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Polyethylenestructure3PEanticorrosivecoatingofsteelpipeinsulation,3PEanti-corrosioninsulationperformanceandtheheatlossisonlytwenty-fivepercentofthetraditionalpipe,orlong-termoperationcansavemoreresources,lowerenergycost,andstillhasarelativelystrongwaterproofandcorrosionresistance,anddoesnotneedatrench,directlyyoucanbuywaterorunderground,isalsointheconstructionissimpleandrapid,comprehensivecostisalsorelativelylow,undertheconditionoflowtemperatureandhasgoodcorrosionresistanceandimpactresistance,andalsocanbedirectlyembeddedintheenvironmentofpermafrost.Polyethylenethreelayerprotectivelayer,alsoknownas3PEanti-corrosionsteelpipe,isinrecentyearstheintroductionofadvancedanti-corrosiontechnologyfromabroad.Itiscalledfusionbondedepoxy/extrudedpolyethyleneprotectivelayerstructure,thestructureconsistsofthreelayers:thebottomlayerfusionbondedepoxy(over80m);themiddlelayerisadhesive(170-250m);thesurfacelayerofextrudedpolyethylene(
目前，直縫埋弧焊管應用已擴展到眾多領域，除石油天然氣長輸管道外，還向海洋平台、海hai上shang浮fu吊diao等deng海hai洋yang結jie構gou方fang麵mian發fa展zhan。埋mai弧hu焊han管guan作zuo為wei海hai洋yang結jie構gou用yong管guan具ju有you明ming顯xian的de優you勢shi，如ru壁bi厚hou均jun勻yun，工gong藝yi簡jian單dan，性xing能neng受shou製zhi管guan工gong藝yi影ying響xiang較jiao小xiao，易yi於yu實shi現xian高gao強qiang度du、gaorenxingdeyaoqiu，qieqiguigetiaozhenglinghuo，kemanzubutongguanjingdeyaoqiu。danshi，youyuhaiyangjiegouyongguandefuyihuanjingyulululiutishusongguanyousuobutong，haiyangjiegouyongguanfuyizaibolang、海潮、fengbaojihanlengliubingdengyanjundehaiyanggongzuohuanjingzhong，yiner，duihaiyangjiegouyongguanchuleyaoqiujuyouyibanguandaoxingnengwai，haiduiqiqiangrenxinghehanfengzhiliangtichulegenggaodeyaoqiu。gangguandezhuyaocaizhiweiD36鋼、S355鋼及具有Z向性能的結構鋼板，厚度一般在20～50mm之間，由於板材厚度較大，且碳含量及碳當量均較大，可焊性較差，淬硬傾向大，使焊接接頭的熔合性能降低，且易產生冷裂紋。
厚壁直縫埋弧焊管焊縫存在的橫向裂紋分別采用厚度為20～50mm的D36，D36-Z35和S355結構鋼板，通過JCOE成型方式生產海洋經驗交流·54·HANGUAN焊管平台用直縫埋弧焊管，直徑為508～1372mm。焊縫采用X形坡口，內焊為三絲埋弧焊，外焊為多層多道三絲埋弧焊。焊接完成24h或48h後hou對dui焊han縫feng進jin行xing超chao聲sheng波bo檢jian測ce，橫heng向xiang掃sao查zha時shi發fa現xian在zai焊han縫feng壁bi厚hou中zhong間jian位wei置zhi有you林lin狀zhuang回hui波bo出chu現xian，進jin一yi步bu檢jian測ce發fa現xian有you時shi整zheng條tiao焊han縫feng斷duan續xu存cun在zai類lei似si信xin號hao，深shen度du在zai焊han縫feng中zhong間jian位wei置zhi。為wei了le查zha清qing缺que陷xian的de性xing質zhi，對dui某mou些xie反fan射she信xin號hao高gao的de地di方fang進jin行xingX射(she)線(xian)拍(pai)片(pian)，未(wei)發(fa)現(xian)缺(que)陷(xian)。經(jing)碳(tan)弧(hu)氣(qi)刨(pao)後(hou)再(zai)次(ci)進(jin)行(xing)磁(ci)粉(fen)檢(jian)測(ce)，證(zheng)實(shi)該(gai)缺(que)陷(xian)為(wei)橫(heng)向(xiang)裂(lie)紋(wen)。裂(lie)紋(wen)大(da)部(bu)分(fen)橫(heng)穿(chuan)焊(han)縫(feng)，但(dan)未(wei)擴(kuo)展(zhan)到(dao)母(mu)材(cai)中(zhong)，裂(lie)紋(wen)深(shen)度(du)在(zai)焊(han)縫(feng)壁(bi)厚(hou)的(de)中(zhong)間(jian)位(wei)置(zhi)，為(wei)外(wai)焊(han)的(de)一(yi)層(ceng)，與(yu)超(chao)聲(sheng)波(bo)檢(jian)測(ce)的(de)深(shen)度(du)基(ji)本(ben)吻(wen)合(he)。