MTS DYNAMIC POSITIONING CONFERENCE October 09 ......Joey Fisher (IEng IMarEng MIMarEST, AVI)...

MTS DYNAMIC POSITIONING CONFERENCEOctober 09 - 10, 2018

MTS Guidelines and Class Rules. How to bridge the gaps?

Joey Fisher (IEng IMarEng MIMarEST, AVI)Managing Director, M3 Marine Expertise Pte Ltd

Introduction

M3 Marine Expertise – Established in 2010 and based in Singapore

The company considers that the information shared in the paper could benefit the DP community.

Realisation that there are gaps in processes that allow the delivery of predictable outcomes and incident free DP operations.

Process gaps are presented in the form of examples of ‘challenges’ that have been experienced during the DP FMEA processes for

DP Class 2 and DP Class 3 vessels.

Examples of challenges;

➢ One example related to Competency and the independence and segregation of redundant systems (Paper).

➢ Examples 1 – 4 related to the independence and segregation of redundant systems in the design of DP electrical

systems (cross connections).

➢ Summary

➢ Conclusion

M3 Marine Expertise Pte Ltd

1 Commonwealth Lane #09-13 ONE Commonwealth Singapore 149544 t: +65 6327 4606 m: [email protected] w: www.m3marine.com.sg 2

Example 1 – Cross connections necessitated by SOLAS and class rules

DP Class 3 Multipurpose Offshore Construction and Diving Support Vessel

1A1, SF, DYNPOS AUTRO, DYNPOS ER, E0, DK(+), CLEAN DESIGN, COMF-V(3) C(3), FIFI-II, NAUT-OSV (A), ICE-1C, DSV-SAT,

DSV-SURFACE, HELDK-SH(CAA-N), BIS, SPS, SHIP SHAPED OFFSHORE SUPPORT UNIT, OFFSHORE SERVICE VESSEL +, BWM-T,

RECYCLABLE, SUPPLY VESSEL (HULL ONLY).

• 24-man saturation diving system with NORSOK compliance

• Air diving system with two twin-lock compression chambers

• 400T Offshore Knuckle Jib Crane

• 25T Offshore Knuckle Jib Crane

• 10T Offshore Telescopic Jib Crane

• 10T Offshore Fixed Jib Crane

• Length (overall) : 145.90 m

• Length (between perpendiculars) : 133.80 m

• Breadth Moulded : 27.00 m

• Draft (maximum) : 7.50 m




A description of all operatingmodes in order to provide anunderstanding of the modes ofoperation that are relevant forthe power system.



ELECTRICAL PHILOSOPHY – MAIN CLASS RULES


DP ER notation requires autonomy for the Diesel Generators and additional redundancy.

Individual UPSs facilitated a dual power supply arrangement and automatic changeover to an emergency supply.



Opportunity!

• TECHOP_ODP_11_(D)_Cross

Connections

• TECHOP_ODP_13_(D)_Control

Power Supplies and Auto

Changeovers

Control Power Arranged Within the

Same Redundant Group

Arrangements for Dead Ship

Recovery – SOLAS Ch.ii-1 41.1.4.


Approved with Comment

At least two generators (one on each switchboard) need to be arranged for start from dead ship (rule reference).

Dead ship – Dead ship condition is the condition under which the entire machinery installation is not in operation. All batteries

and / or pressure vessels are considered depleted. Emergency generation is considered available.

Applicable rule references;

• Interpretation of SOLAS Ch.II-1/41.5.1.1

Guidance note:

On installations without a dedicated emergency generator in accordance with C104, only one engine room is considered to be in

dead ship conditions, since there should be redundancy in starting arrangement for each engine room as required for emergency

generator sets. However, necessary energy for auxiliaries needed for start (fuel, lubrication oil priming, etc.) must have the same

arrangement as the source for starting energy.

For vessels with two or more independent engine rooms but not complying with C104, the requirements for dead ship starting still

applies, i.e. dead ship condition in both/all engine rooms simultaneously.




TECHOP_ODP_13_(D)_Control

Power Supplies and Auto

Changeovers

• Common point created in the

Redundancy Concept

• Configuration errors followed

by a failure can exceed the

WCFDI

• Analysis for mitigation




However, in our experiences; designers, shipyards and equipment manufacturers are reluctant to support or invest in such analysis

with documentation that studies and verifies the effects of such failures, or provide detailed information to that would allow

others to do this.

