EUROPEAN STANDARD

NORME EUROPÉENNE

EUROPÄISCHE NORM

EN 12007-2

January 2000

ICS 23.040.20

English version

Gas supply systems - Pipelines for maximum operating pressureup to and including 16 bar - Part 2: Specific functional

recommendations for polyethylene (MOP up to and including 10bar)

Systèmes d'alimentation en gaz - Canalisations pourpression maximale de service inférieure ou égale à 16 bar -Partie 2: Recommandations fonctionnelles spécifiques pour

le polyéthylène (MOP inférieure ou égale à 10 bar)

Gasversorgungssysteme - Rohrleitungen mit einemmaximal zulässigen Betriebsdruck bis einschließlich 16 bar

- Teil 2: Besondere funktionale Empfehlungen fürPolyethylen (MOP bis einschließlich 10 bar)

This European Standard was approved by CEN on 9 April 1999.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.

CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATIONC OM ITÉ EUR OP ÉEN DE NOR M ALIS AT IONEUROPÄISCHES KOMITEE FÜR NORMUNG

Central Secretariat: rue de Stassart, 36 B-1050 Brussels

© 2000 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.

Ref. No. EN 12007-2:2000 E

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ContentsPage

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Definitions and abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54.2 Materials and components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54.3 Maximum operating pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64.4 Assembly techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74.5 Material properties for flow stopping by squeeze-off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74.6 Pipework inside buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

5 Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85.1 Storage, handling and transportation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85.2 Jointing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85.3 Laying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95.4 Connection to existing systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6 Quality control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116.1 Inspection prior to installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116.2 Inspection during laying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

7 Pressure testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Annex A (INFORMATIVE) Storage, handling and transportation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Annex B (INFORMATIVE) Fusion joint integrity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Annex C (INFORMATIVE) Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

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Foreword

This European Standard has been prepared by Technical Committee CEN/TC 234 "Gas supply", the secretariat ofwhich is held by DIN.

This European Standard shall be given the status of a national standard, either by publication of an identical text orby endorsement, at the latest by July 2000, and conflicting national standards shall be withdrawn at the latest byJuly 2000.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the followingcountries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden,Switzerland and the United Kingdom.

There is a complete suite of functional standards prepared by CEN/TC 234 "Gas Supply" to cover all parts of thegas supply system from the input of gas to the transport system up to the inlet connection of the gasappliances,whether for domestic, commercial or industrial purposes.

In preparing this standard a basic understanding of gas supply by the user has been assumed.

Gas supply systems are complex and the importance on safety of their construction and use has led to thedevelopment of very detailed codes of practice and operating manuals in the member countries. These detailedstatements embrace recognised standards of gas engineering and the specific requirements imposed by the legalstructures of the member countries.

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1 Scope

This standard describes the specific functional recommendations for polyethylene (PE) pipelines in addition to thegeneral functional recommendations of EN 12007-1 for:

a) a maximum operating pressure (MOP) up to and including 10 bar;

b) an operating temperature between -20 C and +40 C.0 0

This European Standard specifies common basic principles for gas supply systems. Users of this EuropeanStandard should be aware that more detailed national standards and/or codes of practice can exist in the CENmember countries.

This European Standard is intended to be applied in association with these national standards and/or codes ofpractice setting out the above mentioned basic principles.

2 Normative references

This European Standard incorporates by dated or undated references, provisions from other publications. Thesenormative references are cited at the appropriate places in the text and the publications are listed hereafter. Fordated references, subsequent amendments to or revisions of any of these publications apply to this EuropeanStandard only when incorporated in it by amendment or revision. For undated references the latest edition of thepublication referred to applies.

prEN 1555-1 Plastics piping systems for gaseous fuels supply - Polyethylene (PE) - Part 1: GeneralprEN 1555-2 Plastics piping systems for gaseous fuels supply - Polyethylene (PE) - Part 2: PipesprEN 1555-3 Plastics piping systems for gaseous fuels supply - Polyethylene (PE) - Part 3: FittingsprEN 1555-4 Plastics piping systems for gaseous fuels supply - Polyethylene (PE) - Part 4: ValvesprEN 1555-5 Plastics piping systems for gaseous fuels supply - Polyethylene (PE) - Part 5: Fitness for

purpose of the systemEN 12007-1 Gas supply systems - Pipelines for maximum operating pressure up to and including 16 bar -

