換熱器焊接1

1、JFail.Anal.Preven.(2011)11:611–617DOI10.1007s1166801194828案例歷史同行評審管板焊縫裂紋的裂紋–燃氣蒸汽換熱器維修提交：10十一月2010201114修訂的形式：六月在線發(fā)表：2011七月6ASM國際2011摘要嚴重的裂縫被發(fā)現(xiàn)在管子與管板焊縫開裂的啟動燃氣蒸汽在氣體廠熱交換器操作期間。失效分析及修復過程是本文報道。幾個月的運行修復后的修復是成功的。關鍵詞熱交換器管接頭焊縫裂紋故障

2、背景在這項研究的對象是一個修復焊接管–管板接頭上的裂紋的燃氣蒸汽在氣體廠換熱器。換熱器是九個相同的管殼式換熱器，固定管換熱器類型（1殼–1管通型），由同一制造商，與氣體在管側被冷卻的殼側蒸汽裂解過程。設計溫度和殼側壓力分別為653LF（LC345）和1812磅（127.4公斤平方厘米）。在換熱器管束由484管固定在水平位置。冷拔無縫管是由SA213t11鋼1.75。OD（44.45毫米）97BWG（4.57毫米）921英尺（6.4米）L

3、G。管板是由SA182f11Cl2鋼1.5。（38毫米）厚。，歸1600LF8h，1325鍛煉LF8h，用空氣作為冷卻劑。殼體的內徑是55.75。（1416毫米）和由SA51670n鋼。該管的管板的填充材料是鎢極氬弧焊焊絲er80sb2。S.AdullahRamsisEngineeringP.O.Box28967EastRiffaBahrainemail:shaker@.bhH.M.Ezuber(&)CollegeofEngineeri

4、ngUniversityofBahrainP.O.Box32038IsaTownBahrainemail:換熱器已被送到工地，在天然氣廠，據(jù)報道，通過每一焊道的染料滲透劑檢查后，25psig的空氣，在膨脹試驗的肥皂，著色滲透探傷軋制后，著色滲透探傷焊后熱處理（熱處理），和3031psi的殼程水壓試驗。在煮，入口被暴露在300液晶的最高溫度，而出口達到220LC。九的換熱器，泄漏已被發(fā)現(xiàn)在兩個管板焊縫的兩個換熱器在啟動的操作。裂縫是在入口

5、目前，管與管板焊接。它通常是一種常見的做法在管子與管板的密封焊縫是用來補充脹管接頭確保氣密性[1，2]。管接頭是常見的焊接時，管子管板是合適的材料[1]。在實踐中，大多數(shù)是多道焊縫。焊接接頭往往是熱處理（預熱和焊后熱處理）使用前提高延展性和韌性，降低焊接應力[3]。填充材料成分應該是幾乎相同的基體金屬確保大學形成強度和耐熱耐腐蝕[3，4]。應力腐蝕開裂是一種常見的故障模式在管子管板接頭。失敗是不當?shù)拿浌苤饕c異常之間的間隙，管子與管板[

6、5]，拙劣的管子管板焊縫或缺陷在現(xiàn)場焊后熱處理[6]。123JFail.Anal.Preven.(2011)11:611–617613Fig.3Enlargedviewsonpolishedcrosssectionsshowingthethroughwallcrackthedepositedweldmetal.Theresultspresentedinthisfigureclearlyshowthatthechemicalanalysi

7、softubetubesheetthedepositedweldmetalarevirtuallyidentical.ThechemicalcompositionsareconsistentwithwhatbeexpectedftheSA213T11SA182F11CL2ER80SB2materials.Quantitativechemicalanalysisofthetubethetubesheettheweldmaterialisg

8、iveninTable1.Thechemicalcompositionofthematerialscomplieswiththemanufacture’sspecificationswithASTMspecificationsA387Grade11(coverplate)ASTMA182(pipes)whicharecrectfthetypeofservicesought[3].Itisgenerallycommontonotethat

9、thecarboncontentofthefillermetalislowerthanthatofthebasemetal.TheaveragevaluesoftensiletestyieldelongationsgiveninTable2aretypicalvaluesofthesteelmaterials.Figure5isanoverallSEMimageofapolishedcrosssectionofadialedsample

10、.Athroughwallcrackinadepositedweldisobserved.Thecrackpropagationisquitestraightthereisnoevidenceofductilebehaviateitherendofthecrack.MicrohardnessTables34showapproximatemedianhardnessvaluesfvariousregions(tubetotubesheet

11、:startingwiththetubebasematerialpassingthroughtheHAZtheweldrootanothersegmentoftheHAZfinallyinthedepositedwedmetal)alongthemaximummeasuredhardness.TheweldmetalHAZshowmuchhigherhardnessthanthebasemetal.Someinterestingdiff

12、erencesaresystematicallyobservedinhardnessvaluesofHAZofthetubetubesheetmaterials.HardnessofHAZofthetubematerialislessthanthatofthetubesheetmaterial.Thisdenotesscanteffectivenessofthestressrelievingtreatment[4].Thehighhar

13、dnessintheinterfacebetweenweldthetubeHAZarereptedtoberelatedtomicrostructuralembrittlement[6].PossibleRootCauseTheresultsofthechemicalanalysisshowthattherearenoapparentdefectsinthespecificationoftheweldmaterialthetubemat

14、erialthetubesheetmateriali.e.nodiscrepancieswithmanufacture’sspecificationswerefoundinchemicalcomposition.Thediameterofthetubesheetholeftubeshasunifmproperdiameterthroughthewholethicknessofthetube(i.e.nmalclearancebetwee

15、nthetubethetubesheet)consideredtobeadequatecomplieswiththedesignspecification.Asaresultfabricationerrhasbeenruledoutastherootcauseoftheproblem.Thermalcalculationrecdsconfirmthattheexchangerisoperatedinnucleateboilingmode

16、.Afilmvapblanketingoftubesisnotpossible.Thetubewalltemperatureisveryclosetoboilerfeedwater(BFW)saturatedtemperatureshelltemperature.Basedontheseanalysesnoexcessivetubethermalexpansioninrelationtoshellisexpected.Thevapbla

17、nketingfilmboilingisunlikelyconsideredasacauseofthetubeweldfailuresexperiences.Therootcauseofthecracksispossiblyattributedtopowkshopinthetubetotubesheetwelds.Lessthanadequateweldthroatthicknessappearedtobethefactthatgove

18、rnedwhethernotaparticulartubetotubesheetweldremainedintact.Thisispossiblycausedbyincrectweldingcondition(increcttchgunangleincrectedgeperation).Theincrectwelddesignfabrication(increctweldsizequality)oftheweldjointsthusre