Barriers!

PILLARS

REQUIRE MORE

FOCUS WHEN

CROSS

CONNECTIONS

EXIST




Isolation of these power supplies is not prohibited by the requirements for dead ship recovery.



Example 2 – Unwanted cross connections potentially introduced by the classification society

DP Class 2 Multipurpose Offshore Construction and ROV Support Vessel

1A1, SF, E0, DYNPOS AUTR, CLEAN DESIGN - TIER III, NAUT OSV(A), ICE-C, DK(+), COMF V(3) C(3), HELDK-SH, BMW-T,

OFFSHORE SERVICE VESSEL +, RECYCLABLE, DYNPOS E, ECA, SPS2008


• Breadth Moulded : 22.00 m

• Draft (design) : 5.70 m

• 150T Offshore Knuckle Jib Offshore Crane

• 25T Offshore Knuckle Jib Offshore Crane

• Dedicated ROV Hanger, Control Rooms, Interfaces etc




For the diesel generator main switchboard sections, the autonomous control power was arranged with individual UPS units.

Each UPS unit is supplied from the main switchboard bus section within the same redundant group as the diesel generator. An

alternative power supply is arranged from the emergency switchboard via a manual changeover switch.




Approval with Comment from Class (Main Class Rules)

An independent control power supply system shall be arranged for each of the switchboard sections and be arranged with

change over possibilities.

Is this relevant?

Discussions……

Highlighted that the definition of ‘independent control power supply system’ was referenced in another part of the

classification society rules and is as follows;

When independent power supplies are required, these supplies shall be from separate sections of

the main switchboard or from distribution boards supplied from separate sections of the main

switchboard.




Designers change the design of the power supply arrangements

MSB A UPS No.2, (for DG No.2) – MSB B / MSB B UPS No.3, (for DG No.3) – MSB A

DP FMEA service provider

provides an assessment.

• Failure modes which can

exceed the WCFDI.

• Not in accordance with the

class rules for DP systems or

rules for the DP ‘Enhanced’

notation.

• Comment closed without an

explanation.



Example 3 – A cross connection that could not be removed

DP Class 2 High Speed Catamaran Crew Boat

1A1, HSLC CREW R1, DYNPOS-AUTR, FIRE FIGHTING CAPABILITY


• Beam : 12.50 m

• Hull Draft (maximum) : 2.17 m

• A motion compensated gangway






REDUNDANT GROUP 1

REDUNDANT GROUP 3

REDUNDANT GROUP 2

REDUNDANT GROUP 4

LEGEND:


Extract from Applicable Class Rules

If the system neutral is connected to earth, means of disconnection shall be fitted so that the system earthing may be disconnected

for maintenance or insulation resistance measurement. Such means shall be for manual operation only.

In any four wire distribution system the system neutral shall be connected to earth at all times without the use of contactors.




DP FMEA Considerations

• Neutral is common to equipment in both redundant groups.

• Effects of a short circuit between one phase and neutral.

• Potential common point of failure which could have effects in both redundant groups?

• Suggestion for separation of the neural conductor during DP operations, possibly by the use of 4-Pole circuit breakers.

• However, class rules did not allow;

No fuse, switch or breaker shall be inserted in earthing connections or conductors. Earthed neutrals may be disconnected

provided the circuit is disconnected at the same time by means of multipole switch or breaker.

The design requirement: synchronise the generators and start the thrusters before opening the bus tie.

Therefore, the installation of a MEN Link at each source was also not an option.

Designer – A fault could not transfer to the other switchboard section without a live return.






Other vessels with earthed neutral

• Four-pole circuit breakers were fitted in the

generator panels and the bus tie panel

• Earth fault detection was provided at each bus

section

• One of the earth connections was automatically

disconnected when the bus tie breaker was

closed.

• Built under the rules of a different

classification society


IMPASSE

• Design is based on one neutral earth connection only, in accordance with the applicable class rules.

• Limited information or case studies – available industry guidance for main power systems is generally associated

with insulated neutral systems.

• Some case studies available on the internet which showed that short circuit faults within common neutral-earth

arrangements had caused inadvertent tripping of circuit breakers that should have been unaffected by the fault.

However, these case studies were specifically related to systems with ground fault detection systems utilizing

current transformers.

• A ground fault detection system (utilizing current transformers) is not installed on this vessel as it is not required

by the classification society for this type of arrangement. The earth fault protection is provided by the overcurrent

and short circuit protection of the circuit breakers, which is acceptable within the classification society rules.