Part 1: General functional recommendationsEN 12327 Gas supply systems - Pressure testing, commissioning and decommissioning procedures -

Functional requirementsISO 12176-1 Plastics pipes and fittings - Equipment for fusion jointing polyethylene systems - Part 1: Butt

fusion ISO/DIS 12176-2 Plastics pipes and fittings - Equipment for fusion jointing polyethylene systems - Part 2:

Electrofusion

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3 Definitions and abbreviations

For the purposes of this standard, the following definitions, symbols and abbreviations apply :

3.1 nominal outside diameter ( d ): The specified outside diameter in millimetres (mm).n

3.2 nominal wall thickness ( e ): Numerical designation of the wall thickness of a component, which is an

convenient round number, approximately equal to the manufacturing dimension in millimetres (mm).

3.3 standard dimension ratio (SDR): The number approximately equal to the quotient of the nominal outsidediameter and the nominal wall thickness.

3.4 design pressure (DP): The pressure on which design calculations are based.

3.5 maximum operating pressure (MOP): The maximum pressure at which a system can be operatedcontinuously under normal operating conditions.

NOTE: Normal operating conditions are: no fault in any device or stream.

3.6 maximum incidental pressure (MIP) : The maximum pressure which a system can experience during a shorttime limited by the safety devices.

3.7 butt fusion joint : A method of jointing PE pipes and fittings where the two pipe ends are heated and broughttogether to be fused without the use of a separate fitting or filler material.

3.8 electrofusion joint : A method of jointing PE pipes, using fittings which have an integrated electric heatingelement.

3.9 squeeze-off: The act of squeezing a pipe to prevent the flow of gas.

3.10 minimum required strength (MRS): The value of the lower confidence limit rounded down to the next lowervalue of the R10 series when the lower confidence limit is below 10 MPa, or to the next lower value of the R20series when the lower confidence limit is 10 MPa or greater.

NOTE: R10 and R20 series are the Renard number series conforming to ISO 3 and ISO 497.

3.11 lower confidence limit (LCL): A quantity, expressed in megapascals (MPa), which can be considered as amaterial property, representing the 97,5 % lower confidence limit of the predicted long term hydrostatic strength forwater at 20 �C for 50 years.

3.12 critical rapid crack propagation pressure (P ) : The pressure level at which a rapid crack propagationRCP

(RCP) can occur in a PE pipeline, defined at a reference temperature

NOTE: Reference temperature is usually 0 C.0

4 Design

4.1 General

The selection of materials, SDR series, dimensions and assembling techniques shall be the responsibility of thepipeline operator.

There are 2 SDRs in common use: SDR 17,6 and SDR 11. Other SDRs are also used.

EXAMPLE: Renovation

4.2 Materials and components

The PE materials and components used shall comply with prEN 1555-1, prEN 1555-2, prEN 1555-3, prEN 1555-4and prEN 1555-5.

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C �

20 x MRSMOP x (SDR�1) x DF

Page 6EN 12007-2:2000

Other components not covered by prEN 1555-1, prEN 1555-2, prEN 1555-3, prEN 1555-4 and prEN 1555-5 shallconform to the relevant European Standards or, in their absence, to national or other established standards andshall be fit for their purpose.

4.3 Maximum operatin g pressure

The MOP should be selected on this basis of the gas supply system operating requirements provided that MOPdoes not exceed 10 bar and the following conditions are satisfied:

a) Verification of the overall service (design) coefficient:

The overall service (design) coefficient C shall be calculated using the equation as given below and shall begreater than or equal to 2. This coefficient C takes into consideration service conditions as well as theproperties and components of a pipeline.

NOTE: Derating factor (D ) is a coefficient used in the calculation of MOP which takes into account theF

influence of operating temperature. Derating factors are listed in prEN 1555-5.

b) Verification of the RCP criterion

The ratio of critical RCP pressure to MOP shall be greater than or equal to 1,5.

The RPC criterion is the critical RCP pressure is dependant upon pipe size and material and should bedetermined in accordance with prEN 1555-2.

The critical RCP pressure is based on a temperature of 0 �C.

Where pipe temperature decreases below 0 �C the P /MOP ratio should be recalculated in accordance withRCP

prEN 1555-5 using a value of RCP pressure determined from the minimum expected operating temperature ofthe pipe. If necessary the value of MOP should be reduced so as to maintain the P /MOP ratio at a valueRCP

greater than or equal to 1,5. See figure 1.

