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PETRONAS TECHNICAL STANDARDS

TECHNICAL SPECIFICATION

THERMOPLASTIC LINED PIPELINES

PTS 31.40.30.34

JANUARY 2011

2011 PETROLIAM NASIONAL BERHAD (PETRONAS)

All rights reserved. No part of this document may be reproduced, stored in a retrieval system or transmitted in any form or by any means(electronic, mechanical, photocopying, recording or otherwise) without the permission of the copyright owner.

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PREFACE

PETRONAS Technical Standards (PTS) publications reflect the views, at the time of publication, ofPETRONAS OPUs/Divisions.

They are based on the experience acquired during the involvement with the design, construction,operation and maintenance of processing units and facilities. Where appropriate they are based on,or reference is made to, national and international standards and codes of practice.

The objective is to set the recommended standard for good technical practice to be applied byPETRONAS' OPUs in oil and gas production facilities, refineries, gas processing plants, chemicalplants, marketing facilities or any other such facility, and thereby to achieve maximum technical andeconomic benefit from standardisation.

The information set forth in these publications is provided to users for their consideration anddecision to implement. This is of particular importance where PTS may not cover every requirementor diversity of condition at each locality. The system of PTS is expected to be sufficiently flexible toallow individual operating units to adapt the information set forth in PTS to their own environment and

requirements.

When Contractors or Manufacturers/Suppliers use PTS they shall be solely responsible for thequality of work and the attainment of the required design and engineering standards. In particular, forthose requirements not specifically covered, it is expected of them to follow those design andengineering practices which will achieve the same level of integrity as reflected in the PTS. If indoubt, the Contractor or Manufacturer/Supplier shall, without detracting from his own responsibility,consult the owner.

The right to use PTS rests with three categories of users:

1) PETRONAS and its affiliates.2) Other parties who are authorised to use PTS subject to appropriate contractual

arrangements.3) Contractors/subcontractors and Manufacturers/Suppliers under a contract with users

referred to under 1) and 2) which requires that tenders for projects, materialssupplied or - generally - work performed on behalf of the said users comply with therelevant standards.

Subject to any particular terms and conditions as may be set forth in specific agreements with users,PETRONAS disclaims any liability of whatsoever nature for any damage (including injury or death)suffered by any company or person whomsoever as a result of or in connection with the use,application or implementation of any PTS, combination of PTS or any part thereof. The benefit of thisdisclaimer shall inure in all respects to PETRONAS and/or any company affiliated to PETRONAS thatmay issue PTS or require the use of PTS.

Without prejudice to any specific terms in respect of confidentiality under relevant contractualarrangements, PTS shall not, without the prior written consent of PETRONAS, be disclosed by usersto any company or person whomsoever and the PTS shall be used exclusively for the purpose theyhave been provided to the user. They shall be returned after use, including any copies which shallonly be made by users with the express prior written consent of PETRONAS.

The copyright of PTS vests in PETRONAS. Users shall arrange for PTS to be held in safe custodyand PETRONAS may at any time require information satisfactory to PETRONAS in order to ascertainhow users implement this requirement.

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TABLE OF CONTENTS

1. INTRODUCTION........................................................................................................ 61.1 SCOPE ........................................................................................................................ 61.2 DISTRIBUTION, INTENDED USE AND REGULATORY CONSIDERATIONS ......... 61.3 DEFINITIONS ............................................................................................................. 61.4 ABBREVIATIONS ....................................................................................................... 81.5 CROSS-REFERENCES ............................................................................................. 92. MATERIALS............................................................................................................. 102.1 GENERAL ................................................................................................................. 102.2 THERMOPLASTIC LINER MATERIALS .................................................................. 112.3 MATERIAL SELECTION GUIDE .............................................................................. 182.4 MATERIAL TESTING ............................................................................................... 192.5 END CONNECTORS ................................................................................................ 233. DESIGN.................................................................................................................... 243.1 INTRODUCTION ...................................................................................................... 243.2 MINIMUM LINER THICKNESS................................................................................. 253.3

LINER DESIGN PROCEDURE................................................................................. 26

3.4 VENT POINT DESIGN .............................................................................................. 323.5 PULL-IN LOADS AND INSERTION LENGTH .......................................................... 343.6 DESIGN OF END CONNECTORS ........................................................................... 354. MANUFACTURE OF THE THERMOPLASTIC LINER............................................ 374.1 PROCESS OF MANUFACTURE .............................................................................. 374.2 FINISH AND WORKMANSHIP ................................................................................. 374.3 DIMENSIONS, WEIGHTS AND TOLERANCES ...................................................... 384.4 QUALITY PROGRAMME .......................................................................................... 384.5 EQUIPMENT MARKING ........................................................................................... 414.6 HANDLING AND STORAGE .................................................................................... 425. LINER INSTALLATION............................................................................................ 435.1 GENERAL - INSTALLATION TECHNIQUES ........................................................... 435.2 PREPARATION PHASE ........................................................................................... 455.3 LINER FABRICATION PHASE ................................................................................. 475.4 LINER INSTALLATION ............................................................................................. 495.5 END FLANGES AND IN-LINE FLANGED JOINTS .................................................. 515.6 TESTING ................................................................................................................... 526. OPERATION............................................................................................................. 536.1 START-UP ................................................................................................................ 536.2 DE-PRESSURISING ................................................................................................. 536.3 PIGGING ................................................................................................................... 536.4 FLOW VELOCITY ..................................................................................................... 536.5 VENTING .................................................................................................................. 536.6 MAINTENANCE ........................................................................................................ 536.7 REPAIR ..................................................................................................................... 546.8 OPERATIONAL PROCEDURE FOR A LINED PIPELINE ....................................... 547. DOCUMENTATION.................................................................................................. 557.1 INFORMATION TO BE SUBMITTED BY THE PRINCIPAL ..................................... 557.2 INFORMATION TO BE SUBMITTED BY THE CONTRACTOR .............................. 558. REFERENCES......................................................................................................... 56

APPENDICES

APPENDIX 1 CURRENT RANGE OF SERVICE EXPERIENCE .......................................... 59APPENDIX 2

EXAMPLE OF OPERATIONAL PROCEDURE ............................................... 61

APPENDIX 3 LINER DESIGN DATA SHEET ........................................................................ 63

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APPENDIX 4 MATERIAL PROPERTIES............................................................................... 65APPENDIX 5 PURCHASE ORDER INFORMATION ............................................................ 66

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1. INTRODUCTION

1.1 SCOPE

This PTS specifies requirements and gives recommendations for the selection, design,

manufacture, installation and operation of thermoplastic liners in carbon steel pipelines andflowlines. It covers both the retro-fitting of thermoplastic liners inside existing carbon steelpipelines and flowlines as well as new pipelines and flowlines.

In the context of this PTS, a liner consists of a number of thermoplastic pipe lengths whichare fused together into sections of up to approximately 1 km. After pressure testing, thesection of liner is inserted into a pre-welded carbon steel pipeline or flowline section. Thecarbon steel pipe provides the pressure containment and the liner the internal corrosionprotection. At the ends of the section the liner is terminated in a thermoplastic flange orother (usually mechanical) connection system, to enable sections to be joined together.

Onshore, offshore, buried and above-ground applications are considered. Within certainlimitations, thermoplastic lined pipelines and flowlines may be used in oil, gas or waterservice. Although the scope is directed towards thermoplastic liners for carbon steel

pipelines and flowlines, much of the content is also relevant for liners inserted in flexibleflowlines and risers.

The liners covered in this PTS are based both on currently applied thermoplastic materialsand on those materials that have the potential to be applied in future, more demandingapplications.

This PTS only gives requirements for the thermoplastic liner. It is assumed that the carbonsteel pipeline or flowline into which the liner is to be inserted has been designed andconstructed in accordance with PTS 31.40.00.20.

Amended perCircular 05/02

Factory-applied liners inside steel pipe and fittings are covered by PTS 31.38.01.11-Gen.Hose lining techniques, using polyester materials with fibre tubes and epoxy to bond these

to the pipe wall, are not covered by this PTS. Pipelines lined with thermoset materials suchas GRE (Glass fibre Reinforced Epoxy) are not covered by this PTS either.

1.2 DISTRIBUTION, INTENDED USE AND REGULATORY CONSIDERATIONS

Unless otherwise authorised by PETRONAS, the distribution of this PTS is confined tocompanies forming part of PETRONAS or managed by a Group company, and toContractors and Manufacturers/Suppliers nominated by them.

This PTS is intended for use in the design, procurement, manufacturing, transport andinstallation of thermoplastic liners for pipelines for oil and gas production, oil refineries,chemical plants, gas plants and supply/marketing installations.

