1、Item No. 24212NACE International Publication 35101This Technical Committee Report has been preparedby NACE International Task Group 037* onThermoplastic Liners for Oilfield PipelinesPlastic Liners for Oilfield Pipelines February 2001, NACE InternationalThis NACE International technical committee rep
2、ort represents a consensus of those individual memberswho have reviewed this document, its scope, and provisions. Its acceptance does not in any respect precludeanyone from manufacturing, marketing, purchasing, or using products, processes, or procedures not includedin this report. Nothing contained
3、 in this NACE International report is to be construed as granting any right, byimplication or otherwise, to manufacture, sell, or use in connection with any method, apparatus, or productcovered by Letters Patent, or as indemnifying or protecting anyone against liability for infringement of LettersPa
4、tent. This report should in no way be interpreted as a restriction on the use of better procedures or materialsnot discussed herein. Neither is this report intended to apply in all cases relating to the subject. Unpredictablecircumstances may negate the usefulness of this report in specific instance
5、s. NACE International assumes noresponsibility for the interpretation or use of this report by other parties.Users of this NACE International report are responsible for reviewing appropriate health, safety,environmental, and regulatory documents and for determining their applicability in relation to
6、 this report prior toits use. This NACE International report may not necessarily address all potential health and safety problems orenvironmental hazards associated with the use of materials, equipment, and/or operations detailed or referredto within this report. Users of this NACE International rep
7、ort are also responsible for establishing appropriatehealth, safety, and environmental protection practices, in consultation with appropriate regulatory authorities ifnecessary, to achieve compliance with any existing applicable regulatory requirements prior to the use of thisreport.CAUTIONARY NOTIC
8、E: The user is cautioned to obtain the latest edition of this report. NACEInternational reports are subject to periodic review, and may be revised or withdrawn at any time without priornotice. NACE reports are automatically withdrawn if more than 10 years old. Purchasers of NACEInternational reports
9、 may receive current information on all NACE International publications by contacting theNACE International Membership Services Department, 1440 South Creek Dr., Houston, Texas 77084-4906(telephone +1281228-6200).ForewordThe objective of this technical committee report is toprovide an overview of th
10、ermoplastic liners used in oilfieldpipelines, and to reflect current practices. This report isintended to assist those who are considering the use ofliners, but have only limited access to resources withknowledge of the terminology, techniques, andapplications of liners in the oilfield. This report
11、does notendorse any specific system or indicate that any of theliner systems described is suitable for particularapplications. It is not the intent of this report to restrict theuse of any liner material but to describe materials andsystems currently in use. Specific material properties arebeyond th
12、e scope of this technical report, as are specificliner design methodologies. Suppliers of the materialscan normally provide the specific mechanical andchemical information needed by a potential user, andinstallers normally provide design services based onregional experience and normal industry-accep
13、tedpractices. Evaluation by the potential user of a particularapplication in conjunction with the system manufacturer isvital to ensuring proper material and liner systemselection. In this report, the words plastic and polymerare used interchangeably.This NACE technical committee report was prepared
14、 byNACE Task Group 037 on Thermoplastic Liners forOilfield Pipelines (formerly T-10E-10, a component of UnitCommittee T-10E on Internal Corrosion for Pipelines). TG037 is administered by Specific Technology Group (STG)35 on Pipelines, Tanks, and Well Casings, and issponsored by STG 10 on Nonmetallic
15、 Materials ofConstruction and STG 33 on Oil and Gas ProductionNonmetallics and Wear Coatings (Metallic). This report ispublished under the auspices of STG 35 on Pipelines,Tanks, and Well Casings._* Chairman Jim Mason, ATOFINA Chemicals, Inc., King of Prussia, PA.NACE International2Definitions and Ab
16、breviationsAnnulus or Annular: Refers to any space between theliner and the host steel pipe.Cross Linking: A chemical reaction process wherebyindividual polymer chains are chemically bonded to eachother to form a network and prevent the polymer chainsfrom irreversibly sliding past each other.Explosi
17、ve Decompression: An extremely rapid pressureloss that can result in damage to the polymer.ID: Inside DiameterHDPE: High-Density PolyethyleneMDPE: Medium-Density PolyethyleneOD: Outside DiameterPolymer: A material generally composed of organicmolecules with a very high molecular weight, which in tur