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Figure 1 – Pressure conditions in a PE-system

4.4 Assembl y techniques

Jointing procedures can vary depending upon the PE material and sizes used.

Fusion should be used as the jointing method. The fusion jointing techniques for the construction of PE pipelinesshall be butt fusion and electrofusion.

Mechanical joints can also be used for making PE to PE joints. Mechanical joints shall be used for jointing PE toother materials such as cast iron or steel, these are often refered to as transition fittings (for definitions ofmechanical joints see EN 12007-3).

Care shall be taken for fusion joints made on older PE materials which are not in accordance with prEN 1555-1.

Written jointing procedures, authorised by the pipeline operator, shall be available prior to the construction of a pipeline.

4.5 Material properties for flow stoppin g by squeeze-off

When squeeze-off techniques are considered, the suitability of pipe for squeeze-off should be established inaccordance with prEN 1555-2.

4.6 Pipework inside buildin gs

The pipework element of the gas supply system situated in buildings shall be designed, constructed and protectedso that the effects of a fire on pipework do not lead to an explosion or significant aggravation of the fire. For furtherguidance reference should be made to EN 12007-1.

In accessable areas service lines shall be protected from external interference.

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2.,93

3,35

4,19

5,03

Europa

5,86

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5 Construction

5.1 Stora ge, handlin g and transportation

Care shall be taken during the transport, handling and storage of pipes, fittings and other components to ensure at allstages that their specified properties and conditions, which can be affected by environmental factors, are preservedand that physical damage and distortions are avoided.

EXAMPLE: At low temperatures, flexibility and fracture resistance are reduced.

Pipes and fittings shall be inspected and those with surface defects deeper than 10 % of the nominal wall thicknessshall not be used.

PE pipes and fittings stored outside are subjected to UV degradation when exposed to direct daylight. PE materialsare stabilized to give protection for a UV radiation level of 3.5 GJ/m². National bodies should give recommendationsfor allowed storage times in their countries. The average radiation level for one year in European countries are givenin figure 2.

Figure 2 – Isobaric Curves of Global Radiation in Gigajoules per m per year2

Pipes shall not be used where it is considered that they have exceeded the maximum UV exposure limit, unless theyhave been tested to demonstrate acceptable performance in accordance with existing standards.

Further guidance on storage, handling and transportation of PE pipes and fittings is given in annex A.

5.2 Jointin g

5.2.1 General

Personnel shall be competent in appropriate jointing methods.

Pipes and other pipeline components should be joined by fusion.

Jointing procedures shall be carefully followed to obtain good quality joints. Cleanliness and the absence of stress are essentialfor reliable joints.

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5.2.2 Fusion jointin g

Satisfactory fusion jointing procedures based upon recognised standards and experience of the pipeline operator canbe used. In the absence of fusion jointing procedures ISO 11413 and ISO 11414 should be applied.

Fusion equipment shall conform with ISO 12176-1 for butt fusion and ISO/DIS 12176-2 for electrofusion.

Consideration shall be given to the use of shielding, end caps or longer heating times when jointing in adverse weatherconditions.

NOTE: Strong winds or cold weather can reduce the quality of the PE fusion joint if not protected.

Pipes and/or fittings with fusion ends of different SDR values shall not be jointed by butt fusion.

The following are minimum requirements for assembly of fusion joints:

– Cleaning of the pipe and/or fitting ends and the surface of the heated tools;– Protection against dust and other contaminating influences;– Clamping of the pipe and/or fitting ends;– Verification of the alignment and the gap between fitting and/or pipe ends;– Use of rerounding clamps where pipe ovality exists;– Preparation of the fusion ends, by either scraping in case of electrofusion and planing in case of butt fusion;– Marking for depth of penetration into the electrofusion sockets;– Maintenance and correct functioning of the fusion equipment and check of its compatibility with the requiredparameters;– Taking into account the fusion parameters as written in the jointing procedure.

5.2.3 Mechanical joints

5.2.3.1 General

All mechanical joints shall be resistant to end load in accordance with prEN 1555-3.

All mechanical joints shall be assembled in accordance with the manufacturer’s instructions and the metallic parts offittings shall be corrosion resistant or protected against corrosion.

