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)按照管(guan)件口徑(jing)分一(yi)般有(you)(you)(you)等徑(jing)三通(tong)(tong)［圖16.25（a）］、異徑(jing)三通(tong)(tong)［圖16.25（b）］等。按照支管(guan)方向分有(you)(you)(you)正三通(tong)(tong)和(he)斜(xie)三通(tong)(tong)（y形三通(tong)(tong)），斜(xie)三通(tong)(tong)常常代替一(yi)般正三通(tong)(tong)，用于輸送(song)有(you)(you)(you)固體顆粒(li)或(huo)沖刷腐蝕較嚴重的管(guan)道上。按照材料(liao)分有(you)(you)(you)碳鋼、合金鋼、不銹鋼、銅、PVC等三通(tong)(tong)。按照連(lian)接方式分有(you)(you)(you)普(pu)通(tong)(tong)三通(tong)(tong)、螺紋三通(tong)(tong)、卡套三通(tong)(tong)、承插三通(tong)(tong)。
③. 三(san)(san)通(tong)接頭(tou)成(cheng)形是(shi)將(jiang)大(da)于(yu)(yu)三(san)(san)通(tong)直徑(jing)的(de)(de)(de)管(guan)(guan)坯(pi)，壓(ya)(ya)扁(bian)至(zhi)約(yue)三(san)(san)通(tong)直徑(jing)的(de)(de)(de)尺(chi)寸，在(zai)(zai)(zai)拉伸(shen)(shen)支(zhi)(zhi)(zhi)管(guan)(guan)的(de)(de)(de)部位(wei)(wei)開一個孔；管(guan)(guan)坯(pi)經(jing)加(jia)熱，放入成(cheng)形模(mo)中，并在(zai)(zai)(zai)管(guan)(guan)坯(pi)內裝入拉伸(shen)(shen)支(zhi)(zhi)(zhi)管(guan)(guan)的(de)(de)(de)沖(chong)模(mo)；在(zai)(zai)(zai)壓(ya)(ya)力(li)的(de)(de)(de)作用(yong)(yong)下(xia)管(guan)(guan)坯(pi)被徑(jing)向(xiang)壓(ya)(ya)縮，在(zai)(zai)(zai)徑(jing)向(xiang)壓(ya)(ya)縮的(de)(de)(de)過(guo)程中金(jin)屬向(xiang)支(zhi)(zhi)(zhi)管(guan)(guan)方(fang)向(xiang)流動并在(zai)(zai)(zai)沖(chong)模(mo)的(de)(de)(de)拉伸(shen)(shen)下(xia)形成(cheng)支(zhi)(zhi)(zhi)管(guan)(guan)。整(zheng)個過(guo)程是(shi)通(tong)過(guo)管(guan)(guan)坯(pi)的(de)(de)(de)徑(jing)向(xiang)壓(ya)(ya)縮和支(zhi)(zhi)(zhi)管(guan)(guan)部位(wei)(wei)的(de)(de)(de)拉伸(shen)(shen)過(guo)程而成(cheng)形。與液壓(ya)(ya)脹形三(san)(san)通(tong)不同的(de)(de)(de)是(shi)，三(san)(san)通(tong)接頭(tou)支(zhi)(zhi)(zhi)管(guan)(guan)的(de)(de)(de)金(jin)屬是(shi)由(you)管(guan)(guan)坯(pi)的(de)(de)(de)徑(jing)向(xiang)運動進(jin)行補償的(de)(de)(de)，所(suo)以也稱為徑(jing)向(xiang)補償工藝。由(you)于(yu)(yu)采用(yong)(yong)加(jia)熱后壓(ya)(ya)制三(san)(san)通(tong)，材(cai)(cai)料成(cheng)形所(suo)需要的(de)(de)(de)設備噸位(wei)(wei)降低(di)。熱壓(ya)(ya)三(san)(san)通(tong)對材(cai)(cai)料的(de)(de)(de)適(shi)應性較(jiao)寬，適(shi)用(yong)(yong)于(yu)(yu)低(di)碳(tan)鋼(gang)、合金(jin)鋼(gang)、不銹鋼(gang)的(de)(de)(de)材(cai)(cai)料，特別是(shi)大(da)直徑(jing)和管(guan)(guan)壁偏厚(hou)的(de)(de)(de)三(san)(san)通(tong)，通(tong)常采用(yong)(yong)這種成(cheng)形工藝。
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)三通(tong)，首(shou)先給出(chu)(chu)最大端(duan)(duan)的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)徑(jing)，然(ran)后(hou)是(shi)與(yu)最大端(duan)(duan)相(xiang)(xiang)對(dui)應(ying)的(de)那一(yi)端(duan)(duan)的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)徑(jing)，最后(hou)給出(chu)(chu)支管端(duan)(duan)的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)徑(jing)；對(dui)于異(yi)徑(jing)四(si)通(tong)，首(shou)先給出(chu)(chu)最大端(duan)(duan)的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)徑(jing)，其次是(shi)與(yu)最大端(duan)(duan)相(xiang)(xiang)對(dui)應(ying)的(de)另(ling)一(yi)端(duan)(duan)的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)徑(jing)，第三個給出(chu)(chu)的(de)是(shi)另(ling)外兩端(duan)(duan)中較大端(duan)(duan)的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)徑(jing)，最后(hou)給出(chu)(chu)剩余(yu)一(yi)端(duan)(duan)的(de)公(gong)(gong)(gong)稱(cheng)(cheng)(cheng)通(tong)徑(jing)，見(jian)圖16.27。
