聚丙烯重力排污管道的100年服务寿命预测

Proceedingsofthe17thPlasticPipesConferencePPXVIISeptember22-24,2014,Chicago,Illinois,USA100-YEARS-SERVICE-LIFETIMEPREDICTIONOFPOLYOLEFINGRAVITYSEWERPIPES聚丙烯重力排污管道的100年使用寿命预测TiemMeijeringTEPPFA（欧洲管材和管件协会）Brussels,BelgiumJeannetteMulderWavin（瓦云）NetherlandsGünterDreilingBorealis（北欧化工）Linz,AustriaHeinzVogtLyondellbasell（巴塞尔）Frankfurta.M,GermanyABSTRACT文摘Inthisstudy,ithasbeendemonstratedthata100yearsservice-lifetimefornon-pressuresewagepipes,solidwallpipesandstructured-wallpipesofPEandPP,canbeexpectedprovidedsomebasicconditionsaremet.Ithasbeendemonstratedthattheresistancetothermo-oxidativedegradationoftheappliedmaterialsissufficienttoassureanend-of-lifetimeofatleast100years.Providedthattheallowablestressesatlongtermaremet,brittlepipefailureisnotlikelytooccur.Thebehaviorofthesolidwallandstructured-wallpipesunderconstantdeflectionandstrainconditionshasbeenevaluatedandrelaxationtestshavebeencarriedout,showingthatatlongtermtheremainingstressesinthepipedonotexceedcriticalvalues.Thecompositionofsewerwaterandtherealsewerwatertemperaturehasnosignificanteffectonthelifetimeprediction.Aseriesofexcavationprojectshavebeenexecutedwherethesewerpipeswerealreadyinserviceduringuptoaperiodof38years.Fromthetestprogramithasbeenconcludedthatnoreductionofpipequalityhasbeentakenplaceandthepredictionofatotalservicetimeof100yearsisapparent.该研究表明，只要满足一些基本条件，PE和PE的无压排污实壁管，双壁波纹管预期能够达到100年的服务寿命。如满足长期许用应力，不发生管道的脆性破坏，则所用材料的抗热氧化降解能力足以确保这一点。实壁和结构壁管道在恒定形变和应变条件下的性能被评价，应力松弛测试也被进行，这些均表明管道长期运行中的残余应力并没有超过临界值。污水和真实污水温度的混合物并没有对预期寿命有显著影响。一些使用已达38年的污水管道被挖出进行多项研究。从检测结果可以得到结论，管道的质量没有降低，总的100年的服务时间预测是真实可信的。INTRODUCTION介绍Thepredictionofthelifeexpectancyofplasticpipesystemsiswelldocumentedforpressureapplications,wherestressesinthepipewallareactingcontinuously.HydrostatictestsatdifferenttemperaturesallowuswithArrheniusextrapolationstomakeareliableestimateofthepredictedlifetimeatspecificpressureandtemperatureranges.塑料管道系统中压力管道的平均寿命预测已有许多检测报告。不同温度下的液压测试使得我们能利用阿累尼乌斯外推方法可靠估计塑料管道在特定压力和温度范围内的寿命。Innon-pressureapplicationsinsewageanddrainage,solidwallandstructured-wallpipesareinstalledandoperatewithoutinternalpressures.Afterinstallationandsubsequentsoilsettlement,acontinuousdeflectionandsoaconstantstrainloadingapplies.However,inthecurrentinternationalproductstandardsfornon-pressuresewagepipesmanufacturedfromPEorPPnoreferencehasbeenmadetothepredictedlifetimeofthesepipes.Ascientificapproachtoestimatethelifetimeofthesepipesandmaterialsinnon-pressureapplicationsisnotavailableandnoadequatetestmethodsaredefined.Thisstudyaimstoprovidesufficientvalidateddatatoenableanin-servicelifeexpectancyofatleast100yearstobedeclaredforPEandPPsewerpipesandcoversPEandPPpipesaccordingtoEN13476-3(TypeBpipes)[1],EN12666[2]andEN1852[3].对于无压排污和排水应用，实壁和结构壁管道在安装和运行过程中内部没有压力。在敷设和随后的土壤沉降后，管道会有连续的形变，产生一个恒应变载荷。然而，现行由PE或者PP制造的无压污水管道国际标准并没有关于这些管道的寿命预测，也没有相应的研究和适当的检测方法。本课题目的就是根据EN13746-3（B型管道）[1],EN12666[2]和EN1852[3]，对PE和PP污水管道能达到100年的平均寿命提供足够有效的数据。Todemonstratethelongtermperformanceofsewerpipes,solidwallandstructured-wall,madefromPEandPP,thefollowingitemshavebeenanalyzedandinvestigated:为了展示由PE和PP制造的实壁，结构壁污水管道的长期性能，下面的内容被分析和调查：a.Collectionofevidenceandprovidingconditionsofsufficientlongtermresistancetothermo-oxidativedegradationoftheusedmaterials.BasedontestdatafromhydrostaticpressuretestsandMRSevaluationandArrheniusextrapolation,theallowablestressesandtherelatedtestrequirementshavebeenevaluated.收集和提供所用材料抗热氧化降解的足够证据。根据液压测试，MRS评估和阿累尼乌斯外推，许用应力和相关测试要求也被评估。b.Thelongtermbehaviorunderconstantstrainloadingofnon-pressuresewerpipeshavebeenanalyzed.Basedonrelaxationtests,calculationshavebeenmadeforthepredictionofthelongtermstresses.Estimationshavebeenmaderegardingtheriskofpipefailureunderconstantdeflectionatlongterm.分析无压管道在恒应变荷载作用下的长期性能。根据松弛测试，计算预测长期应力。c.Thepossibleeffectonthelifetimeofthecompositionandthetemperatureofthesewerwaterhavebeenevaluated评估污水的组成和温度对管道寿命的可能影响。d.Excavationprojectshavebeenexecutedtoanalyzetheremainingqualityofthesewerpipesafteraperiodofoperationandthepredictionofremaininglifetimeofthesepipes.挖出运行过的污水管道，分析其质量，预测这些管道的剩余寿命。e.Thewholetestprogramandtheresultshasbeenvalidatedbyanindependentthirdpartyauthority所有测试和结果都通过授权的第三方实验室进行。1.Long-termresistancetothermo-oxidativedegradation长期抗热氧老化降解Itiswidelyacceptedthatduetochemicaldegradationofthepolymerthedominatingfracturemechanisminnon-pressurepipesisabrittlefailuremode.Toachievea100-years-service-lifetimeithastobeevidentthatnon-pressurepipesdoresistprematurefailurescausedbythermo-oxidativedegradation.人们普遍认为，由于聚合物的化学降解，无压管道的破坏机理是脆性破坏。为了达到100年的使用寿命，必须证明无压管道能够抵抗由于热氧化降解过早引起的过早破坏。Theauto-oxidationofPEandPPiswellunderstood[4,5].ItiswellproventhatthekineticsoftheageingprocessfollowsArrheniusequationwhichquantitativelydescribestherelationshipbetweentherateofthedegradationandtemperature.PE和PP的自动氧化已被人们了解[4,5]。老化过程的动力学服从阿累尼乌斯方程，其定量地描述了降解速度和温度的关系。Arrheniusequationk=constant.Exp(-EA/RT)WhereaskistherateofthedegradationreactionattemperatureT,EAistheenergybarrierwhichhastoovercomeandistheso-calledactivationenergyoftheageingprocess,TistheabsolutetemperatureindegreesKe