• Absence of published data and electrical studies for the arrangements leads to the DP FMEA being inconclusive.

• Designer –Any further information or testing requirements at the discretion of the classification society.




CLASS

Conclusion to be made by either;

• Live test during DP FMEA proving trials

• Detailed simulative analysis

DESIGNER

• Live test during DP FMEA proving trials

Detailed simulative analysis is high cost and verbal advice; not fully confident that the analysis would prove the

theory that only equipment in one redundant group would be affected….



Example 4 – Cross connections within emergency systems

Overview

• Vessel management – renew the vessel’s FMEA documentation (5-year class survey).

• Proactive approach to DP FMEA renewal and removal of fault propagation paths.

• Process of engineering out the cross connections includes consultation with the DP

FMEA provider, consultation with the classification society and management of

change.

• Cross connections on existing vessels – barriers verified by checklists / CAM until

process implementation.

DP Class 2 Platform Supply Vessel FMEA

• Emergency Control Panel – Group E Stops and control circuits that allow for remote

operation of main and emergency fire pumps.

• Supplied with power from the 24V DC systems in each redundant group.

• Diode hidden failure followed by a fault can create a voltage dip on both systems

supplying critical DP equipment.

• Common negative – fault propagation path.




FMEA concludes that there are no effects on the group emergency stop circuits when a failure occurs and the cross connection is

unnecessary.




Class Review

• Not acceptable to remove the cross connection.

Services required for normal operation of the vessel shall be operable with the emergency electrical power generation and

distribution system being unavailable, unless such services are permitted to be powered by emergency electrical power supply

only.

All consumers that support functions required to be available in normal operation, shall be supplied from distribution systems

independent of the emergency electrical power supply system.

All consumers required to be available in emergency operation shall be supplied from distribution systems independent of the

main electric power supply system.

• Discussions between the vessel’s management and the classification society.

• Solution - DC / DC converters to be installed in each power supply providing galvanic isolation.




More appropriate solution;

• DP design philosophy is 2 redundant groups – Port and Starboard

• Each redundant group includes a 220V AC main switchboard

• Emergency switchboard belongs to the Port Redundant Group

• ‘Main’ power supply from Port MSB via 220V AC / 24V DC converter

• ‘Emergency’ power supply – existing, originating from emergency switchboard

• Both main and emergency power supplies from within the same redundant group

• Segregation and independence maintained with no reliance on Fault Tolerance



Summary

Example of a basic misinterpretation of DP class rules, by class

• Competency

• Traditionally been associated with DPOs

• However, the delivery of predictable incident free DP operations is not dependent on DPO competency alone.

• Predictable and desired outcomes are influenced by a multitude of stakeholders including those within classification societies,

DP vessel design companies and DP service providers.

• Draft of document: TECHOP_ODP_16_(P) – ‘Competency Elements for DP Professionals – DP SMEs / DP FMEA

Practitioners’.

❑ Competency development.

❑ Encourage companies to develop / enhance their own competency framework.

❑ Uniform and consistent standards for DP Subject Matter Experts and FMEA practitioners.

❑ Leveraging platform for standardisation.

❑ There is an expectation that Companies will adapt the methodologies for their own internal assessment programmes.

Standardisation can be achieved by doing so, when Companies structure their assessment programmes to be transparent

and auditable.



Example 1 – Cross-connections necessitated by SOLAS and class rules

• Cross connections are sometimes introduced into the design of DP electrical power systems due to mandatory legislation.

• Effective barriers can be implemented to isolate the potential fault propagation paths during DP operations.


• Cross connections can sometime be introduced into the design of DP electrical power systems to comply with the requirements of main class

rules, or an interpretation of the rules.

• Proposed arrangement – not compliant with the rules for the applicable DP notations.

• Proactive rational assessment can support the application for reason.

Example 3 – A cross-connection that could not be removed

• Common neutral-earth arrangement – uncommon in power systems of vessels with DP systems.

• Viewed as a cross connection and potential fault propagation path.

• Modifications, such as the installation of 4-pole circuit breakers, to mitigate unknown effects that could potentially exist would not have been

allowed by the classification society.

• The classification society was essentially the arbitrator and provided advice on how the fault tolerance of the arrangement could be concluded.