Satisfactory mechanical jointing procedures based upon recognised standards and experience of the pipeline operatorcan be used. In the absence of mechanical jointing procedures ISO/DIS 10838-1 and ISO/DIS 10838- 2 should beapplied.

5.2.3.2 Flanged joints

Flanged joints shall be made using the appropriate jointing material.

5.2.3.3 Threaded joints

PE pipes shall not be threaded.

5.2.3.4 Compression joints

Stiffener appropriate to the inside diameter of the PE-pipe shall be applied in joints with a compressive element. Onlythe stiffener supplied with a fitting shall be used for a given joint.

Lubricants shall only be used following the manufacturer´s specification.

Where relative movement can occur, anti-shear-sleeves should be fitted.

5.3 Laying

Care shall be taken to prevent damage to the pipes and fittings during the whole process of laying.

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14 x � x d2n

3 x SDR

Page 10EN 12007-2:2000

Changes of direction of a PE pipeline during construction shall be achieved by means of preformed bends or elbowfittings or by the natural flexibility of the PE pipe within limits. Natural flexing can be used for bend radii greater thanor equal to 25 x d , and for smaller radii dependant upon the SDR and material properties based on operationaln

experience and good engineering practice.

Machine bending of pipes or bending following the application of heat shall not be used.

PE pipes, fittings and valves installed above ground shall be protected against mechanical interference and UVdegradation.

When using carrier pipes the gas pipe should be fully supported or equipped with support rings. Contact with sharpedges shall be avoided at entry and exit from the carrier pipe in order to prevent damage to the gas pipe.

When tightening or untightening a mechanical joint it is essential that movement is not transmitted to the pipe.

EXAMPLE: Torsion.

Consideration shall be given during the laying process to the potential effects on the pipe of relative movements of theground or adjacent constructions or from temperature variations.

Pipes shall not be overstressed by tensile forces during laying.

If the PE pipe is laid by drag care shall be taken that the drag force is not greater than the values (in Newton) givenby the formula:

Stresses caused by different temperatures between laying and operation shall be considered.

Valves shall be installed so that they do not expose the PE pipe to unnecessary stress during opening and closingcycles.

Material around the pipe shall be compacted so as to avoid excessive pipe ovality and shall be done layer by layer.

Backfill materials around the pipe shall be selected to prevent damage to the pipe from contact with sharp edgesduring and after compaction.

5.4 Connection to existin g systems

5.4.1 Static electricit y

Where there can be a release of gas in the working area, static charge accumulation shall be avoided.

EXAMPLE: Draping water soaked cloths of natural fibre over all pipes and fittings likely to be handled so that thecloths touch both the pipe and the ground.

5.4.2 Squeeze-off

The squeeze-off procedure and tooling shall be specified by the pipeline operator. Squeeze-offs shall be located nonearer than 3 x d from joints and 6 x d from other squeeze-offs.n n

The squeeze-off position shall be permanently marked if the section of pipe is not replaced.

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6 Qualit y control

6.1 Inspection prior to installation

The PE pipes and fittings and associated equipment shall be inspected prior to installation to confirm the following:

– Conformity with 4.2, in particular verification of required gas application mark, pipe diameters, SDR, MRS andtolerance class on basis of the pipe and fitting marking information.

– Conformity with 5.1.

EXAMPLE 1: Limitations on outside storage have not been exceeded.EXAMPLE 2: Pipes and fittings showing obvious defects or excessive scoring are discarded, clearly identified asunsuitable and, where appropriate, returned to the source of supply.

– Conformity with 5.2.2 regarding the use of the equipment in accordance with relevant standards and theavailability of written jointing procedures.

6.2 Inspection durin g laying

6.2.1 Laying

Soil and trench conditions shall comply with 5.3.

6.2.2 Joint integrity

Joints shall be visually inspected following procedures approved by the pipeline operator. This inspection can becarried out by the personnel engaged in jointing.

EXAMPLE: For butt fusion visual examination on the fusion bead, shape and geometry.

Any additional inspection shall be carried out by a competent person at a frequency depending on the conditions ofuse. The inspection should be recorded.

Destructive testing on joints made in the field can also be carried out to ensure the quality of fusion in conformity withthe fusion procedure.

Further information regarding inspection methods is given in Annex B.

7 Pressure testin g

The test pressures selected for a pipeline shall be appropriate to its MOP and shall take into account the guidancegiven in Figure 1.

The testing procedure(s) shall be in accordance with EN 12327.