If national and/or local regulations exist in which some of the requirements may be more

stringent than in this PTS, the Contractor shall determine by careful scrutiny which of therequirements are more stringent and which combination of requirements will be acceptableas regards safety, environmental, economic and legal aspects. In all cases the Contractorshall inform the Principal of any deviation from the requirements of this PTS which isconsidered to be necessary in order to comply with national and/or local regulations. ThePrincipal may then negotiate with the Authorities concerned with the object of obtainingagreement to follow this PTS as closely as possible.

1.3 DEFINITIONS

1.3.1 General defin itions

The Contractor is the party which carries out all or part of the design, engineering,

procurement, construction, commissioning or management of a project, or operation or

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maintenance of a facility. The Principal may undertake all or part of the duties of theContractor.

The Manufacturer/Supplier is the party which manufactures or supplies equipment andservices to perform the duties specified by the Contractor.

The Principalis the party which initiates the project and ultimately pays for its design andconstruction. The Principal will generally specify the technical requirements. The Principalmay also include an agent or consultant to act for, and on behalf of, the Principal.

The word shallindicates a requirement.

The word shouldindicates a recommendation.

1.3.2 Specific definitions

Acceptance cri ter ia Defined limits placed on characteristics of materials,products or services.

Annu lus Space between thermoplastic liner and the carbon steelouter pipe.

Bell hole Excavated area allowing access to a buried carbon steelpipeline e.g. for insertion of a section of thermoplasticliner.

Butt fusion welding A process of fusing thermoplastic materials that entailssquaring and aligning the pipe materials, heating the pipeends, bringing the two aligned pipe ends together underpressure and a predetermined cooling time resulting in afused joint having a hydrostatic strength equal to theparent pipe.

Crude oil service Fluids in which the volume fraction of crude oil is at least1%

End connector A device used to provide a leak-tight structuralconnection between two sections of lined pipe. The liningis terminated inside the end connector.

Flanges Face flanges with a bolt circle according to ASME B 16.5or ASME B16.47, including thermoplastic flanges withmetallic backup rings.

Grout porosity Voids in grout, which allow the transport of gas throughthe grout to venting ports.

Hot plate welding Technique whereby thermoplastic pipe is fused bysmelting and re-solidification.

In-line compression joint System of terminating lined pipelines by compression ofthe liner between an internal ring and a CRA material.

Inspectors Individuals designated by the Principal to act on behalf ofthe Principal for monitoring Contractor's quality controltesting and technical acceptance.

Lot number Assignment of a unique code to each lot of pipes tomaintain traceability. A lot is defined as being all pipesproduced from the same base polymer batch with thesame diameter and wall thickness, up to a maximumnumber of 50 pipes.

Modulus Elastic modulus: proportionality constant between appliedstress and strain.

Ovality This is a measurement of the deflected set in a cross-section of pipe and is expressed as a percentage. It is

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measured by taking the maximum measured diameterminus the minimum measured diameter (the out-of-roundness value) and dividing that sum by the averagemeasured diameter and multiplying that result by 100.

PA liner Liner based on Polyamide in combination with fillers andplasticisers.

PE liner Liner based on Polyethylene in combination with fillersand plasticisers.

PK liner Liner based on Polyketone in combination with fillers andplasticisers.

Point of fusion The end of a liner which is available for trimming, heatingand pressing together during the heat fusion process.

PP liner Liner based on Polypropylene in combination with fillersand plasticisers.

PPS liner Liner based on Polyphenylene Sulphide in combination

with fillers and plasticisers.

PTFE liner Liner based on Polytetrafluoroethylene in combinationwith fillers and plasticisers.

PVC liner Liner based on Polyvinylchloride in combination withfillers and plasticisers.

PVDF liner Liner based on Polyvinylidenefluoride in combination withfillers and plasticisers.

Permeation Gradual diffusion of liquid and gas through athermoplastic layer under the influence of pressure.

Records Retrievable information.

Standard Dimension Ratio(SDR)

A specific ratio of the average specified outside diameterto the minimum specified wall thickness (OD/t) for outsidediameter-controlled plastic pipe.

Thermoplastic materials Plastic materials which retain their mechanical propertiesafter heating and cooling.

Vent connection or po int Hole in the carbon steel outer pipe to allow the release ofgas accumulated in the annulus between the liner andthe carbon steel pipe.

Venting The release of gas accumulated in the annulus betweenthe thermoplastic liner and the carbon steel pipeline.

Water service Fluids in which the volume fraction of crude oil is lessthan 1%

1.4 ABBREVIATIONS

CRA Corrosion Resistant Alloy

ESC Environmental Stress Cracking

ID Nominal internal diameter

HDPE High Density Polyethylene

MDPE Medium Density Polyethylene

OD Nominal outside diameter

PA Polyamide

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PE Polyethylene

PK Polyketone

PP Polypropylene

PPSPolyphenylene Sulphide

PTFE Polytetrafluoroethylene

PVC Polyvinylchloride

PVDF Polyvinylidenefluoride

SDR Standard Dimension Ratio

UV Ultra violet light

XLPE or PEX Cross-linked Polyethylene consisting of long polymer chains ina 3-dimensional structure.

1.5 CROSS-REFERENCES

Where cross-references to other parts of this PTS are made, the referenced sectionnumber is shown in brackets. Other documents referenced in this PTS are listed in (8).

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2. MATERIALS

2.1 GENERAL

The Contractor shall be responsible for the selection and supply of all materials required to

meet the specified installation and service conditions (7). The Contractor shall have eithermeasured test data (preferred) or documented methods for predicting the thermoplasticliner material properties for the specified service conditions. For the predictive methods, theContractor shall have available, for review by the Principal, records of tests andevaluations, which demonstrate that the predictive method yields conservative results. If theconveyed fluid contains gas, it shall be demonstrated by testing or documented evidence ofstandard testing that the thermoplastic will not blister or degrade during service, i.e. start-up, continuous operation or shut-down (rapid de-pressurisation).

The Contractor shall also be responsible for documenting the mechanical, thermal, fluidcompatibility and permeability properties of the thermoplastic liner material (2.4).

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2.2 THERMOPLASTIC LINER MATERIALS

A liner is made from a mix of a thermoplastic polymer material, colouring agent, anti-oxidantand plasticiser. Currently there are several thermoplastic polymer materials that are used

for liners in pipelines or for similar applications in flexible flowlines and risers: Polyethylene(PE), Polyamide (PA), and Polyvinylidenefluoride (PVDF). Other polymers such asPolypropylene (PP), Polyvinylchloride (PVC), Polytetrafluoroethylene (PTFE),Polyphenylene Sulphide (PPS) and Polyketone (PK) have the potential to be used but arenot in use at present.

These thermoplastic polymer materials are produced in numerous grades and qualities.The differences in material properties between grades of the same polymer may be asgreat as the difference between different polymers.

The following presents a limited introduction to the generic thermoplastic material types andcommonly applied grades. In particular, for each polymer, it specifies the:

Application envelope (in terms of maximum operating temperature as a function of fluidcomposition);

Typical material properties at ambient conditions;

Appropriate testing standards.

The typical material properties (un-aged) are listed for guidance only, based on anassumed lifetime of twenty years. They should be considered as minimum values atambient un-aged conditions. Specific material data relating to actual service conditions(temperature, life-time) and fluid composition shall always be used in design and installationrequirement analyses.

The minimum design temperature for all thermoplastic materials covered in this PTS isminus 20 C. Lower temperatures may be tolerated but only provided that specific lowtemperature material data are available and the operating temperature does not fall belowthe brittleness temperature of the thermoplastic material.

For a more complete specification of polymer properties, refer to PTS 30.10.02.13-Gen.

2.2.1 Polyethylene (PE)

PE is the most commonly applied liner material. PE liners shall not be exposed to operatingtemperatures above 60 C in water service. In hydrocarbon service (combined liquid andgas phases), the recommended maximum operating temperature is lower and depends onthe fluid composition but shall not exceed 50 C. If only a liquid phase or a dry gas phase ispresent, then a higher temperature (>50C) can be tolerated, but the maximum operatingtemperature shall be specified and agreed by the Principal. This reduction in operatingtemperature results from small organic compounds diffusing into the PE, causing swellingand softening. (Table 2.2.1a) lists the recommended maximum operating temperature as afunction of fluid composition.

Table 2.2.1a Maximum operating temperature fo r PE as a function of fluidcomposition

Fluid Composition Temperature (C)

Oil/gas/water mixture 50

Oil/water mixture 50

Gas and condensate 50

Dry gas 60

Water 60

Numerous PE grades are available. The differences between them primarily result from thepolymerisation processes for the production of the base polymer, chemical modifications or

enhancements with additives. Base polymer density is used to indicate PE type. Low,medium and high-density grades are distinguished as LDPE, MDPE and HDPE. This

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characterisation applies to most vendor data. For lining applications, three types of PE areused; in increasing order of strength and chemical resistance, they are:

MDPE, used in low-pressure water and gas distribution applications;

HDPE, used in all types of service;

Ultra High Molecular Weight (UHMW-HDPE) used in demanding applications.MDPE (or PE 80) is a relatively soft grade and is used in (low) pressure applications atambient conditions. It has good 50-year creep-rupture performance and is easy tomanufacture (extrude) and install.

