49C 300 Enclosure area .................................................................49C 400 Fault detection.................................................................49

D. Fire Extinguishing ................................................................49D 100 Outer area........................................................................49D 200 Inner area.........................................................................49D 300 Enclosure area .................................................................50D 400 Scope...............................................................................50

E. Miscellaneous Equipment.....................................................50E 100 Fire-fighter's outfit ..........................................................50E 200 Portable fire extinguishers ..............................................50

Sec. 7 Launch and Recovery Systems ......................... 51

A. General..................................................................................51A 100 Objectives........................................................................51A 200 Application and scope.....................................................51A 300 Documentation ................................................................51A 400 National codes.................................................................51

B. Design Principles ..................................................................51B 100 Function ..........................................................................51B 200 Launch of Hyperbaric Evacuation Units (HEU).............52B 300 Recovery of hyperbaric evacuation units........................53B 400 Alternative recovery........................................................53B 500 Emergency arrangements ................................................53B 600 Power ..............................................................................53B 700 Umbilical.........................................................................53

C. Strength.................................................................................53C 100 Design loads....................................................................53C 200 Dimensions......................................................................54

D. Dynamic Loads in Launch and Recovery Systems ..............54D 100 General ...........................................................................54

Sec. 8 Pipes, Hoses, Valves, Fittings, Compressors and Umbilicals ........................................................... 55

A. General..................................................................................55A 100 Objectives........................................................................55A 200 Application and scope.....................................................55A 300 Documentation ................................................................55A 400 Materials..........................................................................55A 500 Protection ........................................................................55

B. Pipes and Hoses ....................................................................55B 100 General ............................................................................55B 200 Hoses...............................................................................55B 300 Hoses and components for gases containing oxygen......56

DET NORSKE VERITAS

Recommended Practice DNV-RP-E403, October 2010 Contents –

C. Valves and Pressure Regulators ...........................................56C 100 Valve design ...................................................................56

D. Fittings and Pipe Connections .............................................. 56D 100 Detachable connections .................................................. 56

E. Compressors ......................................................................... 56E 100 General............................................................................56

F. Umbilicals............................................................................. 56F 100 General............................................................................56F 200 Hoses............................................................................... 56F 300 Electrical cables ..............................................................56F 400 Sheathing ........................................................................ 56F 500 Strength members ........................................................... 56F 600 Testing of mechanical properties.................................... 56F 700 Tests after completion.....................................................56

Sec. 9 Machinery and Machinery Piping Systems...... 57

A. General..................................................................................57A 100 Objectives .......................................................................57A 200 Application and scope.....................................................57A 300 Documentation................................................................57

B. Hydraulic Power Systems.....................................................57B 100 General............................................................................ 57B 200 Hydraulic fluids .............................................................. 57B 300 Components .................................................................... 57

C. Propulsion Machinery (SPHL) .............................................57C 100 General............................................................................ 57C 200 Diesel engines................................................................. 57C 300 Electric propulsion motors.............................................. 57C 400 Hydraulic propulsion motors .......................................... 58

D. Pumping and Piping Systems ...............................................58D 100 General............................................................................ 58

Sec. 10 Hull structure, Buoyancy Stability and Trim.. 59

A. General..................................................................................59A 100 Objectives ....................................................................... 59A 200 Application and scope..................................................... 59A 300 Documentation................................................................ 59

B. Design ...................................................................................59B 100 General............................................................................ 59B 200 Buoyancy, stability and trim........................................... 59

App. A Certification (Guidance) .................................... 60

DET NORSKE VERITAS

Recommended Practice DNV-RP-E403, October 2010 – Contents

DET NORSKE VERITAS

Recommended Practice DNV-RP-E403, October 2010 Sec.1 –

SECTION 1GENERAL

A. General

A 100 Objectives

101 This recommended practice gives criteria and guidanceon design, fabrication, installation, testing and commissioningof hyperbaric evacuation systems.

102 These guidelines and specifications for hyperbaric evac-uation systems have been developed with a view to promotingthe safety of all divers in saturation and achieving a standard ofsafety for divers which corresponds, so far as is practicable, tothat provided for other seagoing personnel, and which will sat-isfy chapter 3 of the Code of Safety for Diving Systems (reso-lution A.536(13), as amended by resolution A.583(14)). [IMOGuidelines Res. A.692(17): 1]

103 The safety of other seagoing personnel is regulated bythe IMO Convention 'Safety of Life at Sea' (SOLAS).

104 Hyperbaric evacuation systems that are installed on adiving support vessel are, as a minimum, regarded as transfer-able diving systems and should be certified as such. (SeeDNV-OS-E402 “Diving Systems”). However, the minimumsize requirements given in the standard shall be considered ineach case.The functionality of the hyperbaric evacuation system as anescape route and a life saving appliance, is subject for approvalby the maritime authorities to which the diving support vesselis registered.

105 The purpose of these Guidelines and Specifications is torecommend design and construction criteria, equipment, sur-vey standards and contingency planning for the evacuationsystems referred to in chapter 3 of the Code of Safety for Div-ing Systems (resolution A.536(13)).[IMO Guidelines Res.A.692(17): 1]

106 Therefore, the objectives of this recommended practiceare to:

— provide an internationally acceptable code of safety forhyperbaric evacuation systems by defining minimumrequirements for the design, materials, fabrication, instal-lation, testing, commissioning, operation, repair, and re-qualification

— serve as a technical reference document in contractualmatters between purchaser and contractor

— serve as a technical reference document for verificationservices

— serve as a guideline for designers, purchaser, and contrac-tors.

107 The objective of this recommended practice is also thatthe design, materials, fabrication, installation, commissioning,operation, repair, and re-qualification, of hyperbaric evacua-tion systems are safe and conducted with due regard to publicsafety and the protection of the environment.

108 The objectives of this section are to outline the function-ality of the recommended practice and its related codes, stand-ards and recommended practices.

109 General guidance is provided as to the use and interpre-tation of the standard.

A 200 Application, scope and assumptions

201 The guidelines and specifications apply to new hyper-baric evacuation units which are constructed more than twelvemonths after the date on which the Assembly of the Interna-tional Maritime Organization adopts these guidelines andspecifications for units which can be mated to a surface com-

pression chamber. However, any existing system which, com-plies with the provisions of these Guidelines andSpecifications may be considered for endorsement of thesafety equipment certificate in accordance with 4.2. (Sec.11B101 in this RP))[IMO Guidelines Res. A.692(17): 2]

202 This RP is applicable to all geographical areas.

203 In addition to this RP, applicable national regulationsshall be adhered to.

204 It is assumed that the most recent revisions of documentsare applied, when the contract for building is signed. (Ref.DNV Rules for Classification of Ships Pt.1 Ch.1 Sec.1 B300)

205 This recommended practice applies to hyperbaric evac-uation systems. The hyperbaric evacuation system may thus belocated on and operated from a ship, barge, mobile platform,fixed installation or an onshore site (in the latter case e.g. fortraining and research purposes).

206 Requirements for support vessels are included such asthe requirements for stability, floatation and positioning abil-ity.

207 The design of arrangements, systems and individualcomponents may alternatively or supplementary to the recom-mended practice be based on recognized standards, codes,national regulations and other methods of safety and strengthevaluation than specified in the recommended practice. Thebasis shall be equivalent to the requirements given in this rec-ommended practice.

208 This recommended practice applies to hyperbaric evac-uation systems used in diving activities.For application in other activities, special considerations mayneed to be agreed by the parties to the contract and or involvedstatutory regulators.

209 The requirements also apply to the sub-systems dedi-cated to the support of hyperbaric evacuation. This includesthe hyperbaric evacuation units, the escape trunks, the launch-ing appliance, the life support systems including life supportpackages (LSP) mobilised in the field, power systems support-ing evacuation and fire protection systems supporting evacua-tion.

210 The scope is defined in each section for the various dis-ciplines and may refer to standards that apply to the disciplinein general, such as for electrical systems. In these cases thisrecommended practice only contains requirements that are par-ticular to hyperbaric evacuation systems, whereas the genericrequirements are given in the referred standard or code. Thecombined requirements shall then constitute the scope.

211 This section bears impact on all other sections.

212 Verification is based on the assumption that the hyper-baric evacuation system will be properly maintained and oper-ated by competent personnel, and that a pre check procedure isfollowed to ensure that all systems and components functionproperly before start of each operation, and that current, waveand wind conditions will be within the design limits. Theassumed operational procedures shall be stated in the approvedextract of the operations philosophy.

A 300 Documentation

301 General documentation requirements are given in Sec.2H. Documentation for disciplines in each section is given inA300 for each section.

302 General arrangements and contingency plans shall bedocumented.

DET NORSKE VERITAS

http://www.dnv.com

http://www.dnv.com

http://www.dnv.com

Recommended Practice DNV-RP-E403, October 2010 – Sec.1

A 400 Other codes

401 Other references than those listed may be used providingthey represent the same level of safety as those listed.

402 Where reference is made to codes other than DNV doc-uments, the valid revision shall be taken as the revision thatwas current at the date of issue of this recommended practice.

403 The requirements in this recommended practice are incompliance with the IMO guidelines and specifications forhyperbaric evacuation systems - Resolution A.692(17), in thefollowing referred to as the 'IMO Guidelines Res. A.692(17)'.If any parts of the Recommended Practice are subject to dis-cussion or misunderstanding, the IMO text shall prevail as aminimum.

404 The requirements in this recommended practice arebased on requirements given in DNV-OS-E402 "OffshoreStandards for Diving Systems", DNV Rules for Classificationof Ships, and principles outlined in other DNV OffshoreStandards.

Guidance note:Additional requirements for the hyperbaric evacuation systemmay be applicable due to the statutory requirements given in cer-tain geographic areas, or onboard ships flying certain flags.

---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---

A 500 Exemptions and deviations

501 Any exemptions from statutory regulations shall besought from the maritime authorities prior to conducting theoperations.

502 Deviations may be considered on the basis of acceptablerisk assessment showing that the same level of safety isattained through alternative means.

A 600 Hyperbaric evacuation methods

601 It is recognised that there are various methods availablefor evacuating divers in an emergency and that the suitabilityof the various options for a safe hyperbaric evacuation dependson a number of factors including the geographical area of oper-ation, environmental conditions, and any available offshore oronshore medical and support facilities. Options available todiving contractors will include:

— hyperbaric self-propelled lifeboats— towable hyperbaric evacuation units— hyperbaric evacuation units which may or may not be tow-

able suitable for offloading on to an attendant vessel— transfer of the diving bell to another facility— transfer of the divers from one diving bell to another when

in the water and under pressure— negatively buoyant unit with inherent reserves of buoy-

ancy, stability and life support capable of returning to thesurface to await independent recovery [IMO GuidelinesRes. A.692(17): 2]

602 It is understood that a diving bell is not available for res-cue of divers in the decompression chambers onboard the sup-port vessel, when the bell is working at depth.A diving bell in this case is therefore interpreted as an availableoption for evacuating the divers in the bell, should an emergencyarise that prevents return of these divers to the support vessel.

603 Consideration to leave the bell in water in the event thata critical situation prevents recovery should be made by thediving supervisor and captain in joint consultation.

604 Transferring the bell divers from one bell to another is anavailable option, providing there are two bells on the supportvessel whereby one bell acts as an emergency escape route inthe event that the other bell is marooned. Transfer of the belldivers may also be carried out to the bell of another diving sup-port vessel in the vicinity.

605 The Guidelines and Specifications do not thereforeattempt to specify which particular type of hyperbaric evacua-tion system should be employed and recommend that clientsand diving contractors examine and identify the option mostsuited for the area and type of operation in which they areengaged.[ IMO Guidelines Res. A.692(17): 2.]

606 Consideration may have to be given to the provision ofseparate evacuation facilities for divers in saturation at signif-icantly different depths. [IMO Guidelines Res. A.692 (17): 2]

607 If there is a pressure differential of 18 bar or morebetween the persons needing evacuation, the hyperbaric evac-uation system should be designed so that the pressure differen-tial may be maintained.

Guidance note:For split level diving, and diving operations deeper than 200 m,two hyperbaric evacuation systems may be required to cover thevarious pressure levels.


A 700 Contingency planning and emergency instruc-tions

701 A potentially dangerous situation can arise if a floatingunit, from which saturation diving operations are being carriedout, has to be abandoned with a diving team under pressure.While this hazard should be reduced by pre-planning, underextreme conditions consideration may have to be given tohyperbaric evacuation of the divers.The hyperbaric evacuation arrangements should be studiedprior to the commencement of the dive operation and suitablewritten contingency plans made. [IMO Guidelines Res. A.692(17): 3.1]

Guidance note:The contingency plans shall consider the evacuation routethrough the chamber complex, to avoid having a chamber at sur-face delay the evacuation.


702 Responsibilities, lines of command and back-up com-mand structures shall be identified, also for cases where thecaptain and diving supervisor might be unavailable. It isimportant to avoid irresolute or wrong decisions.

703 Identification of all resources for recovery and establish-ing co-ordinated lines of communication is essential including,but not limited to, available support vessels, crane capacity,fixed installations, available deck space etc.

704 Plans should include the closing of vent valves in cham-ber doors as the divers are leaving each chamber, to avoiddelayed venting of trunk to HEU.

705 There must be a detailed written procedure for thelaunching of the HES that identifies clearly who is responsiblefor each part of the operation.

706 Personnel need to be qualified for the operations includ-ing, but not limited to, operating the handling system, operatingthe boat (SPHL or towing work boat as the case may be), divingsupervision and life support technician. A certain degree ofredundancy should be planned in case one person is debilitated.

707 The manning of the launch station shall be included inthe plan.

708 Diving shall not be carried out if the HES is not availablefor rescue.

709 Once the hyperbaric evacuation unit has been launched,the divers and any support personnel may be in a precarioussituation where recovery into another facility may not be pos-sible and exposure to seasickness and accompanying dehydra-tion will present further hazards. It is, therefore, necessary thatdiving contractors ensure that any such contingency plansinclude appropriate solutions.

DET NORSKE VERITAS


It should be emphasised that hasty or precipitate action maylead to a premature evacuation situation, which could be morehazardous in the final analysis. [IMO Guidelines Res. A.692(17): 3.2]

710 In preparing the contingency plans, the various possibleemergency situations should be identified taking into consider-ation the geographical area of operation, the environmentalconditions, the proximity of other vessels, and the availabilityand suitability of any onshore or offshore facilities.The facilities for rescue, recovery and subsequent medicaltreatment of divers evacuated in such circumstances should beconsidered as part of the contingency plan.Copies of contingency plans should be available on board theparent vessel, ashore and in the hyperbaric evacuation unit.[IMO Guidelines Res. A.692 (17): 3.3]

711 Contingency procedures are normally sectioned intothree phases:

1) Divers transfer and HEU launch.

2) HEU in water.

3) HEU/divers recovered.

712 Each phase may again be divided into various scenarios,including; decompression in water, decompression offshore,towing, transport on supply vessel, lifting and recovery to ahyperbaric facility (hyperbaric contingency centre) or otherDSV.

713 Flow charts shall accompany the contingency plan, toease visualisation.

714 A copy of the emergency procedures and any other rele-vant procedures or manuals must be available at the life sup-port control point. This must include any plans for reception ofthe HES onshore or at another location.

A 800 Rescue treatment facilities

801 Where, in the event of diver evacuation, decompressionwould take place in another surface compression chamber thecompatibility of the mating devices should be considered[IMO Guidelines Res. A.692 (17): 3.1]

802 Detailed emergency assessment and tests should be car-ried out.

B. Normative References

B 100 Service specifications

101 The latest revision of the following documents mayapply: VOID

B 200 Standards

201 The latest revision of the following documents applies:VOID

B 300 Recommended practices

301 The latest revision of the following documents applies:VOID

B 400 Rules and regulations

401 The latest revision of the following documents applies:

B 500 Standards for Certification

501 The latest revisions of the following documents apply:

DNV Standard for Certification No. 2.22 Lifting Appliances.

B 600 Guidelines and Classification Notes

601 Intentionally left blank.

C. Informative References

C 100 General

SOLAS 1974 (International Convention for the Safety of Life at Sea)

IMO Resolution A.831(19)

Code of Safety for Diving Systems, 1995

IMO Resolution A.692(17) Guidelines and Specifications for Hyperbaric Evacuation Systems, 1991

A.O.D.C. 035 "Code of practice for the safe use of electricity underwater"AODC 062 "Use of battery operated equipment in hyperbaric conditions.API Codes for hosesAPI 17E Specification for Subsea Production Control UmbilicalsASME PVHO-1-1997 edition (or latest)

Safety Standard for Pressure Vessels for Human Occupancy

ASME PVHO-2-2002 edition (or latest)

Safety Standard for Pressure Vessels for Human Occupancy in Service Guidelines for PVHO Acrylic Windows.

ASME VIII Div.1 ASME Boiler and Pressure Vessel CodeASTM G93-96 Standard Practice for Cleaning Methods and Cleanliness Levels for Materials and Equipment

Used in Oxygen-Enriched EnvironmentsBS 4778 Part 2 Quality vocabulary. Quality concepts and related definitionsBS 5355 Specification for filling ratios and developed pressures for liquefiable and permanent gases.BS6501 Flexible metallic hosesDIN EN 853, 856, 857 Rubber Hoses and Hose Assemblies DMAC 11 Provision of First Aid and the Training of Divers, Supervisors and Members of Dive Teams in

First Aid, DMAC 15 Medical Equipment to be Held at the Site of an Offshore Diving Operation, DNV Rules for Classification of ShipsDNV-OS-A101 Safety Principles and ArrangementsDNV-OS-D201 Electrical Systems and EquipmentDNV-OS-D202 Instrumentation and Telecommunication systemsDNV-OS-D301 Fire Protection

DET NORSKE VERITAS


DNV-OS-E402 Offshore Standard for Diving SystemsDNV-OSS-305 Rules for Certification and Verification of Diving SystemsEN 10204 Metallic Products - Types of Inspection DocumentsEN 13445 Unfired pressure vesselsEN 1708-1:1999 Welding - Basic weld joint details in steelEN 1968:2002 Periodic Inspection and testing of Seamless gas cylindersEN 45011 General requirements for bodies operating product certification systemsEN 738-1, -2 and -3:1997/1998 Pressure regulators for use with medical gasesEN 849:1996 Transportable Gas Cylinders - Cylinder Valves - Specification and Type TestingEN ISO 11114-3:1997 Transportable Gas Cylinders - Compatibility of Cylinder and Valve Materials with Gas Con-

tents - Part 3: Autogenous Ignition Test in Oxygen AtmosphereEN ISO 11120:1999 Gas cylinders - Refillable seamless steel tubes for compressed gas transport, of water capacity

between 150 l and 3000 l - Design construction and testing (ISO 11120:1999):EN ISO 2503:1998 Gas Welding Equipment - Pressure Regulators for Gas Cylinders used in Welding, Cutting and

Allied Processes up to 300 barEN-1964-1:2000 Transportable gas cylinders (part 1:1999, part 2:2001 or part 3:2000)EU directive 1999/36/EECIEC-Publication No. 92—101 (1980)

«Electrical Installations in Ships, Part 1 General Requirements» Clause 3 1.2.

ILO Convention 133, 1970 Accommodation of crewsIMCA D004 The initial and periodic examination, testing and certification of hyperbaric evacuation launch

systemsIMCA D 014 IMCA International Code of Practice for Offshore DivingIMCA D 018 Code of practice on the initial and periodic examination, testing and certification of diving

plant and equipment.IMCA D 024 DESIGN for saturation (bell) diving systemsIMCA D-02/06 The evaluation and testing of the environmental control of hyperbaric evacuation systemsIMO (MODU) Code chapter 6,IMO res. MSC.61(67) (FTP Code)IMO res. MSC.81(70)IMO res. MSC/Circ.645 of 6 June 1994

Guidelines for Vessels with dynamic positioning systems

IMO res. MSC/Circ.776 of 12 December 1996

Guidelines For the Approval of equivalent Fixed Gas Fire-Extinguishing Systems, as referred to in SOLAS 74, for Machinery Spaces and Cargo Pump-Rooms

IMO res. A.468 (XII) Code on noise levels onboard ships.IMO res. A.741(18) ISMIMO res. A.809(19) in reference to SOLAS Regulation III/6.2.1 and III/6.2.2.IEC Publication No. 79-10IEC 60079-10 Ed. 4.0:2002 (b)

Electrical apparatus for explosive gas atmospheres - Part 10: Classification of hazardous areas

IEC Publication No. 479 (1974)

«Effects of currents passing through the human body».

IEC Publication No. 60331 Tests for electric cables under fire conditions - Circuit integrityISO 10 380 Flexible metallic hosesISO 10013 Guidance on developing quality manuals.ISO 10474 Steel and Steel Products - Inspection Documents ISO 13628-5 Petroleum and natural gas industries – Design and operation of subsea production systems –

Part 5: Subsea control umbilicals”ISO 6385-1981 Ergonomic Principles in the Design of Work SystemsISO 8402 Quality management and quality assurance -- VocabularyISO 9000 Guidance on the selection and use of quality systemsISO 9001 Quality management systems -- Requirements(NFPA) National Fire Protection Agency Codes

(Where two or more equivalent references are listed, one should be chosen and applied) NFPA53M (National Fire Protection Agency)

"Manual on Fire Hazards in Oxygen-Enriched Atmospheres 1990"

DET NORSKE VERITAS


Guidance note:The latest revision of the DNV documents may be found in thepublication list at the DNV website www.dnv.com.For other sources see DNV-OSS-305 Appendix C.


D. Verbal Forms and Definitions

D 100 Auxiliary verbal forms

101 “Shall”: Indicates requirements strictly to be followedin order to conform to this recommended practice and fromwhich no deviation is permitted.

102 “Should”: Indicates that among several possibilities,one is recommended as particularly suitable, without mention-ing or excluding others, or that a certain course of action is pre-ferred but not necessarily required. Other possibilities may beapplied subject to agreement.

103 “May”: Verbal form used to indicate a course of actionpermissible within the limits of the standard.

104 “Agreement”, “by agreement”: Unless otherwise indi-cated, this means agreed in writing between manufacturer,contractor and purchaser.

D 200 Definitions

201 Administration: 3.1 "Administration" means the Gov-ernment of the State whose flag a ship or floating structurewhich carries a diving system is entitled to fly or in which theship or floating structure is registered.

202 As-built survey: Survey of the installed and completedhyperbaric evacuation system, which is performed to verifythat the completed installation work meets the specifiedrequirements, and to document deviations from the originaldesign, if any.

203 Bell: see “Diving bell”.

204 Bottle: "Bottle" means a pressure container for the stor-age and transport of gases under pressure. [IMO GuidelinesRes. A.692 (17): 3.2]

205 Breathing mixture: "Breathing mixture" means air orany other mixture of gases used for breathing during evacua-tion and, if applicable, during decompression. [IMO Guide-lines Res. A.692 (17): 3.3]

206 Built In Breathing System (BIBS): A system of gas deliv-ery to masks located in the hyperbaric evacuation unit, decom-pression chambers and bells. This system facilitates breathingin the event of a contaminated atmosphere, and allows for theuse of therapeutic gases during decompression. (See Sec.4)

207 Certification: Used in this document to mean all the ver-ification activities associated with a process leading up to theissue of a Certificate. A manufacturer’s works certificate (W),3.1B in accordance with ISO10474/EN10204, will normallybe required as a minimum level of certification.

Guidance note:In this recommended practice when Certification is used it des-ignates the overall scope of work or multiple activities for theissue of a Certificate, whilst Verification is also used for singleactivities associated with the work. This in essence means that

Certification is Verification for which the deliverable includesthe issue of a Certificate.

Other (related) definitions are:

BS 4778: Part 2: Certification: The authoritative act of docu-menting compliance with requirements. EN 45011: Certification of Conformity: Action by a third party,demonstrating that adequate confidence is provided that a dulyidentified product, process or service is in conformity with a spe-cific standard or other normative document.ISO 8402: 1994: Verification: Confirmation by examination andprovision of objective evidence that specified requirements hasbeen fulfilled.


208 Chamber: Surface decompression, pressure or compres-sion chambers (see also DDC); hereafter called the chambers,and are pressure vessels for human occupancy.

209 Closed Circuit Breathing System (CCBS) ‘: A system forsupply of breathing gas to the diver and saving of his exhaledgases for re-circulation after scrubbing and replenishing. (seeSec.4)

210 Collapse depth: The depth at which a general collapse ofthe pressure hull will take place.

211 Commissioning: In relation to hyperbaric evacuationsystems, refers to activities which take place after installationand prior to operation, comprising the tests and trials outlinedin Sec.2 I.

212 Compact umbilical: Umbilical consisting of compositebundles of hoses, cables and strength members in a braiding orsheathing. (See Sec.8)

213 Compartment: Part(s) of a hyperbaric evacuation unit ora chamber sufficiently large to contain at least one person andwhich may have an internal pressure different from adjacentcompartments. (see Sec.3)

214 Compression chamber: "Compression chamber" meansa pressure vessel for human occupancy with means of control-ling the differential pressure between the inside and outside ofthe chamber. [IMO Guidelines Res. A.692 (17): 3.15]

215 Construction phase: All phases during construction,including fabrication, installation, testing and commissioning,up until the installation or system is safe and operable forintended use. In relation to hyperbaric evacuation systems, thisincludes manufacture, assembly, testing, commissioning andrepair.

216 Contractor: A party contractually appointed by the Pur-chaser to fulfil all, or any of, the activities associated withdesign, construction and operation.

217 Corrosion allowance: Extra wall thickness added duringdesign to compensate for any reduction in wall thickness bycorrosion (internally and externally) during operation.

218 Deck Decompression Chamber (DDC): Deck mountedchamber for decompression. (See Sec.3)

219 Depth: "Depth means" the pressure, expressed in metresof seawater, to which the diver is exposed at any time during adive or inside a surface compression chamber or a diving bell.[IMO Guidelines Res. A.692 (17): 3.4]

220 Design depth: The maximum depth for which the hyper-baric evacuation is designed to operate.

NORSOK Standard U-100 Manned Underwater OperationsDirective 97/23/EEC Pressure Equipment Directive (Directive 97/23/EC of the European Parliament and of the

Council of 29 May 1997 on the approximation of the laws of the Member States concerning pressure equipment(OJ No L 181 of 1997-07-09))

PD5500:2000 Specification for Unfired Fusion Welded Pressure VesselsSAE J 517 Rubber Hoses and Hose Assemblies

DET NORSKE VERITAS


221 Design life: The initially planned time period from ini-tial installation or use until permanent decommissioning of theequipment or system. The original design life may be extendedafter a re-qualification.

222 Design premises: A set of projects specific design dataand functional requirements which are not specified or whichare left open in the standard.

223 Design: All related engineering to design the hyperbaricevacuation system including structural as well as material andcorrosion.

224 Design temperature, maximum: The highest possibletemperature to which the equipment or system may be exposedto during installation and operation. Environmental as well asoperational temperatures should be considered.

225 Design temperature, minimum: The lowest possibletemperature to which the equipment or system may be exposedto during installation and operation, irrespective of the pres-sure. Environmental as well as operational temperaturesshould be considered.

226 Diver heating: A system for actively heating the diversin the inner area.

227 Divers: Normally defined as personnel subjected tohigher ambient pressure than one atmosphere.

228 Diving bell: "Diving bell" means a submersible com-pression chamber, including its ancillary equipment, for trans-fer of divers under pressure between the work location and thesurface compression chamber, and vice versa. [IMO Guide-lines Res. A.692 (17): 3.5]

229 Diving system: "Diving system" means the whole plantand equipment necessary for the conduct of diving operationsusing transfer-under-pressure techniques. [IMO GuidelinesRes. A.692 (17): 3.6]

230 dmax: Maximum operating depth of the hyperbaricevacuation system. This may for some systems be the depthcorresponding to the maximum pressure for pressurizing crewin the event of hyperbaric rescue.

231 DSV: Class Notation in DNV representing ‘Diving Sup-port Vessel'.

232 ECU: Environmental Control Unit. Maintains Tempera-ture, reduces humidity and may include removal of carbondioxide. (See Sec.4).