Consideration shall be given to the need for any special precautions to be taken to protect persons and property if airor inert gas is used as the test medium.

For testing temperatures below 0 �C the possibility of a reduction in critical RCP pressure shall be taken into accountin the pipeline preparation and testing procedure adopted.

Pressurised PE pipelines at ambient temperature are subjected to expansion by creep that could affect the results ofpressure testing. At higher test pressures this effect can be significant. Appropriate allowances should be made forpressure losses due to creep when interpreting pressure test results.

If air is used, oil from the compressor shall be prevented from entering the pipeline and the air temperature shall notexceed 40 �C, to prevent damage to the pipes and/or fittings.

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Section A-A

Supporting frame

A

A

Page 12EN 12007-2:2000

Annex A (INFORMATIVE)

Storage , handling and transportation

A.1 General

PE pipes are available in coils, drums or in straight lengths in accordance with prEN 1555-2.

The correct storage, handling and transportation of the PE pipes and fittings should be ensured at all times, to fulfillthe specified conditions when they are used.

A.2 Stora ge

A.2.1 Stora ge conditions

PE pipes and fittings should be stored so as to minimize the possibility of the material being damaged by crushing,piercing or extended exposure to direct daylight.

Straight pipes should be stacked on a reasonably flat surface, free from sharp objects, stones or projections likely todeform or damage them. Special care should be taken under site conditions.

Fittings should be stored in their original packing, until ready for use.

Contact with aggressive chemical products like liquid hydrocarbons should be avoided.

A.2.2 Bundles

Pipe bundles should not be stacked unless the supporting frames are equally spaced to transfer safely the load frombundle to bundle through the corresponding frame and to avoid distortion of the pipe and facilitate safe lifting ofbundles.

The supporting frames in stacks should not be nailed together, (see section A-A, Figure A.1)

The distance X should be agreed between manufacturer and pipeline operator and should not exceed 2.5 m (seefigure A.1).

Figure A.1

A.2.3 Stackin g loose strai ght pipes

Where individual straight pipe lengths are stacked in pyramidal fashion, deformation can occur in the lower layers,particularly in warm weather. Therefore, such stacks should not exceed a height of 1m.

The exact height at which PE straight pipes can be stacked depends on many factors such as material, size, wallthickness and ambient temperatures. However, at no time should the loading cause the pipe section to be forced outof shape. The manufacturer´s stacking recommendations should always be followed.

For long periods of storage at high ambient temperatures consideration should be given to fitting end caps to minimizepipe end distortion for large diameter thin wall thickness pipes.

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EXAMPLE: d > 250 mm, SDR 26.n

A.2.4 Drums and coils

PE pipes can be coiled or packed on drums.

Consideration should be given to avoiding single point contact of the coils.

Attention should be paid to the weight of loaded drums which can usually be from 1000 kg to more than 2000 kg.

A.2.5 Storin g

In case of outside storage, the cumulative exposure period should be determined with reference to the Pipe ProductionCode marked on the pipe which includes the date of manufacture. Using this date and the received UV radiation levelsat the storage site checks can be made for total UV exposure, see 5.1.

Storage time can be extended by protecting the pipe from UV radiation.

NOTE: Covering of the pipe to protect it against UV exposure can sometimes create excessive heat which canalso be detrimental to the pipe performance.

For more exact assessment radiation instrumentation can be employed especially for longterm storage sites understrong UV-conditions.

A.2.6 First in - first out

In managing storage sites the exposure time should be minimized by issuing from store on a "first in - first out" rotationwith the date of manufacture used as control. The pipe with the earliest date of manufacture should be issued first forinstallation.

The same "first in - first out" principle should also be used for fittings.

A.3 Handlin g

A.3.1 General

Care should be taken to avoid excessive damage.

If handling equipment is used in contact with the pipes, a protection to avoid damage should be provided.

If handling equipment is not used, techniques which are not likely to damage the pipes and/or fittings should bechosen.

Metal chains or slings should not be used in direct contact with the pipe.

EXAMPLE: during loading and unloading operations.

When pipes are dragged along the ground, roller units or skids should be employed to minimize damage.

A.3.2 Handlin g in cold weather

At low temperatures, flexibility and fracture resistance are reduced and more care should be taken when handling PEpipes and components, especially fittings with fusion joints.

