①. 三通接頭是管件的一種，它的連接形式就是直接將三(san)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)通(tong)(tong)(tong)(tong)按(an)照管(guan)件口徑分一般有(you)等徑三(san)(san)通(tong)(tong)(tong)(tong)［圖16.25（a）］、異徑三(san)(san)通(tong)(tong)(tong)(tong)［圖16.25（b）］等。按(an)照支管(guan)方向(xiang)分有(you)正(zheng)三(san)(san)通(tong)(tong)(tong)(tong)和斜三(san)(san)通(tong)(tong)(tong)(tong)（y形三(san)(san)通(tong)(tong)(tong)(tong)），斜三(san)(san)通(tong)(tong)(tong)(tong)常常代替一般正(zheng)三(san)(san)通(tong)(tong)(tong)(tong)，用于輸送有(you)固(gu)體顆粒或(huo)沖(chong)刷腐蝕較嚴重的管(guan)道上。按(an)照材料分有(you)碳鋼(gang)、合金鋼(gang)、不銹鋼(gang)、銅、PVC等三(san)(san)通(tong)(tong)(tong)(tong)。按(an)照連接方式分有(you)普通(tong)(tong)(tong)(tong)三(san)(san)通(tong)(tong)(tong)(tong)、螺紋三(san)(san)通(tong)(tong)(tong)(tong)、卡套三(san)(san)通(tong)(tong)(tong)(tong)、承插三(san)(san)通(tong)(tong)(tong)(tong)。
③. 三(san)(san)(san)(san)(san)通(tong)(tong)(tong)接頭成(cheng)形是(shi)將(jiang)大于(yu)三(san)(san)(san)(san)(san)通(tong)(tong)(tong)直徑的(de)(de)(de)(de)(de)管(guan)坯(pi)，壓(ya)扁至約三(san)(san)(san)(san)(san)通(tong)(tong)(tong)直徑的(de)(de)(de)(de)(de)尺寸，在(zai)(zai)拉伸(shen)(shen)支管(guan)的(de)(de)(de)(de)(de)部位開一個(ge)孔(kong)；管(guan)坯(pi)經(jing)加(jia)熱(re)，放入(ru)成(cheng)形模(mo)中，并(bing)在(zai)(zai)管(guan)坯(pi)內裝入(ru)拉伸(shen)(shen)支管(guan)的(de)(de)(de)(de)(de)沖模(mo)；在(zai)(zai)壓(ya)力的(de)(de)(de)(de)(de)作用下管(guan)坯(pi)被徑向(xiang)(xiang)(xiang)壓(ya)縮，在(zai)(zai)徑向(xiang)(xiang)(xiang)壓(ya)縮的(de)(de)(de)(de)(de)過(guo)程(cheng)中金屬向(xiang)(xiang)(xiang)支管(guan)方向(xiang)(xiang)(xiang)流動并(bing)在(zai)(zai)沖模(mo)的(de)(de)(de)(de)(de)拉伸(shen)(shen)下形成(cheng)支管(guan)。整個(ge)過(guo)程(cheng)是(shi)通(tong)(tong)(tong)過(guo)管(guan)坯(pi)的(de)(de)(de)(de)(de)徑向(xiang)(xiang)(xiang)壓(ya)縮和支管(guan)部位的(de)(de)(de)(de)(de)拉伸(shen)(shen)過(guo)程(cheng)而成(cheng)形。與液壓(ya)脹(zhang)形三(san)(san)(san)(san)(san)通(tong)(tong)(tong)不(bu)同(tong)的(de)(de)(de)(de)(de)是(shi)，三(san)(san)(san)(san)(san)通(tong)(tong)(tong)接頭支管(guan)的(de)(de)(de)(de)(de)金屬是(shi)由管(guan)坯(pi)的(de)(de)(de)(de)(de)徑向(xiang)(xiang)(xiang)運(yun)動進行補(bu)償的(de)(de)(de)(de)(de)，所以也稱為徑向(xiang)(xiang)(xiang)補(bu)償工(gong)藝。由于(yu)采(cai)用加(jia)熱(re)后壓(ya)制(zhi)三(san)(san)(san)(san)(san)通(tong)(tong)(tong)，材料(liao)(liao)成(cheng)形所需要的(de)(de)(de)(de)(de)設備噸位降低(di)。熱(re)壓(ya)三(san)(san)(san)(san)(san)通(tong)(tong)(tong)對材料(liao)(liao)的(de)(de)(de)(de)(de)適應性較(jiao)寬，適用于(yu)低(di)碳鋼(gang)、合(he)金鋼(gang)、不(bu)銹鋼(gang)的(de)(de)(de)(de)(de)材料(liao)(liao)，特別(bie)是(shi)大直徑和管(guan)壁偏厚的(de)(de)(de)(de)(de)三(san)(san)(san)(san)(san)通(tong)(tong)(tong)，通(tong)(tong)(tong)常采(cai)用這種成(cheng)形工(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(dui)(dui)于異(yi)徑(jing)三通(tong)(tong)，首先給(gei)(gei)出最(zui)(zui)(zui)大(da)端(duan)(duan)的(de)公(gong)稱(cheng)(cheng)(cheng)(cheng)通(tong)(tong)徑(jing)，然后(hou)(hou)是與最(zui)(zui)(zui)大(da)端(duan)(duan)相對(dui)(dui)應的(de)那(nei)一端(duan)(duan)的(de)公(gong)稱(cheng)(cheng)(cheng)(cheng)通(tong)(tong)徑(jing)，最(zui)(zui)(zui)后(hou)(hou)給(gei)(gei)出支(zhi)管端(duan)(duan)的(de)公(gong)稱(cheng)(cheng)(cheng)(cheng)通(tong)(tong)徑(jing)；對(dui)(dui)于異(yi)徑(jing)四通(tong)(tong)，首先給(gei)(gei)出最(zui)(zui)(zui)大(da)端(duan)(duan)的(de)公(gong)稱(cheng)(cheng)(cheng)(cheng)通(tong)(tong)徑(jing)，其次(ci)是與最(zui)(zui)(zui)大(da)端(duan)(duan)相對(dui)(dui)應的(de)另一端(duan)(duan)的(de)公(gong)稱(cheng)(cheng)(cheng)(cheng)通(tong)(tong)徑(jing)，第三個給(gei)(gei)出的(de)是另外兩(liang)端(duan)(duan)中較大(da)端(duan)(duan)的(de)公(gong)稱(cheng)(cheng)(cheng)(cheng)通(tong)(tong)徑(jing)，最(zui)(zui)(zui)后(hou)(hou)給(gei)(gei)出剩余(yu)一端(duan)(duan)的(de)公(gong)稱(cheng)(cheng)(cheng)(cheng)通(tong)(tong)徑(jing)，見圖16.27。
