①. 三通接頭是管件的一種，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. 三通(tong)(tong)(tong)(tong)(tong)(tong)按(an)照管件口(kou)徑分(fen)(fen)一般(ban)有(you)(you)等(deng)徑三通(tong)(tong)(tong)(tong)(tong)(tong)［圖16.25（a）］、異徑三通(tong)(tong)(tong)(tong)(tong)(tong)［圖16.25（b）］等(deng)。按(an)照支管方向分(fen)(fen)有(you)(you)正三通(tong)(tong)(tong)(tong)(tong)(tong)和斜(xie)三通(tong)(tong)(tong)(tong)(tong)(tong)（y形三通(tong)(tong)(tong)(tong)(tong)(tong)），斜(xie)三通(tong)(tong)(tong)(tong)(tong)(tong)常常代(dai)替一般(ban)正三通(tong)(tong)(tong)(tong)(tong)(tong)，用于(yu)輸(shu)送有(you)(you)固體顆(ke)粒(li)或沖(chong)刷(shua)腐蝕較(jiao)嚴重的管道上。按(an)照材料(liao)分(fen)(fen)有(you)(you)碳(tan)鋼、合金鋼、不銹鋼、銅、PVC等(deng)三通(tong)(tong)(tong)(tong)(tong)(tong)。按(an)照連接方式分(fen)(fen)有(you)(you)普通(tong)(tong)(tong)(tong)(tong)(tong)三通(tong)(tong)(tong)(tong)(tong)(tong)、螺紋三通(tong)(tong)(tong)(tong)(tong)(tong)、卡套三通(tong)(tong)(tong)(tong)(tong)(tong)、承插(cha)三通(tong)(tong)(tong)(tong)(tong)(tong)。

   ③. 三(san)(san)通(tong)接(jie)頭成(cheng)(cheng)形(xing)(xing)是(shi)將(jiang)大于三(san)(san)通(tong)直(zhi)徑(jing)的(de)(de)管(guan)(guan)(guan)(guan)坯(pi)(pi)(pi)，壓(ya)(ya)扁至(zhi)約(yue)三(san)(san)通(tong)直(zhi)徑(jing)的(de)(de)尺(chi)寸，在(zai)拉(la)伸支(zhi)管(guan)(guan)(guan)(guan)的(de)(de)部(bu)位開一個孔；管(guan)(guan)(guan)(guan)坯(pi)(pi)(pi)經加(jia)熱(re)(re)，放入成(cheng)(cheng)形(xing)(xing)模中，并在(zai)管(guan)(guan)(guan)(guan)坯(pi)(pi)(pi)內裝入拉(la)伸支(zhi)管(guan)(guan)(guan)(guan)的(de)(de)沖(chong)(chong)模；在(zai)壓(ya)(ya)力的(de)(de)作用下管(guan)(guan)(guan)(guan)坯(pi)(pi)(pi)被(bei)徑(jing)向(xiang)(xiang)壓(ya)(ya)縮，在(zai)徑(jing)向(xiang)(xiang)壓(ya)(ya)縮的(de)(de)過(guo)程(cheng)中金屬(shu)向(xiang)(xiang)支(zhi)管(guan)(guan)(guan)(guan)方向(xiang)(xiang)流(liu)動并在(zai)沖(chong)(chong)模的(de)(de)拉(la)伸下形(xing)(xing)成(cheng)(cheng)支(zhi)管(guan)(guan)(guan)(guan)。整個過(guo)程(cheng)是(shi)通(tong)過(guo)管(guan)(guan)(guan)(guan)坯(pi)(pi)(pi)的(de)(de)徑(jing)向(xiang)(xiang)壓(ya)(ya)縮和支(zhi)管(guan)(guan)(guan)(guan)部(bu)位的(de)(de)拉(la)伸過(guo)程(cheng)而成(cheng)(cheng)形(xing)(xing)。與液壓(ya)(ya)脹形(xing)(xing)三(san)(san)通(tong)不同的(de)(de)是(shi)，三(san)(san)通(tong)接(jie)頭支(zhi)管(guan)(guan)(guan)(guan)的(de)(de)金屬(shu)是(shi)由管(guan)(guan)(guan)(guan)坯(pi)(pi)(pi)的(de)(de)徑(jing)向(xiang)(xiang)運(yun)動進行補(bu)償的(de)(de)，所以也稱為徑(jing)向(xiang)(xiang)補(bu)償工藝。由于采用加(jia)熱(re)(re)后壓(ya)(ya)制(zhi)三(san)(san)通(tong)，材(cai)(cai)料成(cheng)(cheng)形(xing)(xing)所需要(yao)的(de)(de)設備噸(dun)位降低。熱(re)(re)壓(ya)(ya)三(san)(san)通(tong)對材(cai)(cai)料的(de)(de)適(shi)應性較(jiao)寬，適(shi)用于低碳鋼、合金鋼、不銹(xiu)鋼的(de)(de)材(cai)(cai)料，特別是(shi)大直(zhi)徑(jing)和管(guan)(guan)(guan)(guan)壁偏厚(hou)的(de)(de)三(san)(san)通(tong)，通(tong)常采用這(zhe)種成(cheng)(cheng)形(xing)(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、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(yi)(yi)徑(jing)(jing)三通(tong)(tong)(tong)，首先(xian)給(gei)出(chu)最(zui)(zui)大(da)端(duan)(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)，然后是(shi)與(yu)最(zui)(zui)大(da)端(duan)(duan)(duan)(duan)相對(dui)應(ying)(ying)的(de)(de)那一(yi)(yi)端(duan)(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)，最(zui)(zui)后給(gei)出(chu)支管端(duan)(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)；對(dui)于(yu)異(yi)(yi)徑(jing)(jing)四通(tong)(tong)(tong)，首先(xian)給(gei)出(chu)最(zui)(zui)大(da)端(duan)(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)，其次是(shi)與(yu)最(zui)(zui)大(da)端(duan)(duan)(duan)(duan)相對(dui)應(ying)(ying)的(de)(de)另(ling)一(yi)(yi)端(duan)(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)，第三個給(gei)出(chu)的(de)(de)是(shi)另(ling)外兩(liang)端(duan)(duan)(duan)(duan)中較大(da)端(duan)(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)，最(zui)(zui)后給(gei)出(chu)剩余一(yi)(yi)端(duan)(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)，見圖16.27。