233 Enclosure area: Those areas inside the hyperbaric evac-uation unit that are exposed to atmospheric conditions duringoperation, i.e. the room or area inside the HEU that surroundsor contains the hyperbaric chamber (Inner area). (This area ismostly applicable to SPHLs.) (See also Outer area.)

234 Exo-structure: Fairings and bumpers, structure outsidethe pressure hull.

235 Fabrication: Activities related to the assembly ofobjects with a defined purpose. In relation to hyperbaric evac-uation systems, fabrication refers to e.g. Hull structures,Chambers, Pressure vessels for gas storage, EnvironmentalControl Systems, Handling Systems etc.

236 Fabricator: The party performing the fabrication.

237 Failure: An event affecting a component or system andcausing one or both of the following effects:

— loss of component or system function— deterioration of functional capability to such an extent that

the safety of the installation, personnel or environment issignificantly reduced

238 Fatigue: Cyclic loading causing degradation of thematerial.

239 Gas containers: Cylinders, bottles and pressure vesselsfor storage of pressurized gas. (see Sec.3 and 4)

240 Handling design load: Load imposed by the workingweight of the hyperbaric evacuation unit and all other forcesacting on the unit.

241 Handling system: "Handling system" means the plantand equipment necessary for raising, lowering and transport-ing the hyperbaric evacuation unit from the surface compres-sion chamber to the sea or on to the support vessel, as the casemay be. [IMO Guidelines Res. A.692 (17): 3.9]The system and equipment necessary to connect and discon-nect the HEU to the chambers as well as transport the HEUbetween the surface support unit and the sea, including anyguide rope systems and auxiliary systems. (ref. Sec.7 - see alsoLARS)

242 Hazardous areas: "Hazardous areas" means those loca-tions in which an explosive gas-air mixture is continuouslypresent, or present for long periods (zone 0); in which anexplosive gas-air mixture is likely to occur in normal operation(zone 1); in which an explosive gas-air mixture is not likely tooccur, and if it does it will only exist for a short time (zone 2).[IMO Guidelines Res. A.692 (17): 3.10]

243 Hydrogen Pressure Induced Cracking (HPIC): Internalcracking of wrought materials due to a build-up of hydrogenpressure in micro-voids (Related terms: hydrogen inducedcracking, stepwise cracking).

244 Hydro-test or Hydrostatic test: See Pressure test.

245 Hyperbaric chamber: (see also DDC, TUP and SDC)Chamber/compartment designed to operate at pressures above1.5 bar.

246 Hyperbaric Evacuation System (HES): "Hyperbaricevacuation system" means the whole plant and equipment nec-essary for the evacuation of divers in saturation from a surfacecompression chamber to a place where decompression can becarried out. The main components of a hyperbaric evacuationsystem include the hyperbaric evacuation unit, handling sys-tem and life-support system. IMO Guidelines Res. A.692 (17):3.7]HES includes system for evacuating support crew.

247 Hyperbaric Evacuation Unit (HEU): "Hyperbaric evac-uation unit" means a unit whereby divers under pressure can besafely evacuated from a ship or floating structure to a placewhere decompression can be carried out. [IMO GuidelinesRes. A.692 (17): 3.8] (See also HRC, HRV and SPHL).

248 Hyperbaric Rescue Chamber: (See HEU above.)

249 Hyperbaric Rescue Vessel (HRV): IMO uses the termHyperbaric Evacuation Unit (HEU). See above.

250 Inner area: The areas which are inside the hyperbaricevacuation unit and diving system chambers.

251 Inspection: Activities such as measuring, examination,testing, gauging one or more characteristics of a product orservice and comparing the results with specified requirementsfor determine conformity.

252 Installation (activity): The operations related to install-ing the equipment, hyperbaric evacuation system or supportstructure both on the hyperbaric evacuation unit and on thesupport vessel, e.g. mounting chambers, gas cylinders, ECUs,panels, interconnecting piping, handling systems etc., includ-ing final testing and preparation for operation.

253 Installation Manual (IM): A document prepared by theContractor to describe and demonstrate that the installationmethod and equipment used by the Contractor will meet thespecified requirements and that the results can be verified.

254 Life support systems: "Life-support system" means thegas supplies, breathing gas system, decompression equipment,environmental control system, heating or cooling and otherequipment required to provide a safe environment for thedivers in the hyperbaric evacuation unit under all ranges ofpressure that they may be exposed to during evacuation and, if

DET NORSKE VERITAS


applicable, during the decompression stages. [IMO GuidelinesRes. A.692 (17): 3.11]The systems comprising gas supply systems, breathing gassystems, pressure regulating systems, environmental controlsystems, and systems required to provide a safe habitat for thecrew, in the diving system and compartments under normalconditions during diving operation.

255 Living compartment: A compartment which is intendedto be used as the main habitation for the divers and which isequipped as such.

256 Load: Any action causing stress, strain, deformation,displacement, motion, etc. to the equipment or system.

257 Load effect: Effect of a single load or combination ofloads on the equipment or system, such as stress, strain, defor-mation, displacement, motion, etc.

258 Load effect factor: The partial safety factor by which thecharacteristic load effect is multiplied to obtain the design loadeffect.

259 Lot: A number of components from the same batch. E.g.The same heat, the same heat treatment batch and with thesame dimensions.

260 Manufacture: Making of articles or materials, some-times in large volumes. In relation to hyperbaric evacuationsystems, refers to activities for the production of pressure ves-sels, panel, and life support systems etc., performed under con-tracts from one or more Contractors.

261 Manufacturer: The party who is contracted to be respon-sible for planning, execution and documentation of manufac-turing.

262 Manufacturing Procedure Specification (MPS): A man-ual prepared by the Manufacturer to demonstrate how the spec-ified properties may be achieved and verified through theproposed manufacturing route.

263 Material resistance factor: Partial safety factor trans-forming a characteristic resistance to a lower fractile resistance.

264 Material strength factor: Factor for determination of thecharacteristic material strength reflecting the confidence in theyield strength.

265 Mating device: "Mating device" means the equipmentnecessary for connecting and disconnecting a hyperbaric evac-uation unit and a surface compression chamber. [IMO Guide-lines Res. A.692 (17): 3.12].

266 Maximum operating depth dmax: "Maximum operatingdepth" of the diving system is the depth in metres of seawaterequivalent to the maximum pressure for which the diving systemis designed to operate. [IMO Guidelines Res. A.692 (17): 3.13].

267 NDT level: The extent and acceptance criteria for theNDT of the components.

268 Nominal outside diameter: The specified outside diame-ter. This shall mean the actual outside diameter.

269 Nominal wall thickness: The specified non-corrodedwall thickness, which is equal to the minimum steel wall thick-ness plus the manufacturing tolerance.

270 Normal cubic meters: (Nm3) is taken as cubic meters ofgas at standard conditions of 0°C and 1.013 bar.

271 Operation, Incidental: Pressure related conditions thatare not part of normal operation of the equipment or system. Inrelation to hyperbaric evacuation systems, incidental condi-tions may lead to incidental pressures.

272 Operation, Normal: Pressure related conditions thatarise from the intended use and application of equipment orsystem, including associated condition and integrity monitor-ing, maintenance, repairs etc. In relation to hyperbaric evacua-tion systems, this should include, start and finish of dives (pre-and post-dive checks), incidents, gas transfer and changing out

of consumables. However, as hyperbaric evacuation systemsare designed for evacuation in emergencies, pressure equip-ment shall also work normally under such conditions.

273 Out of roundness: The deviation of the perimeter from acircle. This can be stated as ovalisation (%), or as local out ofroundness, e.g. flattening, (mm).

274 Outer area: Those areas of the hyperbaric evacuationsystem that are exposed to atmospheric conditions duringoperation, i.e. the room or area that surrounds or contains thehyperbaric evacuation system. (see also Enclosure area)

275 Ovalisation: The deviation of the perimeter from a cir-cle. This has the form of an elliptic cross section.

276 Owner: The party ultimately responsible for design,construction and operation.

277 Oxygen systems: Systems intended for a gas with ahigher oxygen percentage than 25%.

278 Partial safety factor: A factor by which the characteris-tic value of a variable is modified to give the design values.

279 Personal equipment: Equipment carried by the crew ontheir person including suits and helmets.

280 Planned Maintenance System (PMS): A system for plan-ning and recording maintenance activities.

281 Pressure control system: In relation to hyperbaric evac-uation systems, this is the system for control of the pressure inthe various systems, comprising the pressure regulating sys-tem, pressure safety system and associated instrument andalarm systems.

282 Pressure regulating system: In relation to hyperbaricevacuation systems, this is the system which ensures that, irre-spective of the upstream pressure, a set pressure is maintained(at a given reference point) for the component.

283 Pressure safety system: The system which, independentof the pressure regulating system, ensures that the allowableset pressure is not exceeded.

284 Pressure test: The hydrostatic pressure test initially per-formed at the manufacturer of the pressure vessel in accord-ance with requirements in the design code.

285 Pressure, Collapse: Characteristic resistance againstexternal over-pressure.

286 Pressure hull: The pressure resistant structure which issubjected to a differential pressure and which provides spacefor the personnel and equipment.

287 Pressure, Design: In relation to hyperbaric evacuationsystem assemblies, this is the maximum internal pressure dur-ing normal operation, referred to a specified reference point, towhich the component or system section shall be designed. Thedesign pressure must take account of the various pressurisedcomponents in the adjoining systems, and their relative designpressures.

288 Pressure, System test: In relation to hyperbaric evacua-tion systems, this is the internal pressure applied to the compo-nent or system during testing on completion of installationwork to test the hyperbaric evacuation system for tightness(normally performed as hydrostatic testing).

289 Pressure vessel: "Pressure vessel" means a containercapable of withstanding an internal maximum working pres-sure greater than or equal to 1 bar. [IMO Guidelines Res.A.692(17): 3.14].

290 Purchaser: The owner or another party acting on hisbehalf, who is responsible for procuring materials, componentsor services intended for the design, construction, installation ormodification of a hyperbaric evacuation system.

291 Quality Assurance (QA): Planned and systematicactions necessary to provide adequate confidence that a prod-uct or service will satisfy given requirements for quality.

DET NORSKE VERITAS


292 Quality Plan (QP): The document setting out the spe-cific quality practices, resources and sequence of activities rel-evant to a particular product, project or contract. A quality planusually makes reference to the part of the quality manual appli-cable to the specific case.

293 Reliability: The probability that a component or systemwill perform its required function without failure, under statedconditions of operation and maintenance and during a speci-fied time interval.

294 Re-qualification: The re-assessment of a design due tomodified design premises and or sustained damage.

295 Resistance: The capability of a structure, or part of astructure, to resist load effects.

296 Risk: The qualitative or quantitative likelihood of anaccidental or unplanned event occurring, considered in con-junction with the potential consequences of such a failure. Inquantitative terms, risk is the quantified probability of adefined failure mode times its quantified consequence.

297 Safety Class: Generically; a concept sometimes adoptedto classify the significance of a particular component or systemwith respect to the consequences of failure.

298 Self Propelled Hyperbaric Lifeboat (SPHL): A self pro-pelled HEU.

299 Significant wave height: In this context, if the waveheights are arranged in order of reducing magnitude the meanheight of the highest third of the waves is called the significantwave height. (From Eric Tupper "Introduction to Naval Archi-tecture" 3rd ed. p.91) (See Sec.7 and Appendix A).

D 300 Definitions (continued)

301 Specified Minimum Tensile Strength: The minimum ten-sile strength prescribed by the specification or standard underwhich the material is purchased.

302 Specified Minimum Yield Stress: The minimum yieldstress prescribed by the specification or standard under whichthe material is purchased.

303 Submersible: A manned self-propelled or tethered vehi-cle capable of operating under water with at least one compart-ment having an internal pressure of 1 Bar.

304 Submersible Decompression Chamber (SDC): (see Belland Sec.3).

305 Suitable breathing gas: A gas or gas mixture that isbreathable to crew for the pressure and duration they areexposed to it.

306 Supplementary requirements: Requirements for materialproperties of component that are additional to the basicrequirements, and that are intended to apply to componentsused for specific applications.

307 Top: Maximum operation time, i.e. the time from start ofpressurization of the hyperbaric evacuation, until the hyper-baric evacuation is back to atmospheric conditions.

308 Transfer compartment: Compartment that is intended tobe used for a lock-in or -out operation of crew between othercompartments, hyperbaric evacuation chamber, bell or outerarea. Also known as TUP (Transfer under Pressure)

309 Transferable diving system: A diving system designedto be easily transferable in one or more units and which may beinstalled onboard a ship, barge or platform for a short period oftime not exceeding one year. A transferable diving system maybe assembled from different units into a particular configura-tion suitable for a specific working operation.

310 Ultimate Tensile Strength: The measured ultimate ten-sile strength.

311 Umbilical: A link between support vessel and the hyper-baric evacuation unit, which may contain power supply cables,

communication/signal cables, gas hoses and hot water hoses(see Sec.8).

312 Verification: An examination to confirm that an activity, aproduct or a service is in accordance with specified requirements.

313 Work: All activities to be performed within relevant con-tract(s) issued by owner, Operator, Contractor or Manufacturer.

314 Working weight: (See Sec.7 C103). The weight of thehyperbaric evacuation unit in air, including the weight of per-sonnel, tools, entrained water etc.

315 Yield Stress: The measured yield tensile stress.

E. Abbreviations and Symbols (Guidance)

E 100 Abbreviations

ALC Approximate Lethal ConcentrationAODC Association of Diving Contractors (now IMCA)API American Petroleum InstituteASME American Society of Mechanical EngineersASTM American Society for Testing and MaterialsAUT Automatic Ultrasonic TestingBS* British Standard (Note: Now PD – Public docu-

ment)C-Mn Carbon ManganeseCE Conformité Européene (European Conformity) CRA Corrosion Resistant AlloyDNV Det Norske VeritasDP Dynamic PositioningEBW Electronic Beam WeldedFMEA Failure Mode Effect AnalysisHAZ Heat Affected ZoneHAZOP Hazard and Operability StudyHFW High Frequency WeldingHPIC Hydrogen Pressure Induced CrackingIM Installation ManualIMCA International Marine Contractors AssociationISO International Organisation for StandardisationKV Charpy valueLBW Laser Beam WeldedMPQT Manufacturing Procedure Qualification TestMPS Manufacturing Procedure SpecificationMSA Manufacturing Survey ArrangementNACE National Association of Corrosion EngineersNDE Non-Destructive ExaminationNDT (Non-Destructive Testing) see NDENOAL No Observed Adverse effect LevelNPD Norwegian Petroleum Directorate P ProductionQ QualificationQA Quality AssuranceQC Quality ControlQP Quality PlanQRA Quantitative Risk AnalysisROV Remotely Operated VehicleUTS Ultimate Tensile StrengthWPS Welding Procedure SpecificationYS Yield Stress

DET NORSKE VERITAS


E 200 Symbols

201 Latin characters

A = Cross section areaD = Nominal outside diameter. dmax = Maximum operating depth of systemDmax = Greatest measured inside or outside diameterDmin = Smallest measured inside or outside diameterDi = D-2tnom = Nominal internal diameterE = Young’s Modulusf0 = Ovality,

D

DD minmax

H = Wave heightHs = Significant wave heightID = Nominal inside diameterO = Out of roundness, Dmax - DminOD = Nominal outside diameterT = Operating temperatureTmax = Maximum design temperatureT min = Minimum design temperature

DET NORSKE VERITAS


SECTION 2DESIGN PHILOSOPHY AND PREMISES

A. General

A 100 Objectives

101 The purpose of this section is to present the safety phi-losophy applied in this recommended practice.

102 It also identifies and provides a basis for definition ofrelevant system design characteristics. Further, key issuesrequired for design, construction, operation and re-qualifica-tion of hyperbaric evacuation systems are identified.

103 This section also refers to minimum requirements fordocumentation for design, manufacture, installation and someoperational aspects.

104 Some general guidance is given, such as safety philoso-phy and design premises.

A 200 Application and scope

201 This section applies to all hyperbaric evacuation sys-tems, which shall be built in accordance with this recom-mended practice.

202 Requirements for testing are included here.

203 This section bears impact upon all other sections in thisrecommended practice.

A 300 Documentation

301 Documentation shall be made available to all concernedparties in good time before work starts, and in accordance withthe principles stated in ISO 9001 4.2 and ISM - IMO Resolu-tion A.741(18) 11 Documentation.

302 Specific lists are given in A300 under each section.

303 For general requirements, see H.

A 400 Units

401 SI Units shall be adopted in this document, and shouldalso be adopted in all design and manufacturing specificationsrelating to the scope of this document.

B. Safety Philosophy

B 100 General

101 The integrity of a hyperbaric evacuation system con-structed to this recommended practice is ensured through asafety philosophy integrating different parts as illustrated inFigure 1-Safety Philosophy structure.

B 200 Safety objective

201 An overall safety objective shall be established, plannedand implemented, covering all phases from conceptual devel-opment until demobilisation and scrapping.

Guidance note:All companies have some sort of policy regarding humanaspects, environment and financial issues. These are typically onan overall level, but more detailed objectives and requirements inspecific areas may follow them. These policies should be used asa basis for defining the safety objective for a specific hyperbaricevacuation system. Typical statements can be:

- There shall be no serious accidents or loss of life during theconstruction period;

Statements such as the above may have implications for all orindividual phases only. They are typically more relevant for thework execution (i.e. how the contractor executes his job) and spe-cific design solutions. Having defined the safety objective, it can

be a point of discussion as to whether this is being accomplishedin the actual project. It is therefore recommended that the overallsafety objective be followed up by more specific, measurablerequirements.

If no policy is available, or if it is difficult to define the safetyobjective, one could also start with a risk assessment. The riskassessment could identify all hazards and their consequences,and then enable back-extrapolation to define acceptance criteriaand areas that need to be followed up more closely.


Figure 1 Safety Philosophy structure

B 300 Systematic review

301 As far as practical, all work associated with the design,construction and operation of the hyperbaric evacuation sys-tem shall be such as to ensure that no single failure shall leadto life-threatening situations for any person or to unacceptabledamage to the facilities or the environment.

302 A systematic review or analysis shall be carried out at allphases in order to identify and evaluate the consequences ofsingle failures and series of failures in the hyperbaric evacua-tion system, such that necessary remedial measures can betaken. The extent of the review or analysis shall reflect the crit-icality of the hyperbaric evacuation system, the criticality of aplanned operation and previous experience with similar sys-tems or operations.

Guidance note:A methodology for such a systematic review is quantitative riskanalysis (QRA). This may provide an estimation of the overallrisk to human health and safety, environment and assets andcomprises:

- hazard identification- assessment of probabilities of failure events- accident developments- consequence and risk assessment.

It should be noted that legislation in some countries requires riskanalysis to be performed, at least at an overall level to identifycritical scenarios that might jeopardise safety and reliability.Other methodologies for identification of potential hazards areFailure Mode and Effect Analysis (FMEA) and Hazard andOperability studies (HAZOP).

Safety of the system may be ensured by use of a safety classmethodology. The system is then classified into one or moresafety classes based on failure consequences, normally given bythe particular operation. For each safety class, a set of partialsafety factors is assigned to each limit state.

SafetyObjective

SystematicReview (QRA)

Safety ClassMethodology

Qualityassurance

DET NORSKE VERITAS


Alternatively quality assurance systems may be applied.


303 Special attention shall be given to the risk of handling,fire and evacuation.

304 This recommended practice requires that gross errors(human errors) shall be controlled by:

— requirements for organisation of the work— competence of persons performing the work— verification of the design— quality assurance during all relevant phases.

305 For the purpose of this recommended practice, it isassumed that the owner of a hyperbaric evacuation system hasestablished a quality objective. The owner should, in bothinternal and external quality related aspects, seek to achievethe quality level of products and services intended in the qual-ity objective. Further, the owner shall provide assurance thatintended quality is being, or shall be, achieved.

306 A quality system shall be applied to assist compliancewith the requirements of this recommended practice.

Guidance note:

ISO 9000 gives guidance on the selection and use of quality sys-tems, and ISO 10013 gives guidance on developing quality man-uals.


C. Environmental Conditions

C 100 General

101 Systems and components shall be designed for the envi-ronmental conditions expected at their installed location (onthe vessel or otherwise) and their geographic site of operation.

102 All systems and components shall be able to operate sat-isfactorily and safe in accordance with their specifications atthe environmental conditions stated in C200.

103 Additional requirements for various systems and com-ponents may, however, be given elsewhere in the recom-mended practice.

104 All components located outside the pressure hull shallbe designed for operation under an external hydrostatic pres-sure or an internal pressure, equivalent to the maximum oper-ating depth, depending on what the compartment is normallysubjected to.

105 The effects of environmental phenomena relevant forthe particular location and operation in question should betaken into account.

106 Environmental phenomena that might impair properfunctioning of the system or cause a reduction of the reliabilityand safety of the system should be considered, (including fixedand land-based installations):

— temperature— wind, tide, waves, current— ice, earthquake, soil conditions— marine growth and fouling.

C 200 External operational conditions and outer area

201 Design inclinations shall be according to Table C1.

Guidance note:For handling systems the operational design sea-state is given inSec.7 C100.


202 It should be demonstrated that no damage or operationaldifficulties develop at transient inclinations in any direction uptwice the angle specified by 201.

203 Components of the emergency and normal life supportsystems shall be operable at inclinations in accordance withLSA requirements given in SOLAS.

204 Portable components and tools etc. shall be providedwith proper means of securing for any inclination.

205 Temperature: The range of ambient temperature is stip-ulated between -10°C to 55°C, unless otherwise specified. Forgreater temperature ranges, temperature protection shall beprovided.

206 Humidity: 100%.

207 Atmosphere contaminated by salt (NaCl): Up to 1 mgsalt per 1 m3 of air, at all relevant temperatures and humidityconditions.

C 300 Submerged components

301 Range of ambient temperature: -2°C to 30°C.

302 Range of ambient pressure: 1 bar to 1.3 times the pres-sure corresponding to maximum operating depth dmax.

303 Salinity of ambient water: 35 parts per thousand.

304 The pressure equivalent to depth of seawater at 0°C with3.5% salinity may be taken as 1 006 bar per 10 msw (meter sea-water), as a mean value between 0 and 200 m depth.

For saltwater, the density may be taken to vary as follows:

— 0.05% increase for each 100 m of depth increase— 0.4% increase for an increase in salinity from 3.5% to

4.0%— 0.3% decrease for an increase in temperature from 10°C to

20°C.

The lower limit of the density of water shall be taken as 1 000 kg /m

305 For the selection and detailed design for external corro-sion control, the conditions relating to the environment shouldbe defined.

C 400 Internal conditions

401 Range of ambient pressure: 1 bar to 1.3 times the pres-sure corresponding to dmax with pressurisation and depressuri-sation rates as specified in Sec.4 C100.

402 Range of ambient temperature: 5°C to 55°C, unless oth-erwise specified.

Table C1 Design inclinations

Location Roll Permanent list

Pitch Trim

Chambers and other surface installations:On a ship

+/-22.5o +/-15o +/-10o +/-5o

On a mobile Offshore unit +/-15o +/-15o

Components in a hyperbaric evacuation unit

+/-45o +/-22.5o

DET NORSKE VERITAS


403 Relative humidity: Up to 100%.

404 Atmosphere contaminated by salt (NaCl): Up to 1 mg saltper 1 m3 of air, at relevant temperatures and humidity conditions.

405 A description of the internal conditions during storage,construction, installation, pressure testing and commissioningshall be prepared. The duration of exposure to seawater orhumid air, and the need for using measures to control corrosionshould be considered.When choosing materials, paints etc. the potential for emissionof hazardous compounds shall be considered.Statutory requirements apply for determination of exposurelimits such as:

— American Conference of Governmental Industrial Hygi-enists, Documentation of the Threshold Limit Values andBiological Exposure

— European Commission Directive on Occupational Expo-sure Limit Values

— Health and Safety Executive Occupational Exposure Lim-its.

C 500 Corrosive operational conditions

501 In order to assess the need for corrosion control, includ-ing corrosion allowance and provision for inspection and mon-itoring, the following conditions shall be defined:

— maximum and average operating temperature and pressureprofiles of the components, and expected variations duringthe design life

— expected content of dissolved salts in fluids, residual oxy-gen and active chlorine in sea water)

— chemical additions and provisions for periodic cleaning— provision for inspection of corrosion damage and expected

capabilities of inspection tools (i.e. detection limits andsizing capabilities for relevant forms of corrosion damage)

— the possibility of wear and tear, galvanic effects andeffects in still water pools should be considered.

C 600 Collection of environmental data (Guidance)

601 The environmental data should be representative for thegeographical areas in which hyperbaric evacuation systemsmay be operated. Estimates based on data from relevant loca-tions may be used.

602 Environmental parameters may be described using char-acteristic values based on statistical data or long-term observa-tions.

603 Statistical data may be utilised to describe environmen-tal parameters of a random nature (e.g. wind, waves). Theparameters should be derived in a statistically valid mannerusing recognised methods.

604 Air and sea temperatures statistics may be provided giv-ing representative design values specified in the terms of deliv-ery. Monitoring of temperature may be required duringconstruction, installation and commissioning phases if the effectof temperature or temperature variations has a significant impacton the safety of the hyperbaric evacuation system. The interac-tive effects of temperature and humidity should be considered.

605 Wind. Where appropriate, wind effects should be con-sidered in the design of handling systems, including the possi-bility of wind induced vibrations of exposed free spans.

For spans adjacent to other structural parts, possible effectsdue to disturbance of the flow field should be considered whendetermining the wind actions. Such effects may cause anincreased or reduced wind speed, or a dynamic excitation byvortices being shed from adjacent structural parts.

606 Tide effects should be considered when this is a signifi-cant parameter, e.g. handling systems on shore based installa-tions. The assumed maximum tide should include bothastronomic tide and storm surge. Minimum tide estimates

should be based upon the astronomic tide and possible nega-tive storm surge.

607 Waves. Maximum sea-state, defined by maximum sig-nificant wave height, shall be specified and used in the designcalculations.

The wave data to be used in the design of handling systems arein principle the same as the wave data used in the design of thevessel/structure supporting the system. Direct and indirectwave effects may need to be taken into consideration.

When appropriate, consideration should be given to waverefraction and shoaling, shielding, and reflecting effects.

Where the handling system is positioned adjacent to otherstructural parts, possible effects due to disturbance of the flowfield should be considered when determining the wave actions.Such effects may cause an increased or reduced velocity, ordynamic excitation by vortices being shed from the adjacentstructural parts.

Where appropriate, consideration should be given to wavedirection and short crested waveform.

608 Current. The effect of current should be taken into con-sideration.

Current velocities should include contributions from position-ing systems, tidal current, wind-induced current, storm surgecurrent, and other possible current phenomena. For near-shorefixed installations, long-shore current due to wave breakingshould be considered.

The variations in current velocity magnitude and direction as afunction of water depth may need to be considered. For fixedinstallations, the current velocity distribution should be thesame as the one used in the design of the structure supportingthe system.

609 Ice. For areas where ice may develop or drift, consider-ation shall be given to possible effects, including:

— ice forces on the system (added loads may be due toincreased diameters or surface area)

— impacts from drifting ice— icing problems during construction and installation.

D. Premises

D 100 Concept development

101 Data and description of system development and generalarrangement of the hyperbaric evacuation system shall beestablished.

102 The data and description should include the following,as applicable:

— safety objective— locations, foundations and interface conditions— hyperbaric evacuation system description with general

arrangement and system limits— functional requirements including system development

restrictions, e.g., significant wave height, hazardous areas,fire protection

— installation, repair and replacement of system elementsand fittings

— project plans and schedule, including planned period forinstallation

— design life including specification for start of design life,e.g. final commissioning, installation

— data of contained liquids and gases— capacity and sizing data— geometrical restrictions such as specifications of diameter,

requirement for fittings, valves, flanges and the use offlexible hoses

— second and third party activities.

