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(san)(san)通(tong)按(an)照管(guan)(guan)件口徑分一般有等徑三(san)(san)通(tong)［圖(tu)16.25（a）］、異(yi)徑三(san)(san)通(tong)［圖(tu)16.25（b）］等。按(an)照支管(guan)(guan)方向分有正三(san)(san)通(tong)和斜三(san)(san)通(tong)（y形三(san)(san)通(tong)），斜三(san)(san)通(tong)常(chang)(chang)常(chang)(chang)代替一般正三(san)(san)通(tong)，用于輸(shu)送有固(gu)體顆粒(li)或(huo)沖刷腐蝕較嚴重(zhong)的管(guan)(guan)道上(shang)。按(an)照材料分有碳鋼(gang)、合金鋼(gang)、不銹(xiu)鋼(gang)、銅、PVC等三(san)(san)通(tong)。按(an)照連接(jie)方式(shi)分有普通(tong)三(san)(san)通(tong)、螺紋三(san)(san)通(tong)、卡(ka)套三(san)(san)通(tong)、承插三(san)(san)通(tong)。
③. 三通(tong)(tong)(tong)接(jie)頭(tou)成形(xing)是將大(da)于三通(tong)(tong)(tong)直徑的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)坯(pi)，壓(ya)扁至(zhi)約三通(tong)(tong)(tong)直徑的(de)(de)(de)尺寸，在(zai)拉伸支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)的(de)(de)(de)部位開一個孔；管(guan)(guan)(guan)(guan)(guan)坯(pi)經加熱(re)，放(fang)入成形(xing)模(mo)中(zhong)，并在(zai)管(guan)(guan)(guan)(guan)(guan)坯(pi)內(nei)裝入拉伸支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)的(de)(de)(de)沖模(mo)；在(zai)壓(ya)力的(de)(de)(de)作用(yong)下管(guan)(guan)(guan)(guan)(guan)坯(pi)被徑向壓(ya)縮，在(zai)徑向壓(ya)縮的(de)(de)(de)過程中(zhong)金(jin)屬向支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)方向流動并在(zai)沖模(mo)的(de)(de)(de)拉伸下形(xing)成支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)。整個過程是通(tong)(tong)(tong)過管(guan)(guan)(guan)(guan)(guan)坯(pi)的(de)(de)(de)徑向壓(ya)縮和支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)部位的(de)(de)(de)拉伸過程而成形(xing)。與液壓(ya)脹形(xing)三通(tong)(tong)(tong)不同(tong)的(de)(de)(de)是，三通(tong)(tong)(tong)接(jie)頭(tou)支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)的(de)(de)(de)金(jin)屬是由(you)管(guan)(guan)(guan)(guan)(guan)坯(pi)的(de)(de)(de)徑向運動進行補償的(de)(de)(de)，所以也(ye)稱為徑向補償工(gong)藝(yi)。由(you)于采用(yong)加熱(re)后壓(ya)制三通(tong)(tong)(tong)，材(cai)料(liao)成形(xing)所需(xu)要(yao)的(de)(de)(de)設備噸位降(jiang)低。熱(re)壓(ya)三通(tong)(tong)(tong)對材(cai)料(liao)的(de)(de)(de)適應性較寬，適用(yong)于低碳鋼(gang)、合(he)金(jin)鋼(gang)、不銹鋼(gang)的(de)(de)(de)材(cai)料(liao)，特(te)別是大(da)直徑和管(guan)(guan)(guan)(guan)(guan)壁偏(pian)厚的(de)(de)(de)三通(tong)(tong)(tong)，通(tong)(tong)(tong)常采用(yong)這種(zhong)成形(xing)工(gong)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(tong)、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(yu)異徑(jing)(jing)(jing)(jing)(jing)三通(tong)，首先(xian)給出最(zui)大(da)端(duan)(duan)(duan)(duan)(duan)(duan)的(de)公(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)(jing)(jing)(jing)，然后(hou)是與(yu)(yu)最(zui)大(da)端(duan)(duan)(duan)(duan)(duan)(duan)相對應的(de)那一端(duan)(duan)(duan)(duan)(duan)(duan)的(de)公(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)(jing)(jing)(jing)，最(zui)后(hou)給出支(zhi)管端(duan)(duan)(duan)(duan)(duan)(duan)的(de)公(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)(jing)(jing)(jing)；對于(yu)異徑(jing)(jing)(jing)(jing)(jing)四通(tong)，首先(xian)給出最(zui)大(da)端(duan)(duan)(duan)(duan)(duan)(duan)的(de)公(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)(jing)(jing)(jing)，其次是與(yu)(yu)最(zui)大(da)端(duan)(duan)(duan)(duan)(duan)(duan)相對應的(de)另(ling)一端(duan)(duan)(duan)(duan)(duan)(duan)的(de)公(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)(jing)(jing)(jing)，第三個給出的(de)是另(ling)外兩端(duan)(duan)(duan)(duan)(duan)(duan)中較大(da)端(duan)(duan)(duan)(duan)(duan)(duan)的(de)公(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)(jing)(jing)(jing)，最(zui)后(hou)給出剩余一端(duan)(duan)(duan)(duan)(duan)(duan)的(de)公(gong)(gong)稱(cheng)(cheng)通(tong)徑(jing)(jing)(jing)(jing)(jing)，見(jian)圖16.27。