A.3.3 Strai ght pipes

Initial handling and storage of straight pipes should be made with the pipe in packaged form, thus minimizing damageduring this phase. When loading, unloading or handling, mechanical equipment should be used to move or stack thepacks.

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A.3.4 Coils

Coils of pipe stacked on pallets can easily be handled using a forklift truck.

Individual coils should not be rolled off the edge of the loading platforms or trailers. These coils should be slungindividually when off-loading with a crane.

A.3.5 Drums

Taking account of their weight, handling of drums should be helped by mechanical equipment. Special trailers makeit easier and safer.

Before installing the pipe in the trench or by insertion it should be ensured that the drum is placed correctly and thatits axle is steady during the unrolling operation.

A.3.6 Uncoilin g

Especially at low temperatures particular care should be taken during uncoiling operations to protect the operatoragainst effects of uncontrolled spring back of the pipe.

While unrolling from drums the rotation rate should be checked and care should be taken that the pipe is not damaged.

If PE pipes have been unrolled, care should be exercised when cutting the required length at its bending part situatednear the drum or the coil.

A.4 Transportation

A.4.1 Strai ght pipes

When transporting straight pipes, the vehicle bed should be free from nails and other protuberances likely to damagethe pipe. The pipes should have sufficient support to minimize bending stresses likely to damage the pipe and to avoidpipe deformation.

The vehicles should have side supports and the pipes should be secured effectively during transportation. All postsshould be flat with no sharp edges.

During transportation, the pipes should be continuously supported to minimize movement between the pipes and theirsupports.

A.4.2 Coiled pipe

Coiled pipe with d � 63 mm can be supplied on pallets. The coils should be firmly secured to the pallets, which shouldn

in turn be firmly secured to the vehicle. Coiled pipe with d > 63 mm should be supplied individually.n

There should be facilities to restrain each coil securely throughout transit and the loading process.

A.4.3 Drums

The drum should be firmly attached to the vehicle and its height and width should be considered in planning theintended route.

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Annex B (INFORMATIVE)

Fusion joint integrity

B.1 General

All fusion joints should be visually inspected in the field.

The quality of the joint depends on the strict adherence to the written and authorized fusion procedure, the use ofwell maintained equipment conforming to the relevant specification and the competence of fusion operators.

B.2 Visual inspection criteria

Attention should be drawn to the following visual inspection criteria, which are suitable for quality control of fusionjoints.

B.2.1 Butt fusion

Some general guidelines for the visual examination of butt fusion joints are given below:

B.2.1.1 Bead s ymmetr y

Good quality joints should have a smooth symmetrical bead shape around the entire pipe circumference as shownin figure B.1. The bead depression "A" should not extend below the pipe surface.

An unsymmetrical bead profile between the same components should initially be considered as indicative of poorjoint quality and therefore an assessment by an authorised person should be undertaken. The effect on beadsymmetry of differences in melt flow rates (MFR) between the parts to be joined should be considered in thesecondary assessment.

Figure B.1

Where the pipes and/or fittings have different melt flow rates (MFR) the bead can be unsymmetrical but stillsatisfactory. In assessing the results of the joint tests under standard conditions acceptable levels of symmetryshould be determined.

B.2.1.2 Alignment

Pipes, fittings and valves should be as closely aligned as possible.

An allowable misalignment V should not exceed 0,1 e . Where this leads to values below 1 mm, testing of jointsn

should be undertaken to identify the maximum allowable misalignment.

This value should not be exceeded anywhere around the circumference of the two parts adjacent to the fusionbead.

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Bmax

Bmin

Page 16EN 12007-2:2000

Figure B.2

B.2.1.3 Bead width

The bead width B (figure B.2) is influenced by the PE material, the production type (extruded or injection moulded),the type and temperature of the heater plate and the applied fusion cycle; consequently it is difficult to specify asingle set of bead width values. It is however a good indicator that the necessary fusion procedure has beenfollowed.

One method of determining acceptable bead width value B is experimentally with pipe and butt fusion machinesoperating at the specified conditions. The mean value B is determined from several joints made under theconditions defined in the written fusion procedures. The measured bead width B should not exceed ± 20 % of thismean value.

The use of GO NO-GO gauges, manufactured to the recommended values, could facilitate the control (see figureB.5).

Variation in the bead width of a single joint (figure B.3) indicates a poor condition of the fusion equipment andshould be strictly limited.