DET NORSKE VERITAS


D 200 Execution plan

201 An execution plan shall be developed, including the fol-lowing topics:

— general information, including project organisation, scopeof work, interfaces, project development phases and pro-duction phases

— contacts with purchaser, authorities, third party, engineer-ing, verification and construction contractors

— legal aspects, e.g. insurance, contracts, statutory require-ments.

D 300 Plan for manufacture, installation and operation

301 The design and planning for a hyperbaric evacuationsystem shall cover all development phases including manufac-ture, installation and operation.

302 The autonomy of the system should be specified in themobilisation plan and redundancy levels should be addressed.

303 Manufacture. For a documentation overview, see H:Documentation.

304 Installation. Detailed plans, drawings and proceduresshall be prepared for all installation activities. The followingshould as a minimum be covered:

— hyperbaric evacuation system location overview (plannedor existing)

— other vessel (or fixed location) functions and operations— list of hyperbaric evacuation system installation activities— alignment rectification— installation of foundation structures— installation of interconnecting services— installation of protective devices— hook-up to support systems— as-built survey— final testing and preparation for operation.

305 Operation. Plans for hyperbaric evacuation system oper-ation, inspection, maintenance and repair shall be preparedprior to start of operation.

All operational aspects should be considered when selectingthe hyperbaric evacuation concept.

The hyperbaric evacuation system operational planning shouldas a minimum cover:

— organisation and management— start-up and shut-down (pre- and post dive)— operational limitations— emergency operations— maintenance— corrosion control, inspection and monitoring— general inspection— special activities.

306 Demobilisation shall be planned and prepared. Evalua-tion should include the following aspects:

— safety aspects, during and after demobilisation— environmental aspects, e.g. pollution - in accordance with

the regulatory requirements in the country where the sys-tem is being demobilised

— impact on other structures— possible reuse of equipment at a later stage (re-qualifica-

tion and certification).

E. System Design Principles

E 100 System integrity

101 Hyperbaric evacuation systems shall be designed, con-structed and operated in such a manner that they:

— fulfil the specified operational requirements— fulfil the defined safety objective and have the required

support capabilities during planned operational conditions— have sufficient safety margin against accidental loads or

unplanned operational conditions.

102 The various pressures in a hyperbaric evacuation systemshall not exceed the design pressures of the components duringnormal steady-state operation.

103 The possibility of changes in the operating conditionsand criteria during the lifetime of the system should be consid-ered.

104 Any re-qualification deemed necessary due to changesin the design conditions shall take place in accordance withprovisions set out in each section of the standard.

E 200 Design and construction principles

201 The design and construction of the hyperbaric evacua-tion system should be such that it is suitable for the environ-mental conditions envisaged, account being taken of thehorizontal or vertical dynamic snatch loads that may beimposed on the system and its lifting points particularly duringevacuation and recovery. [IMO Guidelines Res. A.692 (17):5.1].

202 Engines shall be designed to operate at tilt and list con-ditions that may be encountered. This is especially relevant inthe case of lubrication systems. In addition, the engine shouldbe located in a water tight compartment if possible.

203 Moving the HEU away from a foundering mother-shipmay be essential and shall be considered in the planning.Increasing the manoeuvrability of SPHL should be considered,including possibility of bow thrusters.

204 Redundant fuel lines and generators shall be consideredwhere power supply is essential. Some, or all, of the followingfunctions may fail in the event of a failure in the primaryenergy supply: propulsion, steering, environmental control,cooling, communications, lights, analysing (battery charging)and heating.In many units the power transfer is by a mechanical belt drivewhere a broken belt will cause failure in all units. In such cases,failure mode and effect needs to be considered and mitigatingsolutions incorporated. This may be in the form of redesignavoiding the use of a belt drive. Alternative energy sourcesmay be considered.

205 The maximum significant wave height (Hs) shall be esti-mated for the operating environment in the geographic region.For certain regions, estimated Hs may be 6 metres. The strength and positioning of the towing point needs to beevaluated accordingly. In many cases, existing designs need tobe modified as the towing point causes unwanted vesselmotions and the strength may not be sufficient.

206 Materials used in the construction of hyperbaric evacua-tion systems should be suitable for their intended use. [IMOGuidelines Res. A.692 (17): 5.4].

207 Paint Work shall be in good condition and free from seri-ous corrosion.

208 Insulation (if fitted) should be clean and in good condi-tion.

209 The hygroscopic properties need to be considered incases where the materials used are subject to conditions wherehumidity may increase the weight or cause deterioration inquality. Storage conditions shall also be considered. This isespecially important in areas where temperature changes maycause condensation and freezing.

210 Seals on mating faces must be clean, undamaged andcovered lightly in silicone grease. If the sealing area is paintedthen this must be in good condition.

DET NORSKE VERITAS


211 The hyperbaric evacuation system should be providedwith the necessary control equipment to ensure its safe opera-tion and the well-being of the divers. [IMO Guidelines Res.A.692 (17): 5.7].

212 Component parts of a hyperbaric evacuation systemshould be designed, constructed and tested in accordance withstandards acceptable to the Administration. [IMO GuidelinesRes. A.692 (17): 5.5].

E 300 Self-Propelled Hyperbaric Lifeboat (SPHL)

301 If self propelled hyperbaric lifeboats are required bystatutory regulations or installed to comply with operationalcriteria, the following requirements apply:

302 If the diving system is fitted on a drill rig or productionfacility where hydrocarbons may be released then the HES isrequired to have a means of propulsion or other method ofensuring it can be rapidly moved clear of the site.

303 The self propelled hyperbaric lifeboat's hull, machinery,equipment, manoeuvrability and seagoing properties shouldcomply with SOLAS 1974 (International Convention for theSafety of Life at Sea) and a relevant recognised national code.

Guidance note:Lifeboats may be type approved.


304 For self-propelled hyperbaric lifeboats (SPHLs) the(diesel) engine shall be able to run during launching.

305 The self propelled hyperbaric lifeboat shall be fittedwith seating arrangement sufficient to carry the maximumnumber of divers and crew members in a sitting position.

E 400 Crew facilities

401 Self Propelled hyperbaric lifeboat shall have a shelteredarea for at least 3 crewmembers in addition to the divers in thechamber. In this sheltered area the controls for the hyperbaricevacuation unit shall be located.

E 500 Pressure control system

501 A pressure control system shall be used to prevent theinternal pressures at any point in the hyperbaric evacuationsystem rising to excessive levels, or falling below prescribedlevels. The pressure control system comprises the pressure reg-ulating systems, pressure safety systems and associated instru-mentation and alarm systems.

502 The purpose of the pressure regulating system is tomaintain the operating pressures within acceptable limits dur-ing normal operation. The set pressures of the pressure regulat-ing system shall be such that the local operational pressures arenot exceeded at any point in the hyperbaric evacuation system.

Guidance note:Due account shall be given to the tolerances of the pressure reg-ulating system and the associated instrumentation.


503 The purpose of the pressure safety systems is to protectthe systems during abnormal conditions, e.g. in the event offailure of the pressure regulating systems. The pressure safetysystems shall operate automatically in accordance with the"fail safe" principles and with set pressures such that there is alow probability for:

— the internal pressure at any point in the system to exceedthe design pressure (maximum operating pressure) (seeSec.4 B200), or

— the unintentional loss of pressure at any point in the systemto exceed set values (see Sec.4 E300).

504 The hyperbaric evacuation system may be divided intosections with different design pressures provided the pressure

control system ensures that; for each section, the local opera-tional pressure cannot be exceeded during normal operationsand that the design pressure cannot be exceeded during abnor-mal operation. The pressure control shall also ensure that unwanted loss ofpressure in one section does not occur as a result of an abnor-mal condition in another section.

F. Arrangement Layout and Location of the Hyperbaric Evacuation System

F 100 General

101 The systems shall be so designed that the effect of a sin-gle failure cannot develop into hazardous situations for thecrew.

Guidance note:Whereas this is a general requirement for the systems, it is recog-nised that certain components cannot fulfil this requirement inand of themselves. A typical example of this is the acrylic win-dows.In these cases the applicable standards will specify stringentsafety factors. For other cases a formal safety assessment may berequired.


102 The hyperbaric evacuation system shall be so designedthat the crew and assisting personnel are provided with safeand effective operating conditions. Ergonomic principlesshould be applied in the design of working systems. (I.e. inaccordance with ISO 6385-1981.)

103 Attended hyperbaric evacuation systems, such asSPHLs, shall contain a minimum of two compartments, one forthe attending crew and one for the divers. Machinery compo-nents shall be housed in a suitable compartment situated in, butseparate from, the compartment for the attending crew.

104 Where hyperbaric evacuation units are designed to beplaced on board a rescue vessel, attachment points should beprovided on the unit to enable it to be secured to the deck.[IMO Guidelines Res. A.692 (17): 7.4]

105 When the hyperbaric evacuation system is takenonboard and mobilised for use, supports and equipment relatedto the hyperbaric evacuation system shall be permanentlyattached to the hull structure – or to the support vessel as thecase may be. Fitting by means of lashing is not considered aspermanent fitting.

F 200 Stability and floatation of support vessel (for installations on ships and mobile offshore units)

201 The diving support vessel should normally have a Sup-ply Vessel notation.

202 Design conditions should be set according to the possi-ble conditions encountered at sea, and shall be outlined in themobilisation plan.

203 The vessel shall comply with the requirements to Stabil-ity and Floatation given in DNV Rules for Classification ofShips Pt.5 Ch.7 Sec.3 D and Sec.4 B for additional class nota-tion SF or equivalent statutory requirements.

204 For diving operations involving more than 50 specialpersons in addition to the marine crew, the support vesselshould normally comply with the IMO SPS Code.

F 300 Location of the hyperbaric evacuation system

301 The location of a hyperbaric evacuation system on aship, mobile unit or fixed structure, or land site, shall be in asafe area with respect to explosive gas-air mix.

Safe areas are in these context areas which are not defined ashazardous zones in International Electro technical Commis-

DET NORSKE VERITAS


sion's Publication No.79-10, and IMO (MODU) code, chapter6, as follows:

— Zone 0: in which an explosive gas-air mixture is continu-ously present or present for long periods.

— Zone I: in which an explosive gas-air mixture is likely tooccur in normal operation.

— Zone 2: in which an explosive gas-air mixture is not likelyto occur, and if it occurs it will only exist for a short time.

Upon special consideration and agreement in each case, how-ever, hyperbaric evacuation systems may be located in spaceswhich normally would be defined as Zone 2.

302 When any part of the hyperbaric evacuation system issited on deck, particular consideration shall be given to provid-ing reasonable protection from sea, icing or any damage whichmay result from other activities onboard the ship or floatingstructure.

303 The hyperbaric evacuation system shall be so arrangedthat hyperbaric evacuation operations shall not be affected bypropellers, thrusters or anchors.

Guidance note:Some units need to limit the length of umbilicals so that it cannotbe drawn into the propellers or thrusters.


F 400 Layout of the hyperbaric evacuation system

401 The layout of the hyperbaric evacuation system shallensure protection from accidental damage and accessibility for:

— safe operation— maintenance— inspection.

F 500 Avoidance of contaminants

501 Materials producing atmospheric contamination, includ-ing permanent equipment stored in pressure vessels, shall bekept to a minimum within the pressure hull in order to preventdevelopment of toxic concentrations. Finishes such as paintcontaining lead are not to be applied inside the pressure hull.

502 The specifications of the finishers shall be submitted forapproval.

F 600 Entry and egress

601 If the hyperbaric evacuation is so designed that entryand/or egress of personnel shall take place during normal oper-ations, sufficient hatches shall be provided for this purpose.

602 For hyperbaric evacuation units that are so designed thatthe entry and egress of personnel shall take place after thehyperbaric evacuation unit has been lifted out of the water, ameans shall be provided to ensure that it will then be possiblefor the personnel to exit the hyperbaric evacuation unit.

603 Each compartment shall be fitted with a means of open-ing at least one hatch from the exterior side.

604 Closing mechanisms for entrance hatches shall bedesigned to enable a compression of sealing gaskets for thehyperbaric evacuation chamber also in surface condition.

F 700 Mechanical equipment

701 All system components should be designed to avoid res-onance with exciting forces from the machinery in the hyper-baric evacuation system.

702 Where mechanical appendages and other protrudingcomponents, may lead to hazards of entanglement and entrap-ment, such appendages are either to be arranged with a systemfor jettison, provided with appropriate effective fairing or shallbe stowed in such a way as to avoid entanglement.

703 Due consideration shall be given to the effect of any

combination of jettison able items on the equipment locatedwithin the hyperbaric evacuation.

704 Penetrations for umbilicals and other hull penetrationsshall be protected against mechanical damage by suitable fair-ings.

G. Materials and Structures

G 100 Materials

101 Materials shall be selected with such qualities asrequired for the intended operations. This includes special steelqualities for cold climate operations.

G 200 Supports and foundations for the hyperbaric evacuation system

201 Pressure vessel(s) exposed to static and dynamic loads -while allowing contraction and expansion of the pressure ves-sel(s) under pressure variations, temperature variations andhull deflections - shall be supported in a proper manner. Thestress level in the pressure vessel(s), connected pipes, the sup-ports and foundations shall be kept within acceptable level.

202 The part of the hull structure supporting the hyperbaricevacuation unit, is to be evaluated with respect to deflection, inorder not to expose the hyperbaric evacuation unit to excessivedeflections. The evaluation shall take into considerationdefined acceptable level of deflection for the hyperbaric evac-uation unit.

Guidance note:Supports are generally understood to be part of the hyperbaricevacuation system or pressure vessels, whereas the foundationsare generally understood to be part of the ship's structure/hull.


203 The supports and foundations shall be calculated for val-ues of accelerations determined as shown in DNV Rules forClassification of Ships Pt.3 Ch.1 Sec.4 or other acceptablestandards. The values reflect a probability level of 10-8.

204 The pressure vessels with supports shall be designed fora static inclination of 30° without exceeding the allowablestresses as specified in E903.

205 Suitable supports and foundations shall be provided towithstand a collision force acting on the hyperbaric evacuationsystem corresponding to one half the weight of the system inthe forward direction and one quarter the weight of the systemin the aft direction.

206 The loads mentioned in 204 and 205 need not to be com-bined with each other or with wave-induced loads.

207 Unless removal of the pressure vessel(s) is a simpleoperation, the foundation(s) should be able to sustain the staticload of the pressure vessel(s) during periodic hydro testing orit should be possible to shore/support the foundations in orderto avoid unacceptable deflections.

208 Rotating machinery, such as generator sets, shall be sup-ported such that noise and vibration is kept to a minimum.

G 300 Supports and foundations for handling systems and lifting appliances

301 Supports and foundations for handling systems and lift-ing appliances shall be determined according to DNV Rulesfor Classification of Ships Pt.3 Ch.3 Sec.5 or according toother recognised standards.

302 The dynamic coefficient shall as a minimum be taken as2.2 or more when the lifting appliance is used for handlingmanned objects such as manned Hyperbaric Evacuation Sys-tems. For other lifting appliances, not used for lifting people,the dynamic coefficient should be 1.5 or more.

DET NORSKE VERITAS


303 The side structure of the HEU may need to be strength-ened with respect to possible impact loads from launching overthe side.

G 400 Supports and foundations for other equipment

401 The support of other equipment, not categorised underG200 or G300, shall be considered. Drawings showing thedeck structure below the foundation shall be submitted forapproval when the static forces exceed 50 kN or when theresulting bending moments at deck exceed 100 kNm. Thedrawings shall clearly indicate the relevant forces and bendingmoments acting on the structure.

402 When considering the structural strength of the deckstructure the static loads shall be multiplied by a dynamic fac-tor equal to 1.6 or more.

403 Acceptable stress levels may be taken as follows:

404 To obtain satisfactory transfer of heavy loads from thehyperbaric evacuation system foundations, the structure belowdeck shall be in line with the foundation structure. This may beobtained by fitting adequate brackets, intercostals, rings orsimilar fittings.

405 Regarding material qualities, reference is made to DNVRules for Classification of Ships Pt.3 Ch.1 Sec.2 B300 andB500 or to the applied standard.

406 The welding shall be considered with respect to theactual stress level.

H. Documentation

H 100 General

101 This section specifies the requirements for documenta-tion during hyperbaric evacuation system design, manufactur-ing, fabrication, installation, commissioning and operation.

102 In accordance with quality system requirements, such asthose outlined in ISO 9001:2000-4.4 (especially 4.4.5) and 4.5(especially 4.5.2), design output shall be documented andexpressed in terms that can be verified and validated againstdesign input requirements.The supplier shall establish and maintain documented proce-dures to control all documents and data. This may in part bedone in accordance with a DNV document requirements lists.

103 All documentation requirements shall be reflected in adocument register. The documentation shall cover design,manufacturing, fabrication, installation and commissioning.As a minimum, the register should reflect activities from thestart of design to operation of the hyperbaric evacuation sys-tem.

104 The documentation shall be submitted to the relevantparties for acceptance, verification or information as agreed inample time before start of fabrication.

105 Verified documentation shall be available at the worksite before manufacturing commences.

H 200 Documentation of arrangement

a) Plans showing general arrangement of the hyperbaricevacuation system, location and supporting arrangement.

b) Plans showing the lay-out of control stand(s).

c) Proposed program for tests and trials of systems for nor-mal operation and for emergency use.

d) Extract from the operation philosophy, stating the opera-tional procedures, which are to be the basis for the design.

e) Plans for the emergency systems.

201 List stating the following particulars for the hyperbaricevacuation system:

— maximum operating depth dmax and maximum operatingdepth for the hull (if applicable) and chambers

— maximum operation time Top (normal operations)— maximum endurance time in emergency mode— maximum number of crew for the hyperbaric evacuation

unit (atmospheric pressure) and hyperbaric evacuationchambers (hyperbaric pressure)

— maximum number of crew in the TUP and receivingchamber(s)

— maximum operational sea-state— working weight of the hyperbaric evacuation unit— displacement of the hyperbaric evacuation unit.

H 300 Documentation for systems in operation

301 In order to carry out periodical surveys, the minimumdocumentation should include:

— personnel responsible for the operation of hyperbaricevacuation system

— history of hyperbaric evacuation system operation withreference to events which may have significance to designand safety

— a log of the total number of dives and hours under pressurein the periods between annual surveys

— records of new equipment installed and old equipmentremoved

— installation condition data as necessary for understandinghyperbaric evacuation system design and configuration,e.g. previous survey reports, as-built installation drawingsand test reports

— inspection and maintenance schedules and their records.

302 In case of mechanical damage or other abnormalitiesthat might impair the safety, reliability, strength and stabilityof the hyperbaric evacuation system, the following documen-tation shall, as a minimum, be prepared prior to start-up of thehyperbaric evacuation system:

— description of the damage to the hyperbaric evacuationsystem, its sub-systems or components with due referenceto location, type, extent of damage and temporary meas-ures, if any

— plans and full particulars of repairs, modifications andreplacements, including contingency measures

— further documentation with respect to particular repair,modification and replacement, as agreed upon in line withthose for the manufacturing or installation phase.

H 400 Filing of documentation

401 Maintenance of complete files of all relevant documen-tation during the life of the hyperbaric evacuation system is theresponsibility of the owner.

402 The engineering documentation should be filed by theowner or by the engineering contractor for a minimum of 10years.

403 Design basis and key data for the hyperbaric evacuationsystem should be filed for the lifetime of the system. Thisincludes documentation from design to start-up and also docu-mentation from possible major repair or modification of thehyperbaric evacuation system. Certificates of major compo-nents should also be kept.

404 Files to be kept from the operational and maintenancephases of the hyperbaric evacuation system should, as a mini-mum, include final in-service inspection reports from start-up,periodical and special inspections, condition monitoringrecords, and final reports of maintenance and repair.

Bending stresses: 160 f1 N/mm2

Shear stresses: 90 f1 N/mm2

DET NORSKE VERITAS


I. Inspection, Surveys, Testing and Drills

I 100 General

101 Testing of the hyperbaric evacuation system with hyper-baric evacuation unit and the handling system should be car-ried out to the maximum possible extent to SOLASrequirements and to DNV Rules for Certification of DivingSystems.

102 When a hyperbaric evacuation system is built accordingto this recommended practice, an inspector or surveyor shouldverify that:

— the design and scantlings comply with the approved plansand the requirements in this recommended practice andother specified recognized standards, codes, and nationalregulations

— that the materials and components are certified accordingto this recommended practice and the terms of delivery

— that the work is carried out in accordance with the speci-fied fabrication tolerances and required quality of welds

— that piping systems conducting gas in life support systemsare cleaned in accordance with an approved cleaning pro-cedure conforming to requirements given in ASTM G93-96 Standard Practice for Cleaning Methods and Cleanli-ness Levels for Materials and Equipment Used in Oxygen-Enriched Environments

— that gas cylinders are clean and sealed— that all required tests are carried out.

103 The inspection should be carried out at the manufactur-ers, during the assembly and during installation. The extentand method of examination should be agreed in the terms ofdelivery.

104 The tests to be carried out are stated in 200 and 300.Additional tests may, however, be required. The testing aftercompleted installation should be in compliance with anapproved program.

I 200 Testing at the manufacturers

201 Pressure tests:

a) Welded pressure vessels and seamless steel gas containersfor internal pressure shall be hydrostatic tested to an inter-nal pressure in accordance with the design code. Eachcompartment shall be tested separately.

b) Pressure vessels for external pressure shall, in addition tothe internal pressure testing, be hydrostatic tested to anexternal pressure in accordance with the design code.Pressure hulls shall be fitted with hatches, windows andpenetrators.

c) Acrylic plastic windows shall be tested in accordance withASME PVHO-1a-1997 Article 7.The applied hydrostatic test pressure shall be the greaterof;

— 1.3 times the design pressure, or— the test pressure of the chamber for which the window

is intended, but shall not exceed 1.5 times the designpressure of the window.

d) Compressor components and associated piping compo-nents subjected to pressure shall be hydrostatic tested inaccordance with the design code.

202 Compressors:

— compressors shall be tested for the gas types, pressure anddelivery rate intended

— the tests shall incorporate measurements of humidity andpossible, contaminants in the gas delivered.

203 Closed circuit breathing system (CCBS) – when fitted ,should be tested according to an approved test program incor-porating the following:

— breathing resistance at work— simulation of the most probable failures and recording of

the resulting system responses— performance of the system with regard to gas composition,

pressure and temperature as function of the variables— the results of the tests should be made available for

approval.

204 Flexible hoses shall be tested as specified in the designcode and in Sec.8.

205 Umbilicals shall be tested as specified in the design codeand in Sec.8.

206 Electrical pressure vessel penetrators shall be tested asspecified in the design code and in Sec.5.

207 Hyperbaric evacuation unit:

— the working weight and the buoyancy shall be ascertained— the stability in normal and emergency modes shall be

tested— emergency release systems for hoisting rope and umbilical

shall be tested.

I 300 Testing after completed installation

301 Each hyperbaric evacuation system should be subject toan initial survey before being put into service. This shouldcomprise a complete and thorough examination of the hyper-baric evacuation system, equipment, fittings, arrangementsand materials including functional tests which should be suchas to ensure they are suitable for the intended service and incompliance with these guidelines and specifications; [IMOGuidelines Res. A.692 (17): 4.1].

302 Pressure tests. Piping for the life support systems shallbe pressure tested to 1.5 times the maximum working pressureproviding this is allowed for in the design code. Hydraulic sys-tems may, however, be tested to the smaller of 1.5 times themaximum working pressure, or 70 bar in excess of the maxi-mum working pressure.

303 Purity tests. Piping systems intended to be used inbreathing gas and oxygen systems shall be tested for purity inaccordance with requirements given in ASTM G93-96 Stand-ard Practice for Cleaning Methods and Cleanliness Levels forMaterials and Equipment Used in Oxygen-Enriched Environ-ments.

The tests shall comprise:

— measurement of contamination of the cleaning agent usedat the last stage of the cleaning

— tests for possible traces of cleaning agents left in the pipingsystem.

304 Gas leakage tests. The gas storage, chambers and lifesupport systems for gas shall be tested for leakage at the max-imum working pressure. The test shall be carried out with thegas or liquid type the system is supposed to contain and whichhas the highest leakage rate properties, or a gas/liquid withequivalent properties. A leakage rate up to 1% pressure drop in 24 hours for thewhole chamber system can be accepted. The leakage test timeshould be minimum 6 hours.

Guidance note:Note that for systems with max. pressure between 20 bar and 30bar and chamber temperatures between 20°C and 30°C, a tem-perature drop of about 3°C will cause a pressure drop of about1%. (See BS 5355 Specification for filling ratios and developedpressures for liquefiable and permanent gases).


DET NORSKE VERITAS


305 Launch and recovery systems (LARS) shall be subjectedto tests for structural strength and for function and power:

— a static load test to a load equal to the design load (seeSec.7 C100) shall be carried out

— functional and power testing of normal and emergencysystems shall be carried out with a functional test load of1.25 times the working weight in the most unfavourableposition. It shall be demonstrated that the systems arecapable of carrying out all motions in a safe and effectivemanner

— monitoring of functional parameters during the test, e.g.pressure peaks in hydraulic systems may be required

— a recovery test of the hyperbaric evacuation unit shall becarried out simulating emergency operations conditions

— the centre of gravity of the hyperbaric evacuation unitshall be verified by conducting an inclining experiment

— stability and buoyancy should be tested at surface for bothnormal and emergency operations.

306 Life support systems for normal and emergency opera-tion shall be tested for proper functioning.

307 Various systems. The following systems shall be testedfor proper functioning:

— sanitary— communication— fire detection— fire alarm— fire extinction— heating.

Other systems onboard the surface installations, significant forthe safety of the hyperbaric evacuation system, are also to betested.

308 Electrical systems

— A test for insulation resistance shall be applied to everycircuit between all insulated poles and earth, and betweenindividual insulated poles. A minimum value of 1 megaohm shall be attainable.

— Tests for redundancy shall be carried out.— Main and emergency power supplies shall be tested.

309 Instrumentation. The correct calibration of all essentialinstrumentation (compartment and other pressure gauges, gasanalysis instruments etc.) shall be checked. All alarms shall betested.

310 Environmental control systems.

Monitoring system:

— Failure conditions shall be simulated as realistically aspossible, if practicable by letting the monitored parameterspass the alarm and safety limits. Alarm and safety limitsshall be checked.

Automatic control systems:

— Normal alterations of the environment shall be imposedand the functions of the system tested.

— A copy of the approved test program should be completedwith final set points and endorsed by the Surveyor.

311 Sea trials. Functional tests of all systems for normaloperation and for emergency operation shall be carried outaccording to approved procedures. It is recommended that the scope given in IMO Res. MSC.81(70) be applied to SPHLs. Part of this scope may also beapplied to rescue chambers.

a) It shall be demonstrated that the normal launch and recov-ery system functions effectively with the working weightof the hyperbaric evacuation unit to tilt and list conditions

applied for the testing of regular lifeboats onboard the sup-port vessel.

b) For SPHLs, a lifeboat towing and painter release test shalldemonstrate that the fully equipped lifeboat, loaded with aproperly distributed mass equal to the mass of the numberof persons for which it is to be approved, can be towed ata speed of not less than 5 knots in calm water and on aneven keel. There should be no damage to the lifeboat or itsequipment as a result of this test. For hyperbaric evacuation chamber, a similar test shall becarried out prior to installation onboard. The speed shall be recorded in the reports submitted to theauthorities for acceptance.

c) A davit-launched lifeboat painter release test shall demon-strate that the painter release mechanism can release thepainter on a fully equipped and loaded lifeboat that isbeing towed at a speed of not less than 5 knots in calmwater. The painter release mechanism shall be tested inseveral distinct directions of the upper hemisphere notobstructed by the canopy or other constructions in the life-boat. For hyperbaric evacuation chamber, a similar test shouldbe carried out prior to installation onboard.

d) An emergency recovery test shall be carried out.

I 400 Surveys and testing during operations

401 Each hyperbaric evacuation system should be subject to:

— a survey at intervals specified by the Administration butnot exceeding 2 years; and

— an annual inspection within 3 months of each anniversarydate of the survey to ensure that the hyperbaric evacuationsystem, fittings, arrangements, safety equipment and otherequipment remain in compliance with the applicable provi-sions of the Guidelines and Specifications and are in goodworking order. [IMO Guidelines Res. A.692 (17): 4.1].

