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)(tong)(tong)(tong)按(an)照(zhao)管件口徑分一般(ban)有等徑三(san)(san)通(tong)(tong)(tong)(tong)［圖16.25（a）］、異徑三(san)(san)通(tong)(tong)(tong)(tong)［圖16.25（b）］等。按(an)照(zhao)支管方(fang)向(xiang)分有正三(san)(san)通(tong)(tong)(tong)(tong)和斜三(san)(san)通(tong)(tong)(tong)(tong)（y形三(san)(san)通(tong)(tong)(tong)(tong)），斜三(san)(san)通(tong)(tong)(tong)(tong)常(chang)(chang)常(chang)(chang)代替一般(ban)正三(san)(san)通(tong)(tong)(tong)(tong)，用于輸送有固體顆粒或(huo)沖(chong)刷腐蝕較嚴(yan)重的管道上(shang)。按(an)照(zhao)材料分有碳鋼(gang)(gang)、合金鋼(gang)(gang)、不銹鋼(gang)(gang)、銅(tong)、PVC等三(san)(san)通(tong)(tong)(tong)(tong)。按(an)照(zhao)連接(jie)方(fang)式分有普(pu)通(tong)(tong)(tong)(tong)三(san)(san)通(tong)(tong)(tong)(tong)、螺紋三(san)(san)通(tong)(tong)(tong)(tong)、卡套三(san)(san)通(tong)(tong)(tong)(tong)、承插三(san)(san)通(tong)(tong)(tong)(tong)。

   ③. 三通(tong)接頭成形(xing)(xing)(xing)是將大于(yu)(yu)三通(tong)直(zhi)徑(jing)(jing)的(de)(de)管(guan)(guan)(guan)坯(pi)(pi)，壓扁(bian)至(zhi)約三通(tong)直(zhi)徑(jing)(jing)的(de)(de)尺寸，在(zai)拉(la)伸(shen)(shen)支(zhi)(zhi)管(guan)(guan)(guan)的(de)(de)部位開(kai)一個(ge)孔(kong)；管(guan)(guan)(guan)坯(pi)(pi)經加熱，放(fang)入成形(xing)(xing)(xing)模中(zhong)，并在(zai)管(guan)(guan)(guan)坯(pi)(pi)內裝入拉(la)伸(shen)(shen)支(zhi)(zhi)管(guan)(guan)(guan)的(de)(de)沖模；在(zai)壓力的(de)(de)作用(yong)(yong)下管(guan)(guan)(guan)坯(pi)(pi)被(bei)徑(jing)(jing)向(xiang)壓縮，在(zai)徑(jing)(jing)向(xiang)壓縮的(de)(de)過程(cheng)中(zhong)金(jin)屬(shu)向(xiang)支(zhi)(zhi)管(guan)(guan)(guan)方(fang)向(xiang)流動并在(zai)沖模的(de)(de)拉(la)伸(shen)(shen)下形(xing)(xing)(xing)成支(zhi)(zhi)管(guan)(guan)(guan)。整個(ge)過程(cheng)是通(tong)過管(guan)(guan)(guan)坯(pi)(pi)的(de)(de)徑(jing)(jing)向(xiang)壓縮和支(zhi)(zhi)管(guan)(guan)(guan)部位的(de)(de)拉(la)伸(shen)(shen)過程(cheng)而成形(xing)(xing)(xing)。與液壓脹形(xing)(xing)(xing)三通(tong)不同的(de)(de)是，三通(tong)接頭支(zhi)(zhi)管(guan)(guan)(guan)的(de)(de)金(jin)屬(shu)是由(you)管(guan)(guan)(guan)坯(pi)(pi)的(de)(de)徑(jing)(jing)向(xiang)運(yun)動進行(xing)補償的(de)(de)，所(suo)以也稱為(wei)徑(jing)(jing)向(xiang)補償工藝。由(you)于(yu)(yu)采(cai)用(yong)(yong)加熱后壓制三通(tong)，材料(liao)成形(xing)(xing)(xing)所(suo)需要的(de)(de)設備噸位降低。熱壓三通(tong)對材料(liao)的(de)(de)適(shi)應性較寬，適(shi)用(yong)(yong)于(yu)(yu)低碳鋼(gang)(gang)、合金(jin)鋼(gang)(gang)、不銹(xiu)鋼(gang)(gang)的(de)(de)材料(liao)，特別是大直(zhi)徑(jing)(jing)和管(guan)(guan)(guan)壁(bi)偏厚的(de)(de)三通(tong)，通(tong)常采(cai)用(yong)(yong)這種成形(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)三(san)通(tong)(tong)(tong)，首先給(gei)出(chu)最(zui)大(da)(da)端(duan)(duan)的(de)(de)(de)公(gong)(gong)稱通(tong)(tong)(tong)徑(jing)，然后(hou)是(shi)與(yu)(yu)最(zui)大(da)(da)端(duan)(duan)相對(dui)應(ying)的(de)(de)(de)那(nei)一(yi)端(duan)(duan)的(de)(de)(de)公(gong)(gong)稱通(tong)(tong)(tong)徑(jing)，最(zui)后(hou)給(gei)出(chu)支管端(duan)(duan)的(de)(de)(de)公(gong)(gong)稱通(tong)(tong)(tong)徑(jing)；對(dui)于異(yi)徑(jing)四通(tong)(tong)(tong)，首先給(gei)出(chu)最(zui)大(da)(da)端(duan)(duan)的(de)(de)(de)公(gong)(gong)稱通(tong)(tong)(tong)徑(jing)，其次(ci)是(shi)與(yu)(yu)最(zui)大(da)(da)端(duan)(duan)相對(dui)應(ying)的(de)(de)(de)另(ling)一(yi)端(duan)(duan)的(de)(de)(de)公(gong)(gong)稱通(tong)(tong)(tong)徑(jing)，第三(san)個給(gei)出(chu)的(de)(de)(de)是(shi)另(ling)外兩端(duan)(duan)中較(jiao)大(da)(da)端(duan)(duan)的(de)(de)(de)公(gong)(gong)稱通(tong)(tong)(tong)徑(jing)，最(zui)后(hou)給(gei)出(chu)剩余一(yi)端(duan)(duan)的(de)(de)(de)公(gong)(gong)稱通(tong)(tong)(tong)徑(jing)，見圖16.27。