18、nare composed of repeating units of smaller molecularweight.Plastic: A generic, though not very specific, term forpolymer.Thermoplastic: A polymer that can be melted and re-solidified an indefinite number of times.Thermoset: A polymer that, once solidified, cannot bemade fluid again. Examples includ
19、e epoxy and vinylesters.GeneralLiner DescriptionThe thermoplastic liner system described in this reportcombines layers of materials that allow the total structureto behave homogeneously, but with a combination of theproperties provided by the individual materials. The linerrelies on the host pipe to
20、 provide mechanical strength,while the liner provides corrosion protection. In plastic-lined steel, for example, the corrosion/erosion resistanceof the inner plastic pipe and the strength/mechanicaldurability of the metal case are both exploited. Thisallows for design pressures equal to those of the
21、 hostpipe.Plastic-lined steel is differentiated from plastic-coatedsteel in that:1. The thickness of plastic coatings is measured in mils(thousandths of an inch), whereas liners typically varyfrom 0.125 to 1.00 in. (3.2 to 25 mm) in thickness.2. The critical manufacturing variable in coated systemsi
22、s the adhesion to the substrate metal, whereas forliners, attaining a mechanically fitted cohesive unit isthe critical element.3. A plastic coating retains little, if any, mechanicalstrength, whereas the liner itself has pressure-containing structural integrity.Installation MethodsThe installation o
23、f a liner into a host pipe involvesmechanically fitting two piping systems together so theywill act as a single unit.The systems1-5currently being used in the oilfield forpipelines can be generally described as follows:1. The liner is hydraulically and thermally expandedradially out to the steel pip
24、e following insertion.2. The liner is installed after a temporary diameter-reduction process. After completion of the insertion,the liner expands to the internal diameter of the steelpipe.Service ApplicationsPipelinesGeneralBecause water induces electrochemical corrosion oncarbon steel pipe, the app
25、lications are usually made topipelines that contain water as a component of thecontained fluid. As a general rule, plastic-lined steelreplaces plastic pipe in situations when:1. The pressure ratings exceed those of plastic pipe, or2. The ruggedness and durability of steel are required.The in situ li
26、ning of pipelines has been used whenpipelines are experiencing corrosion problems or when agiven pipeline is being switched to a service that isexpected to experience corrosion. Specifically, liners areused to rehabilitate pipelines and to stop internalcorrosion. These situations arise when:1. Acces
27、s to the existing pipeline is restricted, orimpossible.2. The defects are produced by rapid pitting corrosion.NACE International3Water PipelinesAffected systems can include:1. Oilfield produced-water injection and disposalsystems2. Water-gathering systems3. Water-transfer trunklines4. Plant open-dra
28、in disposal lines5. Submarine outfall lines6. Port ballast linesLiquid Hydrocarbon PipelinesAffected systems can include:1. Oil flowlines with produced water2. Oil-gathering trunklines3. Multiphase gathering lines (oil/gas/water)4. Oil-transmission lines5. Refined hydrocarbon product linesLiners are
29、 used for internal corrosion control by oil andgas production companies, particularly when theproduced fluids contain oil, water, H2S, and CO2. Linersare being used for oil fields that are under CO2-enhancedrecovery schemes when significant quantities of CO2areproduced with the oil and water, creati
30、ng potential forsevere corrosion.When pipelines transport oil from a facility that separatesthe oil/water/gas mix for shipment to a refinery, water canaccumulate in low spots. These pipelines have also beenrehabilitated with liners.Gas PipelinesHydrocarbon gas pipelines sometimes contain water,assoc
31、iated hydrocarbon liquids, and other corrosives suchas H2S and CO2.Similar internal corrosion mechanisms exist with gaspipelines as with the water and liquid hydrocarbonpipelines. They differ primarily in that the risk of blowoutsand toxic fumes is generally greater with gas pipelines;thus the need
32、for adequate corrosion protection becomesgreater.System Design FactorsMechanical/Operational AspectsBased on the specific application, the liner design typicallyconsiders the following general pipeline factors:1. Current method of operating the pipeline (history ofline)2. Pipeline length, ID, and co
33、ndition (new, pitted,abraded, scaled, etc.)3. Operating pressure range (minimum, average,maximum)4. Operating temperature range (minimum, average,maximum)5. Pipeline repair points/methods of repair6. Flow requirements7. Future pipeline service and service/operatingconditions8. Pipeline geometry (fit