402 Surveys shall be carried out by Recognised Organisa-tions (RO).

403 Survey of gas storage cylinders mounted externally onHEUs may need more frequent inspections.

404 Lifting wires need frequent inspections and may needend to end turning. (Ref. IMCA D-18).

405 Hyperbaric survival packs, scrubbers and survival kitsshall be unpacked, checked and repacked. Some such packsneed to be returned to the manufacturer for checking.

406 Parameters that could jeopardise the safety of the crew,and or violate the integrity of a hyperbaric evacuation system,shall be monitored and evaluated with a frequency that enablesremedial actions to be carried out before personal harm is doneor the system is damaged.

Guidance note:As a minimum the monitoring and inspection frequency shouldbe such that the hyperbaric evacuation system, and consequentlythe hyperbaric evacuation operation, should not be endangereddue to any realistic degradation or deterioration that may occurbetween two consecutive inspection intervals.


407 Instrumentation may be required when visual inspection orsimple measurements are not considered practical or reliable, andavailable design methods and previous experience are not suffi-cient for a reliable prediction of the performance of the system.

I 500 Maintenance

501 The availability of any hyperbaric evacuation systemprovided is dependent on the regular testing and maintenanceof the system.A planned maintenance and testing programme shall be

DET NORSKE VERITAS


devised with the responsibility for carrying out the mainte-nance tasks being allocated to specific crew members.Maintenance and testing schedules shall be available forrecording the execution of the tasks and the signatures of thepersons allocated the tasks. Such schedules shall be maintainedon board and be available for inspection. [IMO GuidelinesRes. A.692 (17): 14].

502 Components in the hyperbaric evacuation system shouldbe so designed, constructed and arranged as to permit easyinspection, maintenance, cleaning and, where appropriate, dis-infection. [IMO Guidelines Res. A.692 (17): 5.6].

503 Planned maintenance is important as the system willoften be exposed to the environment and is rarely operated.

I 600 Drills

601 Concept of operation, training and Evacuation DrillsPeriodic training exercises should be carried out to test theoperation of the hyperbaric evacuation system and the effi-ciency of the personnel responsible for the hyperbaric evacua-tion of the divers. Such training exercises should not normallybe carried out while the chambers are pressurised, but shouldbe carried out at each available opportunity. [IMO GuidelinesRes. A.692 (17): 4].Content and frequency of the training exercises shall as a min-imum follow the regulations of the maritime authorities and beincluded in the familiarisation programme for new personnel.Familiarisation programmes shall be carried out for allinvolved personnel, including management.

J. Marking and Signboards

J 100 General

101 Dedicated hyperbaric evacuation units should be col-oured orange and be provided with retro-reflective material toassist in their location during hours of darkness. [IMO Guide-lines Res. A.692 (17): 13.1].

102 Each hyperbaric evacuation unit designed to be water-borne should be marked with at least three identical signs asshown below. IMO Guidelines Res. A.692 (17): 13.2].

103 One of these markings should be on top of the unit andbe clearly visible from the air and the other two be mountedvertically on both side and as high as possible and be capableof being seen while the unit is afloat.

Note: All dimensions in millimetres [IMO Guidelines Res.A.692 (17): 13.2]

104 Where applicable, the following instructions and equip-ment should be clearly visible and be kept readily availablewhile the unit is afloat:

— towing arrangements and buoyant towline;— all external connections, particularly for the provision of

emergency gas, hot/cold water and communications;— maximum gross weight of unit in air;— lifting points;— name of the parent ship and port of registration; and— emergency contact telephone, telex and facsimile num-

bers.

[IMO Guidelines Res. A.692 (17): 13.3]

105 Warning instructions

Where appropriate, the following instructions should be perma-nently displayed on every hyperbaric evacuation unit in two sep-arate locations so as to be clearly visible while the unit is afloat:

"Unless specialised diving assistance is available:

1) Do not touch any valves or other controls;

2) Do not try to get occupants out;

3) Do not connect any gas, air, water or other supplies;

4) Do not attempt to give food, drinks or medical supplies tothe occupants; and

5) Do not open any hatches".

[IMO Guidelines Res. A.692 (17): 13.4].

106 Labels (nameplates) of flame retardant material bearingclear and indelible markings shall be placed so that all equip-ment necessary for operation (valves, detachable connections,switches, warning lights etc.) can be easily identified. Thelabels are to be permanently fixed.

107 All gas containers shall be marked with a consistent col-our code visible from the valve end, showing the name, chem-ical formula of the gas it contains and the percentage of eachgas. Piping systems shall be marked with a colour code, andthere shall be a chart posted in the control room explaining thecode. One example of such a colour code is given in the fol-lowing guidance note:

Guidance note:


J 200 Gas containers

201 Each container shall be permanently and legibly markedon the collar or neck ring (where the thickness of the materialis greater than the design minimum) as follows:

— the design code— the manufacturer's mark or name— the manufacturer's serial number— the test pressure (bar) and date of hydrostatic test— surveyor's mark and identification

FIGURE OF SIGNwhite cross 300 x 300white letters 150 high: DIVER RESCUEwhite letters 50 high: CALL RESCUE SERVICES

AT ONCE -KEEP IN SIGHT-

FIGURE OF DIVER BELLyellow 300 high green background

1.200 long x 450 high (min.)

Table J1 ISO 32-1977 (E)code proposesName of gas Chemical formula Colour codeOxygen O2 WhiteNitrogen N2 BlackAir - White and BlackHelium He BrownOxygen/Helium mixed gas O2/He White and BrownCarbon dioxide CO2 Grey

DET NORSKE VERITAS


— settled pressure (bar) at 15°C— volumetric capacity of the container, in litres— tare weight, i.e. the mass of the container including valve,

in kg.

In addition marking of gas content shall be carried out accord-ing to K100.

J 300 Other pressure vessels than gas containers

301 Each pressure vessel shall be permanently and legiblymarked at a suitable location in accordance with the require-ments in the design code. As a minimum the following infor-mation shall be present:

— the design code— the manufacturer's mark or name— the manufacturer's serial number— the test pressure (bar) and date of hydrostatic test

— the maximum working pressure— the inspection body’s mark and identification— the maximum set pressure of the safety relief valves.

J 400 Launch and recovery system

401 The launch and recovery system shall, in an easily visi-ble place, be fitted with a nameplate giving the following par-ticulars:

— identification number— static test load— functional test load— working weight— surveyor's mark and identification.

The above loads shall be specified for each transportation sys-tem involved.

DET NORSKE VERITAS


SECTION 3PRESSURE VESSELS FOR HUMAN OCCUPANCY,

GAS STORAGE AND OTHER PURPOSES

A. General

A 100 Objectives

101 This section aims to give general guidance on:

— conceptual and detailed design of pressure vessels forhuman occupancy, for gas storage and for other purposes

— manufacturing of such pressure vessels— quality control during manufacturing and fabrication of

such pressure vessels including documentation require-ments

— load conditions— interlock arrangements for doors and hatches.

102 For quantitative design parameters and functionalrequirements, reference is made to relevant standards andguidelines, including normative references given in Sec.1 Band DNV Rules for Classification of Ships.

103 Further requirements for piping and pipe connectionscan be found in Sec.8.

104 The pressure vessel forming the chamber of the HESshall be designed and built to a recognised international stand-ard and fit for the purpose. Specific codes are suggested in thetext.


201 This section applies to all pressure vessels in hyperbaricevacuation systems designed to comply with this recom-mended practice. Note that in addition to this recommendedpractice, and the applied design standards, further nationalrequirements may apply.

202 ASME PVHO-1-1997 edition (or latest) "Safety Stand-ard for Pressure Vessels for Human Occupancy", shall be usedfor design of acrylic plastic windows, regardless of whichstandard is used for the design of the pressure vessel.

203 Material specifications are given in the applied codesand standards (EN/ASME).

204 Welding of pressure vessels and general workmanshiprequirements are not specified herein. Further requirements forwelding and workmanship are given in the relevant codes andrules.

205 Installation of pressure vessels is specified as generalrequirements. Further requirements for installation are given in the relevantclassification rules for the support vessel.

A 300 Documentation

301 Pressure vessels shall be documented as follows:

Plans showing structural arrangement, dimensions, weldingseams, attachments and supports of the hyperbaric evacuationchambers and other pressure vessels, with details of doors,locks (medical locks and equipment locks), view ports, pene-trations, flanged and welded connections.

Plans showing expansion allowances under working condi-tions for interconnected multi-vessel systems.

Documents stating:

— grade of material— welding methods, type and size of filler metal— design pressure

— particulars of heat treatment— fabrication tolerances— extent and type of non-destructive testing of welded con-

nections— type of thermal insulation materials and particulars, i.e.:

flammability and specific heat conductivity— type of buoyancy materials and particulars, i.e. specific

weight, specific water absorption and buoyancy dependenton exposure time

— drawings and specifications of all windows with detaileddrawings and specifications of the penetration which theappropriate window is to fit. It shall be determined that thetolerances are sufficient including gaskets, O-rings andretainer rings

— calculations of thicknesses and or stresses— fatigue evaluation and if necessary fatigue analysis.

For seamless steel gas cylinders and vessels:

— plans showing proposed dimensions and details such asvalves and safety devices shall be made for each type andsize of vessel.

Details shall include:

— production method— heat treatment.

Material specifications for the completed vessel with informa-tion on the following:

— chemical composition— tensile strength— yield strength— elongation— impact test values— Brinell hardness.

The following particulars shall be provided for information:

— type of gas— filling pressure at 15°C— safety relief valve setting— weight of empty vessel and volumetric capacity.

A 400 Testing and marking after completion

401 The required testing and marking of pressure vessels arespecified in Sec.2 I and J, and the applied standard found inB102 and E102.

402 Materials selection associated with the production ofpressure vessels is covered in the applied standard and or inDNV Rules for Classification of Ships.Requirements and guidance on inspection and monitoringassociated with the production of pressure vessels can be foundin the applied standard and DNV-OSS-305.

A 500 Material protection

501 Areas of steel pressure vessels that can be subjected tocorrosion shall be protected by approved means. 'The surfaceof the window seats cavity shall be protected against corrosion.

502 Windows mounted on the hyperbaric evacuation andchambers shall be protected to avoid damage by impact and toprevent chemicals, which can deteriorate the acrylic plastic, tocome in contact with the window from the outside.

DET NORSKE VERITAS


Guidance note:Many solvents for paints, acetone and other agents will deterio-rate the acrylic plastic and reduce the strength significantly.


503 All penetrators in pressure vessels for human occupancyshall be designed to minimise corrosion from any fluid passingthrough them.

Guidance note:In some cases this requirement may best be met by the use of asleeve passing through the hull penetration.


A 600 Design loads

601 The design pressure for hyperbaric evacuation andchambers shall not be less than that corresponding to the max-imum operating depth as defined in Sec.1 D. The effects of thefollowing loads shall be considered and shall be taken intoaccount if significant:

— dynamic loads due to movements of the hyperbaric evac-uation unit and the support vessel

— local loads from lifting lug arrangement, supports etc.— loads due to restrictions in expansions— loads due to weight of content during normal operation

and pressure testing— loads due to rough handling— loads on exo-structure imposed by waves.— loads due to hyperbaric evacuation unit and tunnel

clamped on to the chamber— the stress evaluation shall apply the distortion theory (von

Mises criterion).

Guidance note:Multipurpose vessels may carry heavy deck loads, which cancause stresses and strains on the mountings of the hyperbaricevacuation system components. If this cannot be avoided throughdesign of the installed hyperbaric evacuation system, it should bemonitored during such operations.


602 The design load is normally to correspond to valuesderived from fatigue evaluations done in accordance with theapplied design code, unless otherwise agreed and specified.

Guidance note:For pressure vessels designed to ASME VIII Div.1, fatigue eval-uation is done in accordance with ASME VIII Div.2.Fatigue evaluation is found in the appendixes to the codes.


603 Pressure vessel(s) exposed to static and dynamic loads -while allowing contraction and expansion of the pressure ves-sel(s) under pressure variations, temperature variations andhull deflections - shall be supported in a proper manner. Thestress level in the pressure vessel(s), connected pipes, the sup-ports and foundations shall be kept within acceptable level.

B. Design of Chambers

B 100 Chambers

101 All pressure vessels for human occupancy shall bedesigned, constructed and tested according to one of the fol-lowing codes and standards:

a) EN 13445 "Unfired pressure vessels".

b) ASME VIII Div.1 "Boiler and Pressure Vessel Code" orASME VIII Div.2.

102 Hyperbaric chambers shall be classified in the highestcategory in the applied code or standard.

103 Other codes and standards may be evaluated andaccepted on a case by case basis.

104 All pressure vessels for human occupancy shall be certi-fied.

105 The dimensions of the living compartment shall be suf-ficient for the hyperbaric evacuation crew facilities required bySec.4.

Guidance note:Statutory requirements may require larger dimensions.


106 The minimum inner dimensions measured in the middleof the chamber, shall be as given in Table B1, where evacua-tion chambers are assumed used only in transit to a hyperbaricrescue facility. Free height shall be assured to prevent headinjuries.

107 The minimum inner volume shall be 0.6 cubic metres(m3) per person that the chamber is designed to evacuate.

108 For hyperbaric evacuation units, where the chambers arealso used as regular decompression chambers incorporated aspart of the diving system, the design shall be such that a con-version to hyperbaric evacuation is possible to do within therequired timeframe. This shall be tested as part of a type test.Conversion shall be possible whilst the evacuees are enteringthe chamber.

109 As above, where the chambers are also used as regulardecompression chambers incorporated as part of the divingsystem, the living compartment shall normally have a size suf-ficient for installation of bunks with length and breadth equalto 198 cm x 80 cm. (see Sec.4 I101).

110 All windows in pressure vessels for human occupancyshall be certified.

Guidance note:3.2 certificates may be required in the contract or the terms ofdelivery.


111 For hyperbaric evacuation units, the living compartmentand other compartments that can be used for decompressionshall be provided with means for locking in provisions, medi-cine and equipment necessary for the operation of the system.The evacuees in each living compartment shall have access totoilet facilities as specified in Sec.4 I110.Paints, cabling and other materials shall be considered fortoxic or noxious properties as specified in Sec.1 H305.

112 In the design of pressure vessels including accessoriessuch as doors, hinges, door landings, closing mechanisms,penetrators and view ports, the effects of rough handlingshould be considered in addition to design parameters such aspressure, temperature, vibration, operating and environmentalconditions.In general, piping penetrations through the chamber shouldhave isolating valves on both sides. [IMO Guidelines Res. A.692 (17): 5.3].

The hyperbaric evacuation unit shall be provided with properprotection against mechanical damage.

113 Arrangements should be provided to allow the occupantsto be observed. If view ports are provided they should be situ-ated so that risk of damage is minimised. [IMO Guidelines Res.A.692 (17): 6.5].

Table B1 Free height above the deck plates in centimetres (cm)

Evacuation chamber Decompression chamber

170 cm 200 cm

DET NORSKE VERITAS


The hyperbaric evacuation unit shall be provided with windowsthat as far as practicable allow the occupants in all compart-ments to observe crew outside the hyperbaric evacuation unit.

114 For self propelled hyperbaric lifeboats, the chambershall have windows towards the sheltered part in the lifeboat.

115 The hyperbaric evacuation unit shall be equipped withone extra external lifting fastening.

Guidance note:Note that the design and location of the extra lifting fasteningneeds to be considered in view of the need to bring the hyperbaricevacuation unit to a mating trunk on decompression chambers asrequired by Sec.7 B300.


116 Arrangement should be provided to enable an uncon-scious diver to be taken into the unit. [IMO Guidelines Res.A.692 (17): 6.3].Internally in the hyperbaric evacuation chambers, there shallbe an attachment at the top for lifting of disabled evacuees ona stretcher. In some cases a special stretcher may need to beutilised. The pulley system length must be enough to reach the chamberfloor.

117 Hyperbaric evacuation units shall have possibilities forentry and exit when landed on the deck of a support vessel. Incases where there is only one door mounted at the bottom ofthe HEU, entry and exit may be facilitated by a dedicated sup-port frame.

Guidance note:In cases where a dedicated support frame is not available, sandbags may be used to some effect.


B 200 Doors, hatches, windows, branches, etc.

201 The means provided for access into the compressionchamber should be such as to allow safe access to or from thesurface compression chambers. [IMO Guidelines Res. A.692(17): 6.2].Minimum dimensions of doors, hatches and medical locks.

Doors, hatches and trunks for human transportation shall ingeneral be:

— the minimum diameter of doors and hatches shall be 600 mm— the minimum diameter in the escape trunk to the hyper-

baric evacuation chamber shall be 800 mm— the length of the hatch trunk on the HEU shall not protrude

outside the surrounding exo-structure, thus protecting theflange from being damaged during handling.

Guidance note:For doors and hatches in between chambers, standard pipe withnominal bore 24" may be acceptable.


Where it is intended to carry out decompression of the diversafter hyperbaric evacuation in another surface compressionchamber, then consideration must be given to the suitability ofthe mating arrangements on that surface compression chamber.Where necessary, a suitable adapter and clamping arrangementsshould be provided. [IMO Guidelines Res. A.692 (17): 6.6].

202 A medical lock should be provided and be so designedas to prevent accidental opening while the compression cham-ber is pressurised.Where necessary, interlock arrangements should be providedfor this purpose.The dimensions of the medical lock should be adequate to ena-ble essential supplies, including CO2 scrubber canisters, to betransferred into the compression chamber, and be of suchdimensions as to minimize the loss of gas when the lock is

being used. [IMO Guidelines Res. A.692 (17): 6.]

203 All doors should be so designed that, where fitted, thelocking mechanisms can be operated from both sides. [IMOGuidelines Res. A.692 (17): 6.4].All doors shall be able to be secured in the open position.Doors shall be fitted with a means of pressure equalisation.Means enabling the doors to be opened from either side shallbe provided.

Guidance note:As the above requirement also applies to the internal doors inchamber complexes, it does follow that locking devises are notallowed on the pressurised side of these doors unless they can beoperated from the other side. 'Clip' locks are frequently used onthese doors to prevent slamming due to the vessels movement inthe sea. However, the 'clip' setting must be such that they can bepushed/pulled open from either side without the use of excessiveforce.


204 Interlocks should be provided to prevent the inadvertentrelease of the hyperbaric evacuation unit from the surface com-pression chamber while the access trunking is pressurised.[IMO Guidelines Res. A.692 (17): 6.2].For:

— doors— hatches— mating arrangements— pressurised locks and trunks— pressurised containers— accompanying equipment under pressure

where opening or unintentional pressure drop may entail dan-ger or cause injury, the closing mechanisms shall be physicallysecured by locking mechanisms (interlocks).

This applies to units which do not seal by pressure andincludes, but is not limited to:

— mating arrangements between hyperbaric evacuation unitsand transfer compartments/trunks

— mating arrangements between hyperbaric escape trunksand chambers where these are not bolted

— equipment locks— medical locks— soda lime (CO2 scrubber) containers for external regener-

ation of the chamber environments.

205 Compression chamber doors should be so designed as toprevent accidental opening while pressurised. [IMO Guidelines Res. A.692 (17): 6.4].The closing mechanisms with accompanying locking mecha-nisms shall be arranged so that:

— opening cannot take place unless the pressures are equalon both sides or unless the pressures in the units are atambient level

— correct position of the closing mechanisms and the lockingmechanisms shall be ensured before it is possible to applypressure

— the pressures in the units, shall directly control the lockingmechanisms, and

— the penetrators and piping for pressure sensing shall bearranged so that blockage is avoided.

206 Trunks between doors shall be equipped with pressureequalising valves. Penetrators for pressure equalising shall bearranged so that blockage is avoided.

207 Where mountings are secured by studs, these shall havefull thread holding in the shell for a length of at least one diam-eter. Holes for studs shall not penetrate the shell.

208 The mating flange should be adequately protected fromdamage at all times including during the launch and recovery

DET NORSKE VERITAS


stages. [IMO Guidelines Res. A.692 (17): 6.2].

In the event that the hydraulic system is unable to lift the unitsufficiently off the mating spool-piece, contingencies shall bein place.

Windows with a diameter above 500 mm and thickness lessthan 90 mm shall be protected against impact. Impact protec-tion may be provided by:

— recessing the external surface of the window at least 50mm below the surrounding structure

— one or more external bumpers extending across the win-dow.

209 Damage control plugs may be provided to enable thecrew to seal off windows to prevent damage or leakage devel-oping. One plug for each size window in each compartmentwould be sufficient.

210 For pressure vessels where fatigue can be a possiblemode of failure, attention shall be given to the possible adverseeffects of the following design features:

— pad type reinforcement of openings— set-on branches— partial penetration welds of branches— weld profiles.

C. Materials and Fabrication of Pressure Vessels

C 100 Materials and components

101 Steel grades shall comply with the applied design codeand standard.

102 Other material grades may be acceptable after specialconsideration. In such cases, additional testing may berequired and qualification procedures shall be reconsidered.

103 Materials for main pressure retaining parts are normallyto be delivered with product certificates (3.2).

Guidance note:Product certificates, 3.2 certificates, see ISO 10474


104 Stainless steel cladding, stainless steel tubes, fittings etc.which are welded to pressure vessels of non-stainless steelshall be of a stabilised or low-carbon grade. Acceptable gradesmay be found in the applicable construction standards or inDNV Rules for Classification of Ships Pt.2 Ch.1 Sec.4.

105 Materials regarded as equivalent to those specified in therelevant sections in Pt.2 of the DNV Rules for Classification ofShips, and fibre reinforced plastic materials may be acceptedafter consideration in each case provided safety values equiv-alent to a steel hull are maintained.

106 Pressure vessels shall be certified by a competentinspection body when:

where:p = design pressure in bar.

V = volume in m3.

The certification level should be product certificates 3.2.

Smaller pressure vessels shall be certified if they provide anessential function in the system.

Guidance note:Pressure vessels on-line in a system providing breathing gas tothe crew will be considered essential.


C 200 Fabrication

201 Pressure vessels for hyperbaric evacuation systems shallbe manufactured by works approved by a recognised body, forthe production of the type of pressure vessels being delivered.

202 Welding shall be carried out according to approveddrawings. Qualification of welders, welding procedure specifications,welding procedures and testing shall be according to theapplied design code or standard.

203 The following tests have to be carried out in addition tothe tests specified in the applied design code or standard:

— all butt welds in hyperbaric evacuation hyperbaric evacu-ations and chambers shall be radiographed over their fulllength

— branches and reinforcement of openings, including allweld connections to the shell, shall be subjected to 100%magnetic particle testing.

204 When the applied code or standard requires heat treat-ment of dished ends after hot or cold forming, mechanical test-ing may be required after the final heat treatment. The detailsbetween intermediate heads and cylindrical shells of chambersmay be done in accordance with requirements given in,

a) EN 1708-1:1999 Welding - Basic weld joint details in steelTable 9:Internal diaphragms and separators, or

b) ASME Section VIII - Division I Fig. UW-13.1.

The outside diameter of the head skirt shall have a close fit tothe cylinders.

The butt weld and filled weld shall be designed to take shearbased on 1.5 times the maximum differential pressure that canexist. The allowable stress value for the butt weld shall be 70%of the nominal design stress for the shell material and that ofthe fillet weld 50%. The area of the butt weld in shear shall betaken as the width at the root of the weld times the length of theweld. The area of the fillet weld shall be taken as the minimumleg dimension times the length of the weld.

205 The surface dimensions and finish of sealing systemsand seals for hatches and windows are generally to complywith the tolerances specified by the manufacturers of the win-dows and the sealing systems.

206 Flat disc windows shall have a bearing gasket betweenthe window and its seat. This gasket shall serve as a secondaryseal. The gasket shall be bonded to the seat.

The retainer ring shall provide adequate initial compression ofthe sealing arrangement to compensate for the displacement ofthe window due to the pressure. The minimum seating diame-ter in relation to window dimensions shall be specified.

The included conical angle of the seating surface of conicalflanges shall be within +0.00 or -0.25 degrees of the nominalvalue.

The surface finish of seats of metallic materials for conical-,double bevelled disc and spherical shell windows shall have anaverage roughness less than R = 1.5 m.

207 Before installation of a window in its flange, completecleanliness of the seating surfaces shall be ensured. The seat-ing surface and any o-ring grooves shall be lubricated with anoxygen compatible lubricant. Mineral oil lubricants shall,under no circumstances, be used for this purpose.

C 300 Fabrication tolerances

301 Fabrication tolerances are to meet the requirements inthe applied codes and standards.

302 Local tolerance requirements for ring frames are givenin Figure 1, for vessels subject to external pressure.

0.1Vp

DET NORSKE VERITAS


Figure 1 Maximum deviations for ring stiffeners

D. Strength of Hulls and Pressure Vessels

D 100 Structural analysis

101 Pressure vessels shall be documented by structural anal-ysis for specified design conditions according to the appliedcodes and standards.

102 For details not covered by the applied codes and stand-ards, finite element analysis may be acceptable if properlyplanned, modelled and documented.

Alternatively, by applying strain gauges, stress measurementsmay be carried out according to an approved programme andshall be properly documented. The tests shall be planned, andcarried out during the first pressure test.

103 Fatigue evaluation and, if necessary, fatigue analysisshall be carried out for the number of full pressure cycles givenin A602. The evaluation and analysis shall be carried outaccording to the applied design code and standard.

D 200 Vessels subjected to external pressure

201 Frames and panels supporting pressure-retaining partsshall be designed for a force of minimum 1.2 times the actualload.

202 Additional stresses shall be within the limits given in theapplied design code or standard, for combined stresses.

D 300 Flanges for windows

301 Flanges for windows with conical seating shall havedimensions preventing the flange deformations to exceed thefollowing limits when window and pressure vessel is subjectedto the design pressure:

— radial: 0.002 times the smaller diameter of the acrylic plas-tic window, and

— angular: 0.5°.

E. Gas Cylinders

E 100 General

101 Gas cylinders shall be produced by manufacturersauthorised for such production and certified by a competentinspection body when:

where:p = design pressure in bar.

V = volume in m3.

The certification level shall be product certificates 3.2.

Smaller gas cylinders shall be certified if they provide anessential function in the system.

Guidance note:

Cylinders on-line in a system providing breathing gas to the crewwill be considered essential.


102 They shall be designed, constructed and tested accord-ing to one of the following standards, norms or directives:

a) EN-1964-1:2000 Transportable gas cylinders (part1:1999, part 2:2001 or part 3:2000)

b) EN ISO 11120:1999 Gas cylinders - Refillable seamlesssteel tubes for compressed gas transport, of water capacitybetween 150 l and 3000 l - Design construction and testing(ISO 11120:1999).

Other codes and standards may be evaluated and accepted on acase by case basis.

Guidance note:

For permanent installations within EU, the directives apply asnational regulations. (ref. EU directive 1999/36/EEC.)


103 The materials applied shall be certified as certificateslevel 3.2.

104 Shell thickness shall meet the criteria given in theapplied code or standard for test pressure. The working pres-sure for a given geographical area is given by reference to astandard such as BS 5355 Specification for filling ratios anddeveloped pressures for liquefiable and permanent gases.

105 Corrosion allowance shall be specified in the terms ofdelivery reflecting the intended use of the gas cylinder, butshall not be less than 1 mm.

E 200 Heat treatment

201 Heat treatment shall follow the requirements given inthe applied code or standard, and shall be documented.

E 300 Tolerances and surface conditions

301 Tolerances and surface condition shall meet the criteriagiven in the applied code or standard, and shall be documentedin the design documentation. If the applied code or standarddoes not specify requirements for tolerances and surface con-ditions, then it may be necessary to specify this in the terms ofdelivery.

0.1Vp

DET NORSKE VERITAS


E 400 Production tests

401 Production tests shall be carried out in accordance withthe requirements given in the applied code or standard. Furtherproduction tests, and required attendance during testing, maybe specified through the terms of delivery.

