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)按照管(guan)(guan)件口徑分一般(ban)有等(deng)徑三(san)(san)通(tong)(tong)(tong)［圖16.25（a）］、異(yi)徑三(san)(san)通(tong)(tong)(tong)［圖16.25（b）］等(deng)。按照支管(guan)(guan)方向分有正(zheng)三(san)(san)通(tong)(tong)(tong)和斜三(san)(san)通(tong)(tong)(tong)（y形三(san)(san)通(tong)(tong)(tong)），斜三(san)(san)通(tong)(tong)(tong)常常代(dai)替(ti)一般(ban)正(zheng)三(san)(san)通(tong)(tong)(tong)，用于輸送(song)有固體(ti)顆粒或沖刷腐(fu)蝕較(jiao)嚴重的管(guan)(guan)道上。按照材(cai)料(liao)分有碳鋼(gang)(gang)(gang)、合(he)金(jin)鋼(gang)(gang)(gang)、不(bu)銹(xiu)鋼(gang)(gang)(gang)、銅、PVC等(deng)三(san)(san)通(tong)(tong)(tong)。按照連接方式(shi)分有普通(tong)(tong)(tong)三(san)(san)通(tong)(tong)(tong)、螺紋(wen)三(san)(san)通(tong)(tong)(tong)、卡套(tao)三(san)(san)通(tong)(tong)(tong)、承插三(san)(san)通(tong)(tong)(tong)。

   ③. 三(san)(san)通(tong)(tong)(tong)(tong)接頭(tou)成(cheng)(cheng)形(xing)是將大(da)于三(san)(san)通(tong)(tong)(tong)(tong)直徑的(de)(de)(de)(de)管(guan)(guan)坯(pi)，壓(ya)(ya)(ya)(ya)扁(bian)至約三(san)(san)通(tong)(tong)(tong)(tong)直徑的(de)(de)(de)(de)尺寸，在拉(la)伸(shen)(shen)支管(guan)(guan)的(de)(de)(de)(de)部(bu)位開一個(ge)孔；管(guan)(guan)坯(pi)經加熱，放(fang)入成(cheng)(cheng)形(xing)模中，并在管(guan)(guan)坯(pi)內裝入拉(la)伸(shen)(shen)支管(guan)(guan)的(de)(de)(de)(de)沖模；在壓(ya)(ya)(ya)(ya)力(li)的(de)(de)(de)(de)作用(yong)下管(guan)(guan)坯(pi)被(bei)徑向(xiang)壓(ya)(ya)(ya)(ya)縮(suo)，在徑向(xiang)壓(ya)(ya)(ya)(ya)縮(suo)的(de)(de)(de)(de)過程中金(jin)屬(shu)(shu)向(xiang)支管(guan)(guan)方向(xiang)流動并在沖模的(de)(de)(de)(de)拉(la)伸(shen)(shen)下形(xing)成(cheng)(cheng)支管(guan)(guan)。整個(ge)過程是通(tong)(tong)(tong)(tong)過管(guan)(guan)坯(pi)的(de)(de)(de)(de)徑向(xiang)壓(ya)(ya)(ya)(ya)縮(suo)和支管(guan)(guan)部(bu)位的(de)(de)(de)(de)拉(la)伸(shen)(shen)過程而成(cheng)(cheng)形(xing)。與液壓(ya)(ya)(ya)(ya)脹形(xing)三(san)(san)通(tong)(tong)(tong)(tong)不同的(de)(de)(de)(de)是，三(san)(san)通(tong)(tong)(tong)(tong)接頭(tou)支管(guan)(guan)的(de)(de)(de)(de)金(jin)屬(shu)(shu)是由管(guan)(guan)坯(pi)的(de)(de)(de)(de)徑向(xiang)運動進行補(bu)償的(de)(de)(de)(de)，所以也稱為徑向(xiang)補(bu)償工藝。由于采用(yong)加熱后壓(ya)(ya)(ya)(ya)制三(san)(san)通(tong)(tong)(tong)(tong)，材料(liao)成(cheng)(cheng)形(xing)所需要的(de)(de)(de)(de)設備噸(dun)位降低。熱壓(ya)(ya)(ya)(ya)三(san)(san)通(tong)(tong)(tong)(tong)對(dui)材料(liao)的(de)(de)(de)(de)適應性(xing)較寬(kuan)，適用(yong)于低碳鋼、合金(jin)鋼、不銹(xiu)鋼的(de)(de)(de)(de)材料(liao)，特別是大(da)直徑和管(guan)(guan)壁偏厚的(de)(de)(de)(de)三(san)(san)通(tong)(tong)(tong)(tong)，通(tong)(tong)(tong)(tong)常采用(yong)這種成(cheng)(cheng)形(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(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(dui)于異(yi)徑(jing)(jing)(jing)三(san)通(tong)，首先給出(chu)(chu)最(zui)大(da)端(duan)的(de)公稱(cheng)通(tong)徑(jing)(jing)(jing)，然后是與(yu)最(zui)大(da)端(duan)相(xiang)(xiang)對(dui)應(ying)的(de)那一端(duan)的(de)公稱(cheng)通(tong)徑(jing)(jing)(jing)，最(zui)后給出(chu)(chu)支管端(duan)的(de)公稱(cheng)通(tong)徑(jing)(jing)(jing)；對(dui)于異(yi)徑(jing)(jing)(jing)四通(tong)，首先給出(chu)(chu)最(zui)大(da)端(duan)的(de)公稱(cheng)通(tong)徑(jing)(jing)(jing)，其次是與(yu)最(zui)大(da)端(duan)相(xiang)(xiang)對(dui)應(ying)的(de)另(ling)一端(duan)的(de)公稱(cheng)通(tong)徑(jing)(jing)(jing)，第三(san)個給出(chu)(chu)的(de)是另(ling)外兩端(duan)中較大(da)端(duan)的(de)公稱(cheng)通(tong)徑(jing)(jing)(jing)，最(zui)后給出(chu)(chu)剩余一端(duan)的(de)公稱(cheng)通(tong)徑(jing)(jing)(jing)，見圖(tu)16.27。