Figure B.3

B.2.1.4 Bead removal

Removal of the external fusion bead, using appropriate tooling, is possible without damage to the pipe (figure B.4).The removed bead is then available for inspection.

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Figure B.4

Bead gauges can be used to assess the bead width (figure B.5). A visual examination of the underside of the beadcan be undertaken; evidence of contamination, holes, offsets and melt damage should be cause for rejection.

Figure B.5

The bead should be solid and rounded with a broad root as shown in figure B.6. Hollow beads with a thin root andcurled appearance could have been formed with excessive pressure or no heat soak.

Figure B.6

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A bend back test (figure B.7) every few centimetres and observation for the presence of slit defects should bemade. Slit defects are indicative of fine dust contamination entrained within the fusion interface, possibly arisingfrom contact with a dirty heater plate.

Figure B.7

B.2.2 Electrofusion

B.2.2.1 Electrofusion socket

B.2.2.1.1 Pipe ali gnment

It should be checked that the pipes and fittings have been properly aligned conforming to the written jointingprocedures.

B.2.2.1.2 Scrapin g

It should be checked that an efficient scraping in accordance with the written jointing procedures over the entirecircumference has been carried out (figure B.8).

There should be clear evidence of scraping on either side of the socket. Particular attention should be given to theinspection of the bottom of the pipe.

Figure B.8

B.2.2.1.3 Penetration

The presence of depth of penetration marking should be checked to confirm that complete penetration of pipe orspigot ends has been achieved (figure B.9).

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Figure B.9

B.2.2.1.4 Melt material

It should be checked that melt from the fusion process or fusion wires have not exuded outside the confines of thefitting (figure B.10).

Figure B.10

B.2.2.1.5 Heatin g indicators

If the fitting is designed with heating indicators they should be in a position complying with the manufacturer'sinstructions after fusion has been completed (figure B.11).

Figure B.11

B.2.2.1.6 Coolin g time

The clamp should not be removed before the cooling time has elapsed.

B.2.2.1.7 Electric wire position

Abnormal displacement after fusion of the electric coils should not occur.

B.2.2.2 Saddle or tappin g tee

B.2.2.2.1 Scrapin g

It should be checked that an efficient scraping in accordance with the written jointing procedures over the entirefusion area has been carried out (figure B.12). When the fusion area includes the entire circumference of the pipeparticular attention should be given to the inspection of the bottom of the pipe.

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Figure B.12

B.2.2.2.2 Visual control

The stack of the saddle should be perpendicular to the central line of the main.

The fitting should not collapse the pipe.

Nowhere should melt from the fusion process exude outside the confines of the saddle, (figure B.13).

Figure B.13

B.2.2.2.3 Heating indicators

If the fitting is designed with heating indicators they should be in a position complying with the manufacturer'sinstructions after fusion has been completed (figure B.11).

B.2.2.2.4 Coolin g time

When a special clamp is required for saddles or tapping tees, it should not be removed nor the joints disturbed beforethe cooling time as defined in the fusion procedure has elapsed.

B.2.3 Ancillar y toolin g

The application of ancillary tooling should not result in significant damage to pipe surfaces adjacent to the fusion joint.

EXAMPLE: pipe clamps

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Annex C (INFORMATIVE)

Bibliography

EN 12007-3 Gas supply systems - Pipelines for maximum operating pressure up to and including 16 bar - Part3: Specific functional recommendations for steel

EN 12007-4 Gas supply systems - Pipelines for maximum operating pressure up to and including 16 bar - Part4: Specific functional recommendations for renovation

ISO 3 Preferred numbers - Series of preferred numbersISO 497 Guide to the choice of series of preferred numbers and of series containing more rounded values

of preferred numbers.ISO/DIS 10838-1 Mechanical fittings for polyethylene piping systems for the supply of gaseous fuels -Part 1: Metal

fittings for pipes of nominal outside diameter less than or equal to 63 mmISO/DIS 10838-2 Mechanical fittings for polyethylene piping systems for the supply of gaseous fuels - Part 2: Metal

fittings for pipes of nominal outside diameter greater than 63 mmISO 11413 Plastics pipes and fittings - Preparation of test piece assemblies between a polyethylene (PE)

pipe and an electrofusion fitting.ISO 11414 Plastics pipes and fittings - Preparation of polyethylene (PE) pipe/pipe or pipe/fitting test

assemblies by butt fusion.

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