• Detailed analysis alongside the test would have been preferred to verify independence in terms of fault tolerance.



Summary


• Proactive approach to raising standards and engineering out unnecessary cross connections on vessels in service.

• Engineering out cross connections is a process, involving FMEA review or renewal, MOC and engagement with classification society.

• Effective barriers can be implemented to isolate the potential fault propagation paths during DP operations.



➢ Are these challenges all part of the DP FMEA process?

➢ Is there an over-reliance on the FMEA process?

➢ Is it more convenient and less time consuming for such issues be overlooked during the DP FMEA

process?

➢ Is this contributory to varying standards of DP FMEAs?

Summary

Discussion Points

• Challenges with the implementation of the MTS DP Vessel Design Philosophy Guidelines and the supplementary

TECHOPs (D), during the FMEA process for a DP vessel.

• Not solely due to competence or lack of awareness.

• Main class rules for modern vessels

The power supplies to the distribution boards shall be arranged with automatic changeover facilities between the two sources.

Failure of one of the power supplies to the distribution board(s) shall initiate an alarm (audible and visual signal) in wheel house

(CAM-HMI).



Discussion Points

• Most classification society rules for DP systems – Redundancy / Design Philosophy – The transfer of failures

between redundant subsystems is to be prevented by separation of the redundant systems

• Philosophy is not always disseminated to other specific sections of the same rules that specify requirements

for Power Systems and Control Systems, possibly allowing for fault propagation paths to be introduced into

the design.

• Most classification society rules for DP systems do not specifically address fault propagation paths created

by some common designs.



Discussion Points

➢ Supplying equipment and control systems with power from outside of the same redundant group



Discussion Points

➢ Automatic power supply changeovers between redundant groups



Discussion Points

➢ Dual feeding of equipment such as thrusters



Discussion Points

➢ Co-location of equipment supplied from redundant power distribution systems in DP Class 3 vessel designs



Discussion Points

➢ Network storms



Conclusions

There are often challenges with implementation of the MTS DP Design Philosophy Guidelines

and design TECHOPs, along with the fundamental principles of class rules for DP Class 2 and

DP Class 3 vessels. These challenges can only be overcome with processes that address the

following;

• Competence.

• Conflicts between class rules issued by different classification societies.

• Conflicts between main class rules and additional rules for vessels with dynamic positioning

systems.

• Conflicts between class rules and the fundamental principles of DP redundancy, provided

within the MTS DP Vessel Design Philosophy Guidelines.



Conclusions

Competence – Draft TECHOP_ODP_16_(P) – ‘Competency Elements for DP Professionals – DP SMEs / DP FMEA

Practitioners’

Conflicts – IMO Guidelines for Vessels and Units with Dynamic Positioning (DP) Systems - MSC.1/Circ.1580, published in June

2017 includes an important statement which is as follows;

For equipment classes 2 and 3, connections between otherwise redundant and separated systems should be kept to a

minimum and made to fail to the safest condition. Failure in one system should in no case be transferred to the other

redundant system.

This was not specifically stated in IMO MSC Circular 645.

Classification societies

• Promote this philosophy and provide detailed rule requirements to address fault propagation paths created by commonality in

equipment and system designs.

• Provide guidance for processes which address conflicts between the requirements of the main class rules and those rules

applicable to DP systems. Such guidance would be well placed within the class rules for vessels with dynamic positioning

systems.



Conclusions

The philosophies of segregation, independence and autonomy promulgated through the MTS DP Vessel Design Philosophy

Guidelines and applicable TECHOPs can be achieved through engagement with designers and classification societies. It is

possible to remove most unnecessary fault propagation paths and implement effective barriers for others.

Alternative design options should be always explored before accepting a cross connection into the design of a DP vessel.

Experience in recent years suggests that operating companies with strong technical management have an increased awareness

of the risk associated with power supplies which are cross connected between redundancy groups. This is likely attributable

to their awareness of the applicable TECHOPs along with attendance at the MTS sponsored DP workshops that have been

that have been held throughout the world. Such awareness has been shown by a willingness to remove unnecessary cross

connections and implement barriers, on existing vessels in service and those under construction.



THANK YOU.

Joey Fisher (IEng IMarEng MIMarEST, AVI)Managing Director, M3 Marine Expertise Pte Ltd

MTS DYNAMIC POSITIONING CONFERENCE October 09 ......Joey Fisher (IEng IMarEng MIMarEST, AVI)...

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