HDPE (or PE 100) is the basic engineering grade of PE. Compared to MDPE, it has ahigher yield and ultimate strength, a higher modulus and better chemical resistance. Theseimproved properties come with the penalty of slightly more difficult extrusion andinstallation. However, HDPE is more sensitive to notches and has a lower environmentalstress cracking (ESC) resistance than MDPE.

UHMW-HDPE is developed for aggressive chemical environments and high toughness.Compared to HDPE it has a higher yield and ultimate strength, a higher modulus and betterchemical resistance. This results in reduced swelling in crude oil and an increasedcapability of bridging pinhole leaks in the carbon steel outer pipe. However, these improvedproperties come with a penalty of considerably more difficult extrusion and installation.

The above description is for general information only. There is a general trend away frommerely specifying PE grades, and it is recommended to specify the material properties ofPE listed in (Table 2.2.1b) instead.

A summary of typical material properties of PE in ambient conditions is presented in (Table2.2.1b). This Table is for comparison purposes only. Manufacturers shall submit therelevant (minimum) material property specifications at the specific service conditions.

Table 2.2.1b "Typical" material properties of PE

Typical properties PE (MD) PE (HD) PE (UHMW)

Density (g/cm3) 0.926-0.94 0.941-0.965 0.989

Tensile properties at

23CYield strength (MPa) 18 25 32Stress at break (MPa) 20 20 25Elongation at break(%)

>400 >400 >400

Modulus (MPa) 400 700 1100

Thermal conductivity(W/m.K)

0.35 0.4 0.4

Coefficient of thermalexpansion

(K1

)

200 x 10-6

200 x 10-6 200 x 10-6

Mechanical properties(function oftemperature)

23 C 40 C 60 C 23 C 40 C 60 C 23 C 40 C 60 C

Modulus (MPa) 400 250 130 700 450 250 1100 600 400Poisson ratio 0.35 0.38 0.4 0.35 0.38 0.4 0.35 0.38 0.4

All PE pipe and fittings supplied to this PTS shall be stabilised against degradation by UV-light in accordance with standard practices by a minimum of 2% (by mass) of Carbon Black(ASTM D 3350).

A UV stabiliser as specified by ASTM D 3350, code C or D shall be added.

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2.2.2 Polyamide (PA)

PA is a commodity engineering plastic that is more expensive than PE. Therefore, it shouldonly be considered for application outside the range of PE. PA has excellent resistance tohydrocarbons but limited resistance to water at elevated temperatures. (Table 2.2.2a) liststhe recommended maximum operating temperature as a function of fluid composition.

Because of the molecular structure of PA, different grades e.g. PA-6 and PA-11, canessentially be considered as different materials. PA-11 is used as a liner in conventionalflexible flowlines and risers transporting gas and crude with low water cuts. It has goodmaterial properties for liner applications, high modulus and strength, with relatively highstrain to failure in its un-aged condition. It has been used to line carbon steel pipelines attemperatures up to 75 C.

Table 2.2.2a Maximum operating temperature for PA-11 as a funct ion of fluidcomposition





Dry gas 80

Water 75

A summary of typical material properties of PA is presented in (Table 2.2.2b). This Table isfor comparison purposes only. Manufacturers shall submit the relevant (minimum) materialproperty specifications at the specified service conditions.

Table 2.2.2b "Typical" material properties of PA-11

Typical properti es PA-11

Density (g/cm3) 1.04

Tensile properties at 23 CYield strength (MPa)Stress at break (MPa)Elongation at break (%)Modulus (MPa)

40-6080

>30650-1400

Thermal conductivity (W/m.K) 0.25

Coefficient of thermal expansion

(K1

)

100 x 10-6

Mechanical properties (functionof temperature)

Modulus (MPa)Poisson ratio

23 C

6500.35

40 C

5000.36

60 C

4000.37

80 C

3000.38

PA liners shall comply with the requirements of ASTM D 4066 and ASTM F 1733.

2.2.3 Polyv iny lidenefluoride (PVDF)

PVDF is a fluoropolymer that is more expensive than both PE and PA. Therefore it shouldonly be considered for applications outside the range of PE and PA, i.e. for hydrocarbonapplications above 80 C and water applications above 60 C. PVDF has excellentchemical resistance. Superior thermal stability implies that the application envelope interms of temperature for PVDF extends well beyond that of PA, up to 120 C for allapplications. (Table 2.2.3a) lists the recommended maximum operating temperature as afunction of fluid composition.

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Table 2.2.3a Maximum operating temperature for PVDF as a funct ion of fluidcomposition

Fluid composition Temperature (C)


Oil/water mixture 120Gas and condensate 120

Dry gas 120

Water 120

PVDF has good mechanical properties. The modulus and yield strength are high but theyield strain is low. The pure polymer is difficult to extrude and to overcome this, plasticisedgrades (both homopolymer and co-polymer) are used, for example as pressure sheaths inflexible flowlines and risers. Only co-polymer grades of PVDF should be used to minimiseproblems associated with leaching out of the plasticiser.

A summary of typical material properties of PVDF is presented in (Table 2.2.3b). This Tableis for comparison purposes only. Manufacturers shall submit the relevant (minimum)

material property specifications at the specified service conditions.Table 2.2.3b "Typical" material properties of PVDF

Typical properties PVDF (homopolymer) PVDF (co-polymer)

Density (g/cm3) 1.78 1.78

Tensile properties at23 CYield strength (MPa) 55 25Stress at break (MPa) 40 35Elongation at break (%) >20 >50Modulus (MPa) 2200 1000

Thermal conductivity(W/m.K)

0.19 0.18

Coefficient of thermal

expansion (K1

)

130 x 10-6 140 to 180 x 10-6

Mechanical properties(function oftemperature)

23 C 40 C 75 C 90 C 120C 23 C 40 C 75 C 90 C 120C

Modulus (MPa) 2200 1750 1000 750 400 1000 650 250 150 110Poisson ratio 0.35 0.35 0.40 0.45 0.5 0.35 0.35 0.40 0.45 0.5

PVDF liners shall comply with the requirements of ASTM D 3222 and ASTM F 491.

2.2.4 Polypropylene (PP)

PP is a commodity engineering plastic. It is not currently used as a thermoplastic linermaterial but has the potential for such use in the future. Although chemically similar to PE,PP has important mechanical property differences. It can tolerate a higher operating

temperature than PE, and it is not susceptible to ESC. PP has excellent resistance to waterand liquid hydrocarbons, but limited resistance to aromatics. (Table 2.2.4a) lists themaximum recommended operating temperature as a function of fluid composition.

Table 2.2.4a Maximum operating temperature fo r PP as a function of fluidcomposition





Dry gas 85

Water 85

In general, the mechanical properties of PP, i.e. high modulus and high yield strength withsufficient strain to failure, are sufficient for liner installations. A summary of typical material

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properties of PP is presented in (Table 2.2.4b). This Table is for comparison purposes only.Manufacturers shall submit the relevant (minimum) material property specifications at thespecified service conditions.

Table 2.2.4b "Typical" material properties of PP

Typical properties PPDensity (g/cm3) 0.9

Tensile properties at 23 CYield strength (MPa) 35Stress at break (Mpa) 40Elongation at break (%) >100Modulus (MPa) 1200



(K1

)

180 x 10-6

PP liners shall comply with the requirements of the ASTM D 2657, ASTM D 4101 and

ASTM F 492.

2.2.5 Polyphenylene Sulph ide (PPS)

PPS is an engineering plastic with a price similar to that of PVDF. It is not currently used asa thermoplastic liner but has the potential for such use in the future. It has excellent hightemperature properties and should only be considered for applications in the temperaturerange of PDVF and beyond. It has good chemical resistance to water, dry gas and mosthydrocarbons, except aromatics. (Table 2.2.5a) lists the recommended maximum operatingtemperature as a function of fluid composition.

Table 2.2.5a Maximum operating temperature fo r PPS as a function of fluidcomposition





Dry gas 180

Water 180

There are many different grades of PPS available but because of its molecular structurePPS shall be plasticised to enable extrusion and to provide the flexibility required to enableinsertion as a liner.

PPS has good mechanical properties, high modulus and strength but a limited strain tofailure. A summary of typical material properties of PPS is presented in (Table 2.2.5b). This

Table is for comparison purposes only. Manufacturers shall submit the relevant (minimum)material property specifications for the liner material at the specified service conditions.

