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)(san)通(tong)(tong)(tong)按(an)(an)照管件(jian)口徑(jing)分(fen)(fen)一(yi)般(ban)有等徑(jing)三(san)(san)(san)(san)通(tong)(tong)(tong)［圖16.25（a）］、異徑(jing)三(san)(san)(san)(san)通(tong)(tong)(tong)［圖16.25（b）］等。按(an)(an)照支管方向(xiang)分(fen)(fen)有正(zheng)三(san)(san)(san)(san)通(tong)(tong)(tong)和(he)斜三(san)(san)(san)(san)通(tong)(tong)(tong)（y形三(san)(san)(san)(san)通(tong)(tong)(tong)），斜三(san)(san)(san)(san)通(tong)(tong)(tong)常(chang)常(chang)代(dai)替一(yi)般(ban)正(zheng)三(san)(san)(san)(san)通(tong)(tong)(tong)，用于輸送(song)有固(gu)體顆粒或(huo)沖刷腐蝕較嚴重的(de)管道上。按(an)(an)照材料分(fen)(fen)有碳鋼(gang)、合金鋼(gang)、不(bu)銹鋼(gang)、銅、PVC等三(san)(san)(san)(san)通(tong)(tong)(tong)。按(an)(an)照連接方式分(fen)(fen)有普通(tong)(tong)(tong)三(san)(san)(san)(san)通(tong)(tong)(tong)、螺紋三(san)(san)(san)(san)通(tong)(tong)(tong)、卡套(tao)三(san)(san)(san)(san)通(tong)(tong)(tong)、承插(cha)三(san)(san)(san)(san)通(tong)(tong)(tong)。

   ③. 三通(tong)接(jie)頭成(cheng)形(xing)(xing)是將大于(yu)三通(tong)直(zhi)徑(jing)(jing)(jing)的管(guan)(guan)(guan)坯(pi)，壓(ya)扁至約三通(tong)直(zhi)徑(jing)(jing)(jing)的尺寸，在(zai)拉(la)伸(shen)支(zhi)(zhi)管(guan)(guan)(guan)的部(bu)位(wei)(wei)開一個孔；管(guan)(guan)(guan)坯(pi)經加熱，放(fang)入成(cheng)形(xing)(xing)模中，并在(zai)管(guan)(guan)(guan)坯(pi)內裝入拉(la)伸(shen)支(zhi)(zhi)管(guan)(guan)(guan)的沖(chong)模；在(zai)壓(ya)力的作用(yong)(yong)下管(guan)(guan)(guan)坯(pi)被徑(jing)(jing)(jing)向(xiang)壓(ya)縮，在(zai)徑(jing)(jing)(jing)向(xiang)壓(ya)縮的過程(cheng)中金(jin)屬向(xiang)支(zhi)(zhi)管(guan)(guan)(guan)方向(xiang)流動并在(zai)沖(chong)模的拉(la)伸(shen)下形(xing)(xing)成(cheng)支(zhi)(zhi)管(guan)(guan)(guan)。整個過程(cheng)是通(tong)過管(guan)(guan)(guan)坯(pi)的徑(jing)(jing)(jing)向(xiang)壓(ya)縮和支(zhi)(zhi)管(guan)(guan)(guan)部(bu)位(wei)(wei)的拉(la)伸(shen)過程(cheng)而成(cheng)形(xing)(xing)。與液(ye)壓(ya)脹形(xing)(xing)三通(tong)不同的是，三通(tong)接(jie)頭支(zhi)(zhi)管(guan)(guan)(guan)的金(jin)屬是由管(guan)(guan)(guan)坯(pi)的徑(jing)(jing)(jing)向(xiang)運動進行補償(chang)的，所(suo)以(yi)也稱(cheng)為徑(jing)(jing)(jing)向(xiang)補償(chang)工藝(yi)。由于(yu)采用(yong)(yong)加熱后壓(ya)制(zhi)三通(tong)，材(cai)料成(cheng)形(xing)(xing)所(suo)需要(yao)的設備噸位(wei)(wei)降低。熱壓(ya)三通(tong)對材(cai)料的適(shi)應性較寬(kuan)，適(shi)用(yong)(yong)于(yu)低碳(tan)鋼(gang)、合(he)金(jin)鋼(gang)、不銹(xiu)鋼(gang)的材(cai)料，特別是大直(zhi)徑(jing)(jing)(jing)和管(guan)(guan)(guan)壁偏厚(hou)的三通(tong)，通(tong)常采用(yong)(yong)這種(zhong)成(cheng)形(xing)(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(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. 對于異(yi)(yi)徑三(san)通(tong)(tong)，首先給(gei)出(chu)(chu)(chu)最(zui)大(da)端(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)徑，然(ran)后(hou)是與(yu)最(zui)大(da)端(duan)(duan)(duan)相(xiang)對應的(de)(de)那一端(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)徑，最(zui)后(hou)給(gei)出(chu)(chu)(chu)支管端(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)徑；對于異(yi)(yi)徑四通(tong)(tong)，首先給(gei)出(chu)(chu)(chu)最(zui)大(da)端(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)徑，其次是與(yu)最(zui)大(da)端(duan)(duan)(duan)相(xiang)對應的(de)(de)另一端(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)徑，第三(san)個給(gei)出(chu)(chu)(chu)的(de)(de)是另外兩端(duan)(duan)(duan)中較(jiao)大(da)端(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)徑，最(zui)后(hou)給(gei)出(chu)(chu)(chu)剩余一端(duan)(duan)(duan)的(de)(de)公(gong)稱(cheng)通(tong)(tong)徑，見(jian)圖(tu)16.27。