F. Acrylic Plastic Windows

F 100 General

101 The following requirements apply to windows madefrom cast stock of unlaminated polymethyl methacrylate plas-tics, in the following denoted acrylic plastic, with a design lifeof 10 years, suitable for:

— 10 000 load cycles— sustained temperatures in the range -18°C to +66°C— pressurisation or depressurisation rates not exceeding 10

bar/second— use in environments that cannot cause chemical or physi-

cal deterioration of the acrylic plastic (i.e. resistant againstsaltwater and gases used in life support systems).

102 They shall be designed, constructed and tested accord-ing to the following standard:

a) ASME PVHO-1-1997 "Safety Standard for Pressure Ves-sels for Human Occupancy".

Other codes and standards may be evaluated and accepted on acase by case basis.

Guidance note:

The ASME PVHO is generally accepted as the standard of choicefor the diving industry.


F 200 Materials

201 Materials for acrylic plastic windows shall be manufac-tured and tested in accordance with ASME PVHO-1-1997"Safety Standard for Pressure Vessels for Human Occupancy".A later edition may be specified in the terms of delivery.

F 300 Manufacturers of cast material

301 Manufacturers wishing to supply cast acrylic plastic forhyperbaric evacuation systems, shall be approved for such pro-duction. The material shall have an approved chemical compo-sition and to be produced, heat treated and tested according tothe ASME PVHO-1-1997 "Safety Standard for Pressure Ves-sels for Human Occupancy". Approval shall be granted on thebasis of a thorough test of material from the current productionand a report after inspecting the works, and verification of QAand QC against requirements given in ASME PVHO-1.

F 400 Certification of cast material

401 Each delivery of cast material shall be accompanied bya certificate issued by the manufacturer. The certificate shall(as a minimum) contain the following:

— name and address of manufacturer— certificate number and date— designation of product— numbers and dimensions of the pieces covered by the cer-

tificate — material test results and properties— signature.

402 The following text shall be printed in the right upper-most corner of the certificate:

403 "This certificate will be accepted by (approval body) onthe basis of completed approval tests and the (approval body’s)surveillance of production control and products. The manufac-turer guarantees that the product meets the requirements of(approval body) and that inspection and tests have been carriedout in accordance with (code or standard) ".

404 The cast material shall be marked with the manufac-turer's name and with the number and date of the certificate.

405 If a later edition of the ASME standard requires furtherdocumentation and markings, the ASME requirements shall bemet.

F 500 Certification of windows

501 Each batch of acrylic plastic windows used in hyper-baric evacuation systems shall have a certificate issued by theapproval body, showing the test results and the annealing con-ditions according to the standard.

502 Each window shall have an identification marked on itfor traceability. Identification of each window shall include;design pressure, maximum temperature, initials for 'P.V.H.O.',window fabricator's identification mark, fabricators serialnumber and year of fabrication.

For ease of viewing, the above information shall be located onthe windows seating surface with an indelible marker. Accept-able marking methods are given in ASME PVHO-1.

Stamping or marking that can cause crack propagation is notpermitted.

F 600 Geometry and thickness

601 Windows shall be of the standard designs according tothe ASME PVHO-1-1997 "Safety standard for pressure ves-sels for human occupancy".

602 Windows for two-way pressurisation shall meet therequirements applicable to one-way windows in both direc-tions. For double bevelled disc windows, not more than 50%of the thickness shall be utilised in determination of short termcritical pressure.

603 O-ring grooves shall not be located in window bearingsurfaces serving primarily as support or in the acrylic windowitself.

F 700 Fabrication

701 The included conical angle of the seating surface of awindow shall be within +0.25/-0.00 degrees of the nominalvalue.

702 The deviation of a spherical window from an idealsphere shall be less than 0.5% of the specified nominal externalradius of the spherical section.

703 Each window shall be annealed after all forming and pol-ishing operations are completed. The annealing process shall beaccording to the annealing schedule in ASME PVHO-1.

704 During the manufacturing process each window shall beequipped with identification and a manufacture process riderfor recording of all pertinent data.

F 800 In service inspection

801 In service inspection and testing shall be carried out inaccordance with requirements given in ASME PVHO-2 guide-lines.

DET NORSKE VERITAS


SECTION 4LIFE SUPPORT SYSTEMS

A. General

A 100 Objectives

101 This section aims to give general guidance and require-ments on:

— conceptual and detailed design of life support systems— manufacturing of life support systems— quality control during manufacturing and fabrication of

components and subsystems for life support systems.

102 The section presents key-issue requirements for gas dis-tribution capacities, environmental conditioning and oxygensystems. Documentation requirements are identified. Thehyperbaric evacuation unit shall have a self-contained supportsystem with capacity for at least 72 hours.

103 Design and acceptance criteria include capacities for gasstorage, choice of valves and fittings for certain applications,environmental control parameters, breathing resistance forbreathing systems (including BIBS) and hyperbaric evacuationcrew facilities.

104 Requirements for the design of oxygen systems areaimed at reducing the hazards posed by flash fires.

105 This section contains requirements to ensure safearrangements in pressurised systems and control stations.

106 Further requirements for pipes, hoses, valves and fittingsare given in Sec.8.

107 Requirements for shut off valves, pressure relief anddrainage are aimed at ensuring the safeguard of personnel andplant, as are the requirements for alarm systems.


201 For quantitative design parameters and functionalrequirements, reference is made to relevant standards andguidelines, including DNV Rules for Classification of Ships.

202 Requirements for testing are given in Sec.2 I.

203 Requirements for installation are only rudimentary.

204 This section has an impact on all other sections in thisrecommended practice.

A 300 Documentation

301 Life support systems shall be documented as follows:

a) Plans showing schematic arrangement of all piping sys-tems.

b) Documents stating:

— material specifications— maximum working pressure— dimensions and thickness— contained fluids— type of valves and fittings— specifications of flexible hoses.

c) Plans (diagrams) showing arrangement and giving specifi-cations of the gas storage and supply (gas banks, compres-sors, boosters etc.).

d) Plans showing the arrangement and giving specificationson environmental control systems and equipment (heat-ing/cooling, CO2-absorption, circulation, lighting), hyper-baric evacuation crew facilities, sanitary and drainagesystems.

e) Component lists, with specifications on make and type and

documentation on any tests carried out on all equipmentused in the life support system. Plans showing cross-sec-tion and giving particulars on materials and dimensions ofumbilical.

f) Calculations showing the heat and cooling consumptionfor the system under given environmental thermal condi-tions.

g) Description of proposed cleaning procedure for breathinggas and oxygen system.

h) Calculation and/or verification tests (according to IMCAGuidelines D 02/06 of life support capacity.

B. Gas Storage

B 100 Capacity

101 In determining the duration and amount of life supportnecessary, consideration should be given to the geographicaland environmental conditions, the O2 and gas consumptionand CO2 generation under such conditions, the heat input orremoval and the emergency services that may be available forthe decompression of the divers. [IMO Guidelines Res. A.692(17): 8.1].The hyperbaric evacuation unit shall have a self-containedsupport system with capacity for at least 72 hours.

102 Where it is intended that divers may be decompressedwithin the hyperbaric evacuation unit, provision should bemade for the necessary equipment and gases, including thera-peutic mixtures, to enable the decompression process to be car-ried out safely. [IMO Guidelines Res. A.692 (17): 8.6].

103 There shall be a permanently installed gas storage plantor suitable space for portable gas containers. The size of thecontainers or space shall be sufficient to provide the crew withadequate quantities of gases for operation at maximum operat-ing depth for both normal and emergency modes.

104 Gas losses as a result of using toilet facilities which dis-charge to outside the hyperbaric evacuation unit and medicallock operation should be taken into account in determining theamount of gases required. [IMO Guidelines Res. A.692(17): 8.1].Leakage must also be determined during testing of the HEU,and taken into consideration when calculating gas.

105 The minimum gas storage capacity of fixed installedcontainers or space for portable containers intended for emer-gency operations shall be sufficient to:

— maintain pressure in the hyperbaric evacuation chamber(ref. 104 above) with a suitable breathing gas, and

— maintain a proper oxygen partial pressure in the chamberfor at least 72 hours. The ppO2 shall be kept within therange 35 - 50 kPa

— for pure oxygen, the minimum volume may be taken as 4Nm3 for each evacuee diver for hyperbaric evacuation sys-tems.

1 Nm3 is given as 1 cubic metre of the gas at 0°C and 1.013 barstandard condition.

106 Sufficient oxygen is considered to be metabolic con-sumption by the maximum number of divers at 0.5 litres/minuteper diver for at least 72 hours. The oxygen supply must be fittedwith a device where it is injected in a controlled manner. Typi-cally this will be a dosage device.

DET NORSKE VERITAS


107 For emergency use of masks there shall be sufficientfacilities to supply adequate quantities of gases. Such quanti-ties are not normally possible to be carried by the HEU, andwill have to be provided by an external source (e.g. a Life Sup-port Package (LSP)). The facilities shall be capable of provid-ing a relevant delivery rate both at maximum depth and duringdecompression of hyperbaric evacuees. The containersrequired by 102 may be used also for these emergency pur-poses.

B 200 Shut-off, pressure relief and drainage

201 Pressure vessels shall be fitted with over pressure reliefdevices and shut off valves except as provided for in E302 andE303.

202 Pressure vessels without individual shut-off valves andwith: pV < 50, installed in groups with a total pV < 100, can have a common overpressure relief device andshut-off valve.

p = design pressure in bar

V = volume in m3 (standard conditions).

203 For gas storage of breathing gases and oxygen, the pres-sure relief device shall be a safety valve. Safety valves shall beset to open at a pressure approx. 3% above the developed pres-sure at 55°C, based on filling the cylinders at 15°C to maxi-mum filling pressure. The total relieving capacity shall besufficient to maintain the system pressure at not more than110% of design pressure.Developed pressure under above-mentioned conditions maybe taken as given in reference to a standard such as BS 5355 Specification for filling ratios and developed pres-sures for liquefiable and permanent gases.

204 Containers where water can accumulate shall be pro-vided with drainage devices. (E.g. volume tanks and filters).

205 Containers for storage of oxygen and other gas storagecontainers are not to be stored inside the chambers.

206 A gauge shall be provided to enable the pressure in theemergency gas containers to be indicated to the operators/evacuees in the relevant compartments.

C. Gas distribution

C 100 General

101 In addition to any controls and equipment fitted exter-nally, compression chambers should be provided with ade-quate controls within for supplying and maintaining theappropriate breathing mixtures to the occupants, at any depthdown to the maximum operating depth. As far as practicable,the controls should be capable of operation without the personwho operates them having to remove his/her seat belt. [IMOGuidelines Res. A.692 (17): 8.2].

102 The gas distribution system consists of all componentsand piping necessary for distribution of gas for normal andemergency operations.

103 Piping for gas and electrical cables shall be separated.

104 The persons operating the chamber, whether they arewithin or outside it, should be provided with adequate controlsto provide life support. [IMO Guidelines Res. A.692 (17): 8.2].The distribution system to each compartment shall facilitate:

— two independent alternatives for pressurisation with aminimum pressurisation rate of 2 bar/minute to 2 bar andat 1 bar/minute thereafter

— depressurisation— decompression rate of minimum 1 bar/minute at pressures

exceeding 2 bar for hyperbaric systems— maintenance of a suitable breathing atmosphere in the

inner area (When adding pure oxygen to the compart-ments, a separate piping system shall be provided.)

— supply of suitable breathing gas for masks (this supplyshall be independent for each living compartment.)

— exhaust from masks intended for oxygen if a closed circuitbreathing gas system is not used.

105 There shall be two independent supplies of gas to thehyperbaric evacuation chamber. One from the support vesselor life support package and one from the supplies onboard theHEU.In case the HEU crew has to leave the HEU, it shall be possibleto secure the chamber system in a way that makes it possiblefor the divers inside to take over the control of O2 make-up, gassupply and temperature control.

106 Provision should be made external to the hyperbaricevacuation unit, and in a readily accessible place, for the con-nection of emergency hot or cold water and breathing thera-peutic mixture. The dimensions of the connections provided should be as fol-lows:

— 3/4 in. NPT (female) - hot or cold water— 1/2 in. NPT (female) - breathing mixture

The connections should be clearly and permanently markedand be suitably protected. [IMO Guidelines Res. A.692 (17):8.9].

107 Filters and automatic pressure reducers shall be soarranged that they can be isolated without interrupting vital gassupplies.

108 Valves in piping systems to masks and hyperbaric evac-uation chambers shall be so arranged that:

— leaking valves cannot cause unintentional gas mixtures— oxygen cannot unintentionally be supplied to other piping

systems than that intended for oxygen.

109 The discharge from overpressure relief devices andexhaust shall be led to a location where hazard is not created.

110 Where gas mixtures with oxygen content less than 20%are stored in enclosed spaces, there shall be an oxygen analyserwith an audio-visual low level alarm in addition to the ventila-tion requirements in Sec.6 B204.

111 For the pilot compartment in SPHLs, a manual means ofbleeding off any pressure difference which may occur during amission shall be provided.

C 200 Built in Breathing Systems (BIBS)

201 A breathing system should be provided with a sufficientnumber of masks for all the occupants under pressure. [IMOGuidelines Res. A.692 (17): 8.8].Each compartment shall be equipped with gas supply connec-tions for breathing masks corresponding to the maximumnumber of evacuees for which the chamber is rated, plus one.Other compartments shall have at least 2 masks. The masksshall be arranged for breathing from each seat when in use, butmay be stowed when not needed.

202 The masks shall be available within the HEU system forrapid connection when required.

203 The exhaust sides of the masks intended for oxygen shallbe connected to external dump, or to be of a closed circuit type.

204 The mask systems shall be secured against inadmissiblepressure drop on the exhaust side.

205 The gas supply system shall be arranged to ensurehomogenous gas content in the inner area.

206 For self propelled hyperbaric lifeboats with attendingcrew, masks for breathing or breathing apparatus shall beavailable for the crew members and life-support technicians at

DET NORSKE VERITAS


atmospheric pressure. The masks shall be connected to air stor-age sufficient for a minimum of 30 minutes breathing.

The SPHL pilots/crew shall be equipped with masks corre-sponding to the number of crew plus one. The masks shall bearranged for supply from normal and emergency supply alter-natively.

207 The life support system shall be provided and shall bedesigned for duration of at least 72 hours. The system shall beindependent of the Life Support Package systems and of nor-mal life support systems.

208 There shall be sufficient space for means of providingpassive thermal insulation in cold climates where this isrequired.

C 300 Life Support Package (LSP) and equipment for connection to support and rescue vessels

301 The hyperbaric evacuation unit (HEU) shall have anarrangement for a possible connection of umbilical to the sup-port vessel. The umbilical connection shall enable mainte-nance of proper environmental conditions in the chamber forsuch a time as required for transit to a reception facility or tofacilitate the decompression on site. The umbilical shall con-tain cables and connections for communication.

302 Additional or emergency life support facility shall beprovided for the HEU. The owner shall ensure that the facilityis ready for use at all times during diving.

This may be in the form of a Life Support Package (LSP) thatshall be kept at a suitable location from where it can reach theHEU within reasonable time. A contingency plan, with riskanalysis if necessary, shall be performed for verification. Com-patibility of the LSP to the HEU shall be verified.

303 The location of the LSP when it is not in use should becarefully considered. Ease of maintaining the unit in good con-dition may need to be weighed against the need to keep the unitin the vicinity of the diving operation.Emergency situations may occur during transit of the DSVfrom one location to another, or to shore. This should be takeninto account when deciding the location of the LSP.

304 It shall be possible to use the LSP with the HEU in thewater in the event that a lift is not possible. An umbilical shallbe longer than the towing line to the HEU.

305 For cases where the HEU is lifted on to a deck, a liftingarrangement and support cradle should accompany the LSP.Cradles must not damage the mating flange. The LSP and cra-dle should also be suitable for transportation by helicopter. Insuch cases planning should include studies with the helicoptercompanies.

As an alternative to a cradle, sand bags may be considered ifthis suits the HEU design.

306 Procedures for use of the LSP shall be included in thecontingency plan and shall be available with the LSP andinside the HEU.

307 In the event that diving competent personnel are notavailable at the site of the LSP, contact numbers shall beincluded in the LSP documentation so that competent person-nel can be contacted.

308 Relevant emergency procedures shall be available in theHEU chamber, in the HEU control and with the LSP.

C 400 Stand-by facility at surface

401 For hyperbaric evacuation chambers requiring supportfrom outside, the life support package should include facilitiesto connect the umbilical to the HEU. Such facilities mayrequire a suitable work-boat.

D. Oxygen Systems

D 100 General

101 Oxygen shall be stored and distributed in containers andpiping systems exclusively intended for oxygen systems.

102 Containers for oxygen shall be stored in open air or inrooms exclusively intended for oxygen. The rooms shall beseparated from adjacent spaces and ventilated according toSec.6 and shall be fitted with an audio-visible oxygen alarm, ata manned control station.

103 The pressure in the oxygen systems shall be reducedfrom storage pressure to the minimum pressure necessary forproper operation. The pressure reduction shall be arranged asclose as possible to the storage containers.

Guidance note:A maximum pressure of 40 bar will normally be accepted whendmax is less than 350 m.


104 Two separate distribution systems should be providedfor supplying oxygen to the compression chamber.Components in the system should be suitable for oxygen serv-ice. [IMO Guidelines Res. A.692 (17): 8.3].Components fitted in oxygen systems shall be of types espe-cially designed and tested for this purpose. (See Sec.8 A102and B300).

105 Oxygen shall not be stored or ducted in any form closeto combustible substances or hydraulic equipment.

106 Oxygen dumped from the hyperbaric evacuation systemshall be ducted to a safe dumping place.

107 All traces of oil and grease shall be removed from thesystem before filling with oxygen.

108 Piping for oxygen and electrical cables shall be sepa-rated as far as practicable.

109 The oxygen supply system shall be designed so that thepartial pressure of oxygen can be maintained within the limitsof partial pressure oxygen in the inner area, required by thedecompression schedules.

E. Piping Systems

E 100 General

101 Low-pressure systems supplied from high-pressure sys-tem shall be provided with pressure relief valves. The totalrelieving capacity shall be sufficient to maintain the systempressure at not more than 110% of design pressure. The reliefdevice shall be located adjoining, or as close as possible, to thereducing valve.

102 All systems shall be provided with means of manuallyrelieving the pressure.

103 Filters shall be provided on the high-pressure side of gassystems.

104 Pipe ends in hyperbaric chambers (NOTE: In this casefor differential pressures exceeding 1 bar) shall be arranged sothat injuries due to suction are avoided. Open ended exhaustpipe work shall be fitted with guards for finger protection. Gasinlet pipe work shall be fitted with some form of diffuser.

105 All pipe penetrations in the hyperbaric evacuation unithull and in hyperbaric chambers shall be fitted with externaland internal shut-off valves mounted directly on the shell plat-ing. Valves may be mounted close to the shells, provided thatthe piping between the shell and valve is well protected and hasa minimum thickness according to the rules. All penetratorsmust be clearly marked to show their function. Valves must befree of corrosion and must move freely through their full range

DET NORSKE VERITAS


of operation. All external valves shall be secured in either theopen or closed position to avoid accidental operation duringlaunching.

E 200 Hyperbaric evacuation chambers

201 In addition to the requirements in E105 all penetrationsfor lines designed for gas distribution (e.g. supply, exhaust andequalisation) shall be fitted with non-return valves or flowfuses as appropriate for the direction of gas flow. Lines specif-ically designed for non distribution purposes (e.g. analysis)shall be kept to the minimum diameter possible and limited toa maximum of 5 mm.

202 The piping between externally mounted non-returnvalve or flow-fuse and the external shut-off valve shall be wellprotected and have minimum thickness according to Sec.8.

Definitions to the expressions DSV-SURFACE, DSV-BOUNCE and DSV-SAT are found in DNV-OSS-305 andDNV-OS-E402.

203 The compartments shall be fitted with a safety valve ora visual and audible overpressure alarm alerting the operatorsat the manned control station.

Penetrations for safety valves shall be provided with shut-offvalves on both sides of the shell plating. These shut off valvesshall be sealed in the open position. Any safety valves shall beset to open at a pressure of approx. 3% above the design pres-sure.

204 Valves in pressure vessels designed for holding water/liquid shall be considered in each case.

F. Environmental Conditioning in Hyperbaric Evacuation Chambers and Adjoining

Decompression Chambers and Tunnels

F 100 Thermal control of hyperbaric evacuation units

101 Means should be provided to maintain all the occupantsin thermal balance and in a safe and breathable atmosphere forall environmental conditions envisaged - air temperature, seatemperature and humidity - and with the maximum and mini-mum number of divers likely to be carried.The effects of hypothermia should be considered and the effec-tiveness of the arrangements provided should be established asfar as is reasonable and practicable under all conditions envis-aged. However, in no such case should the duration of theunit's autonomous life-support endurance be less than 72hours. [IMO Guidelines Res. A.692 (17): 8.1].

102 Hyperbaric evacuation unit shall have a thermal controlsystem with controls and capacity sufficient to maintain a com-fortable temperature for the evacuees in the chamber (refIMCA Guidelines D 02/06). The thermal system shall be fittedwith a temperature indicator at a manned control station.

103 The thermal systems shall be provided with redundancy.This redundancy is in the event of a possible loss of mainpower.

104 Hyperbaric evacuation units operating in cold climatesshall have emergency means of preventing excessive heat lossby the evacuees for a period of 72 hours at dmax and shall beindependent of the main thermal control unit.

Guidance note:This can be achieved by heating the chamber environment, theevacuees directly by heated suits, or by passive thermal insula-tion as well as heating the evacuee’s breathing gas by active orregenerative methods.The requirement should meet the event that fewer evacuees maybe present in the HEU and thereby provide less heat than what iscalculated for with the full contingency.


105 The compartments shall be provided with a system forheating and cooling, enabling temperature regulation withinthe acceptable temperature zone defined vs. depth in IMCAGuidelines D 02/06 Figure 4. The system shall be tested todetermine the regulations from set point under steady condi-tions.

F 200 Humidity reduction in chambers

201 A system to reduce the humidity in the living compart-ments shall be provided. A relative humidity of 70% should bemaintainable under steady conditions.

F 300 Noise reduction

301 Silencers shall be fitted and the system shall be sodesigned that the crew cannot be exposed to harmful noise lev-els.

Guidance note:IMO resolution A.468 (XII) code on noise levels onboard ships.


302 Silencers shall be fitted with shields which provide pro-tection against possible fragmentation but which do not affectthe gas flow.

F 400 Gas circulation systems for chambers

401 Adequate equipment should be provided and be suitablysituated to maintain oxygen and carbon dioxide levels andthermal balance within acceptable limits while the life-supportequipment is operating. [IMO Guidelines Res. A.692 (17):8.4].

402 Internal circulation systems for gas in the chambers shallbe such that homogeneous gas content is ensured.

403 Pressurising and exhaust systems shall be arranged toensure an even mixing of gas.

404 The circulation system shall have sufficient capacity toavoid stratification of gas layers in the chambers and maintaina homogenous gas mix at the set operational parameters.

405 Materials shall be considered for toxic or noxious prop-erties.

F 500 Removal of carbon dioxide

501 Carbon dioxide removal systems or atmosphericrenewal systems shall be arranged for the hyperbaric evacua-tion chambers. All compartments shall be arranged with redun-dancy in carbon dioxide removal systems.

502 Carbon dioxide removal systems or atmosphericrenewal systems for normal operation shall have the capacityto maintain the partial pressure of carbon dioxide below 1 kPacontinuously based on a production rate of 490 ml per minuteper person.

503 Bell divers shall have a self-contained, self-poweredemergency absorption system with a capacity for 24 hours.

504 Environmental effects on scrubbing materials, such astemperature and humidity shall be taken into account. Whererequired, heating shall be provided to maintain the temperatureof the containers.

F 600 Regeneration of gas (if applicable)

601 Where a system for regeneration of gas is fitted, thisshall ensure only a limited content of contaminants. The sys-tem shall be capable of maintaining the contaminant gas con-tent below a threshold limit partial pressure given at themaximum operating depth of the hyperbaric evacuation sys-tem.

602 Water traps for gas reclaim shall be designed for sim-plicity of cleaning, disinfecting and drying.

DET NORSKE VERITAS


G. Gas Control Systems

G 100 Control stands

101 Requirements for instrumentation are given in Sec.5.

102 The control stands shall have means for:

— choice between gas storage containers— pressurising and pressure regulation (including escape

trunk)— decompression (including escape trunk)— equalising the pressure between compartment and escape

trunk— controlling oxygen flow to compartments— controlling oxygen and mix gas supply to masks.

G 200 Helium and oxygen mixing systems for direct supply for breathing (if fitted)

201 If systems for mixing of helium and oxygen for subse-quent direct supply for breathing are fitted, these shall meetrequirements stipulated in DNV-OS-E402.

H. Closed Circuit Breathing Systems (CCBS) (if fitted)

H 100 General

101 Installation of CCBS is not required as a condition forthe standard. Indeed it must be determined if the evacuees arecapable of breathing on masks under the conditions they willbe subjected to.However, if such systems are installed, they shall comply withthe requirements stipulated in DNV-OS-E402.

I. Facilities, Food and First Aid

I 100 General

101 The hyperbaric evacuation unit is to be designed for therescue of all divers in the diving system at the maximum oper-ating depth.The compression chamber should provide a suitable environ-ment and adequate facilities, including, where appropriate,seat belts, for the maximum number of persons for which theunit is designed.The seating or other arrangements provided should bedesigned to provide an adequate degree of protection to thedivers from impact collisions during launch and while the unitis afloat. [IMO Guidelines Res. A.692 (17): 6.1].The chamber shall be equipped with one seat and one seatbeltfor each diver.

102 Protective headgear shall be provided for the occupants.

103 For the contingency of rescues requirements shall bepossible to meet in practical terms. Design of the evacuationfacilities shall be based on ergonomic studies taking into con-sideration all relevant aspects of the operating conditions.

104 First-aid equipment, sickness bags, paper towels, wastedisposal bags and all necessary operational instructions forequipment within the compression chamber should be availa-ble within the chamber, on board the parent vessel and ashore.[IMO Guidelines Res. A.692 (17): 8.11].

105 First aid kit must be provided to the level specified in thediving contractor’s manuals. (Ref. Medical Equipment to beHeld at the Site of an Offshore Diving Operation, DMAC 15and Provision of First Aid and the Training of Divers, Super-visors and Members of Dive Teams in First Aid, DMAC 11).

106 The kit must be in a suitable protective container clearly

marked with a white cross on a green background.

107 The kit must have been checked for integrity within thelast 6 months with the date the next check is due clearlymarked on it.

108 An adequate supply of food and water should be pro-vided within the hyperbaric evacuation unit.In determining, in particular, the amount of water to be pro-vided, consideration should be given to the area of operationand the environmental conditions envisaged. [IMO GuidelinesRes. A.692 (17): 8.7].

109 Under the SOLAS regulations a lifeboat must containcertain items. An HEU should therefore contain all of the fol-lowing that are relevant to the type of HEU:

— watertight containers containing a minimum of 3 litres ofdrinking water per occupant for the maximum number ofoccupants

— a rustproof dipper/ladle with lanyard — a rustproof graduated drinking vessel — food rations comprising a minimum of 10 000 kJ per per-

son for the maximum number of occupants. Food to bepacked in airtight packs kept in a watertight container

— three tin openers— six doses of anti sea sickness medicine and one seasick bag

per occupant, all for the maximum number of occupants.Seasickness pills must be available for issue to all diversprior to launching the HEU.

110 Where the chamber is intended to be occupied for morethan 12 hours, arrangements for the collection or discharge ofhuman waste should be provided. Where discharge arrange-ments are provided they should be fitted with suitable inter-locks. [IMO Guidelines Res. A.692 (17): 6.1].

One toilet shall normally be required per pressure level. Thetoilet may be flush type or disposable bag type. In connectionwith the toilet there shall be a scavenging or cleaning facilityto get rid of bacteria and odour. The toilet facility should belocated separately from the normal seating arrangement.Discharge of human waste must be considered carefully, asseasickness will possibly be a major problem.Self contained scrubbers for CO2 are in such cases of little use,and dependency on such units alone should not be planned.