34、tings, terrain, right of way,location, and accessibility)9. Timing of project/critical-path minimum downtime10. Regulatory requirementsIn addition to the factors outlined above, the designnormally includes an assessment of the liner-specificfactors in the following sections, which can be dependenton
35、 the material selected for the liner.Collapse ResistanceThrough engineering design and correct pipelineoperation procedures, irreversible liner collapse can beprevented. Collapse may cause flow obstructions, and inan extreme case, liner failure. The host pipe constrainsthe liner and enhances collaps
36、e resistance. To preventliner collapse, engineering design has typically consideredthe mechanical properties of the liner pipe as affected bythe service environment. This includes the effects ofhydrocarbon absorption and operating temperature on themechanical properties of the liner material. This d
37、esign isthen integrated with pipeline operating conditions,particularly operating temperature, cyclic operatingpressures, start-up and depressuring practices, andventing.Application of an internal vacuum can cause the liner tocollapse. However, this type of operation is not normallydone in the field
38、. Occasionally, in oilfield injectionpipelines, if flow is stopped a vacuum can be created dueto injection wells continuing to take fluids after flow hasstopped.Process streams containing H2S or CO2, near the uppertemperature limit of the liner, are more prone to create theNACE International4conditi
39、ons for buildup of high annular pressure due topermeation. The resultant differential annular pressurecan force the liner inward and potentially cause collapse.Collapse is a greater consideration during any cyclicoperating conditions. In gas-free liquid pipelines, theannular pressure normally remain
40、s negligible. Upondepressurization of the pipeline, proper operating practicecan prevent collapse.Thermal EffectsThe effect of temperature is generally considered in linerdesign based on the ambient temperature duringinstallation and the operating temperature of the pipeline.Typical allowable temper
41、atures during installation arebased on the liner material properties and the installationprocess.A 30C (54F) temperature change in the liner results inapproximately a 1% elongation (on heating) or contraction(on cooling). The liner is usually installed in such a way asto leave it in a residual state
42、 of axial tension. As such,thermal contraction increases axial tension, and thermalexpansion can reduce the axial tension to a zero value orlight axial compression. This axial tension has generallybeen considered acceptable and in many casesbeneficial, especially when there is not an interference fi
43、tbetween the liner and the steel host pipe. While the lineris under pressure, the forces of circumferential frictionbetween the liner and the steel pipe ID exceed axialtension or compression forces.If slight axial compression develops, it is confined as aresult of the thrust isolation of the flanges
44、 and surfacefriction with the ID of the steel pipe. If axial compression isexcessive, it can result in collapse of the liner at the endof the segment (“accordion collapse”). During shutdown,if the temperature drops, the liner increases in tension butcannot move because the end flanges are locked int
45、oposition.At elevated operating temperatures, liner materials canhave increased chemical interaction with the producedfluid. This is generally considered in the liner design.Such interactions can include hydrocarbon absorption,resulting in swell and reduced stiffness. The linermaterials can undergo
46、decomposition or cross-linking asa result of exposure to chemicals at productiontemperatures.End ConnectionsThe most common method of connecting lined segmentsof the pipeline has been to use steel flanges andthermoplastic polymer flange adapters. The flangeadapters are used to form a gasket between
47、the steelflange faces. A reinforcing steel ring is placed around thepolymer flange adapters. The flange adapters can bemade by injection molding, machined from a billet of linerpolymer, or formed in place using the liner end. In thecase of the molded and machined flange adapters, theadapter is norma
48、lly fused onto the liner using conventionalbutt fusion techniques.Care is usually taken to avoid over-compression of theadapters during bolt-up. This is normally prevented by theuse of a spacer ring that sets the steel flange facespacing to the specified distance for optimumcompression seal deformat
49、ion, as recommended by theliner material supplier.Liner Material SelectionThe selection of liner material is normally an importantpart of the liner design process. There are manythermoplastic polymer materials that can be formed intopipe and can be used as a liner. Not all thermoplasticpolymer materials are suitable for use as liners in oilfieldpipelines due to the fluids and operating conditions. Ofthe materials that can be used as a liner, no singlematerial is suited to all operating conditions. Certaingeneral polymer characteristics have been evaluated inthe
