PWHTofSmallDiameterPipe

小口徑管道的焊后熱處理FRANKHOPPLEINTRODUCTION簡介BasicPWHTofpipeisthesameregardlessofpipediameter.However,inPWHTofsmalldiameterpipecaremustbegiveninpositioningoftheheatpads.Thisisthe“key”forasuccessfulPWHTofsmallpipe.不管管徑的大小，管道焊后熱處理的基本要求都是一樣的。然而進行小口徑管道的焊后熱處理必須注意加熱片的位置，這是小口徑管道成功進行焊后熱處理的關(guān)鍵點。

CheckListofImportantItems

檢查重要項目的一覽表Theuseofspacers(pipenipples)orothermaterialmadeofbasicallythesametypematerialasthepipebeingPWHT.墊塊（管嘴）或其他與焊后熱處理管道材料相同類型的其他材料的使用Positioningtheheatpads.加熱片的位置CheckcontinuityoftheTCsafterinstallationofheatpad.安裝完加熱片后檢查熱電偶是否合適

Properuseofinsulation絕緣材料的正確使用ProblemAreaRegardingSmallDiameterPWHT

關(guān)于小口徑管道的焊后熱處理中問題點Valves閥門Gussetsandvalvescombination加強板和閥門組件TCattachments熱電偶附件Heatpads加熱片Thefollowingslideshowpresentationshowsavailableoptionsinregardsto:

以下的幻燈片介紹了有關(guān)的可選用的多種選擇Valves,gussetsandtheircombination.閥門，加強件和他們的組件Recommendationandstrategiesforsuccessfulpostweldheattreatment(PWHT).成功進行焊后熱處理的建議和策略Inmostcases,thevalveshouldbetakenapartandthevalvefacetapedusingducttape.

大多數(shù)情況下，閥門應(yīng)該拆開，并且閥蘭面應(yīng)該用柔性帶子包扎起來Theuseofpipenipplesupportforheaterpad.使用管接頭支撐加熱片Thiswillkeeptheheaterpadfromoverlappingitself這樣可以避免使加熱片的自身重疊AnotherexampleofaweldednipplespacertobeusedforPWHTofsmalldiameterpipe.

另一個例子當進行小管徑的焊后熱處理時，使用一個焊接的管接頭作為墊塊AttachtheTCsonthevalvebodyoppositesideofthevalveface.AftercompletionofTCattachment,thepipespacersareinstalled.在法蘭面的反面把熱電偶連接到閥門本體上，安裝完熱電偶附件后，安裝管道隔離片ThefollowingpicturesshowtheTCplacementandpipespacers.以下圖片顯示了熱電偶的附件和管道墊塊Thermocouples(TC)PlacementonValves

閥門上熱電偶放置方法AttachthetwosetsTCsonthevalvebodyoppositesideofthevalveface.在法蘭面反面的本體上連接兩套熱電偶Extracareinassuringproperthermocoupleattachmentisamustonsmalldiameterpiping.特別關(guān)注的是，確保合合適熱電偶連連件必須連接接到小管徑管管道上Anotherexampleofinstallingheatpadsupportsusingtapeandwire.另外一個例子子是使用帶子子和鐵絲安裝裝加熱墊子的的支撐件OncetheTCandpipespacersareinstalled,installationoftheheatpadisnext.一旦熱電偶和和管子隔離片片安裝完成后，下一一步是安裝加加熱片Heatpadinstallationmustbe““installedandattached”withcaremakingsuretheheatpadiswrappedaroundpipefirstthenaroundthespacers.Asnugfitisamustwithnooverlapoftheheaterelements.加熱片必須注意““安裝并且連連接上”，以以確保加熱片片首先綁扎在在管道然后是是隔離塊上。。加熱元件之之間必須平滑滑過渡沒有重重疊InstallationofHeatPads安裝加熱片InstalledTC,spacerandheatpad,readyforinsulation安裝熱電偶，隔離塊和加熱熱片后，準備保溫Theheatpadiswrappedaroundthevalve,pipespacer,andpipe.Endsofheatpadarelocatedonthespacersides.加熱熱片片沿沿著著閥閥門門、管道道墊塊塊和和管管子子綁綁扎扎，，加加熱熱片片的的末末端端位位于于墊墊塊塊的的一一側(cè)側(cè)Remembertheheatpadhasasnugfitaroundthepipeandspacer.注意意加加熱熱片片在在管管子子和和隔隔離離片片周周圍圍有有平平滑滑的的過過渡渡Installationoftheheatpadaroundthepipe,valve,andgussetinaverticalposition在垂垂直直位位置置沿沿著著管管道道，閥門門和和支支撐撐件件安安裝裝加加熱熱片片Installationoftheheatpadaroundvalveandgusset.在閥閥門門和和支支撐撐件件周周圍圍安安裝裝加加熱熱片片Installationoftheheatpadaroundthepipe,valve,andgussetinahorizontalposition.在橫橫向向位位置置沿沿著著管管子子，閥門門和和支支撐撐件件周周圍圍安安裝裝加加熱熱片片Afterusingglasstapetoholdtheheatpadinposition,wireisusedtosecuretheheaterends.使用用玻玻璃璃纖纖維維帶帶子子把把加加熱熱片片固固定定好好位位置置后后，用鐵鐵絲絲固定定加加熱熱器器末末端端Whenheatpadsareinstalledintheverticalposition,extrasupportwireshouldbeused.在垂垂直直位位置置安安裝裝加加熱熱片片，需要要使使用用額額外外的的鐵鐵絲絲支支撐撐加加熱熱片片Important!Aftercompleteinstallationoftheheatpad,checkTCforcontinuity.重要要的的是是安安裝裝完完加加熱熱片片后后，檢查查熱熱電電偶偶是是否否良良好好Insulationofheaterpadsonpipeswithsmalldiametersisbasicallythesameaslargediameterpipes.在小小管管徑徑管管道道上上安安裝裝加加熱熱片片和和在在大大口口徑徑管管道道上上基基本本上上是是一一樣樣的的Donotoverinsulate.Thiscanleadtoheatcontrolproblemswhenrampingdown.不要要重疊疊保保溫溫，，這這會會導(dǎo)導(dǎo)致致在在降降溫溫過過程程中中出出現(xiàn)現(xiàn)加加熱熱控控制制問問題題Thefinalwrapshouldbetiedwithwireand/orglasstape.最后后一一圈圈必必須須用用鐵鐵絲絲和和/或或玻玻璃璃纖纖維維綁綁扎扎InsulationofHeatPads安裝裝加加熱熱片片Measureandcutinsulationkeepinmindtheinsulationisveryexpensiveandmaybereusedseveraltimesifcareisexercisedincuttingandhandling.因為為保保溫溫棉棉價格格很很貴貴所所以以應(yīng)應(yīng)想想好好怎怎樣樣測測量量和和切切割割以以重重復(fù)復(fù)使使用用多多次次Wireinsulationinplaceespeciallyontheverticalruns.ChecktheTCwiretoassurethatitisnotcoveredbytheinsulation.特別別是是在在垂垂直直位位置置適適當當?shù)牡膶?dǎo)導(dǎo)線線保保溫溫。。檢檢查查熱熱電電偶偶導(dǎo)導(dǎo)線線以以確確保保它它不不保保溫溫棉棉覆覆蓋蓋Wheninsulationiscomplete,performafinalinspectionforlocationofTCwire,HeatPadtails.保溫溫結(jié)結(jié)束束后后，，對對熱熱電電偶偶導(dǎo)導(dǎo)線線，，加加熱熱片片的的尾尾部部進進行行最最后后的