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)(tong)按(an)(an)照(zhao)管件口徑分一(yi)般有(you)(you)(you)等徑三(san)(san)(san)通(tong)(tong)(tong)(tong)［圖(tu)16.25（a）］、異徑三(san)(san)(san)通(tong)(tong)(tong)(tong)［圖(tu)16.25（b）］等。按(an)(an)照(zhao)支管方(fang)向(xiang)分有(you)(you)(you)正(zheng)三(san)(san)(san)通(tong)(tong)(tong)(tong)和斜三(san)(san)(san)通(tong)(tong)(tong)(tong)（y形三(san)(san)(san)通(tong)(tong)(tong)(tong)），斜三(san)(san)(san)通(tong)(tong)(tong)(tong)常常代替一(yi)般正(zheng)三(san)(san)(san)通(tong)(tong)(tong)(tong)，用于輸送有(you)(you)(you)固體顆粒或沖刷腐蝕較嚴重(zhong)的管道上。按(an)(an)照(zhao)材(cai)料分有(you)(you)(you)碳(tan)鋼(gang)、合金鋼(gang)、不銹鋼(gang)、銅(tong)、PVC等三(san)(san)(san)通(tong)(tong)(tong)(tong)。按(an)(an)照(zhao)連(lian)接方(fang)式(shi)分有(you)(you)(you)普通(tong)(tong)(tong)(tong)三(san)(san)(san)通(tong)(tong)(tong)(tong)、螺紋三(san)(san)(san)通(tong)(tong)(tong)(tong)、卡套三(san)(san)(san)通(tong)(tong)(tong)(tong)、承插三(san)(san)(san)通(tong)(tong)(tong)(tong)。
③. 三(san)(san)通(tong)接頭成(cheng)(cheng)形(xing)(xing)(xing)是(shi)(shi)將大于三(san)(san)通(tong)直(zhi)(zhi)徑(jing)的(de)(de)(de)(de)管(guan)(guan)坯(pi)(pi)，壓(ya)(ya)扁至約(yue)三(san)(san)通(tong)直(zhi)(zhi)徑(jing)的(de)(de)(de)(de)尺(chi)寸，在(zai)拉(la)伸支管(guan)(guan)的(de)(de)(de)(de)部位開(kai)一個孔；管(guan)(guan)坯(pi)(pi)經加(jia)熱(re)，放入成(cheng)(cheng)形(xing)(xing)(xing)模(mo)(mo)(mo)中，并在(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)(mo)；在(zai)壓(ya)(ya)力的(de)(de)(de)(de)作(zuo)用下管(guan)(guan)坯(pi)(pi)被徑(jing)向(xiang)(xiang)(xiang)壓(ya)(ya)縮，在(zai)徑(jing)向(xiang)(xiang)(xiang)壓(ya)(ya)縮的(de)(de)(de)(de)過(guo)程中金(jin)(jin)屬(shu)向(xiang)(xiang)(xiang)支管(guan)(guan)方向(xiang)(xiang)(xiang)流動并在(zai)沖(chong)模(mo)(mo)(mo)的(de)(de)(de)(de)拉(la)伸下形(xing)(xing)(xing)成(cheng)(cheng)支管(guan)(guan)。整個過(guo)程是(shi)(shi)通(tong)過(guo)管(guan)(guan)坯(pi)(pi)的(de)(de)(de)(de)徑(jing)向(xiang)(xiang)(xiang)壓(ya)(ya)縮和支管(guan)(guan)部位的(de)(de)(de)(de)拉(la)伸過(guo)程而成(cheng)(cheng)形(xing)(xing)(xing)。與液(ye)壓(ya)(ya)脹形(xing)(xing)(xing)三(san)(san)通(tong)不(bu)同的(de)(de)(de)(de)是(shi)(shi)，三(san)(san)通(tong)接頭支管(guan)(guan)的(de)(de)(de)(de)金(jin)(jin)屬(shu)是(shi)(shi)由(you)管(guan)(guan)坯(pi)(pi)的(de)(de)(de)(de)徑(jing)向(xiang)(xiang)(xiang)運動進行補償(chang)的(de)(de)(de)(de)，所以也(ye)稱為徑(jing)向(xiang)(xiang)(xiang)補償(chang)工藝。由(you)于采(cai)(cai)用加(jia)熱(re)后壓(ya)(ya)制三(san)(san)通(tong)，材(cai)料(liao)成(cheng)(cheng)形(xing)(xing)(xing)所需要的(de)(de)(de)(de)設備(bei)噸位降低。熱(re)壓(ya)(ya)三(san)(san)通(tong)對材(cai)料(liao)的(de)(de)(de)(de)適應性較(jiao)寬，適用于低碳鋼(gang)(gang)(gang)、合金(jin)(jin)鋼(gang)(gang)(gang)、不(bu)銹鋼(gang)(gang)(gang)的(de)(de)(de)(de)材(cai)料(liao)，特(te)別(bie)是(shi)(shi)大直(zhi)(zhi)徑(jing)和管(guan)(guan)壁偏厚的(de)(de)(de)(de)三(san)(san)通(tong)，通(tong)常采(cai)(cai)用這種成(cheng)(cheng)形(xing)(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)于異(yi)徑(jing)(jing)(jing)三通(tong)(tong)(tong)，首先(xian)給(gei)(gei)出最(zui)大(da)(da)端(duan)(duan)(duan)的(de)(de)(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)(jing)，然后(hou)是與(yu)最(zui)大(da)(da)端(duan)(duan)(duan)相對(dui)應(ying)的(de)(de)(de)(de)那一端(duan)(duan)(duan)的(de)(de)(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)(jing)，最(zui)后(hou)給(gei)(gei)出支管端(duan)(duan)(duan)的(de)(de)(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)(jing)；對(dui)于異(yi)徑(jing)(jing)(jing)四通(tong)(tong)(tong)，首先(xian)給(gei)(gei)出最(zui)大(da)(da)端(duan)(duan)(duan)的(de)(de)(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)(jing)，其次是與(yu)最(zui)大(da)(da)端(duan)(duan)(duan)相對(dui)應(ying)的(de)(de)(de)(de)另一端(duan)(duan)(duan)的(de)(de)(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)(jing)，第三個給(gei)(gei)出的(de)(de)(de)(de)是另外(wai)兩端(duan)(duan)(duan)中較大(da)(da)端(duan)(duan)(duan)的(de)(de)(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)(jing)，最(zui)后(hou)給(gei)(gei)出剩余(yu)一端(duan)(duan)(duan)的(de)(de)(de)(de)公(gong)稱(cheng)通(tong)(tong)(tong)徑(jing)(jing)(jing)，見(jian)圖16.27。
