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)通(tong)(tong)(tong)(tong)(tong)(tong)按(an)照(zhao)管件口(kou)徑分一(yi)般(ban)有等徑三(san)(san)通(tong)(tong)(tong)(tong)(tong)(tong)［圖16.25（a）］、異(yi)徑三(san)(san)通(tong)(tong)(tong)(tong)(tong)(tong)［圖16.25（b）］等。按(an)照(zhao)支管方向分有正(zheng)三(san)(san)通(tong)(tong)(tong)(tong)(tong)(tong)和斜三(san)(san)通(tong)(tong)(tong)(tong)(tong)(tong)（y形三(san)(san)通(tong)(tong)(tong)(tong)(tong)(tong)），斜三(san)(san)通(tong)(tong)(tong)(tong)(tong)(tong)常常代替(ti)一(yi)般(ban)正(zheng)三(san)(san)通(tong)(tong)(tong)(tong)(tong)(tong)，用于輸送有固(gu)體顆粒或(huo)沖(chong)刷腐(fu)蝕較嚴重的管道上。按(an)照(zhao)材料分有碳(tan)鋼(gang)、合(he)金鋼(gang)、不銹鋼(gang)、銅(tong)、PVC等三(san)(san)通(tong)(tong)(tong)(tong)(tong)(tong)。按(an)照(zhao)連接方式分有普(pu)通(tong)(tong)(tong)(tong)(tong)(tong)三(san)(san)通(tong)(tong)(tong)(tong)(tong)(tong)、螺紋三(san)(san)通(tong)(tong)(tong)(tong)(tong)(tong)、卡套三(san)(san)通(tong)(tong)(tong)(tong)(tong)(tong)、承插三(san)(san)通(tong)(tong)(tong)(tong)(tong)(tong)。

   ③. 三(san)(san)通(tong)(tong)(tong)(tong)接頭成(cheng)形(xing)是(shi)(shi)將大于三(san)(san)通(tong)(tong)(tong)(tong)直(zhi)徑(jing)的(de)(de)(de)(de)(de)管(guan)(guan)(guan)坯(pi)(pi)，壓扁至約三(san)(san)通(tong)(tong)(tong)(tong)直(zhi)徑(jing)的(de)(de)(de)(de)(de)尺寸，在拉(la)伸(shen)支(zhi)(zhi)管(guan)(guan)(guan)的(de)(de)(de)(de)(de)部位開一個孔；管(guan)(guan)(guan)坯(pi)(pi)經加(jia)(jia)熱(re)，放入成(cheng)形(xing)模(mo)(mo)中，并(bing)在管(guan)(guan)(guan)坯(pi)(pi)內(nei)裝入拉(la)伸(shen)支(zhi)(zhi)管(guan)(guan)(guan)的(de)(de)(de)(de)(de)沖模(mo)(mo)；在壓力的(de)(de)(de)(de)(de)作用(yong)下管(guan)(guan)(guan)坯(pi)(pi)被徑(jing)向(xiang)(xiang)(xiang)壓縮，在徑(jing)向(xiang)(xiang)(xiang)壓縮的(de)(de)(de)(de)(de)過(guo)程中金(jin)屬向(xiang)(xiang)(xiang)支(zhi)(zhi)管(guan)(guan)(guan)方(fang)向(xiang)(xiang)(xiang)流動并(bing)在沖模(mo)(mo)的(de)(de)(de)(de)(de)拉(la)伸(shen)下形(xing)成(cheng)支(zhi)(zhi)管(guan)(guan)(guan)。整(zheng)個過(guo)程是(shi)(shi)通(tong)(tong)(tong)(tong)過(guo)管(guan)(guan)(guan)坯(pi)(pi)的(de)(de)(de)(de)(de)徑(jing)向(xiang)(xiang)(xiang)壓縮和(he)支(zhi)(zhi)管(guan)(guan)(guan)部位的(de)(de)(de)(de)(de)拉(la)伸(shen)過(guo)程而(er)成(cheng)形(xing)。與液壓脹形(xing)三(san)(san)通(tong)(tong)(tong)(tong)不同的(de)(de)(de)(de)(de)是(shi)(shi)，三(san)(san)通(tong)(tong)(tong)(tong)接頭支(zhi)(zhi)管(guan)(guan)(guan)的(de)(de)(de)(de)(de)金(jin)屬是(shi)(shi)由(you)管(guan)(guan)(guan)坯(pi)(pi)的(de)(de)(de)(de)(de)徑(jing)向(xiang)(xiang)(xiang)運動進行補償(chang)的(de)(de)(de)(de)(de)，所以也稱為(wei)徑(jing)向(xiang)(xiang)(xiang)補償(chang)工藝(yi)。由(you)于采(cai)用(yong)加(jia)(jia)熱(re)后壓制(zhi)三(san)(san)通(tong)(tong)(tong)(tong)，材料(liao)成(cheng)形(xing)所需要的(de)(de)(de)(de)(de)設備噸(dun)位降(jiang)低。熱(re)壓三(san)(san)通(tong)(tong)(tong)(tong)對材料(liao)的(de)(de)(de)(de)(de)適(shi)應性較(jiao)寬，適(shi)用(yong)于低碳鋼、合金(jin)鋼、不銹鋼的(de)(de)(de)(de)(de)材料(liao)，特別是(shi)(shi)大直(zhi)徑(jing)和(he)管(guan)(guan)(guan)壁偏厚的(de)(de)(de)(de)(de)三(san)(san)通(tong)(tong)(tong)(tong)，通(tong)(tong)(tong)(tong)常采(cai)用(yong)這(zhe)種成(cheng)形(xing)工藝(yi)。

   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)于異徑(jing)(jing)(jing)三(san)通，首(shou)先(xian)給(gei)出(chu)(chu)最(zui)(zui)大(da)(da)(da)端(duan)(duan)的(de)(de)公(gong)稱(cheng)通徑(jing)(jing)(jing)，然后是(shi)與(yu)(yu)最(zui)(zui)大(da)(da)(da)端(duan)(duan)相(xiang)對(dui)應的(de)(de)那一(yi)端(duan)(duan)的(de)(de)公(gong)稱(cheng)通徑(jing)(jing)(jing)，最(zui)(zui)后給(gei)出(chu)(chu)支管端(duan)(duan)的(de)(de)公(gong)稱(cheng)通徑(jing)(jing)(jing)；對(dui)于異徑(jing)(jing)(jing)四通，首(shou)先(xian)給(gei)出(chu)(chu)最(zui)(zui)大(da)(da)(da)端(duan)(duan)的(de)(de)公(gong)稱(cheng)通徑(jing)(jing)(jing)，其(qi)次是(shi)與(yu)(yu)最(zui)(zui)大(da)(da)(da)端(duan)(duan)相(xiang)對(dui)應的(de)(de)另(ling)一(yi)端(duan)(duan)的(de)(de)公(gong)稱(cheng)通徑(jing)(jing)(jing)，第(di)三(san)個給(gei)出(chu)(chu)的(de)(de)是(shi)另(ling)外兩端(duan)(duan)中較大(da)(da)(da)端(duan)(duan)的(de)(de)公(gong)稱(cheng)通徑(jing)(jing)(jing)，最(zui)(zui)后給(gei)出(chu)(chu)剩(sheng)余一(yi)端(duan)(duan)的(de)(de)公(gong)稱(cheng)通徑(jing)(jing)(jing)，見(jian)圖16.27。