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Table 2.2.5b "Typical" material properties of PPS

Typical properties PPS



90140

53800


Coefficient of thermal expansion (K1) 90 x 10-6

Specifications for PPS liners shall be agreed between the Contractor and the Principal.

2.2.6 Cross-linked Polyethylene (PEX)

PEX is an engineering plastic manufactured by cross-linking PE. It is more expensive thanPE. PEX has excellent resistance to hydrocarbons and water at elevated temperatures upto 85 C. (Table 2.2.6a) lists the recommended maximum operating temperature as afunction of fluid composition.

Table 2.2.6a Maximum operating temperature fo r PEX as a function of fluidcomposition





Dry gas 85

Water 85

The cross-linking of PE implies that PEX is stiffer than PE with a corresponding reduction inflexibility. For liner applications the material properties, modulus and yield strength aregood, with a strain-to-failure strength sufficient for insertion.

A summary of typical material properties of PEX is presented in (Table 2.2.6b). This Tableis for comparison purposes only. Manufacturers shall submit the relevant (minimum)material property specifications for the liner material at the specified service conditions.

Table 2.2.6b "Typical" material properties of PEX

Typical properties PEX



2530

>50800



(K1

)

120 x 10-6

Specifications for PEX liners shall be agreed between the Contractor and the Principal.

2.2.7 Polyketone (PK)

Polyketone (PK) is a relatively new thermoplastic polymer. It has good chemical resistanceto both water and hydrocarbons. However, it is susceptible to oxidation and stabilisers shall

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be used to limit degradation. (Table 2.2.7a) presents the recommended maximumoperating temperature as a function of fluid composition.

Table 2.2.7a Maximum operating temperature fo r PK as a function of fluidcomposition

Fluid Composition Temperature (C)Oil/gas/water mixture 105



Dry gas 105

Water 105

A summary of typical material properties of PK is presented in (Table 2.2.7b). This Table isfor comparison purposes only. Manufacturers shall submit the relevant (minimum) materialproperty specifications at the specified service conditions.

Table 2.2.7b "Typical" material properties of PK

Typical properties PK



55633501600


Coefficient of thermal expansion (K1) 110 x 10-6

Specifications for PK liners shall be agreed between the Contractor and the Principal.

2.2.8 Other materials

Other thermoplastic materials, e.g. PVC, PTFE or co-extruded liners, i.e. multiple layeredliners made from more than one thermoplastic material, can be considered for linerapplications. If such materials are proposed, the material data supplied by the Contractorshall at least comprise the data listed in (Tables 2.2.1a and 2.2.1b) and also satisfy therequirements of (2.4).

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2.3 MATERIAL SELECTION GUIDE

Material selection is a procedure of matching system requirements to the property data ofavailable materials. The loading conditions should be systemically identified and could

comprise combinations of temperature, pressure, axial load and environment as a functionof time. They are matched to materials property acceptance criteria in the design analysis.

The following strategy facilitates thermoplastic polymer material selection by identifyingacceptance criteria in a structured manner:

1. Define pipeline function and requirements.2. Identify fixed boundary conditions.3. Design system and/or analyse design.4. Define function of the individual components.5. Identify service conditions of individual components.6. Identify material requirements to maintain function throughout service life.7. Identify acceptance criteria.

(Table 2.3) gives an example of the applied loads acting on a thermoplastic liner from

transport from the manufacturing plant through to operation.

Table 2.3 Applied loads acting on the liner system

Mechanicalloading

Thermalloading

Environment Duration

Transport Handling Ambient,- 40 C /+ 50 C

Ambient Weeks

Storage Stack weight Ambient Ambient Weeks, months

Construction Pull-in, reduction Ambient + friction Lubricant Minutes, hours

Operation Hydrostaticpressure

Fluid, operatingtemp.

Fluid, slugs Years

Mis-operation Vacuum Rapid cool-down Air Days

Removal Pull-out Ambient Residue Hours, days

The material selection process involves matching the material properties of the candidatethermoplastic liner materials to the loads and boundary conditions listed in (Table 2.3) toprovide the most appropriate material option.

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2.4 MATERIAL TESTING

A full material qualification programme is required to the satisfaction of the Principal, beforethe Contractor can start production of the liner. Thermoplastic pipe material shall be

qualified according to API Spec 15 LE. Thermoplastic pipe material qualified to ISO 4427may also be supplied provided that the following requirements are met: equivalent strengthgrade to API Spec 15 LE and elevated temperature characteristics to ISO 4427, Section4.4, Type A. Changes in the method of manufacture will require additional qualificationtests.

NOTE: API Spec 15 LE and ISO 4427 are specific to PE. However, the general principles of material testingoutlined in both API Spec 15 LE and ISO 4427 are also applicable to other thermoplastics. Specifictemperatures for elevated temperature tests shall be proposed by the Contractor and agreed with thePrincipal.

The following list of tests (mechanical, thermal, permeation, compatibility and ageing tests)represents a complete material qualification programme (Table 2.4). For most applicationsonly a restricted qualification programme will be required. Additional tests, specific to theunique operating conditions, shall be agreed between the Contractor and the Principal.

Other standard test procedures may replace those listed in (Table 2.4) on agreementbetween the Contractor and the Principal. (Table 2.4) also indicates for which applicationsthe tests are required along with the purpose of the tests.

A chemical analysis of the compounds comprising the thermoplastic pipe material shall beavailable for review by the Principal.

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Table 2.4 Standard test procedures required in the materials qualification procedure

Characteristic Appli cations Tests Testprocedure

Purpose Comments

Mechanical/physical properties

All applications Creep modulus ASTM D2990 Collapse calculation

Yield strength/elongation ASTM D 638 Installation requirementUltimate strength/elongation ASTM D 638 Installation requirementStress relaxation properties ASTM E 328 Installation requirement or ISO 527 RModulus of elasticity ASTM D 790 Collapse calculation or ISO 868Hardness ASTM D 2240 QA/QC or ISO 180Impact strength ASTM D 256 QA/QCAbrasion resistance ASTM D 4060 Flow conditions or ASTM D 1044Density ASTM D 792 QA/QC or ASTM D 1505Notch sensitivity ASTM D 256 Defect assessment and QA/QC

Thermal properties All applications Coefficient of thermal expansion ASTM E 831 Installation requirement and collapseassessment

Melt flow index ASTM D 1238 QA/QC ISO 1133Heat distortion temperatures ASTM D 648 QA/QC upper temperature limit Method ABrittleness temperature ASTM D 746 QA/QC lower temperature limit Or glass transition temperature

(ASTM E 1356)

Permeation/Characteristics

Only if gas phase present Fluid permeability See (2.4.1) Collapse calculation venting rates For gas phase components atdesign conditions

Blistering resistance See (2.4.2) No blistering for gas phasecomponents

At design conditions

Compatibility andageing

Only if gas phase present Ageing test See (2.4.3) Degradation in modulus collapsecalculation

All applications Swelling test See (2.4.4) Collapse calculationEnvironmental stress cracking ASTM D 1693 QA/QC durability Method C. For PE only

Weathering resistance ISO 4427 QA/QC only if liner exposed Effectiveness of UV stabiliser

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The following conditions shall apply as a minimum for the fluid permeability test:

a) Test sample shall be taken from the extruded polymer.

b) Minimum sample thickness is 1 mm.

c) Minimum sample diameter is 50 mm.

d) A sufficient number of tests shall be performed to allow for linear interpolation of theresults as a function of temperature.

The procedure for the fluid permeability test may be to pressurise one side of thespecimen and measure fluid flow at the other side when steady state flow conditions arereached. Alternatively, the test can be performed with the same absolute pressure on bothsides using the partial pressure of the component gas as the driving force.

The purpose of the permeability test is to provide an estimate of the gas permeation rateinto the annulus and is for information only. Therefore this test is only necessary if a gasphase is present.

2.4.2 Blistering resistance test

Blistering resistance tests shall reflect the design requirements along with fluid conditions,pressure, temperature, and number of decompressions and decompression rate. As aminimum, the following conditions shall apply:

a) Only gas components of the specified environment shall be used.

b) Conditioning time shall be sufficient to ensure full saturation.

c) Number of decompressions should be a minimum of 20 cycles or the number expectedin practice.

d) The decompression rate should be the expected rate, otherwise a minimum 70 bar per

minute should be used (from design pressure to zero).

e) Sample thickness shall be the same as the wall thickness of the liner.

f) The expected decompression temperature shall be used.

g) The design pressure shall be used as a minimum.

The test procedure is that after each depressurisation the sample shall be examined at amagnification of 20 times for signs of blistering, swelling and slitting. The acceptancecriterion is that no blister formation or slitting is observed.

