①. 三通接頭是管件的一種，它的連接形式就是直接將三通(tong)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)(san)通(tong)(tong)(tong)按(an)(an)照管件口徑(jing)分(fen)(fen)一般有等(deng)徑(jing)三(san)(san)(san)通(tong)(tong)(tong)［圖16.25（a）］、異徑(jing)三(san)(san)(san)通(tong)(tong)(tong)［圖16.25（b）］等(deng)。按(an)(an)照支管方向分(fen)(fen)有正三(san)(san)(san)通(tong)(tong)(tong)和(he)斜三(san)(san)(san)通(tong)(tong)(tong)（y形(xing)三(san)(san)(san)通(tong)(tong)(tong)），斜三(san)(san)(san)通(tong)(tong)(tong)常常代(dai)替一般正三(san)(san)(san)通(tong)(tong)(tong)，用于輸送有固體顆粒或沖刷腐蝕較嚴重的(de)管道上。按(an)(an)照材料(liao)分(fen)(fen)有碳鋼、合金(jin)鋼、不(bu)銹(xiu)鋼、銅(tong)、PVC等(deng)三(san)(san)(san)通(tong)(tong)(tong)。按(an)(an)照連接方式分(fen)(fen)有普(pu)通(tong)(tong)(tong)三(san)(san)(san)通(tong)(tong)(tong)、螺紋三(san)(san)(san)通(tong)(tong)(tong)、卡套三(san)(san)(san)通(tong)(tong)(tong)、承插(cha)三(san)(san)(san)通(tong)(tong)(tong)。

   ③. 三通(tong)(tong)接頭成形(xing)是(shi)將大(da)于(yu)三通(tong)(tong)直(zhi)(zhi)徑(jing)(jing)的(de)(de)(de)(de)(de)管(guan)(guan)坯，壓(ya)(ya)扁(bian)至(zhi)約三通(tong)(tong)直(zhi)(zhi)徑(jing)(jing)的(de)(de)(de)(de)(de)尺寸，在(zai)(zai)(zai)拉伸(shen)支(zhi)(zhi)管(guan)(guan)的(de)(de)(de)(de)(de)部(bu)位開一個(ge)孔；管(guan)(guan)坯經(jing)加熱(re)(re)，放入(ru)成形(xing)模(mo)中(zhong)(zhong)，并在(zai)(zai)(zai)管(guan)(guan)坯內裝入(ru)拉伸(shen)支(zhi)(zhi)管(guan)(guan)的(de)(de)(de)(de)(de)沖(chong)模(mo)；在(zai)(zai)(zai)壓(ya)(ya)力的(de)(de)(de)(de)(de)作(zuo)用(yong)(yong)下管(guan)(guan)坯被徑(jing)(jing)向(xiang)(xiang)壓(ya)(ya)縮(suo)，在(zai)(zai)(zai)徑(jing)(jing)向(xiang)(xiang)壓(ya)(ya)縮(suo)的(de)(de)(de)(de)(de)過程(cheng)中(zhong)(zhong)金屬向(xiang)(xiang)支(zhi)(zhi)管(guan)(guan)方向(xiang)(xiang)流(liu)動并在(zai)(zai)(zai)沖(chong)模(mo)的(de)(de)(de)(de)(de)拉伸(shen)下形(xing)成支(zhi)(zhi)管(guan)(guan)。整個(ge)過程(cheng)是(shi)通(tong)(tong)過管(guan)(guan)坯的(de)(de)(de)(de)(de)徑(jing)(jing)向(xiang)(xiang)壓(ya)(ya)縮(suo)和(he)支(zhi)(zhi)管(guan)(guan)部(bu)位的(de)(de)(de)(de)(de)拉伸(shen)過程(cheng)而成形(xing)。與(yu)液壓(ya)(ya)脹形(xing)三通(tong)(tong)不同的(de)(de)(de)(de)(de)是(shi)，三通(tong)(tong)接頭支(zhi)(zhi)管(guan)(guan)的(de)(de)(de)(de)(de)金屬是(shi)由管(guan)(guan)坯的(de)(de)(de)(de)(de)徑(jing)(jing)向(xiang)(xiang)運動進行補償的(de)(de)(de)(de)(de)，所以也稱為徑(jing)(jing)向(xiang)(xiang)補償工藝。由于(yu)采(cai)(cai)用(yong)(yong)加熱(re)(re)后壓(ya)(ya)制三通(tong)(tong)，材(cai)料(liao)成形(xing)所需要的(de)(de)(de)(de)(de)設備噸位降低(di)。熱(re)(re)壓(ya)(ya)三通(tong)(tong)對材(cai)料(liao)的(de)(de)(de)(de)(de)適(shi)應性(xing)較寬，適(shi)用(yong)(yong)于(yu)低(di)碳(tan)鋼(gang)、合金鋼(gang)、不銹鋼(gang)的(de)(de)(de)(de)(de)材(cai)料(liao)，特別是(shi)大(da)直(zhi)(zhi)徑(jing)(jing)和(he)管(guan)(guan)壁偏厚的(de)(de)(de)(de)(de)三通(tong)(tong)，通(tong)(tong)常(chang)采(cai)(cai)用(yong)(yong)這(zhe)種(zhong)成形(xing)工藝。

   ④. 四通為管件、管道連接件，用在主管道要分支管處，又稱管件四通(tong)、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(dui)于(yu)異徑(jing)三(san)通(tong)(tong)(tong)，首先給(gei)出最(zui)大(da)端的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)(tong)(tong)徑(jing)，然(ran)后(hou)是與(yu)最(zui)大(da)端相對(dui)應(ying)的(de)那(nei)一端的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)(tong)(tong)徑(jing)，最(zui)后(hou)給(gei)出支管端的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)(tong)(tong)徑(jing)；對(dui)于(yu)異徑(jing)四通(tong)(tong)(tong)，首先給(gei)出最(zui)大(da)端的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)(tong)(tong)徑(jing)，其次是與(yu)最(zui)大(da)端相對(dui)應(ying)的(de)另一端的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)(tong)(tong)徑(jing)，第三(san)個給(gei)出的(de)是另外兩端中較大(da)端的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)(tong)(tong)徑(jing)，最(zui)后(hou)給(gei)出剩余一端的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)(tong)(tong)徑(jing)，見圖16.27。