111 If flush type toilets are installed, the systems shall bedesigned so that drainage cannot take place during sitting use.(See also the requirements for safety locks given in Sec.3B200.

112 Sanitary systems connected to external systems shall bedesigned to avoid an unintentional pressure rise in the externalsystem in case of malfunction or rupture of the hyperbaric sys-tems' sanitary systems.

Guidance note:It is imperative that the various aspects of possible evacuationconditions are considered carefully when providing facilities fora large contingent of crew in cramped spaces. Such aspects mayinclude, but not be limited to: care for injured crew, decontami-nation, vomiting and faeces due to motion sickness, large con-centrations of human waste gases, bacterial contamination, (deadevacuees) provisions of food and water, temperature and humid-ity. Segregation in accordance with the ability to care for oneselfmay be necessary.


I 200 Hyperbaric evacuation units used as decompres-sion chambers during normal operations

201 When the HEU is also used as a decompression chamberbeing part of the diving system during normal diving opera-tions, the following requirements shall be met:

a) One bunk shall be provided for each crew member in the

DET NORSKE VERITAS


decompression chamber living compartment permittingthem to rest comfortably.

b) For chambers used in DSV-SAT systems the bunks

should be provided and measure at least 198 x 80 centime-tres (ref. ILO Convention 133).

c) The living compartment should provide space for a table.

DET NORSKE VERITAS


SECTION 5ELECTRICAL, INSTRUMENTATION, COMMUNICATION

AND NAVIGATION SYSTEMS

A. General

A 100 Objective

101 The purpose of this section is to specify additionalrequirements for electrical systems and equipment servinghyperbaric evacuation systems. Emphasis is placed on the spe-cial needs associated with the design and manufacture ofhyperbaric evacuation systems, whereas general requirementsfor electrical systems and components are given in DNV-OS-D201 “Electrical Installations” and DNV-OS-D202 “Instru-mentation and Telecommunication systems”.

102 The key issues are identified in:

— the service definitions by defining 'essential', 'emergency'and 'non-important' services

— the power supply systems and capacity by specificationsfor emergency supply

— cables and penetrators— documentation requirements.

103 Specific references to other relevant standards are given.

104 Design criteria for electrical penetrators are outlined.Philosophy on earthing is specified, in that hull return is notallowed.


201 These requirements apply to all hyperbaric evacuationsystems utilised on DSV-SAT and DSV-BOUNCE divingsystems.

202 Material specification is included for insulation ofcables in the inner area.

203 Some testing is included in this section. For furtherrequirements for testing, see Sec.2 I.

204 Recognised production standards include those pro-vided by the International Electro technical Commission(IEC).

205 This section bears impact on Sec.2 (location of hyper-baric evacuation system in hazardous zones), Sec.4, Sec.6,Sec.7 and Sec.9.

A 300 Documentation

301 General:

— for electrical systems the following shall be documented(in addition to the requirements in DNV Rules for Classi-fication of Ships Pt.4 Ch.8):

— single line distribution system diagrams for the wholeinstallation. The diagrams shall give information on fullload, cable types and cross sections, and make, type andrating of fuse- and switchgear for all distribution circuits.Calculations on load balance, including emergency con-sumption and battery capacities.

— complete multi-wire diagrams, preferably key diagrams,of control and alarm circuits for all motors or other con-sumers.

— selectivity and short circuit calculations— plans showing arrangements of batteries with information

about their make, type and capacity.— plans showing arrangement and single line diagrams of the

communication system.— complete list of components and documentation on any

tests carried out on all electrical equipment to be perma-

nently installed within the chambers and the hyperbaricevacuation system.

— documentation on communication and navigation system.

A 400 Codes and standards

401 General:

The following codes and standards are applicable:

— DNV Offshore Standard DNV-OS-D201 “ElectricalInstallations”

— DNV Offshore Standard DNV-OS-D202 “Instrumenta-tion and Telecommunication systems”

— A.O.D.C.'s "Code of practice for the safe use of electricityunderwater"

— relevant IEC equipment construction and design stand-ards.

A 500 Service definitions

501 For hyperbaric evacuation systems, the normal mode ofoperation during an evacuation is an emergency condition.Other definitions may therefore seem mute points. However,for the purpose of distinguishing the relative importance ofconsumers, the following definitions are proposed:

Service Definitions

a) Essential services are herein defined as those services thatneed to be in continuous operation for maintaining thehyperbaric evacuation system's functionality with regardto sustaining the safety, health and environment of thecrew and any divers in a hyperbaric environment. Thisincludes services required by the crew monitoring thehyperbaric evacuation and the evacuees.Essential services shall be maintained for the periodrequired by safely terminating the hyperbaric evacuationoperation, including time for decompression of the diversif this is carried out in the HEU.

For services supporting divers in a hyperbaric evacuationunit, all services are essential. Minimum time is consid-ered to be the time required ensuring that the evacuees aresafely recovered into the decompression chambers of ahyperbaric reception facility or to the surface. 72 hours isconsidered to be the minimum time for recovery to thehyperbaric rescue centre.

For services supporting decompression in the HEUdecompression chamber, all required services are essen-tial. The normal decompression schedule is considered tobe the minimum time required ensuring that the divers aresafely brought to the surface. 72 hours is considered to bethe minimum time for recovery to life support package.

b) Emergency services are herein defined as those essentialservices that are required in an emergency condition wherenormal power supplies are lost. Examples of equipmentand systems for emergency services include:

— condition monitoring of emergency batteries— emergency lighting— emergency communication— emergency life support systems including carbon

dioxide removal (unless manual systems are used),gas analysis and temperature monitoring

— alarm systems for the above emergency services.

DET NORSKE VERITAS


All the above services may be considered emergency serv-ices and the required minimum operating time is consid-ered to be 72 hours.

c) Non-important services are those which are not essentialaccording to the above.

B. System Design

B 100 System voltages and distribution systems types

101 Types of distribution systems

Electrical systems with hull return shall not be utilised. Elec-trical distribution systems shall have insulated neutral (IT).

102 System voltages

For installations within the inner area (see definitions underSec.1 D), the following maximum system voltages are permit-ted:

a) The deck decompression chamber and TUP:

— for power and heating equipment: max. 250 V A.C. ifprotected against accidental touching or insulationfailures and fitted with a trip device as outlined inB307

— for lighting, socket outlets, portable appliances andother consumers supplied by flexible cables and forcommunication and instrumentation equipment: max.30 V D.C. These systems shall be supplied by isolat-ing transformers

b) The hyperbaric evacuation unit chamber:

— for all electrical equipment, voltages will be acceptedup to max 30 V D.C., and shall be supplied by isolat-ing transformers

— higher voltages than specified above may be accepta-ble upon special consideration, provided additionalprecautions are taken in order to obtain an equivalentsafety standard, e.g.: by use of earth fault circuitbreakers. (See Guidance note to B307).

103 Electrical circuits and equipment used in water shall beconsidered in each separate case and in accordance withIMCA/AODC "Code of practice for the safe use of electricityunderwater". Provisions shall be made to reduce the possiblefault currents, to which a person can be exposed, to a harmlesslevel.

104 The possible fault current through the person’s bodyshall not exceed the «perception level» which is about 0.5 mA(AC) or 2 mA (DC).If this is not possible, it shall be ensured that the fault currentwill not exceed the «let-go level» which is about 9 mA AC or40 mA DC unless special types of protective disconnectiondevices for the power supply are applied.If the fault current through the person’s body could exceed the«let-go level» 9 m A AC or 40 mA DC, special protectivedevices shall be applied (e.g. earth leakage circuit breaker)which disconnect the electric power supply quickly enough toprevent that heart fibrillation occurs. For this purpose the timerelease characteristics in relation to the magnitude of the pos-sible fault currents are given e.g. in IEC Publication No.479(1974) «Effects of currents passing through the human body».If these conditions cannot be met, the documentation and oper-ations manuals for the hyperbaric evacuation system shall con-tain a statement that persons are not allowed to operate in thewater in the vicinity of the hyperbaric evacuation unit while itselectrical equipment is in operation.

B 200 Power supply systems

201 The electrical systems and installations supplying essen-tial services related to the evacuees and or the hyperbaric evac-uation system shall be supplied from two mutuallyindependent and self contained electric power supply systemsfrom the support vessel. The required supplies relates to thevarious stages in the evacuation operation, including the periodbefore launching and during the launching of the HEU.

202 There shall be two mutually independent and self con-tained electric power supply systems on board the HEUdefined as:

— a main electric power supply system supplying all essen-tial consumers

— an emergency electric power supply system supplyingemergency consumers.

203 Normal operation of the HEU shall be possible with thecomplete emergency electrical power supply system out ofoperation.

204 All consumers that support functions required to beavailable in normal operation, shall be supplied from distribu-tion systems independent of the emergency electrical powersupply system. All consumers required to be available in emergency operationshall be supplied from distribution systems independent of themain electric power supply system. Consumers required having both main and emergency supplyshall be supplied as required by the consumers. The primary supply shall be from the main system. Upon failure of any of the required power supplies, an alarmshall be initiated.

205 The emergency supply may be either:

— a generator, driven by a suitable prime mover, or— an accumulator battery, or— a combination of the above.

If emergency consumers need to be available in the switchoverperiod from main to emergency power, either for operationalreasons or to avoid malfunction of the service, a transitionalpower source (battery back up) for these consumers shall beprovided. The capacity of this transitional power shall be min-imum 30 minutes.

B 300 Distribution systems

301 General, Arrangement. The distribution system shall besuch that, the failure of any single circuit cannot influence orset other services out of function for longer periods.

302 Control gear in the inner area, where elevated levels ofoxygen may be present, shall normally not be fitted. However,special arrangement may be acceptable after consideration ineach case, based on special precautions (e.g. the equipmentmay be pressurised with a suitable gas (purging) or there maybe other explosion protection concepts).

303 Devices for easy disconnection of all electrical installa-tions in the decompression chambers in an emergency situa-tion shall be fitted. These devices shall be located on a mannedcontrol stand. It shall be possible to disconnect each chamberseparately.

304 Emergency circuits wiring shall be fire proof in accord-ance with the requirements in Sec.6 B202.

Guidance note:Allowances are given to IEC 60331 cables protected by A0 divi-sion trays or piping.


305 Fuses or circuit breakers shall not be installed within thehyperbaric evacuation chamber, except for emergency batterypower-supply circuits.

DET NORSKE VERITAS


Guidance note:Fuse-gear may be installed outside the hyperbaric evacuationchamber or decompression chamber. Installation inside may bearranged as mentioned above in B303, however, fuse-gear shallnot be operable by the crew in the chambers.


306 Insulation monitoring:

— each insulated supply system, including the secondaryside of step-down or isolating transformers (or converters)shall be provided with an automatic insulation monitoringdevice, actuating switch-off and alarm by insulation faults.Alarm only may be used if a sudden switch-off of theequipment may cause danger for the evacuees. This insu-lation monitoring shall be continuous

— the indicator shall be located at the manned control stand.

Guidance note:Protection against insulation failures may be achieved by doubleinsulated apparatus or earth fault circuit breakers.


307 Electric motors placed in the inner area shall be providedwith overload alarms or be inherently safe. The alarms may beinitiated by over current, or by temperature detector in themotor itself. For motors in the hyperbaric evacuation chamber,alarms in the hyperbaric evacuation unit may be accepted. Thenormal over current protections (short circuit protection) onthe motors shall also be in place.

Guidance note:The requirement provides safety against overheating, with thepossible development of toxic gasses, and or danger of flash firein oxygen enriched environments. In special cases there may beother risks involved in overheating of the motors. However, if themotor is considered inherently safe, the requirement for the over-load alarms may be revoked. This is considered preferable incases where the number of alarms should be kept at a minimumso as to avoid stressful operating conditions and or confusion.


308 Transformers, converters and inverters shall be fittedwith a cooling arrangement to avoid service temperaturesexceeding 55°C.

B 400 Capacity

401 Power supplies required for the operation of life-supportsystems and other essential services should be sufficient for thelife-support duration. [IMO Guidelines Res. A.692 (17): 10.2]

Capacity of main source of power:

All services for normal operations are according to A501adefined as essential services, and shall be included in the serv-ices to be supplied by the main source of power.

402 Capacity of emergency source of power:

All services for emergency operations are according to A501bdefined as emergency services, and shall be included in theservices to be supplied by the emergency source of power.

Also:

— power supplies required for the emergency services shallbe sufficient for the duration stipulated

— each compression chamber shall be provided with a mainand emergency source of lighting sufficient for the stipu-lated time and of sufficient luminosity to allow the crewand/or evacuees to read gauges and operate essential sys-tems within the chambers

— the emergency source of power and the emergency powerdistribution shall be capable of handling peak loads.

B 500 Environmental requirements

501 General: All electrical equipment and installation,including the power supply arrangements, should be designedfor the environment in which they will be required to be oper-ated and designed to minimize the risk of electrical capacitydepletion as a result of a fault, fire or explosion, electric shock,the emission of toxic gases and galvanic action. [IMO Guide-lines Res. A.692 (17): 10.1].All electrical equipment and installations, including powersupply arrangements, shall be constructed and installed tooperate satisfactorily under all environmental conditions forwhich the hyperbaric evacuation system is designed. SeeDNV-OS-D201 Ch.2 Sec.3 B, C and D.

502 Electrical equipment within the compression chambershould be designed for hyperbaric use, high humidity levelsand marine application. [IMO Guidelines Res. A.692 (17):10.1].Electrical equipment within the decompression chamber shallalso be designed for oxygen-enriched atmospheres. Referenceis made to:

— DNV-OS-D202 “Instrumentation and Telecommunicationsystems”,

— NFPA53M (National Fire Protection Agency) "Manual onFire Hazards in Oxygen-Enriched Atmospheres 1990",

— AODC 035 "Code of practice for the safe use of electricityunderwater", and

— AODC 062 "Use of battery operated equipment in hyper-baric conditions”.

503 All materials of submerged systems shall be such thattheir electrical and mechanical properties are not influenced bywater absorption.

Guidance note:Reference is also given to DNV-OS-D201 and DNV-OS-D202. AODC's "Code of practice for the safe use of electricity under-water" is available from IMCA.


B 600 Inspection and testing requirements

601 All switchboards shall be designed, constructed and cer-tified in accordance with the requirements given in DNV-OS-D201 Sec.4.

602 Testing shall be carried out in accordance with therequirements given in DNV-OS-D201 Sec.10 D.

C. Equipment Selection and Installation

C 100 General

101 Arrangements:

— all electrical equipment and installation shall be designedand arranged in order to minimise the risk of fire, explo-sion, electrical shock, emission of toxic gases to person-nel, and galvanic action of the surface decompressionchamber or hyperbaric evacuation chamber

— the electric power supply arrangement shall be designed tominimise the risk of electrical capacity depletion as aresult of a fault, fire or explosion, electric shock, the emis-sion of toxic gases and galvanic action.

C 200 Enclosures

201 Pressure resistant enclosures in the inner area or on thehyperbaric evacuation shall be designed for 1.3 times thedesign pressure relevant to the location on the hyperbaric evac-uation system. Tests shall be carried out with gas or water asapplicable.

DET NORSKE VERITAS


202 In the water, all metal enclosures shall be earthed bymeans of a copper earth conductor incorporated in the supplycable, with cross-section at least of the same size as the supplyconductors and not less than 1 mm2. For cables having metalwire braid or armour this may alternatively be used as earthconductor, provided that the braiding cross section is suffi-cient.

203 Enclosures of plastic materials are not to give off toxic,noxious or flammable gases when overheated. The plasticmaterials shall be flame retardant at least in compliance withIEC-Publication No. 92—101 (1980) «Electrical Installationsin Ships, Part 1 General Requirements» Clause 3 1.2.

C 300 Earthing

301 All pressure vessels for human occupancy (P.V.H.O. -hyperbaric evacuation chambers) shall be provided with earth-ing connection devices for external main protective earthbonding.

C 400 Batteries

401 The battery charging arrangements should be designedto prevent overcharging under normal or fault conditions. 10.2The battery storage compartment should be provided withmeans to prevent over-pressurisation and any gas released bevented to a safe place. [IMO Guidelines Res. A.692 (17):10.2].

402 Batteries can give off potentially explosive fumes whenbeing charged. This can even be the case with “sealed” batter-ies. All necessary precautions and maintenance must beincluded in the documented maintenance system for the HES.A warning sign shall be fitted in the vicinity of any batterieswhich are trickle charged for use in the HES.

403 Batteries shall not be installed within the inner area(chambers), and should preferably not be installed in thepilot’s compartment, unless approved for such use. Approvalshall be based on evaluation of type, size, capacity and testing.

404 Battery housings shall be provided with adequate protec-tion in accordance with DNV-OS-D201 Ch.2 Sec.2 I300, so thatan accumulation of generated flammable gases is avoided. Thismay be done by providing adequate venting systems or catalyticconverters, so that an accumulation of generated inflammablegases is avoided. Monitoring of accumulated hydrogen gas shall be possible.Switchgear shall normally not be installed in the battery com-partments, unless the components are especially type approvedfor such installations.Means of preventing electrolyte from entering the bilge of thebattery housing in event of mechanical damage of battery cellsshall be provided. If not, special inspection schedules and main-tenance routines shall be laid down in the inspection manual.

405 Batteries and battery foundations shall be constructedand arranged to bear expected maximum inclination in alldirections without the risk of electrolyte leakage to the con-tainer atmosphere.

406 Pressure compensated batteries stored outside the pres-sure hull shall be designed so that leakage of electrolyte toambient seawater is avoided. The electrolyte shall be protectedagainst seawater leakage from ambience.

407 Outside stored pressure compensated batteries shallhave a pressure relief valve for dump of accumulated hydrogengas.

408 Pressure resistant battery pods shall be designed andconstructed to comply with the requirements of Sec.3 of theseRules.

C 500 Cables and penetrators

501 Cables:

a) Cables for use in the outer area (see definition under

Sec.1 D) shall comply with DNV-OS-D201 Ch.2 Sec.9 Band Sec.10 C. All cables shall have an earthed braiding orscreen around the conductors and be equipped with aninsulating outer sheet.

b) Cables for use in the inner area (see definition underSec.1 D) shall comply with the requirements given inC501a, with exception to the materials used. The materialsshall be designed for the purpose of being installed into ahyperbaric atmosphere.

c) Electrical cables shall be halogen free and shall not giveoff toxic, noxious or flammable gases even when over-heated. Dismantled ends of insulated conductors shall beprotected with sleeves of a non-combustible material (e.g.glass fibre weaves). Ordinary ship cables with insulationof a halogenated material (e.g. P.V.C.) shall not beaccepted. Synthetic insulation materials based on P.T.F.E.(Polytetrafluoroethylene) may be accepted.

d) Flexible cables for transmission of electrical power andsignals from the surface support to the hyperbaric evacua-tion, or from hyperbaric evacuation to hyperbaric evacua-tion chamber, shall be constructed as "dry-core cable" (i.e.water shall not reach the insulation of the individual con-ductors).

e) The submerged cables shall be able to withstand an exter-nal hydrostatic pressure of 1.3 times the actual externalpressure.

f) Pressure compensating fluids shall be compatible with thecable insulation and the cable jacket compounds. A speci-fication of the composition of the pressure compensatingfluids shall be submitted for approval.

g) Unless installed in pipes, electrical cables shall be readilyaccessible for visual inspection.

h) Tensile loads shall not be transferred to the electricalcables.

i) Single core AC cables shall be separated and electromag-netically shielded from signal cables.

502 Electrical penetrators for pressure vessels:

a) All electrical penetrators in pressure containing structuresshall be purpose designed and bear a product certificate(3.2) and shall be arranged with separate fittings.

b) Penetrators in pressure vessels shall be gas and water-tighteven in the event of damage to the connecting cables.

c) Electrical penetrators shall be type tested at the manufac-turers as specified below in d. Tests shall be made betweeneach conductor and screen and tests shall be carried out onpenetrators from the same production batch. The testsshall be carried out in the sequence they are listed. Thepenetrators shall show no sign of deficiency during andafter the testing.

d) Tests to be carried out include:

— a voltage test, by applying 1 kV plus twice the designvoltage for 1 minute between each conductor andscreen separately

— a hydrostatic test to a pressure of twice the designpressure, repeated 5 times

— a gas leakage test with the cables cut and open (Test-ing with air to twice the design pressure or withhelium to 1.5 times the design pressure.)

— an insulation test to 5 mega ohms at the design pres-sure, applying saltwater.

C 600 Lighting, inner area

601 Each compression chamber should be provided with asource of lighting sufficient for the life-support time and ofsufficient luminosity to allow the occupants to read gauges and

DET NORSKE VERITAS


operate essential systems within the chamber. [IMO Guide-lines Res. A.692 (17): 10.3].

602 Proper lighting shall be provided in all compartmentsand shall be sufficient to allow surveillance from outside.

603 The hyperbaric evacuation unit shall be fitted with emer-gency lighting.

604 Protection against possible bursting of electrical bulbsshall be in place.

D. Communication

D 100 General

101 The hyperbaric evacuation unit shall have emergencyradio communication (VHF) and location transpondersaccording to requirements given in the LSA code item 2.1.1(SOLAS III part B Reg. 6.2.1.1 and 6.2.2) and complying withIMO Resolution A.809(19).

102 Communications systems shall comply with the relevantrequirements given in DNV-OS-D202 “Instrumentation andTelecommunication systems”.

103 If breathing mixtures containing helium or hydrogen areused, a self-contained primary communication system fittedwith an unscramble device should be arranged for direct two-way communication between the divers and those outside thecompression chamber.A secondary communication system should also be provided.[IMO Guidelines Res. A.692 (17): 12.1].

104 A secondary (back up) communication system may be asound powered phone.

105 A dedicated VHF or equivalent wireless communicationunit should be available at the launching station, and later at theHEU if attended.

D 200 Location systems

201 Hyperbaric evacuation units designed to be waterborneshould be provided with a strobe light and radar reflector.[IMO Guidelines Res. A.692 (17): 12.3].

202 HEUs shall also be fitted with a radio distress beacon.

203 Hyperbaric evacuation units designed to be placed onthe sea-bed to await independent recovery should be providedwith an acoustic transponder. The transponder should be suit-able for operation with a diver-held interrogator-receiverwhich will be retained on board the parent ship. [IMO Guide-lines Res. A.692 (17): 12.4].The equipment provided should meet the requirements speci-fied in the amendments to the Code of Safety for Diving Sys-tems (resolution A.583 (14)). [IMO Guidelines Res. A.692(17): 12.2].

D 300 Surface radio communication

301 Hyperbaric evacuations units shall have VHF communi-cation equipment with at least two channels, for surface com-munications one of which shall be channel 16.

302 Antennas for radio communication shall be permanentlyarranged for operation in any evacuation mode.

D 400 Hardwire telephone communication

401 Except for the diving bell (see Sec.1 A602), there mustbe a dedicated hard wire two way voice communication systembetween life support control, the HES launch point and theHES internally.

402 For hyperbaric evacuation units with more than one hab-itable compartment, hardwire inter-communication system

shall be installed in all compartments.

403 For hyperbaric evacuation units with pilot facilities, ahard-wire communication system shall be installed:

— between chamber compartments and pilot cockpit— between pilot cockpit and support vessel.

404 Hyperbaric evacuation systems intended for use ofhelium shall be provided with helium unscramble provisions.The sound quality shall be of such a level that the breathingpattern of the evacuees can be easily recognised.

D 500 Visual observation of evacuees

501 Visual observation of evacuees in each compartmentshall be possible.

502 Suitable means (e.g. TV) shall be arranged for visualobservation of the evacuees in the hyperbaric evacuationchamber from the control stand for the diving system.

D 600 Other voice communication systems

601 Communication systems shall be arranged for directvoice communication between the control stand and:

— other control stands (LARS)— the diving support vessel bridge (operational command

centre).

602 Alternative means of communication with the crew inthe pilot's compartment and the crew/divers in the hyperbaricevacuation chamber shall be available in an emergency.

603 In addition to the communication system referred to inD102, a standard bell emergency communication tapping codeshould be provided which meets the requirements of that spec-ified in the amendments to the Code of Safety for Diving Sys-tems (resolution A.583 (14)).Copies of the tapping code should be permanently displayedinside and outside the hyperbaric evacuation unit. [IMOGuidelines Res. A.692 (17): 12.2].

A copy of this tapping code shall also be displayed in the divecontrol rooms.

E. Instrumentation

E 100 General

101 In general, instrumentation shall comply with the rele-vant requirements in DNV-OS-D202 and DNV Rules for Clas-sification of Ships Pt.4 Ch.9.

Table D1 Emergency communication tapping code (Suggested)Tapping code Situation

3.3.3 Communication opening procedure (inside and outside)

1 Yes or affirmative or agreed3 No or negative or disagreed

2.2 Repeat please2 Stop5 Have you got a seal?6 Stand by to be pulled up

1.2.1.2 Get ready for through water transfer (open your hatch)

2.3.2.3 You will NOT release your ballast4.4 Do release your ballast in 30 minutes from now

1.2.3 Do increase your pressure3.3.3 Communication closing procedure

(inside and outside)

DET NORSKE VERITAS


E 200 Control stands (including pilot's compartment in SPHLs)

201 In the design of control rooms, attention shall be given toergonomic matters such as communication and a systematicarrangement of equipment, according to a documented traffic flowchart. Further, it shall be ensured that noise or other disturbancewhen working does not occur (see Guidance note to Sec.4 F401).

202 Indication and operation of all vital life support condi-tions to and from the chamber(s) and the hyperbaric evacuationunit(s) shall be arranged at a single control stand or dividedbetween suitably located control stands. The control standsshall be equipped for easy operation and control of the hyper-baric evacuation system. There shall be schematic indicationof gas flow lines. The control stand for the hyperbaric evacua-tion system shall be separated from other control stands.

203 The control stands shall have indicators showing contin-uously:

— the pressure in the gas containers connected— the pressure after all pressure reducers— the pressure in each chamber compartment.

Pressure indicators on the control stand for the hyperbaricevacuation unit and entry compartments/tunnel shall bearranged for a possible comparison between each other or witha permanently installed master indicator. If cross-connectionsare incorporated, these shall be arranged in such a way as togive the operators an indication when cross-connection isbeing conducted.

Instrumentation for pressure measuring of the hyperbaric evac-uation chamber and compartments shall have an accuracy of +/-0.3% of full scale. In addition pressure indicators for the decompression cham-bers shall facilitate depth measurements with an accuracy of +/-0.25 msw in the depth range from 30 msw to 0. For other instrumentation measuring pressure the accuracyshall be +/-1% of full scale.

204 The control stands shall have a system for continuousindication of:

a) Oxygen content in each compartment individually.

b) Oxygen content in the supply to:

— umbilicals (if applicable)— compartments— masks in compartments.

The monitoring systems shall be fitted with audible and visualhigh and low level alarm.

205 Permanent provisions for calibration of and comparisonbetween oxygen analysing instruments shall be arranged onthe control stand.

206 There shall be a system for continuous monitoring ofoxygen content in main supply to the hyperbaric evacuationchamber and masks in the hyperbaric evacuation chamber. Themonitoring systems shall be fitted with audible and visual highand low level alarm. There shall be an audio-visual gas flowindicator in the oxygen supply to the decompression chambers.

207 The control stands shall have a system for regular indi-cation of:

— carbon dioxide content in each transfer compartment indi-vidually, and

— carbon dioxide content in the hyperbaric evacuation cham-ber.

208 In addition to any instrumentation necessary outside thecompression chamber, suitable instrumentation should be pro-vided within the chamber for monitoring the partial pressuresof oxygen and carbon dioxide and be capable of operation for

the duration of the available life-support period. [IMO Guide-lines Res. A.692 (17): 8.5].

209 There shall be systems for indication of temperature andhumidity in the inner area of the compartments located at thecontrol stand.

210 Alarms for abnormal conditions are required at the con-trol stand, if automatic environmental control systems arearranged for regulation of gas composition, pressure and tem-perature in the inner area.