2.4.3 Ageing test

The Contractor shall have either documented test data of the samples aged in the service

environment according to ASTM C 581, or ageing prediction models for the thermoplasticpolymer. The fluid used in ageing tests shall be representative of the service conditionsfluid. Materials that will be subjected to tensile or compressive loads in service shall betested under equivalent stress conditions.

The ageing model shall be based on testing and experience and shall predict the ageing ordeterioration of the polymer under the influence of environmental and load conditions thatrepresent the service conditions. As a minimum, polymer-ageing models shall considertemperature, chemical environment and mechanical load. Special attention should begiven to de-plasticisation, fluid adsorption and changes in dimensions. Creep and stressrelaxation shall be investigated on aged and un-aged samples.

Ageing may be determined from changes in either specified mechanical properties or inspecified physico-chemical characteristics which includes reduction in the plasticiser (if

relevant) content of the material.The purpose of the ageing test to provide the elastic modulus and yield strength and strainfor the material aged in the flow conditions.

2.4.4 Swelling test

The following conditions shall apply for the swell test procedure:

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5 cubic specimens, each approximately 125 mm3, shall be machined from a sample ofthe actual thermoplastic liner.

Specimen dimensions shall be recorded to the nearest 0.01 mm.

Specimen weight shall be recorded to the nearest 0.001 g.

The samples shall be exposed to 500 cm3

of the liquid hydrocarbon mixture of the pipelinefluid for 500 h and at the design temperature in a sealed container.

After exposure, the dimensions and weights shall be recorded to the same accuracy as thepre-expose samples.

Linear swell of the liner, swell

(%), is related to the volumetric swell and shall be calculated

as follows;

where the volumetric swell of the sample, Vswell, is defined as:

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2.5 END CONNECTORS

Steel flange material shall comply with the requirements of PTS 31.40.21.34-Gen.

Thermoplastic flange material shall be the same as the liner.

Retainer rings shall be made from ASTM A 106 grade B or equivalent material. Bolts shallbe ASTM A 193 grade B7. Nuts shall be ASTM A 194 grade 2H.

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3. DESIGN

3.1 INTRODUCTION

The Contractor shall be responsible for the design of the liner system and shall take intoaccount the selected installation method and service requirements.

Thermoplastic liners in carbon steel pipelines can fail due to (in no order of preference):

Environmental stress cracking.

Collapse of the liner due to pressure build-up in the annulus between the liner and thecarbon steel pipe. Gases can permeate through certain thermoplastics and canaccumulate in the annulus. During depressurisation of the pipeline, expansion of thisaccumulated gas may cause collapse of the liner.

Excessive material shrinkage.

Buckling due to excessive swelling.

Lack of strength (short term but also long term after ageing).

Cracks due to lack of liner impact resistance or prior exposure to UV light.

Material defects.

Construction defects (gouges, scores). End termination failures due to creep.

Factors that influence such failures include:

Choice of liner material (amounts and type of thermoplastic, fillers and plasticisers,anti-oxidants, UV stabilisers).

Thickness of liner.

Quality assurance and control during manufacturing, fabrication and installation.

Exposure to UV light prior to installation.

Installation method used and tightness of fit inside the carbon steel pipe line.

Fluid composition (incl. inhibitors, chemicals, etc.).

Minimum and maximum operating temperatures.

Rate of depressurisation. Spacing of vent points.

Frequency of venting.

For liners in hydrocarbon service, factors such as stress relaxation, loss of plasticiser,permeation and absorption of gases and liquids into the polymer should be taken intoaccount.

The design procedure for a thermoplastic liner consists of determining the thickness to limitboth stress and strain to acceptable levels and to prevent collapse. Factors such as creeprate, permeation rate and ESC should also be considered, particularly in terms of how theyare affected by liner wall thickness. The outside diameter of the liner shall be determinedtaking into account the inside diameter of the carbon steel pipe, the requirements of theinstallation technique and handling and storage requirements. Thermoplastic liners often

have to be tailor-made to the application implying that often non-standard dimensions areused.

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3.2 MINIMUM LINER THICKNESS

For water service the minimum thickness shall be 5 mm to avoid difficulties in installationand fusion bonding. For hydrocarbon service a thicker liner shall be used as determined bythe procedure given in (3.3).

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3.3 LINER DESIGN PROCEDURE

The calculation for the required wall thickness of the liner is determined from threeconditions: handling and storage (A), installation (B) and collapse (C). The greatestthickness calculated from requirements (A), (B) and (C) is taken as the design wallthickness. For requirement (C) it is conservatively assumed that the pressure in theannulus is the same as the bore pressure.

A flow diagram visualising the design process is presented in (Figure 3.3). The Contractorshall supply to the Principal the liner design sheet in Appendix 3 as part of the tenderdocumentation.

The liner design procedure for determining wall thickness is described in the followingsteps:

1. Determine the liner outer diameter taking into account both the inside diameter of thecarbon steel pipe and the requirements of the installation technique.

2. Determine the wall thickness from handling and storage requirements (3.3.1).

3. Determine the wall thickness from installation requirements (3.3.2).

4. Select the larger wall thickness from steps 2 and 3.

5. Select the modulus of the thermoplastic material and swelling strain for the serviceconditions.

6. Calculate the liner fit depending on the chosen installation technique (3.3.3.1).

If no gases are present, then go to step 9.

7. Calculate the collapse pressure from (3.3.3.2), (3.3.3.3) or (3.3.3.4) as appropriate,depending on liner fit. Include liner swell if appropriate.

8. Determine the design pressure (including safety factor) and maximum operatingpressure for either the "intrinsically safe" or "allowance for gas expansion" designprocedure (3.3.4).

If no liquids are present, then go to step 10.

9. If the liquid service conditions result in liner swell, then calculate the collapseresistance of the liner (3.3.5).

10. Correct the wall thickness to compensate for any reduction of liner wall thicknessduring installation.

11. If the collapse resistance of the liner is not sufficient then repeat steps 5 to 10 with anincreased liner wall thickness.

The output of successful completion of steps 1 to 11 is the required liner wall thickness,

sufficient to withstand the requirements of handling and storage, installation and collapse.Once the required liner wall thickness has been determined, a final check shall be made toensure that the resulting liner internal diameter does not have an unacceptable impact onthe pipeline hydraulics i.e. pressure drop and fluid velocities (6.4).

In this design procedure it is assumed that the annular volume is not vented.

(Table 3.3) summarises the design procedure for determining the thickness of a liner as afunction of fluid type and tightness of liner fit.

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FIGURE 3.3 LINER DESIGN PROCESS

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Table 3.3 Design procedure as a funct ion of fluid type and tigh tness of fit

Fluid type Tightness of fit Design procedure

Water Loose, partiallyloose, tight

Liner thickness determined from maximum ofhandling or storage (3.3.1) and installation (3.3.2)

requirementsLiquidhydrocarbons

Loose, partiallyloose, tight

Liner thickness determined from maximum ofhandling and storage (3.3.1) or installation (3.3.2)requirementsorswelling (3.3.5)

Gas, liquidhydrocarbonsand watermixtures

Loose Liner thickness determined from maximum ofhandling and storage (3.3.1) or installation (3.3.2)requirements or collapse(3.3.3.2)

Gas, liquidhydrocarbonsand watermixtures

Partially loose Liner thickness determined from maximum ofhandling and storage (3.3.1) or installation (3.3.2)requirementsor collapse(3.3.3.3)

Gas, liquid

hydrocarbonsand watermixtures

Tight Liner thickness determined from maximum of

handling and storage (3.3.1) or installation (3.3.2)requirementsor collapse(3.3.3.4)

3.3.1 Liner thickness - handling and storage

To maintain roundness of the liner and dimensional stability during storage, possibly forseveral months and to minimise distortion during handling, Manufacturers recommend aminimum Standard Dimension Ratio (SDR) ranging from 26 to 17.

A minimum SDR of 26 is recommended for less onerous applications, although inconsultation with the Manufacturer a thinner liner may be used. For all other applicationsan SDR of 17 is recommended.

3.3.2 Liner thickness installationLiners are installed by pulling a pre-fabricated length of thermoplastic pipe into the carbonsteel outer pipe.

The axial stress carried by the liner shall be limited to 50% of the tensile yield strength ofthe thermoplastic polymer. The pulling load consists of the friction load of dragging theliner into the carbon steel pipe, the deformation load, which is a function of the installationtechnique, plus friction loads due to pipe bends etc. (3.5).

3.3.3 Liner thickness - collapse

3.3.3.1 Liner fit

Collapse of a liner can occur if, during normal operation, gases within the bore of thepipeline permeate into the annulus volume between the liner and the host carbon steelpipe. Depressurising the pipeline, e.g. for maintenance, can cause the liner to collapse ifthe wall thickness is not sufficient. If only liquids are present in the pipeline, e.g. in waterinjection lines, then collapse due to gas expansion cannot occur. However, liquids can beabsorbed in the liner causing swelling. Excessive swelling can also cause the liner tocollapse.

