①. 三通接頭是管件(jian)的一種，它的連接形式就是直接將三通與鋼管對焊，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》、ASMEB16.9《工廠制造的鍛軋制對焊管配件》、SH 3408《鋼制對焊無縫管件》、SH 3409《鋼板制對焊管件》、HG/T21635《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》。

   ②. 三(san)(san)通(tong)(tong)(tong)按照管(guan)件口徑(jing)分(fen)(fen)一般有(you)等(deng)徑(jing)三(san)(san)通(tong)(tong)(tong)［圖(tu)16.25（a）］、異(yi)徑(jing)三(san)(san)通(tong)(tong)(tong)［圖(tu)16.25（b）］等(deng)。按照支管(guan)方向分(fen)(fen)有(you)正三(san)(san)通(tong)(tong)(tong)和斜(xie)三(san)(san)通(tong)(tong)(tong)（y形三(san)(san)通(tong)(tong)(tong)），斜(xie)三(san)(san)通(tong)(tong)(tong)常常代替(ti)一般正三(san)(san)通(tong)(tong)(tong)，用于輸送有(you)固(gu)體顆粒(li)或(huo)沖(chong)刷腐蝕較嚴重(zhong)的(de)管(guan)道上。按照材料(liao)分(fen)(fen)有(you)碳鋼、合金鋼、不銹鋼、銅、PVC等(deng)三(san)(san)通(tong)(tong)(tong)。按照連接方式分(fen)(fen)有(you)普(pu)通(tong)(tong)(tong)三(san)(san)通(tong)(tong)(tong)、螺(luo)紋三(san)(san)通(tong)(tong)(tong)、卡套三(san)(san)通(tong)(tong)(tong)、承(cheng)插三(san)(san)通(tong)(tong)(tong)。

   ③. 三(san)(san)(san)通(tong)(tong)接(jie)頭(tou)(tou)成形(xing)(xing)(xing)是(shi)(shi)將大(da)于(yu)三(san)(san)(san)通(tong)(tong)直徑的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)坯，壓(ya)扁至(zhi)約三(san)(san)(san)通(tong)(tong)直徑的(de)(de)(de)(de)尺寸，在拉伸支管(guan)(guan)(guan)(guan)的(de)(de)(de)(de)部位(wei)開一(yi)個(ge)孔；管(guan)(guan)(guan)(guan)坯經加熱(re)，放(fang)入成形(xing)(xing)(xing)模中，并在管(guan)(guan)(guan)(guan)坯內裝(zhuang)入拉伸支管(guan)(guan)(guan)(guan)的(de)(de)(de)(de)沖模；在壓(ya)力的(de)(de)(de)(de)作用(yong)下(xia)管(guan)(guan)(guan)(guan)坯被徑向(xiang)壓(ya)縮，在徑向(xiang)壓(ya)縮的(de)(de)(de)(de)過(guo)程(cheng)中金(jin)屬(shu)向(xiang)支管(guan)(guan)(guan)(guan)方向(xiang)流(liu)動并在沖模的(de)(de)(de)(de)拉伸下(xia)形(xing)(xing)(xing)成支管(guan)(guan)(guan)(guan)。整個(ge)過(guo)程(cheng)是(shi)(shi)通(tong)(tong)過(guo)管(guan)(guan)(guan)(guan)坯的(de)(de)(de)(de)徑向(xiang)壓(ya)縮和支管(guan)(guan)(guan)(guan)部位(wei)的(de)(de)(de)(de)拉伸過(guo)程(cheng)而成形(xing)(xing)(xing)。與(yu)液(ye)壓(ya)脹(zhang)形(xing)(xing)(xing)三(san)(san)(san)通(tong)(tong)不同的(de)(de)(de)(de)是(shi)(shi)，三(san)(san)(san)通(tong)(tong)接(jie)頭(tou)(tou)支管(guan)(guan)(guan)(guan)的(de)(de)(de)(de)金(jin)屬(shu)是(shi)(shi)由管(guan)(guan)(guan)(guan)坯的(de)(de)(de)(de)徑向(xiang)運動進行補償的(de)(de)(de)(de)，所(suo)以也稱為(wei)徑向(xiang)補償工(gong)藝。由于(yu)采用(yong)加熱(re)后壓(ya)制三(san)(san)(san)通(tong)(tong)，材(cai)料成形(xing)(xing)(xing)所(suo)需要的(de)(de)(de)(de)設備噸位(wei)降低(di)。熱(re)壓(ya)三(san)(san)(san)通(tong)(tong)對材(cai)料的(de)(de)(de)(de)適(shi)應性較寬，適(shi)用(yong)于(yu)低(di)碳鋼(gang)(gang)、合金(jin)鋼(gang)(gang)、不銹鋼(gang)(gang)的(de)(de)(de)(de)材(cai)料，特(te)別(bie)是(shi)(shi)大(da)直徑和管(guan)(guan)(guan)(guan)壁(bi)偏厚的(de)(de)(de)(de)三(san)(san)(san)通(tong)(tong)，通(tong)(tong)常(chang)采用(yong)這種成形(xing)(xing)(xing)工(gong)藝。

   ④. 四通為管件、管道連接件，用在主管道要分支管處，又稱管件四(si)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 B 16.9，SH 3408，SH 3409，HG／T21635，DL／T 695，SY／T 0510，DIN 2615等。四通典型圖見圖16.26。

   ⑤. 對于異徑(jing)(jing)三(san)通(tong)，首先給出(chu)(chu)最(zui)(zui)大(da)端的(de)(de)(de)公(gong)(gong)(gong)(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)，然后(hou)是與最(zui)(zui)大(da)端相(xiang)對應(ying)的(de)(de)(de)那一端的(de)(de)(de)公(gong)(gong)(gong)(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)，最(zui)(zui)后(hou)給出(chu)(chu)支管(guan)端的(de)(de)(de)公(gong)(gong)(gong)(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)；對于異徑(jing)(jing)四通(tong)，首先給出(chu)(chu)最(zui)(zui)大(da)端的(de)(de)(de)公(gong)(gong)(gong)(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)，其次(ci)是與最(zui)(zui)大(da)端相(xiang)對應(ying)的(de)(de)(de)另一端的(de)(de)(de)公(gong)(gong)(gong)(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)，第三(san)個給出(chu)(chu)的(de)(de)(de)是另外兩端中(zhong)較大(da)端的(de)(de)(de)公(gong)(gong)(gong)(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)，最(zui)(zui)后(hou)給出(chu)(chu)剩余一端的(de)(de)(de)公(gong)(gong)(gong)(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)，見(jian)圖16.27。