211 It shall be possible to carry out work and to communi-cate effectively in the control room(s) co-ordinating the evac-uation even if there is no normal breathable atmosphere in theroom(s). Release of dangerous quantities or mixtures of gas from cham-ber or gas plant shall never take place in the control room(s).

E 300 Pressure indicators in hyperbaric evacuation chambers compartments

301 Each compartment in the hyperbaric evacuation unitshall be fitted with indicators visible to the evacuees inside,showing:

— internal pressure— pressure of gas stored on the hyperbaric evacuation unit.

302 Means shall be provided for isolating all pressure indi-cators without interrupting vital functions in the gas distribu-tion system.

303 Instrumentation containing mercury or other toxic sub-stances, shall not to be used.

E 400 Oxygen analysing systems

401 Oxygen analysing systems shall have an accuracy of atleast +/-0.015 bar partial pressure oxygen in the analysingrange specified by the decompression schedule.

402 The hyperbaric evacuation chamber compartments shallhave oxygen analysers inside.

403 Two independent oxygen measuring systems shall beprovided.

E 500 Carbon dioxide analysing systems

501 Carbon dioxide analysing systems shall have an accu-racy of +/-0.001 bar partial pressure in the analysing rangespecified by the decompression schedule.

502 Carbon dioxide gas for calibration shall be availablewhen located on the diving support vessel.

503 The hyperbaric evacuation unit shall have self-containedcarbon dioxide analysing systems for each compartment.

504 Two independent monitoring systems for C02 shall beprovided if in normal operation the atmosphere within a com-partment is breathed.

E 600 Other gases

601 Appropriate sensors shall be provided to monitor anyother dangerous gas which may be present in the pilot's com-partments, for example, due to the operation of thermalengines or batteries.

602 The instrumentation for systems intended for other gasesthan air or helium and oxygen mixes shall be considered ineach case.

Guidance note:Certain operations may require instrumentation for the analysisof hydrocarbon gases, H2S, radiation and other contaminants.


603 Calibration gases shall be available for each relevant gasmix whilst the HEU is located on the diving support vessel.

DET NORSKE VERITAS


E 700 Contaminants

701 A system for sampling and analysing of trace contaminantsshall be arranged. Analysing by test tubes may be acceptable.

E 800 Automatic environmental control systems

801 The following requirements apply when systems forautomatic regulation of gas composition, pressure and temper-ature in the inner area are installed.

802 The design principles given in DNV-OS-D202 andDNV Rules for Classification of Ships Pt.4 Ch.9, apply on ageneral basis.

803 The most probable failure in the systems shall result inthe least critical of any possible new conditions (fail to safety).

804 Automatic control systems shall keep process variableswithin the limits specified during normal working conditionsand the alarm systems shall be activated when the limits areexceeded.

805 Alarm at the control stand is required for abnormal con-ditions. The alarm system is also to be activated by failures inthe alarm system such as broken connections to measuring ele-ments. The alarm system shall be independent of the automaticcontrol system so that failure in one of the systems cannotinhibit operation of the other system.

806 A manual back-up system for the automatic control sys-tem is required.

F. Navigation (SPHL)

F 100 Visibility

101 Visibility from the control room of the hyperbaric evac-uation unit (SPHL) shall be provided as follows:

— Visibility outside may be achieved by view ports or by tel-evision systems with displays visible from the pilot’s con-trol station.

— The field of vision shall take into account the operations ofthe hyperbaric evacuation unit (SPHL).

— The collective field of vision bellow the horizontal planethrough the centre of the hyperbaric evacuation chambershall be such that it covers the complete field required forsafe navigation.

F 200 Orientation

201 Heel and trim indicators shall be so arranged that thenecessary information is visible from the pilot’s position.

F 300 Positioning

301 An operational compass shall be fitted, which is lumi-nous or provided with suitable means of illumination. The compass shall be permanently fitted at the steering posi-tion on a suitable mounting arrangement. It shall be determined that the compass performance is satis-factory and that it is not unduly affected by magnetic fittingsand equipment in the lifeboat.

F 400 Speed

401 SPHL shall have instruments for registration of forwardspeed. It shall be possible to register speed relative to themotion through water.

F 500 Lights and reflectors

501 Hyperbaric evacuations units are to have a retrieval flashlight. The retrieval flash light is to be visible on a range of min-imum 2 nautical miles from all directions.The recovery light is to be powered by its own battery, assuringa working time of at least 72 hours.

502 Hyperbaric evacuation Systems shall be fitted with radarreflectors which may be by means of adhesive strips.

F 600 Radiotelegraphy and radiotelephony

601 Radiotelegraphy/radiotelephony shall be installed asrequired by applicable parts of SOLAS Ch. IV reg. 9, 10, 11.

DET NORSKE VERITAS


SECTION 6FIRE PREVENTION, DETECTION AND EXTINCTION

A. General

A 100 Objective

101 The purpose of this section is to specify additionalrequirements for fire protection serving hyperbaric evacuationsystems. Emphasis is placed on the special needs associatedwith the design and manufacture of hyperbaric evacuation sys-tems, whereas general requirements for fire protection aregiven in DNV-OS-E402 "Diving Systems" and for guidanceDNV-OS-D301 “Fire Protection”.

102 Key issues are identified through requirements for mate-rials, insulation and separation from adjacent spaces, sprinklersystems and extinction agents. Reductions in hazards areensured through these issues.

103 For quantitative design parameters and functionalrequirements, reference is made to the relevant standards andguidelines, including DNV-OS-E402 "Diving Systems" andfor guidance DNV-OS-D301 “Fire Protection”.


201 In addition to the basis requirements in DNV-OS-E402"Diving Systems" and guidance in DNV-OS-D301 “Fire Pro-tection”, supplementary information is found in the NationalFire Protection Agency Codes' chapters on hyperbaric systemsand oxygen enriched environments. (Ref. NFPA 53, Recom-mended Practice on Materials, Equipment and Systems Usedin Oxygen-Enriched Atmospheres, 1999 edition.)

202 Further requirements applicable to the support vessel aregiven in SOLAS that shall be applied as far as practicably pos-sible.


204 This section bears impact on Sec.5 (build-up of staticelectricity, degree of protection provided by enclosure IP.

A 300 Documentation

301 Fire prevention, detection and extinction shall be docu-mented as follows:

— a list of all materials to be installed in the inner area, wherepossible with data on and or evaluation of flammabilityand toxicity hazard in conditions under which the materi-als can be used

— plans and specifications of fire detection, fire alarm andfire extinction equipment for both the inner and outer area

— plans and specifications on arrangements and materialsused for prevention of oxygen fires.

A 400 Control stands

401 Control rooms for hyperbaric evacuation systemslocated in hazardous zone 2 shall comply with the require-ments given in DNV-OS-A101 "Safety Principles andArrangements" Sec.4. Other control stands, essential to the function of the hyperbaricevacuation system, shall be protected such that the controlsmay be maintained whilst the crew are being evacuated in theevent of a fire.

B. Fire Protection

B 100 Materials

101 Materials used in the construction and installationshould so far as is possible be non-combustible and non-toxic.

[IMO Guidelines Res. A.692 (17): 9.1].The use of combustible materials shall be avoided whereverpossible. Combustible materials include materials which maybe brought to explode, or burn independently in the resultinggas environment, applicable to:

— the outer area: air at a pressure of 1 bar— the inner area: air at applicable maximum to minimum

pressure range— the enclosure area: air at a pressure of 1 bar (SPHL).

102 Structural components, furniture and knobs, paints, var-nishes and adhesives applied to these, shall be of non-hazard-ous materials., i.e. they shall be tested in accordance withrelevant parts of IMO res. MSC.61(67) (FTP Code) or otheracknowledged standard.

Guidance note:In order to comply with B101, materials for use in inner areashould be tested at an elevated pressure.


103 Materials and arrangements are wherever possible to bemade so as to avoid build-up of static electricity and to mini-mise the rise of spark production due to electrical failures orcombination of materials. In inner areas without electricalequipment, the furniture and floors of electrically conductormaterials may be used. For inner areas where electrical equipment is used, the materi-als and arrangements shall be made so as to minimise contactwith earthed metalwork.Signboard warning of possible ignition caused by static elec-tricity from clothing when oxygen is used (released) shall beposted.

104 Hyperbaric evacuation systems should not be located inzone 0 or zone 1; hazardous areas and high fire risk areasshould be avoided as far as is reasonably practicable. [IMOGuidelines Res. A.692 (17): 5.9].The hyperbaric evacuation system shall be located in a safearea as defined in Sec.2. Hyperbaric evacuation systems situ-ated on open decks shall not be located in the vicinity of ven-tilation openings from machinery spaces, exhausts orventilation outlets from galley.

105 Outer areas situated in enclosed spaces shall be separatedfrom adjacent spaces, by means of A-60 class bulkheads ordecks. Doors between outer area and adjacent enclosed areasshall have the same fire integrity as the bulkheads in which theyare fitted, shall be self-closing. Hold-back arrangements thatare not subject to remote release from bridge and with auto-matic closing upon fire alarm are prohibited. Piping and cables essential for the operation of the hyperbaricevacuation system are regarded as part of the system and shallbe laid in separate structural ducts insulated to A-60 classstandard.

106 For hyperbaric evacuation systems situated on opendecks, the outer area shall be separated from adjacent machin-ery spaces by A-60 class fire divisions except when themachinery space has little or no fire risk.

107 Outer area fitted in enclosed spaces shall be fitted withindependent mechanical ventilation with minimum 8 airchanges per hour.

108 Oxygen dumped from the hyperbaric evacuation systemshall be ducted for dumping at a safe place.

109 Liquid fuel burning machines shall be fitted with either

DET NORSKE VERITAS


alarms or shut-off valves to ensure that day-tanks, if fitted, can-not be filled to overflow.

110 In hyperbaric evacuation units designed to pass throughfires, the breathing gas bottles and piping systems and otheressential equipment should be adequately protected.In addition, thermal insulation should be non-toxic and suita-ble for this purpose. [IMO Guidelines Res. A.692 (17): 8.10].

C. Fire Detection and Alarm System

C 100 Outer area

101 When situated in enclosed spaces the outer area shall beequipped with automatic fire detection and alarm system com-plying with DNV-OS-D301 Ch.2 Sec.4. The section or loop ofdetectors covering the outer area shall not cover other spaces.

C 200 Inner area

201 The inner area should be equipped with automatic firedetection and alarm system complying with DNV-OS-D301Ch.2 Sec.4. The section or loop of detectors covering the innerarea should not cover other spaces. Detectors shall comply with the material and arrangementrequirements given for the oxygenated hyperbaric environ-ments.

C 300 Enclosure area

301 The enclosure area shall be equipped with fire detectionand alarm system as applicable in each case. Portable detectorsmay be accepted.

C 400 Fault detection

401 Provisions shall be made for warning of faults; e.g., volt-age failure, broken line, earth fault, etc., in the fire alarm anddetection system. (Ref. FSS Code Ch.9.2.5.1.5).

D. Fire Extinguishing

D 100 Outer area

101 When situated in enclosed spaces, the outer area shall beequipped with a fixed, manually actuated fire extinguishingsystem with such a layout as to cover the complete system.

102 The extinguishing system shall be either:

— an automatic sprinkler system in accordance with FSSCode Ch.7 or 8, or

— a gas system approved for use in machinery spaces of cat-egory A and with the limitations given in 103.

103 If a gas system is selected, the agent shall be of a typenot hazardous to humans in the concentration foreseeable inthe protected space. The concentration shall be below theNOAEL as defined in IMO MSC/Circ.848.

Guidance note:No fire suppression agent should be used which is carcinogenic,mutagenic, or teratogenic at concentrations expected during use.No agent should be used in concentrations greater than the car-diac sezitisation NOAEL (no observed adverse effect level), northe ALC (approximate lethal concentration). (See IMO MSC/Circ.776)


104 Pressurized gas storage equipment, hyperbaric cham-bers positioned within outer area and including hyperbarictrunks to the evacuation unit passing through enclosed spaces,shall have object protection by means of water-spray of notless than 10 litres/m2 per min of the total horizontal projectedarea. (Res. A.831 (19) refers.

The object protection water spray system shall be independentof any other fixed fire extinguishing system for outer area andbe capable of remote start from bridge, outer area and innerareas protected. The object protection water spray system shallbe capable of operation with any other single space onboard(including engine room) put out of action due to fire.

105 When situated on open deck, the outer area shall be pro-vided with fire extinguishing equipment, which shall be consid-ered in each case. Evacuation systems shall be provided withfire extinguishing systems enabling launching/ handling of theevacuation unit in the event of a fire in the vicinity of the HES.Fire hydrants and hoses may, if correctly positioned, be consid-ered as providing the necessary fire extinguishing on open deck.

106 In hyperbaric evacuation units that are designed to floatand may be used to transport divers through fires, considera-tion should be given, where practicable, to providing an exter-nal water spray system for cooling purposes (see 7.5)(107).[IMO Guidelines Res. A.692 (17): 9.3].

107 Hyperbaric evacuation units on ships required to be pro-vided with fire-protected lifeboats should be provided with asimilar degree of fire protection. [IMO Guidelines Res. A.692(17): 7.5].

108 Portable fire extinguishers shall be of approved type andcomply with DNV-OS-D301 Ch.2 Sec.3.

109 Portable fire extinguishers shall be distributed through-out the space containing the hyperbaric evacuation system sothat no point in the space is more than 10 m walking distancefrom an extinguisher.

110 One of the portable fire extinguishers shall be fitted neareach entrance.

111 A portable fire extinguisher shall be fitted at the controlstand.

112 Spare charges or extinguishers shall be provided onboard, 100% for the first 10 extinguishers and 50% for remain-ing extinguishers.

113 The same type of portable extinguisher shall be usedthroughout the system. Compatibility with the remainingextinguishers, used elsewhere on the vessel, is recommendedfor extinguishers used in the outer area.

D 200 Inner area

201 A fire-extinguishing system should be provided in thehyperbaric evacuation unit which should be suitable for expo-sure to all depths down to the maximum operating depth. [IMOGuidelines Res. A.692 (17): 9.2].It shall be possible to actuate the fixed extinguishing systemfrom both within the hypobaric chambers and from outside.

202 The extinguishing agent shall be water, unless anapproved alternative exists.

203 The fire-fighting device in the inner area shall berechargeable without depressurising the chamber.

204 Provisions shall be made for possible discharge of lessthan the total supply of extinguishing agent.

205 Gauges and monitoring devices that continuously indi-cate the amount of extinguishing agent and the charging pres-sure are to be provided.

206 The fire-fighting device is to be fitted with a seal indicat-ing whether the device has been operated and should be func-tion tested every six months.

207 In addition to the above, each compartment in the innerarea should be equipped with a portable hyperbaric fire extin-guisher approved for the maximum operational depth of thechamber. The extinguishers shall be suitable for Class A, ClassB and Electrical fires up to a maximum of 24 volts. The propel-lant shall be air or Heliox as applicable to the diving operation.

DET NORSKE VERITAS


D 300 Enclosure area

301 The enclosure area, between a lifeboat shell and thechamber, shall be equipped with manually actuated portablefire extinguishers with such a layout as to cover the completearea and expected types of fire.

302 The portable fire-extinguishing equipment shall be of anapproved type suitable for extinguishing oil fires as required inthe LSA Code Sec.4.4 Pt. 4.4.8 Sub.28.

Guidance note:For the definition of a portable fire-extinguisher see Resolutionsfrom the 15th Session of the Assembly of IMO, November 1987.Resolution A.602(15) adopted on 19 November 1987 “Annex:Revised guidelines for marine portable fire extinguishers”, Pt.2definitions sub. 2.2.For classification of suitable extinguishers for extinguishing oilfires, refer to Resolutions from the 15th Session of the Assemblyof IMO, November 1987. Resolution A.602 (15) adopted on 19November 1987 Annex: Revised guidelines for marine portablefire extinguishers, Pt. 3 Classification.


303 If a gas system is selected, the agent shall be of a typenot hazardous to humans in the concentration foreseeable inthe protected space. The concentration shall be below theNOAEL as defined in IMO MSC/Circ.848.

304 Pressurised gas storage containers that are certified inaccordance with Sec.3, shall be fitted with insulation or ameans of cooling, in order to protect such pressure vesselsfrom the heat transfer of an external fire.

305 The engine housing(s) should have a fixed extinguishingsystem approved for use in machinery spaces of cat. A.

306 One of the portable fire extinguishers shall be fitted nearthe entrance to the SPHL cockpit, and one shall be fitted at thecontrol stand in the SPHL.

307 Spare charges or extinguishers shall be provided onboard.

308 The same type of portable extinguisher should, if possi-ble, be used. Compatibility with the remaining extinguishers,used elsewhere on the vessel, is recommended.

D 400 Scope

401 The extent of fire protection will be given special con-sideration in each case, both with regard to the internal parts ofthe hyperbaric evacuation system and to the surface supportvessel. The size of the hyperbaric evacuation system will gen-erally be one of the major factors influencing the type andextent of fire extinguishing devices, whether fixed or portable.

402 The size of the hyperbaric evacuation system will gener-ally be the major factor influencing the type and extent of fireextinguishing devices, whether fixed or portable.

E. Miscellaneous Equipment

E 100 Fire-fighter's outfit

101 When the risk analysis reveals that fire presents a dangerwhilst launching, a complete set of fire-fighter's outfit comply-ing with DNV-OS-D301 Ch.2 Sec.5 for each person requiredfor operation of the hyperbaric evacuation system during a fireshould be located at the main control stands. The sets are addi-tional to other sets on board.

Breathing apparatus are required for control stations mannedduring recovery of hyperbaric evacuation or launching ofevacuation unit.

Guidance note:Fire-fighter's outfit is recommended in consideration of the timeit may take for recovery of the crew into the hyperbaric evacua-tion chamber and all the way up to the evacuation system. Theoperator(s) of the hyperbaric evacuation system may be exposedto hot environments which render evacuation impossible unlessthey are protected whilst performing their work.


E 200 Portable fire extinguishers

201 Portable fire extinguishers shall be of approved type andcomply with DNV-OS-D301 Ch.2 Sec.3.

202 Portable fire extinguishers shall be distributed through-out the space containing the hyperbaric evacuation system sothat no point in the space is more than 10 m walking distancefrom an extinguisher.

203 One of the portable fire extinguishers shall be fitted neareach entrance.

204 A portable fire extinguisher shall be fitted at the controlstand.

205 Spare charges or extinguishers shall be provided onboard, 100% for the first 10 extinguishers and 50% for remain-ing extinguishers.

The same type of portable extinguisher shall be used through-out the system, one type for the outer area and one type for theenclosure area. Compatibility with the remaining extinguish-ers, used elsewhere on the vessel, is recommended for extin-guishers used in the outer area.

DET NORSKE VERITAS


SECTION 7LAUNCH AND RECOVERY SYSTEMS

A. General

A 100 Objectives

101 Launch and recovery systems shall be certified inaccordance with statutory requirements applicable to the FlagState where the support vessel is registered, geographic area ofoperation and terms of delivery.

102 Launch and recovery systems may be Type Approvedand certified by a competent person as lifting appliances inaccordance with the procedures applicable for the issue of therequired certificate. Operational limitations shall be stated inan appendix to the certificate.

103 The purpose of this section is to specify additionalrequirements for lifting appliances serving hyperbaric evacua-tion systems. Emphasis is placed on the special needs associ-ated with the design and manufacture of hyperbaric evacuationsystems, whereas general requirements for lifting appliancesare given in SOLAS and DNV Standard for Certification No.2.22 Lifting Appliances.

104 Key issues are identified through requirements for inter-locking of the mating system between hyperbaric evacuationchamber and transfer compartment shows the emphasis placedon these essential systems.

105 Load conditions need to be defined.


201 SOLAS requirements should be applied as far as practi-cably possible.

202 These requirements may also be applicable as Flag Staterequirements.

203 Some testing requirements are given, limited to thosespecified in the original IMO text. Additional testing may berelevant depending on the type of evacuation system installed.

204 For quantitative design parameters and functionalrequirements, reference is made to relevant standards andguidelines, including DNV Standard for Certification No. 2.22Lifting Appliances.

205 Limitations are given in the rating of the handling sys-tems with respect to a given, specified, sea-state defined as asignificant wave height in meters.


207 This section has impact on the requirements for strengthwith respect to deck loading on the support vessel and to theservices (see Sec.5) from the support vessel.

A 300 Documentation

301 Handling systems shall be documented as a lifting appli-ance in accordance with the applied code or standard. In addi-tion, plans and supplementary documentation shall be madeavailable as follows:

— plans showing the arrangement of the handling systemwith specifications of loads, and dimensions of strengthmembers

— plans showing the function of the systems, and giving par-ticulars of the systems. The plans shall show a schematicarrangement of the hydraulic or pneumatic piping systemsand specification of controls and power supply

— calculation of the design load according to C100— calculation of necessary design load for umbilical and

guide ropes if applicable— plans and specification of structural parts, ropes, sockets,

blocks, sheaves, winches, and emergency ascent arrange-ment for the hyperbaric evacuation and mating arrange-ment

— specifications of materials and welds, and extent of non-destructive testing

— specifications of wire ropes and their end connections— specification of safety devices (limit switches, automatic

stop of operating handle, automatic locking of winch incase of power failure, etc)

— specification of buoyancy of the hyperbaric evacuationunit and correction formulas when the buoyancy is meas-ured at the surface

— plans and specifications for systems used for emergencyretrieval of the hyperbaric evacuation unit

— information on specification of working weight, displace-ment and stability of the hyperbaric evacuation unit, withall hydrostatic properties accounted for.

A 400 National codes

401 The launching system shall comply with a recognisednational code.

402 Capacity launch/recovery systems must have a safeworking load which is at least that of the HES when fullymanned and laden. This shall take account of any modifica-tions or extra equipment since the HES was first installed.The following considerations should be taken into account:dimensioning loads, degree of elasticity, dynamic amplifica-tion, required lifting height, required lifting capacity, degree ofmodification required on existing units and consequences ofthe modifications made.

403 Falls shall be long enough to allow the HES to be fullysupported in the water when the vessel is at its lightest draftand at the worst angle of list and trim.

404 On installation, overload tested in accordance with IMOguidance at full outboard position.

405 When carrying out practice deployments, the HESshould either be pressurised and unmanned or if mannedshould not be pressurised. As far as possible any practice shallsimulate operational conditions. Practice deployments shallnormally only be carried out in sheltered calm waters.

406 If the practice deployment stops short of sea level, thenthe lift wire release mechanism shall be demonstrated by othermeans.

407 Where a secondary means of launch is provided (such asstored energy), then practical deployment of the HES using thesecondary system shall be carried out under the same condi-tions and frequency as the primary system.

408 “Once only” systems or systems which require thereplacement of major components after use need not be prac-tised at the intervals given above

409 An interlock system shall be fitted to the mating systembetween the evacuation unit and the evacuation-tunnel withfunctions as stated in DNV-OS-E402 “Diving Systems” Sec.3B303, B304 and Sec.7 B109.

B. Design Principles

B 100 Function

101 The handling system shall be designed for a safe, effec-tive and easily controllable transportation of the hyperbaricevacuation unit in the design sea-state.

DET NORSKE VERITAS


The lowering of a hyperbaric evacuation unit is, under normalconditions, to be controlled by the drive system for thewinches, and not by mechanical brakes.

Free-fall units shall be considered specially.

Hyperbaric evacuation units shall not be affected by slackumbilicals as these may snag and cause unacceptable heel/trim. This requirement may in some cases be fulfilled by incor-porating buoyancy at parts of the tether/umbilical closest to thehyperbaric evacuation unit whilst allowing slack in the partsclosest to the support vessel. Recalling requirements in Sec.2,a slack umbilical shall not be affected by propellers or thrust-ers.

102 Manoeuvring systems shall be arranged for automaticstop when the operating handle is not operated (dead man’s handle).

103 Hoisting systems shall be fitted with a mechanical brake,which shall be engaged automatically when the hoisting motorstops. In the event of failure of the automatic brake a secondarymeans shall be provided to prevent the load from falling. Thismay be manual in operation and should be simple in design.

104 If the power to the handling system fails, brakes shouldbe engaged automatically.The brake should be provided with manual means of release.[IMO Guidelines Res. A.692 (17): 11.2].The handling system shall be designed so that the systems arelocked in place if the energy supply fails or is switched off.

105 If the hoisting rope can enter the drum with an angleexceeding 2° from the right angle to the drum axis (the "fleetangle"), a spooling arrangement shall be fitted. The rope han-dling system shall not permit ropes to squeeze in between, orintroduce permanent deformation to ropes in underlying layerson the drum.

106 The hoisting system shall be equipped with a devicewhich stops the hyperbaric evacuation unit at its lowermostand uppermost positions. Travelling cranes and trolleys shallbe equipped with mechanical stops at their end positions. Thesystem shall be equipped with limit switches preventing thehandling of the hyperbaric evacuation unit outside of the han-dling area.

107 Precautions shall be taken to avoid exceeding the designload in any part of the handling system including hoistingropes and any umbilical due to:

— large capacity of the power unit— motions of the supporting vessel when the hyperbaric

evacuation is caught or held by the sea— failure on umbilical winch during launching of hyperbaric

evacuation units with umbilical supply.

108 Structural members of the handling system might besubjected to forces imposed by separate units of a power sys-tem (e.g. A-frame tilted by hydraulic actuator on each leg.) Thestructural members are therefore either to be strong enough tosustain the resulting forces when one of the power units fails,or the power units shall be synchronised and an automaticalarm and stop system shall be activated when the synchronis-ing is out of set limits.

109 A locking arrangement shall be fitted to the mating sys-tem between the hyperbaric evacuation unit and the transfercompartment in accordance with the requirements given inSec.3 B204 and B205.

110 Where direct visual monitoring of the winch drums fromthe winch control station is not practical, TV monitoring shallbe fitted.

111 Primary and emergency lighting in all critical handlingareas shall be provided.

B 200 Launch of Hyperbaric Evacuation Units (HEU)

201 Where appropriate:

— means should be provided for the safe and timely evacua-tion and recovery of the unit and due consideration shouldbe given to the environmental and operating conditionsand the dynamic snatch and impact loadings that may beencountered

— the increased loadings due to water entrainment should beconsidered.

Where the primary means of launching depends on the ship'smain power supply, then a secondary and independent launch-ing arrangement should be provided. [IMO Guidelines Res.A.692 (17): 11.1].

202 Timely evacuation is in this case frequently defined as30 minutes from the time the notice to evacuate is given untilthe HEU is 100 metres away from the support vessel.Maritime regulations may state that the time taken from thedivers enter the HEU, until the HEU is 100 metres away fromthe support vessel, should not exceed 15 minutes.

203 Timely evacuation may only be carried out if there isgood communication between the bridge and the various sta-tions involved in the evacuation process. Such communicationshall be hard wired with a wireless backup.

204 Consideration shall be given to maximum tilt and listconditions required by SOLAS. In most cases fenders in theform of skids should be mounted on the hull to prevent damagedue to possible impact during launching.

205 Dynamic amplification due to snatch loads may be asmuch as 5 to 7. However, dampeners fitted in the system mayreduce this.

206 Operational procedures for HRV(s) shall contain infor-mation regarding limitations in launching, towing and liftingoperations, etc. relevant to different weather conditions.

207 The launching arrangements provided should bedesigned to ensure easy connection or disconnection of thehyperbaric evacuation unit from the surface compressionchamber and for the transportation and removal of the unitfrom the ship under the same conditions of trim and list asthose for the ship's other survival craft. [IMO Guidelines Res.A.692 (17): 11.3].

208 Life support connections from the mother ship to theHEU should be designed with a "weak link", to avoid thatessential connectors on the HEU get damaged in case theyhave not been released before launching.

209 Where a power-actuated system is used for the connec-tion or disconnection of the hyperbaric evacuation unit and thesurface compression chamber, then a manual or stored powermeans of connection or disconnection should also be provided.[IMO Guidelines Res. A.692 (17): 11.4].