The pressure required to cause collapse of the liner is dependent on the installationtechnique or more precisely the liner fit within the outer steel pipe. (Table 3.3.3.1)distinguishes liner fit for the different installation techniques into three categories: loose,partially loose and tight.

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Table 3.3.3.1 Categories of liner fit as a function of ins tallation technique

Installation technique Category of li ner fit

Slip lining (no grout) Loose

Folded pipe, Slip lining (with grout) Partially loose

Swagelining, Roll-down, Tite liner TightThe definition of liner fit is based on the constant, C, defined as:

where (mm) is the difference between the inner radius of the carbon steel pipe and theouter radius of the thermoplastic liner. The following inequalities define the liner fit:

where,

t = liner wall thickness (mm)R = average radius of the liner (mm) defined as

where the subscripts oand irefer to the outer and inner radius of the thermoplastic liner

pipe.

3.3.3.2 Loose fitting liners

When the outer steel pipe provides no restraint during collapse, the fit of the liner isdefined as loose and the collapse pressure, Pc(bar), is given by:

where,

E = liner Youngs modulus (MPa)

= liner Poisson ratio

3.3.3.3 Partially loose fitting liners

When the outer steel pipe provides partial restraint during collapse, the fit of the liner isdefined as partially loose and the collapse pressure, Pc(bar), is given by:

3.3.3.4 Tight fitting liners

When the outer steel pipe provides restraint during collapse, the fit of the liner is defined astight and the collapse pressure, Pc(bar), in the absence of swell is given by:

If liquids present in the service conditions cause swelling of the liner, then the collapsepressure, Pc(bar), is given by:

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where,

swell= Liner swell (%), (refer 2.4.4)

NOTES: 1. Liner swell is defined as the average swell across the liner thickness.

2. The modulus used in the above Sections should be representative of the thermoplastic polymermaterial at the design temperature and include allowance for any possible reductions orincreases due to chemical absorption or de-absorption. The visco-elastic nature of somepolymers may also need to be considered.

3.3.4 Design pressure of pipeline

The design pressure, Pdes, of the pipeline is defined as the maximum operating pressure,

Pmop, multiplied by a safety factor, J:

A safety factor, J, of 1.33 is recommended.

3.3.4.1 Intrinsically safe

If the collapse pressure, Pc, of the liner calculated from (3.3.3.1) to (3.3.3.4), is less than

the design pressure, Pdes, of the pipeline, then the liner wall thickness is not sufficient to

prevent collapse. If it is greater, then the liner will not collapse. The following inequalitydefines the intrinsically safe design pressure procedure:

3.3.4.2 Allowance for gas expansion

In (3.3.4.1) it is implicitly assumed that there is an infinite supply of gas to the annulus todrive the collapse process. In reality there is a finite volume of gas in the annulus. It ispossible to account for the expansion of the gas during collapse. However, the initialvolume of the annulus is required. It may not be possible to accurately determine this initialvolume.

The following provides a simplified guide to determining initial annular volume as a functionof the liner fit.

For a loose fitting liner the initial volume, Vinit(mm3/mm), is:

where,

Rs= Inside radius of the steel pipe (mm)

For a partially loose fitting liner, the initial volume is;

For a tight fitting liner it is conservatively assumed that the annulus volume is proportionalto the surface roughness of the outer steel pipe. The initial volume is given by:

where,

= Surface roughness of the steel pipe (mm).

NOTE: Determining the initial volume is imprecise due to the uncertainties in the actual situation. It istherefore recommended that conservative estimates of Vinitbe taken if gas expansion is allowed for

in this way.

The volume of annulus at collapse Vc(mm3/mm) is given by:

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During the collapse process the product of annulus pressure times annulus volumeremains constant. If the collapse pressure, P

c, calculated from (3.3.3.1) to (3.3.3.4), times

the annulus volume at collapse, Vc, is less than the design pressure, Pdes, of the pipeline

times the initial annulus volume at collapse, Vinit, then the liner wall thickness is not

sufficient to prevent collapse. If the product is greater then the liner will not collapse. Thefollowing inequality defines the allowance for gas expansion procedure:

3.3.5 Swelling

If the pipeline fluids are liquid then a possible collapse mechanism can be driven throughswelling of the liner. For example, PE can swell by up to 10% in certain hydrocarbonenvironments (aromatics). To prevent the liner from collapsing due to swelling only, thenthe following design inequality formula shall be used to determine if the liner wall thicknessis sufficient to prevent liner collapse (refer 2.4.4):

NOTE: Swell is defined as the average swell across the liner thickness.

If there is a possibility of the liner swelling while gas is present in the pipeline fluids, then(3.3.3) shall be used to determine the collapse pressure.

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3.4 VENT POINT DESIGN

All thermoplastic lined pipelines shall incorporate vent points unless otherwise agreed bythe Principal. The vent point assembly shall ensure venting of gases from the annulusthroughout the service life of the pipeline. The assembly shall include a valve to allowclosure of the vent. The design of the vent point assembly shall be proposed by theContractor and agreed with the Principal. The minimum number of vent points shall be oneat each flanged end of a section of lined pipe. The vent points have three functions:

To vent (ambient) gas and/or fluids from the annulus during installation.

To vent the permeated gas accumulated in the annulus to prevent collapse.

To allow monitoring of the liners integrity.

Vents can be designed to be:

Continuously closed (plugged)

Valved (closed or open during normal operation)

For water injection lines venting during operation is not necessary and therefore vents arenormally plugged. Lines transporting multi-phase hydrocarbons with H2S concentrations

lower than 50 ml/m3can have continuously open vents (vents shall be valved in order to

be able to close the annulus in case of liner leakage or collapse). For gas transport and for

H2S concentrations of 50 ml/m3and higher, vents will have to be opened and closed on a

periodic basis after consultation with the local HSE regulator.

There are two strategies to determine the spacing between vent points:

1. Minimum vent point spacing - determined from the lined pipe section length, i.e. onevent at each flanged end. This vent point spacing is suitable for:

- intrinsically safe designed liners (3.3.4.1);- water service;

- stabilised dead crude oil or oil/water mixture service.2. Calculated vent point spacing - determined from (3.4.1). This spacing is required for

critical applications defined as:

- gas service;- live crude service;- multiphase service.

NOTE: Due to uncertainties in estimating the initial annulus volume it is recommended when calculating thevent spacing to choose the most conservative gap between the liner and the outer steel pipe.

3.4.1 Vent point spacing

The requirement for additional vent points shall be determined as follows.

During the collapse sequence, the instantaneous product of annulus volume, V, andpressure, P, remains constant (assuming the annulus temperature remains constant), i.e.:

where Pinitis the initial pressure in the annulus. The other terms are defined in (3.3). The

units for pressure and volume are (bar) and (mm3) respectively.

The initial volume may be difficult to accurately determine. (3.3.4.2) provides a guide forestimating this initial volume as a function of liner fit. Summarising (3.3.4.2), the initial

volume per unit length of the lined pipe (mm3/mm) is given by;

where

= gap between the liner and the steel pipe (mm).The initial annulus volume, Vinit (mm

3), is determined from the product of the vent point

spacing, Lvent(mm), and the initial volume per unit length, V init/L, (3.3.4.2) and is given by:

The annulus volume at collapse per unit length Vc/L (mm3/mm), is given by:

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To calculate the collapse volume, Vc (mm3) at collapse, the following assumptions are

made to determine the axial collapse length, Lc:

axial profile of the collapsed liner is triangular;

radial liner profile remains similar;

collapse length, Lc(mm), extends over 5 times the diameter of the liner, i.e.

Under these assumptions the total critical volume at collapse, Vc(mm3), is:

Using values of Pinit, Vinit, Pcand Vc, defined above, the vent point spacing, Lvent(mm), isgiven by:

It is assumed (conservatively) that the initial pressure in the annulus, P init is equal to the

bore pressure.

A sensitivity analysis with respect to the influence of initial annulus gap size, (mm), onthe vent point spacing, Lvent, shall be performed.

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3.5 PULL-IN LOADS AND INSERTION LENGTH

The pull-in load, Fpull(N), for a thermoplastic liner is calculated from the sum of three force

components: Ffriction, the friction load from dragging the liner into the steel pipe, Fbend, the

additional friction loads caused by bends etc. and Freduce, the load applied to the liner fromthe installation technique:

The calculation procedure for determining the maximum loads and stresses acting on theliner during installation shall be as outlined in this Section. If the Contractor wishes to usean alternative procedure this shall be submitted to the Principal for agreement.

