三通接頭是不銹鋼管件的一種，它的連接形式就是直接將不銹鋼三(san)通與鋼管對焊，三通接頭的主要制造標準一般是GB/T 12459《鋼制無縫焊接管件》、GB/T 13401《鋼板制對焊管件》、ASME B16.9《工廠制造的鍛軋制對焊管配件》、SH/T 3408《鋼制對焊無縫管件》、SH/T3409《鋼板制對焊管件》、HG/T 21635《碳鋼、低合金鋼無縫對焊管件》、HG/T 21631《鋼制有縫對焊管件》、SY/T 0510《鋼制對焊管件》。

   ①. 按照管件口(kou)徑分一般有等(deng)徑三(san)通(tong)（straight tee），異徑三(san)通(tong)（reducing tee）等(deng)。

  ②. 按照支管方向分有正三通和斜三通（Y形(xing)三通），斜三通常常代替一般正三通，用于輸(shu)送有固體顆粒或沖刷腐蝕較嚴重的管道上。

  ③. 按照(zhao)材料分有碳(tan)鋼、合金鋼、不銹(xiu)鋼、銅(tong)、PVC等三通。

  ④. 按照(zhao)連(lian)接方(fang)式分有普通三通、螺紋(wen)三通、卡套三通、承(cheng)插三通。典型三通及連(lian)接見圖4.6.11。

  不銹(xiu)鋼(gang)三通(tong)(tong)(tong)接(jie)頭(tou)成(cheng)形(xing)(xing)(xing)(xing)是(shi)將大于三通(tong)(tong)(tong)直徑(jing)的(de)(de)(de)(de)管(guan)(guan)坯(pi)(pi)，壓扁約(yue)至三通(tong)(tong)(tong)直徑(jing)的(de)(de)(de)(de)尺寸，在(zai)(zai)拉(la)伸支管(guan)(guan)的(de)(de)(de)(de)部位開一個(ge)孔；管(guan)(guan)坯(pi)(pi)經加熱，放入成(cheng)形(xing)(xing)(xing)(xing)模(mo)(mo)中，并(bing)在(zai)(zai)管(guan)(guan)坯(pi)(pi)內裝入拉(la)伸支管(guan)(guan)的(de)(de)(de)(de)沖(chong)模(mo)(mo)；在(zai)(zai)壓力的(de)(de)(de)(de)作用(yong)(yong)(yong)下管(guan)(guan)坯(pi)(pi)被徑(jing)向(xiang)壓縮(suo)，在(zai)(zai)徑(jing)向(xiang)壓縮(suo)的(de)(de)(de)(de)過程中金(jin)屬(shu)向(xiang)支管(guan)(guan)方向(xiang)流(liu)動并(bing)在(zai)(zai)沖(chong)模(mo)(mo)的(de)(de)(de)(de)拉(la)伸下形(xing)(xing)(xing)(xing)成(cheng)支管(guan)(guan)。整個(ge)過程是(shi)通(tong)(tong)(tong)過管(guan)(guan)坯(pi)(pi)的(de)(de)(de)(de)徑(jing)向(xiang)壓縮(suo)和支管(guan)(guan)部位的(de)(de)(de)(de)拉(la)伸過程而成(cheng)形(xing)(xing)(xing)(xing)。與(yu)液壓脹(zhang)形(xing)(xing)(xing)(xing)三通(tong)(tong)(tong)不同的(de)(de)(de)(de)是(shi)，三通(tong)(tong)(tong)接(jie)頭(tou)支管(guan)(guan)的(de)(de)(de)(de)金(jin)屬(shu)是(shi)由(you)管(guan)(guan)坯(pi)(pi)的(de)(de)(de)(de)徑(jing)向(xiang)運(yun)動進行補(bu)償(chang)的(de)(de)(de)(de)，所(suo)以也稱(cheng)為徑(jing)向(xiang)補(bu)償(chang)工(gong)藝。由(you)于采用(yong)(yong)(yong)加熱后壓制三通(tong)(tong)(tong)，材(cai)(cai)料成(cheng)形(xing)(xing)(xing)(xing)所(suo)需要的(de)(de)(de)(de)設備(bei)噸位降低(di)。熱壓三通(tong)(tong)(tong)對材(cai)(cai)料的(de)(de)(de)(de)適應性較(jiao)寬，適用(yong)(yong)(yong)于低(di)碳(tan)鋼(gang)、合金(jin)鋼(gang)、不銹(xiu)鋼(gang)的(de)(de)(de)(de)材(cai)(cai)料；特別是(shi)大直徑(jing)和管(guan)(guan)壁偏厚的(de)(de)(de)(de)三通(tong)(tong)(tong)，通(tong)(tong)(tong)常采用(yong)(yong)(yong)這種成(cheng)形(xing)(xing)(xing)(xing)工(gong)藝。

   不銹鋼(gang)四通(tong)為管件、管道連接件，用在主管道要分支管處，又稱管件四通、四通管件、四通接頭。四通有等徑和異徑之分，等徑四通的接管端部均為相同的尺寸；異徑的四通的主管接管尺寸相同，而支管的接管尺寸小于主管的接管尺寸。對于采用無縫管制造四通來講，目前通常所采用的工藝有液壓脹形和熱壓成形兩種。四通以制作方法劃分可分為頂制、壓制、鍛制、鑄造等。制造標準有GB/T 12459，GB/T 13401，ASME B16.9，SH/T 3408，SH/T 3409，HG/T 21635，DL/T 695，SY/T 0510，DIN 2615等。典型四通見圖4.6.12。

  對(dui)(dui)于異(yi)徑三通(tong)(tong)(tong)，首(shou)先給(gei)出(chu)(chu)最(zui)大端(duan)(duan)(duan)的(de)(de)公(gong)(gong)稱(cheng)通(tong)(tong)(tong)徑，然(ran)后(hou)(hou)(hou)是(shi)(shi)與(yu)最(zui)大端(duan)(duan)(duan)相對(dui)(dui)應的(de)(de)那一(yi)端(duan)(duan)(duan)的(de)(de)公(gong)(gong)稱(cheng)通(tong)(tong)(tong)徑，最(zui)后(hou)(hou)(hou)給(gei)出(chu)(chu)支管(guan)瑞的(de)(de)公(gong)(gong)稱(cheng)通(tong)(tong)(tong)徑；對(dui)(dui)于異(yi)徑四通(tong)(tong)(tong)，首(shou)先給(gei)出(chu)(chu)最(zui)大端(duan)(duan)(duan)的(de)(de)公(gong)(gong)稱(cheng)通(tong)(tong)(tong)徑，其次是(shi)(shi)與(yu)最(zui)大端(duan)(duan)(duan)相對(dui)(dui)應的(de)(de)另一(yi)端(duan)(duan)(duan)的(de)(de)公(gong)(gong)稱(cheng)通(tong)(tong)(tong)徑，第三個給(gei)出(chu)(chu)的(de)(de)是(shi)(shi)另外兩端(duan)(duan)(duan)中(zhong)的(de)(de)較大端(duan)(duan)(duan)的(de)(de)公(gong)(gong)稱(cheng)通(tong)(tong)(tong)徑，最(zui)后(hou)(hou)(hou)給(gei)出(chu)(chu)剩余一(yi)端(duan)(duan)(duan)的(de)(de)公(gong)(gong)稱(cheng)通(tong)(tong)(tong)徑（見圖(tu)4.6.13）。