210 The means provided for release of the falls or lift wireafter the unit is afloat should provide for easy disconnection,particular attention being given to units not provided with anattendant crew. [IMO Guidelines Res. A.692 (17): 11.5].

211 In the case of unattended hyperbaric evacuation units,consideration should be given to providing equipment to trans-fer the towline to an attendant vessel before launch of the evac-uation unit. Such an arrangement would enable the unit to betowed clear immediately after launching. [IMO GuidelinesRes. A.692 (17): 3.3].

212 Brake adjustment is critical, and needs to be tested atinstallation and in service. In systems utilising a cord to controlthe brakes, the cord needs to be arranged so that it does not getblown away in the wind or get snagged.

DET NORSKE VERITAS


B 300 Recovery of hyperbaric evacuation units

301 The hyperbaric evacuation unit should be capable ofbeing recovered by a single point lifting arrangement andmeans should be provided on the unit to permit a swimmer tohook on or connect the lifting arrangement. [IMO GuidelinesRes. A.692 (17): 5.2].

302 For SPHLs the single point lifting arrangement shouldincorporate the chamber and engine in such a way that excessloads on the boat are avoided.For some existing SPHLs this requires modifications as theexisting supports and foundations are not adequate for theloads imposed on the unit during lifting. The longitudinalstrength needs to be evaluated.

303 In cases where modifications are carried out, these mayadd weight and an upgrading of the lifting arrangement may berequired.

304 When considering concepts for existing units, one mayevaluate the use arrangements such as salvage docks, rescuescoops or permanently mounted nets. In such cases thearrangement shall not damage the mating flange, propeller orrudder.Regular inspection and maintenance will be needed to ensurethe integrity of such concepts.

305 Where the hyperbaric evacuation unit is designed to berecovered from the sea or from a ship in a seaway, considera-tion should be given to the mode of recovery.Adequate equipment to enable a safe recovery of the unitshould be provided on the unit.Permanently marked clear instructions should be providedadjacent to the lifting equipment as to the correct method forrecovery, including the total weight of the hyperbaric evacua-tion unit.Consideration should be given to the effect which entrainedwater and any bilge water may have on the total weight to belifted by the recovery vessel.Consideration should also be given to any means that can beprovided for the absorption of the dynamic snatch loadsimposed during the recovery of the hyperbaric evacuation unitfrom the sea. [IMO Guidelines Res. A.692 (17): 11.6].

306 Lifting the HEU in sea states of 2 metres significantwave height or more, is generally not recommended unless theHEU and lifting arrangement is designed and tested for givensea states. Consequently towing to sheltered waters, with thepossibility of life support underway, will in most cases be animportant contingency option.

307 The deck space required for an HEU and accompanyinglife support package (LSP) is estimated to be 40 m2.

308 If a spreader bar is required in the lifting gear, the slingsfrom the bar to the HEU should be long enough to avoid hittingthe attendants on the HEU and it should be suitable for trans-portation by helicopter. For areas with different types ofHEUs, more than one spreader bar may be required and theymust therefore be clearly marked to distinguish one from theother. Operational procedures for HRV(s) shall contain infor-mation regarding limitations in launching, towing and liftingoperations, etc. relevant to different weather conditions.

309 Special arrangements and instructions should be pro-vided externally to enable the hyperbaric evacuation unit to berecovered safely. The instructions should be located wherethey will be legible when the hyperbaric evacuation unit isfloating. [IMO Guidelines Res. A.692 (17): 5.8].

310 The HEU shall be equipped with a life jacket, a survivalsuit (if in cold climates), a safety harness and securing lines tofacilitate movement on deck.

B 400 Alternative recovery

401 There should be a normal system and an independentemergency lifting point for recovery of the HEU. The alterna-

tive lifting point shall comply with the same requirements forload strength as the main system.

B 500 Emergency arrangements

501 Release mechanisms for hoisting rope and umbilicalshall be so designed that two separate operations shall be nec-essary to activate them. If hydraulic or pneumatic actuationsystems operated from within the hyperbaric evacuation cham-ber are used, possible penetration of gas into the systems shallbe taken into account.

Primary strength members shall be designed for a load not lessthan 3 times the expected maximum load during operation.Secondary strength members such as securing mechanismsshall be so designed that they cannot activate the release sys-tem in the event of their failing.

502 The hyperbaric evacuation unit shall have means ena-bling it to be located.

B 600 Power

601 The hoisting power system shall be designed and testedto lift a load of 1.25 times the working weight.

602 The power of horizontal transportation systems shall bedesigned and tested for safe handling at list and trim as speci-fied in Table C1.

603 The strength of the mechanical brake for the hoistingsystem shall be based on holding of the design load. After thestatic test, however, the brake may be adjusted to the workingweight of the hyperbaric evacuation plus 40%.

B 700 Umbilical

701 The termination points, where the umbilical enters con-nectors and penetrators, shall not be subjected to significantloads or flexing.

702 The ultimate tensile strength of the umbilical shall not beless than twice the maximum load expected during emergencyoperations.The design load of the umbilical shall be sufficient for themaximum loads expected during operation.

C. Strength

C 100 Design loads

101 If the handling system is designed for operation in sea-states with significant wave heights (see definitions inSec.1 D) not exceeding 2 metres, the design load may be takenas the load resulting from the following:

— 2 times the working weight in air of hyperbaric evacuationunit and attachable members

— weight of structural members of the handling system mul-tiplied by a factor of 1.3 in the vertical direction and 0.3 inthe horizontal direction

— list and trim during operation as given in Table C1— list and trim in locked position as given in Sec.2 C200.

102 Alternatively to C101, or for sea-states with significantwave heights exceeding 2 metres, the design load shall betaken as the largest most probable, resultant load over 24 hoursin the operational design sea-state due to the following:

— working weight of hyperbaric evacuation unit and struc-tural members of the handling system

— dynamical amplification due to list, trim and motion of thevessel

— operation and response of the handling system— hydrodynamic forces— jerks in the hoisting ropes and impact on the system.

DET NORSKE VERITAS


103 The working weight of the hyperbaric evacuation unitshall be taken as the maximum weight of the fully equippedhyperbaric evacuation unit, including each fully equippedcrew member of 100 kg measured when:

— handling in air— handling in sea.

104 In locked positions on a vessel, the handling systemshall have a structural strength at least sufficient for the envi-ronmental conditions described in Sec.2. In addition to themotions and accelerations in the operational design sea-state,the minimum inclinations given in Table C1 shall be taken intoaccount (ref SOLAS Ch.III Pt.B Sec.1 Reg.16 and MODUCode Ch.10 Sec.6):

105 Dynamic loads due to start, stop, or a slack wire rope fol-lowed by a jerk, and hydrodynamic loads shall be determined.

C 200 Dimensions

201 The tension in ropes, due to the design load, shall notexceed that:

a) for steel wire ropes:

— SF = 4 times design load factor (for design loads notexceeding 1.5 times working weight) or

— SF = 3.33 times design load factor (for larger designloads).

b) for synthetic fibre ropes:

— SF = 5 times design load factor where design load fac-tor is defined as the design load divided by the work-ing weight.

Ropes shall be of a type that minimises rotation.

202 Blocks, sheaves, shackles etc. shall comply with recog-nised national codes. Drums and pulley diameters shall corre-spond to the type of rope. For steel wire ropes this drum andpulley diameter shall not be taken less than specified by therope manufacturer, and normally not less than 18 times therope diameter.

203 Structural members shall be fabricated from certifiedmaterials and shall be designed with safety against:

— excessive yielding— buckling— fatigue fracture.

Applicable technical requirements are given in DNV Standardfor Certification No. 2.22 Lifting Appliances, or equivalentaccepted standards. Safety factors at design load shall be takenas specified for Case 1 (Safety against yield: 1.5) in the DNVrules reference.

D. Dynamic Loads in Launch and Recovery Systems

D 100 General

101 Approximation of expected dynamic loads during han-dling of hyperbaric evacuation units and any connected equip-ment shall be calculated as design inputs, for a support vesselmoving at 5 knots and heading in the main direction of incom-ing waves in the design sea-state.

102 Calculations for other headings shall be considered on acase by case basis.

103 The specified methods for calculation of hydrodynamicforces are limited to the cases in which the vertical motions ofthe suspended hyperbaric evacuation unit may be taken equalto the corresponding motions of the support vessel. The condi-tions permitting such assumptions shall be specified.

104 Estimates may be based on calculations in DNV-OS-E402 Appendix A, for surface conditions.Other approximate or more accurate methods may be accepta-ble upon consideration in each case.

Table C1 Permanent inclinationsSupport Vessel type Permanent list Permanent trimShip 20° 10°Semi-submersible (MOU)

MODU Code Ch.3 MODU Code Ch.3

DET NORSKE VERITAS


SECTION 8PIPES, HOSES, VALVES, FITTINGS, COMPRESSORS AND UMBILICALS

A. General

A 100 Objectives

101 The purpose of this section is to specify additionalrequirements for pipes, hoses, valves and fittings servinghyperbaric evacuation systems. Emphasis is placed on the spe-cial needs associated with the design and manufacture ofhyperbaric evacuation systems, whereas general requirementsfor such systems are given in DNV Rules for Classification ofShips Pt.4 Ch.6.

102 Key issues include the requirements for oxygen systemsand to the limited use of hoses except hoses used in umbilicals.

103 This section does not cover general requirements givenin manufacturing codes and standards for particular compo-nents, such as API codes for hoses etc.

104 In the planning stages, all fittings shall be evaluated forneeds and compatibility. (Gas, oxygen, regulators, hoses andfittings).


201 This section applies to all systems essential for the safeoperation of the hyperbaric evacuation system.

202 Manufacturing standards applicable to individual com-ponents shall be supplementary to this recommended practice.

203 Testing after completion is included here and in Sec.1,but testing during manufacture shall be in accordance withapplicable manufacturing codes for the particular component.

204 This section has impact on Sec.3, Sec.4, Sec.6, Sec.7and Sec.9.

A 300 Documentation

301 Pipes, hoses, valves, fittings, compressors and umbili-cals shall be documented as follows:

a) Pipes; plans showing schematic arrangement of all pipingsystems.Documentation stating:

— material specifications— maximum working pressure— dimensions and thicknesses— contained fluids.

b) Type of valves and fittings.

c) Flexible hoses; plans and specifications showing suitabil-ity of the hose in relation to its intended use and documen-tation of tests which have been carried out, as required.

d) Umbilical; plans and specifications giving particulars ofconductors, minimum breaking load and minimum diam-eter of pulley and drums, and specification of maximumdesign loads, elastic properties and weight per unit length.

302 Documentation of tests verifying the properties listedabove and as required by F.

303 See also DNV document requirement lists for divingsystems and lifting appliances.

A 400 Materials

401 Materials used in the breathing gas system shall not pro-duce noxious, toxic or flammable products.

402 In systems conducting oxygen, all materials in contactwith this gas shall be oxygen shock tested according to EN738-1, -2 and -3:1997/1998 "Pressure regulators for use with

medical gases" or equivalent standard applicable to the partic-ular component. (See also EN 849:1996, EN ISO 11114-3:1997 and EN ISO 2503:1998 in informative references).

403 For piping systems of copper, copper alloys and auste-nitic steels with chromium-nickel content above 22%, the testcan be waived.

404 Precautions shall be taken to avoid galvanic corrosion.

405 Non-metallic materials retaining pressurised gas shall beconsidered for gas-permeability.

406 All valves and fittings in connection with pressure hullpenetrations shall be made from material with an elongationafter fracture not less than 15%.

A 500 Protection

501 Piping systems shall be well protected against mechani-cal damage.

B. Pipes and Hoses

B 100 General

101 Piping systems shall comply with the technical require-ments in DNV Rules for Classification of Ships Pt.4 Ch.6.

102 Welding of joints shall be carried out by qualified weld-ers using approved welding procedures and welding consuma-bles. Technical requirements are given in DNV Rules forClassification of Ships Pt.2 Ch.3.

103 The following requirements given in DNV Rules forClassification of Ships Pt.4 Ch.6 shall be followed:

— bending and welding procedures— welding joint particulars— pre-heating— heat treatment after welding and forming— non-destructive testing and production weld testing— brazing of copper and copper alloys.

104 Hydrostatic testing shall be in accordance with the tech-nical requirements and as for corresponding pipe class inbreathing gas systems pertaining to class I - piping systems.

B 200 Hoses

201 In addition to umbilicals, short lengths (up to 2 m) of flex-ible hose may be used when necessary to admit relative move-ments between machinery and fixed piping systems. Forassemblies incorporating specially approved hoses and securingarrangements, lengths up to 5 m may be permitted if fixed pip-ing is not practicable. In such cases the securing arrangementsshall be in place at 1 m intervals of the length of the hose.

In addition to the couplings, the hoses shall be secured in sucha way as to prevent the hose from whip lashing in the event thatthe coupling fails. When applicable, couplings shall incorpo-rate bends so that kinks in the hoses are avoided.

202 Flexible hoses shall not replace fixed piping.

203 Flexible hoses with couplings shall be certified.

204 The bursting pressure of synthetic hoses shall be at least:

— for hoses for fluids: 4 times the maximum working pressure— for hoses for gases: 5 times the maximum working pressure.

205 Hot water hoses shall be designed for conveyance of flu-ids of temperatures not less than 100°C.

DET NORSKE VERITAS


206 Each hose for use in umbilical shall be pressure tested to1.5 times the design pressure before fitting in the umbilical.After hose end fittings have been mounted, a gas leakage testto design pressure shall be performed.

207 Flexible metallic hoses shall comply with ISO 10 380,BS6501 or equivalent. These types of hoses shall not beinstalled in systems subject to excessive vibrations or move-ments.

208 Flexible synthetic hoses shall comply with SAE J517,DIN EN 853, 856, 857 or equivalent. The internal oil resist-ance test may be omitted for hoses intended for gas and wateronly.

B 300 Hoses and components for gases containing oxy-gen

301 Hoses and components for systems conducting gasescontaining more than 25% oxygen shall be able to sustain thepressure shock tests as specified in A402.

Guidance note:

Oxygen pressure shock tests are described in the standardsreferred to in A402. However, the test includes the followingprinciples:

a) Commercial grade oxygen (99% pure) test gas is applied asfollows for 3 identical test specimens:

— the test pressure is not less than the design pressure

— the test specimen is preheated to 60°C and exposed to agas pressure shock up to the specified test pressure withtest gas preheated to 60°C.

b) Each test consists of 20 pressure shocks at approximately 30seconds intervals:

— the total exposure time to each pressure shock is 10 sec-onds, and the gas pressure is released after each shock

— the pressure increase rate during each pressure shock isobtained by a valve with an opening time less than 10milliseconds.


C. Valves and Pressure Regulators

C 100 Valve design

101 Pressure ratings for valves shall be in accordance with arecognised national standard.

102 Design and arrangement of valves shall be such thatopen and closed positions are clearly indicated.

103 Valves are normally to be closed by clockwise rotation.

104 Shut-off valves for oxygen shall be of types which needseveral turns to close. On chamber penetrators, ball valves maybe accepted for emergency use only.

105 Pressure regulators shall have more than one full rota-tion from fully closed to fully opened position.

D. Fittings and Pipe Connections

D 100 Detachable connections

101 Bite and compression type couplings and couplings withbrazing, flared fittings, welding cones and flange connectionsshall be designed according to a recognised standard.

E. Compressors

E 100 General

101 Compressors shall be certified.

102 Compressors shall be equipped with all the accessoriesand instrumentation which are necessary for effective anddependable operation.

103 Compressors shall be designed for the gas types, pres-sure rating and delivery rates as specified by the operation andso designed that the gas is protected against contamination bylubricants.

104 The content of contaminants in delivered air from com-pressors shall not exceed:

— 50 mg water— 1 mg oil per m3 air STP (standard conditions)— 500 ppm CO2, and— 10 ppm CO.

105 Suitable protection shall be provided around movingparts, and the Safety Relief Valves shall exhaust to a safeplace.

F. Umbilicals

F 100 General

101 Umbilicals shall be designed, tested and certified inaccordance with relevant sections in the most recent edition ofone of the following codes:

a) ISO 13628-5 “Petroleum and natural gas industries –Design and operation of sub sea production systems – Part5: Sub sea control umbilicals”, or

b) API Specification 17E “Specification for Subsea Produc-tion Control Umbilicals.”

F 200 Hoses

201 Hoses for umbilicals shall comply with the requirementsgiven in B200.

F 300 Electrical cables

301 Electrical cables for umbilicals shall comply withrequirements given in Sec.5.

302 The minimum average thickness of insulating walls andtemperature classes shall be in accordance with DNV-OS-D201.

F 400 Sheathing

401 Any sheathing of a compact umbilical shall be of adesign which avoids build-up of an inside gas pressure in theevent of a small leakage from a hose.

F 500 Strength members

501 The strength members of umbilicals shall have sufficientstiffness to avoid plastic yielding of electrical conductors atdesign load, and shall be properly secured.

F 600 Testing of mechanical properties

601 Samples of the completed umbilicals shall be testedaccording to a manufacturer’s test programme complying withrelevant requirements in the design code.

F 700 Tests after completion

701 A pressure test to the design pressure of all hoses simulta-neously and verification of the specified properties by insulationtests of electrical conductors as well as impedance measurementsof signal cables to specified properties shall be carried out.

DET NORSKE VERITAS


SECTION 9MACHINERY AND MACHINERY PIPING SYSTEMS

A. General

A 100 Objectives

101 The purpose of this section is to refer to general require-ments for machinery and machinery piping systems. Emphasisis placed on the special needs associated with the design andmanufacture of such systems, including requirements to pro-pulsion and pumping.

102 Key issues are identified by reference to DNV Rules forClassification of Ships.


201 This section applies to all machinery systems. However,specific requirements to life support systems are given inSec.4.

202 For quantitative design parameters and functionalrequirements, reference is made to relevant standards andguidelines, including DNV Rules for Classification of Ships.

203 Some testing requirements are given, Sec.2 I. Additionaltesting may be relevant depending on the type of systeminstalled.

A 300 Documentation

301 Machinery systems shall be documented as follows:

— documentation and drawings for fuel systems, fuel tanks,oxidant systems and exhaust systems for semi-closed andclosed energy generation systems

— propeller arrangements and shafting, bearings and seals— steering arrangements— machinery— energy balances for normal and emergency systems.

B. Hydraulic Power Systems

B 100 General

101 The requirements of these Rules apply to hydraulic sys-tems, hydraulic auxiliary systems, and tool systems supportingthe evacuation operations.

102 For e1ectro-hydraulic systems, electric motors may besubmerged in the hydraulic oil.

B 200 Hydraulic fluids

201 The hydraulic fluid shall be such as not to cause corro-sion or chemically attack the components in the system.

Guidance note:The fluid should preferably be of an inhibitory type with respectto corrosion.


202 The hydraulic fluid shall have a flash point not lowerthan 150°C and shall be suitable for operation at all tempera-tures to which the system may normally be subjected.

203 Hydraulic fluids exposed to commutation in electro-hydraulic systems shall have a sufficient dielectric strength.

204 Where applicable, the possible static differential pres-sures because of different specific gravity of hydraulic fluidand ambient seawater shall be taken into account. Static differ-ential pressure causing seawater leakage through couplingsand seals shall be avoided at design stage.

205 Because of temperature induced volume changes in thehydraulic fluid, a hydraulic reservoir keeping a pressure of atleast 0.15 bar above ambient pressure shall be arranged.

206 The pressure compensating system shall be adequatelydimensioned for both expansions and contractions in the fluidsystems.

207 Means for cooling of the hydraulic fluid shall be incor-porated in the system where found necessary in order to keepan acceptable fluid temperature.

B 300 Components

301 Electric pump motors to be submerged in the hydraulicfluid shall be compatible with the fluid, or the motor shall beof the canned type operating in a second pressure-compensatedfluid isolated from the hydraulic fluid.

302 Hydraulic hoses and valves used in the system shall beof an approved type. (See Sec.8).

C. Propulsion Machinery (SPHL)

C 100 General

101 Hyperbaric evacuation units intended for use in areaswhere debris and solid particles may be carried by currents or bythe water accelerated by the thrusters, shall have screens cover-ing the inlet and outlet of propeller, Kort nozzles and ducts.

102 Hyperbaric evacuation units intended for use in areaswhere there might be a risk of cable and rope entanglementshall have their thrusters shielded against such entanglement.

103 Propellers shall be designed, inspected and tested inaccordance with DNV Rules for Classification of Ships, Pt.4Ch.5 Sec.1 B, C and D.

104 Propeller shafts, intermediate shafts and shafts betweenprime mover and generators shall be designed according toDNV Rules for Classification of Ships, Pt.4 Ch.4 Sec.1.

105 Where propulsion shafts penetrate the hull shell, suitablemeans shall be provided to detect leaking glands or seals.

106 Glands and seals shall be connected to a system givingaudio/visual indication in the event of leakage.

C 200 Diesel engines

201 Diesel engines for drive of electrical generators onboardself propelled hyperbaric evacuation units shall be built,equipped and installed to comply with the DNV Rules forClassification of Ships, Pt.4 Ch.3 Sec.1 in addition to therequirements of this section.

202 Exhaust from open circuit diesel engines shall be ledthrough piping having one check valve outside the hull.

C 300 Electric propulsion motors

301 Electrical propulsion motors shall comply with DNVRules for Classification of Ships, Pt.4 Ch.8 Sec.12 in additionto C200.

302 Open winding water filled motors shall have their statorcoils made of magnetic wire, insulated by a heavy duty water-proof coating. A shaft seal shall be provided in order to preventparticles and organic materials from flowing into the motor.

303 Open winding oil filled motors shall have a shaft oil seal.

304 Pressure equalized motors shall have an adequate oilreserve, and an oil expansion space shall be provided.

DET NORSKE VERITAS


305 Dielectric fluids for use in oil filled motors shall be of atype resistant against the breakdown effects from commutatoraction.

306 Pressure resistant housings for hermetically sealedmotors shall satisfy the strength requirements of Sec.3 of theseRules.

307 Motors designed to run at a high RPM under ambientpressure, shall have their housing made of a material of poorelectric conductivity so that shaft failure because of eddy cur-rents in the housing is avoided.

C 400 Hydraulic propulsion motors

401 Hydraulic thrusters systems shall comply with therequirements given for hydraulic power systems in C100 to302 of this section.

402 Hydraulic propulsion motors shall have a shaft gland or

shaft seal for prevention of sea water penetration into the motor.

D. Pumping and Piping Systems

D 100 General

101 Pumping and piping systems, including valves and fit-tings, shall be designed for a rated pressure equivalent to 1.3times the maximum operating pressure.

102 Piping open to the sea, shall have a valve situated insidethe hull and close to the hull skin. The rated pressure of thesevalves shall be not less than 25 bar. If seat valves are used,these shall be arranged so that the cone will open in counter-direction to the external pressure. The valves shall be providedwith indicators showing the open/closed position.

DET NORSKE VERITAS


SECTION 10HULL STRUCTURE, BUOYANCY STABILITY AND TRIM

A. General

A 100 Objectives

101 The purpose of this section is to outline general require-ments for stability and buoyancy of hyperbaric evacuationunits (HEUs).

102 Key issues are identified by specifically adding to theIMO text in relation to self-propelled hyperbaric evacuationlifeboats.

103 The purpose of this section is to outline general require-ments for buoyancy stability and trim. Emphasis is placed onthe functional requirements of such systems.

104 No specific key issues are identified.


201 This section applies to all hyperbaric evacuation units.

202 SOLAS requirements shall be applied as far as practica-bly possible.

203 These requirements may also be applicable as Flag Staterequirements.

204 Some testing requirements are given, limited to thosespecified in the original IMO text. Additional testing may berelevant depending on the type of evacuation unit installed.

205 This section applies to all hyperbaric evacuation units.

206 Some testing requirements are given, Sec.2 I. Additionaltesting may be relevant depending on the type of systeminstalled.

A 300 Documentation

301 Buoyancy stability and trim shall be documented as fol-lows:

— plans of buoyancy, stability and trim systems if applicable— calculation of buoyancy and stability for all intended oper-

ations. Alternatively to the calculations, tests according toapproved test programs may be a base for acceptance, pro-viding that density conditions are taken into account.

B. Design

B 100 General

101 Hyperbaric evacuation units designed to float should be

provided with adequate stability for all envisaged operatingand environmental conditions and be self-righting.In determining the degree of stability to be provided, consider-ation should be given to the adverse effects of large rightingmoments on the divers.Consideration should also be given to the effect which equip-ment and rescue personnel, required to be placed on the top ofthe system to carry out a recovery from the sea, may have onthe stability of the hyperbaric evacuation unit. [IMO Guide-lines Res. A.692 (17): 7.1].

102 Hyperbaric evacuation units designed to float shouldhave sufficient reserves of buoyancy to enable the necessaryrescue crew and equipment to be carried. [IMO GuidelinesRes. A.692 (17): 7.3].

103 Any HES designed to be free floating must be both pos-itively buoyant and also stable when fully equipped andmanned. This must have been demonstrated by means of prac-tical testing. In all modes of loading the hyperbaric evacuationunit shall be able to establish and maintain buoyancy and sta-bility at any design condition. This shall be accomplishedwithout the use of propulsion.

104 Consideration should be given to the possible floodingof SPHLs.

105 The lower limit of the density of the water shall be takenas 1 000 kg/m3.The upper and lower limits of the temperature of the watershall be taken as 32°C and -2°C respectively.

B 200 Buoyancy, stability and trim

201 Towing attachment points should be so situated thatthere is no likelihood of the hyperbaric evacuation unit beingcapsized as a result of the direction of the tow line. Where towing harnesses are provided they should be lightlyclipped or secured to the unit and, so far as is possible, be freefrom snagging when pulled free. [IMO Guidelines Res. A.692(17): 7.2].

202 The towing line shall be easy to retrieve in roughweather. At the same time, it shall not present a hazard in theform of entanglement in propellers. The towing line and umbilical may need to be paid out with abuoy attached to the end.

203 There must be clear directions in the emergency proce-dures as to how this tow will be effected giving due consider-ation to weather and sea conditions.

DET NORSKE VERITAS

Recommended Practice DNV-RP-E403, October 2010 – App.A

APPENDIX A CERTIFICATION (GUIDANCE)

A. General

A 100 Objectives

101 This section aims to give general guidance and require-ments on certification of Hyperbaric Evacuation Systems andsupplied equipment.


201 This section applies to all other sections in this docu-ment.

202 The requirements may be applied to new constructionsor to conversion of existing systems.

A 300 Documentation

301 The documentation required for verification of compli-ance with the requirements is given under A300 in each sec-tion.

B. Certification

B 100 General

101 Where a hyperbaric evacuation system complies withthe provisions, as applicable, of the Guidelines and Specifica-tions and has been duly surveyed, it may be recorded on thesupplement to the Cargo Ship Safety Equipment Certificate as

providing the life-saving appliances and arrangements fordivers in compression. [IMO Guidelines Res. A.692 (17): 4.2].

102 A programme for certification of hyperbaric evacuationsystems may follow the requirements given in DNV-OSS-305“Rules for Certification and Verification of Diving Systems”.

B 200 Certification levels

201 The levels of certification required in each case shall bedetermined and specified in ISO terms according to ISO 10474that indicates who needs to attend design, manufacture andfinal testing. Further guidance may be found in DNV-OSS-305Appendix A.

B 300 The scope of certification

301 The scope of certification shall be provided by the Mar-itime Authorities where the diving support vessel is registered.

B 400 Plan approval of design

401 Plan approval of design shall be carried out in agreementwith, and according to instructions from, the Maritime Author-ities where the diving support vessel is registered.

B 500 Surveys and testing

501 Surveys and testing may be done in accordance withSec.2 I. Further guidance is given in DNV-OSS-305Appendix B.

DET NORSKE VERITAS

DNV-RP-E403: Hyperbaric Evacuation Systems · DNV-RP-E403 HYPERBARIC EVACUATION SYSTEMS ......

Documents

Transcript of DNV-RP-E403: Hyperbaric Evacuation Systems · DNV-RP-E403 HYPERBARIC EVACUATION SYSTEMS ......