3.5.1 Frict ion load, Ffriction

The friction load contribution to the overall liner pull-in load is derived from twocomponents. One component is due to the weight of the liner and the associated frictionfactor, the other is due to superficial damage to the outside of the thermoplastic liner, i.e.:

where Llineris the length of liner (m) to be installed and W is the weight of the liner per unit

length (N/m). f is the friction factor and for new pipelines is taken as 0.4. For retro-fitting,higher friction factors may be required to simulate the surface roughness of the pipe. If theinstallation procedure includes liner lubrication then f should be reduced to 0.1.

Fscoreis generally zero, unless otherwise quoted by the installer.

3.5.2 Bending load, Fbend

The bending load is defined as a function of the pull-in load, the friction factor and theangle of the bend:

where f is the friction factor, Fpull(N) is the pull-in load and is the bend angle (radians).

3.5.3 Reduction load, Freduce

The reduction load, Freduce (N) is a function of the installation technique. For each

installation technique a reduction pressure, Preduce(MPa), is quoted and the reduction load

is derived by multiplying this pressure by the cross-sectional area of the liner:

where t (mm) is the liner wall thickness and D (mm) is the internal diameter of the steelpipe. For the different installation techniques (Table 3.5.3) lists the reduction pressure.

Table 3.5.3 Reduction pressure as a func tion of installation technique

Installation technique Reduction pressure(MPa)

Slip-lining 0

Roll-down 0

Tite-lining 5

Swage-lining 5

3.5.4 Total pull-in load and maximum installation length

The total pull-in load, Fpull(N), is calculated from the individual load components described

in (3.5.1) to (3.5.3).

The maximum allowable tensile load on the liner is limited to 50% of the tensile yield

strength, yield (MPa).

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3.6 DESIGN OF END CONNECTORS

3.6.1 General

The Contractor shall select the end connection and shall submit this for approval to thePrincipal. The Contractor shall demonstrate by means of a qualification test that the endconnections meet the same operational requirements as the thermoplastic liner. Thedesign shall account for shrinkage, creep, ageing of the thermoplastic material andoperational pressure fluctuations.

In general, only flanged connections shall be considered for termination at the ends ofpipeline sections, see (Figure 3.6.2) for typical arrangement. Screwed connectors shall notbe allowed. Compression-type fittings may be allowed for in-situ retro-fitting. An exampleof a compression type fitting is presented in (Figure 3.6.1).

FIGURE 3.6.1 TYPICAL THERMOPLASTIC LINER COMPRESSION JOINT

3.6.2 Flange type connections

The carbon steel parts of flanged type connections shall comply with the generalrequirements of PTS 31.40.21.34.Gen.

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FIGURE 3.6.2 TYPICAL THERMOPLASTIC LINER FLANGE CONNECTION

The inside diameter of the steel flange shall be identical to that of the carbon steel pipeline.The outside diameter of the thermoplastic flange face shall have the same diameter as theraised face of the carbon steel flange.

The liner weld shall be made by butt fusion welding. If the liner has been pulled in from theother end, then the flange shall be welded to the liner before the axial tension is released.

The thermoplastic flange shall be made from the same material as the liner and have thesame internal diameter as the liner. The minimum length of the flange shall be 150 mm.

The steel retainer rings shall be such that they fit between the thermoplastic flange andinside the bolt circle of the steel flanges.

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4. MANUFACTURE OF THE THERMOPLASTIC LINER

4.1 PROCESS OF MANUFACTURE

The thermoplastic liner shall be manufactured by extrusion. Extrusion involves melting,converging and forming the thermoplastic into a tubular product.

Other manufacturing processes shall not be used by the Manufacturer to produce thethermoplastic liner unless agreed by the Principal.

Only virgin polymers shall be used for the production of the liner, with a maximum of0.2% wt of additives. Use of reworked (or re-cycled) materials shall not be permitted. Theuse of colouring agents should be avoided. A larger quantity of additives may be added ifelectrically conductive properties are required.

Manufacturing of the liner shall not proceed until the material qualification programme hasbeen completed to the full satisfaction of the Principal.

The Contractor shall be responsible for the manufacturing of the liner

The Contractor shall complete the data sheets in Appendix 4 and supply these as part of

the tender documentation. The data provided by the Contractor shall be used as baselinedata for the QC requirements (Section 4.4.4.3)

4.1.1 Flange material

Flanges shall be moulded or machined from extruded material and shall be from the samematerial as the pipe. The wall thickness of the flanges shall be equal to the wall thicknessof the pipe. Flared flanges may be used only for limited lengths which cannot be fitted withfused flanges, and only with the approval of the Principal.

4.1.2 Rotational moulded spools

Rotational moulded spools may be used only with the approval of the Principal. Thematerial used shall have minimum material properties provided by the Contractor as listedin Appendix 4 unless otherwise agreed with the Principal.

The wall thickness of the liner in the spools should be equal to the minimum wall thicknessdetermined in (Section 3.3)

NOTE: There is a maximum wall thickness which can be rotationally moulded.

There shall be no reliance on adhesion of the polymer to the steel surface. For live crudeor gas service, vents shall be provided on the spool pieces.

4.2 FINISH AND WORKMANSHIP

4.2.1 Pipe ends

Pipe ends shall be plain and square. Cut pipe ends shall be clean without ledges, shavingtails, burrs or cracks. The interior of the pipe shall be blown or washed clean of cuttingsand shavings.

4.2.2 Finish

The internal and external surfaces of the plastic liner shall be free from defects such asblisters, cracks, scratches, dents, nicks or sharp tool marks which can affect theperformance of the liner. Absence of these defects shall be determined visually or with aliquid penetrant.

4.2.3 Microscopic examination

Microscopic examination at 10 times magnification or visual examination by means of

transmitted light shall show no voids, foreign inclusions or other internal defects whichaffect the performance of the liner. For alternative non-destructive testing techniques thePrincipal shall be consulted.

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4.3 DIMENSIONS, WEIGHTS AND TOLERANCES

4.3.1 Size, tolerances

Pipe furnished to this PTS shall comply with the dimensions and tolerances given in Table3 of API Spec 15 LE or Tables 3 to 6 of ISO 4427.

The Contractor shall specify nominal values of liner outside diameter and wall thickness.Tolerances on the outside diameter are listed in (Table 4.3.1):

Table 4.3.1 Tolerances on liner outsi de diameter

Liner Nominal Diameter(ND)

Minimum diameter Maximum diameter

ND 60 mm - 0 mm + 0.5 mm

60 < ND 114 mm - 0 mm + 1 mm

ND > 114 mm - 0 mm + 0.01*ND

The tolerance on the liner wall thickness shall be -0%/+5% of the specified value.

4.3.2 Length of liner pipe joint s

The length of individual joints of liner pipe shall be as long as possible, to minimise thenumber of field welds, consistent with transportation, handling and any other projectconstraints.

No jointers (two pieces fused together to make a length) shall be permitted.

The average, maximum and minimum liner joint lengths shall be agreed between theContractor and the Principal.

4.3.3 Ovality and out-of-roundness

The ovality of the pipe shall not exceed 5% when measured in accordance withASTM D 2513.

During production both ovality and out-of-roundness shall be monitored and recorded atthe frequencies specified in (Table 4.4.4.3).

4.4 QUALITY PROGRAMME

4.4.1 Quality Manual

The Manufacturer shall maintain a Quality Manual which describes the quality programme.All prior revisions shall be retained for a period of not less than five years.

4.4.2 Process and quality control requirements

The Quality Manual shall include a documentation programme to assure communication ofapproved manufacturing and inspection procedures to qualified receiving, manufacturingand quality control personnel. The Quality Manual shall be submitted to the Principal forreview and approval, and shall cover at least the following aspects:

raw material acceptance;

extrusion procedures;

pipe manufacturing practices;

welding procedures and qualifications;

inspection and test procedures;

acceptance criteria;

repair procedures.

4.4.3 Quality control equipment

Equipment used to inspect, test or examine material shall be calibrated at specifiedintervals in accordance with the Manufacturers Quality Manual and consistent withreferenced industry standards.

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4.4.4 Quality control tests

4.4.4.1 Conditioning

Unless otherwise specified, all Quality Control (QC) specimens shall be conditioned for a

minimum of 4 hours prior to test in air or 1 hour in water at 23 C

2 C.When conditioning is required for witness tests the specimens shall be conditioned in

accordance with Procedure A of ASTM D 618 at 23 C 2 C and at an agreed level ofrelative humidity and conditioning time.

4.4.4.2 Test conditions

Tests shall be conducted at the Standard Laboratory temperature of 23 C 2 C unlessotherwise specified in the test methods.

4.4.4.3 Material property requirements and frequency

This PTS adopts periodic sampling to determine batch quality control. The Manufacturershall be responsible for ensuring that all pipes meet the specified requirements.

Acceptable QC shall be demonstrated by successfully completing the tests listed in (Table4.4.4.3) of API Spec 15 LE at the specified frequency. Where the Manufacturer has agreedto the supply of pipe produced to ISO 4427, the equivalent quality control tests prescribedby ISO 4427 shall be applied.

NOTE: API Spec 15 LE and ISO 4427 are specific to PE. However, the general principles of quality controlthrough material testing outlined in both API Spec 15 LE and ISO 4427 are also applicable to otherthermoplastics. Minimum strength and specific temperatures for elevated temperature tests shall beproposed by the Contractor and agreed with the Principal.

The melt flow rate shall not deviate by more than 30% from the value specified by theManufacturer. The change in melt flow rate caused by processing, i.e. the differencebetween the measured value for material from the pipe and the measured value for thecompound, shall not be more than 25%.

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(Table 4.4.4.3) lists the quality control tests that are required along with the appropriatestandard test procedure, testing frequency and acceptance criterion. The total number ofQC tests shall be agreed between the Contractor and the Principal.

Table 4.4.4.3 QC requirements on material properties during p roduction

Property ASTM Acceptance cri ter ia FrequencyOutside diameterWall thicknessBurst pressure (upto 100 mm diameter)Strength (Over 100mm diameter)

D 2122D 2122D 1599

D 2122

API Spec 15 LE, Table 3API Spec 15 LE, Table 3To be agreed betweenContractor and PrincipalTo be agreed betweenContractor and Principal

Once every hour or onceevery coil, whichever isless frequent

Hydro-test See 4.4.4.4 Once every coil

Out of roundnessOvalityDensityMelt flow rateModulus

ESC resistanceCarbon black

D 2122D 2122D 1505D 1238D 638

D 1693D 1603

< 5% of quoted value< 5% of quoted value< 2% of quoted value< 30% of quoted value

< 5% of quoted value< 5% of quoted value2% min. unless otherwiseagreed.

Once per lot (productionrun)

For quoted values refer to (Section 4.1)

4.4.4.4 Hydro-testing

Liner pipe sections shall not show any sign of leakage (burst or weep) or ballooning whensubjected to a hydrostatic pressure test. The hydrostatic test pressure shall be agreedbetween the Principal, Contractor and Manufacturer and is maintained for at least 3minutes. As a guide the test pressure should be 1.5 times the rated pressure for the

stand-alone thermoplastic pipe.Failure is defined as:

Ballooning Any abnormal localised expansion of a pipe specimen while underinternal hydraulic pressure.

Burst Failure by a break in the pipe with immediate loss of test liquid andcontinual leakage of test liquid independent of applied pressure.

Weep Failure that occurs through microscopic breaks in the pipe wall,frequently only at or near the test pressure. At lower pressures, thepipe may maintain its integrity.

4.4.4.5 Retest and rejection

If a sample fails to meet any of the QC requirements, additional tests shall be made on thepreviously produced samples back to the previous acceptable sample. Pipes produced inthe interim that do not pass the requirements shall be rejected. Testing frequency shall be

every 10thpipe back to the previously acceptable sample.

4.4.5 Inspection and rejection

4.4.5.1 Inspection by the Principal

All Quality Control tests shall be witnessed by an Inspector approved by the Principal atthe start of production and monitored thereafter at the Principals discretion.

4.4.5.2 Significant defects

Significant defects are those which adversely affect the service life of the liner pipe, e.g.inclusions, bends, dents, scratches, visible cracks, foreign material contaminants or anyother imperfection reducing the wall thickness below minimum acceptable limits (4.3.1).

Material which contains significant defects on inspection shall be rejected.

Significant defects include:

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Scratches in pipe: Surface scratches and nicks in thermoplastic liner may not exceed adepth of 5% of the nominal wall thickness.

Scratches in flanges: thermoplastic flange surfaces shall be free of scratches and nicks.

Bends: bend angles in thermoplastic liner pipes shall not exceed 5. Bend radii shall not be

less than 5 times the nominal liner diameter.

Dents: The maximum depth shall be the lower of 6.5 mm or 2% of the pipe OD.

4.4.5.3 Repair of defects

Repair of defects is not permitted.

4.4.6 Quality control records requirements

4.4.6.1 Purpose

Quality control records are necessary to substantiate that all pipe manufactured to thisPTS conforms to the specified requirements.

4.4.6.2 Records control

Quality control records required by this PTS shall be legible, identifiable, retrievableand protected from damage, deterioration or loss.

Quality control records required by this PTS shall be retained by the pipe supplier andContractor for a minimum of five years following the date of manufacture.

All quality control records required by this PTS shall be signed and dated by the pipesupplier's designated authorised person.

4.4.6.3 The following records shall be maintained and supplied by pipe supplier:

1. Quality manual in accordance with (Section 4.4.1).

2. Quality control test results in accordance with (Section 4.4.4).

3. Design and material qualification data in accordance with (Section 3.1) and(Section 4.1).

4. All procedures utilised by the pipe supplier in the process of fulfilling the order

5. Quality assurance records for all materials supplied by the pipe supplier.

4.5 EQUIPMENT MARKING

Pipe shall be marked by the Manufacturer as follows:

The markings on each length of pipe or fitting shall include in any sequence:

Manufacturer's name or trademarks;

base specification shown on purchase order, e.g. API Spec 15 LE or ISO 4427;

nominal pipe size;

date of manufacture;

SDR;

appropriate material code;

Manufacturer's lot number;

additional markings, as agreed between the Manufacturer, Contractor and Principal.

Pressure rating shall not be marked on the pipe.

The markings on pipe shall be paint stencilled or printed on the outside surface at intervalsof not more than 1.5 m or on each fitting. Indentation marking may be used provided:

The marking does not reduce the wall thickness to less than the minimum value.

The marking has no effect on the long-term strength.

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4.6 HANDLING AND STORAGE

4.6.1 Storage

Coils shall be stored stacked flat one on top of another. Straight lengths shall be stored onhorizontal racks and given support to prevent damage. In either storage form, pipe shallnot come into contact with hot water or steam and shall be kept away from hot surfaces.Coils containing pipes of diameters greater than 1.5 inches (38 mm) and larger shall not bestored on edge.

Pipe shall be covered with adequate protection from direct sunlight. If the pipe has to bestored in the open air before, during or after shipment, it shall be protected fromenvironmental contamination.

Pipe end covers shall be used to prevent ingress of moisture or dirt to the inside of thepipe.

4.6.2 Handling

All pipes shall be cleaned, dried and packed before handling and transportation.

Thermoplastic pipe can be susceptible to damage by abrasion and by sharp objects.Dragging pipe sections or coils over rough ground shall not be permitted. If, due tounsatisfactory storage or handling, a pipe is damaged it shall be rejected.

4.6.3 Transportation

The minimum requirements for transportation shall be as specified in the following:

API RP 5L1 for railroad transportation;

API RP 5LW for marine transportation.

Pipe transported by sea shall not be shipped as deck cargo.

4.6.4 Coiling

Coil diameter should be sufficiently large to prevent excessive strain being applied to thepipe. The minimum recommended inside coil diameter shall be determined by:

Coiling diameters are based on maximum allowable axial strain. For thin-walled pipes,buckling could induce extra axial strain and therefore, before coiling thin-walled pipe, theManufacturer should be consulted for recommendations.

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5. LINER INSTALLATION

5.1 GENERAL - INSTALLATION TECHNIQUES

There are several commercially available liner installation techniques. An overview of thegeneric types is given below and is illustrated by specific examples. The scope of this PTScovers lining technologies that involve pulling a discrete length of thermoplastic pipe into ahost steel pipe. All technologies require an insertion clearance between the liner and thehost pipeline. The scope covers both onshore and offshore installation cases.

There are three generic liner installation techniques:

undersizing;

consecutive reduction and pull-in;

simultaneous reduction and pull-in.

The following summarises these three main types of installation techniques currentlyavailable and is for information only. The Contractor shall propose a specific installationtechnique and submit it to the Principal for approval.

5.1.1 Undersizing

Undersized liner installation involves inserting a liner of outside diameter less than theinside diameter of the host pipe. The difference in diameter is the insertion clearance. It isthe simplest technique for lining pipes and has been applied for many years in oilfieldapplications.

5.1.1.1 Slip-lining

Slip-lining is a technique where the undersized liner is simply pulled into the host steelpipe. The liner is expanded in place by internal pressure, with or without heating, to yieldthe liner while the annulus is vented. There is always a remaining annular gap. Internalpressure, creep and swell are relied upon to obtain a tight liner fit, often after weeks ofoperation. This time period depends strongly on the insertion clearance, liner materialproperties and service conditions. If the pipeline is not pressurised for long periods thenthere is a risk of the liner reverti

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