①. 由于各國管件標準化程度不同，分支管連接方式及管件的選擇也不盡相同。一般情況下，支管連接多采用成形支管連接件、焊接的引出口連接件以及支管直接焊接在主管上等連接形式。值得注意的是選用支管直接焊接在主管上這一種連接形式，要核算管子是否需要補強。補強方法參見SH 3059《石油化工管道設計器材選用通則》、GB50316《工業金屬管道設計規范》的規定。
②. 支管連接件的選擇
a. 主要根據管(guan)道(dao)的設計溫(wen)度、設計壓(ya)力、腐蝕余(yu)量等設計條件確定(ding)的。分支的方法：對(dui)于低壓(ya)大(da)直徑管(guan)則直接(jie)把分支管(guan)焊于主管(guan)上，另外多(duo)數是利用(yong)分支管(guan)件進行(xing)分支。
b. 當從主(zhu)管(guan)(guan)(guan)引(yin)出(chu)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)時(shi)，支(zhi)(zhi)(zhi)管(guan)(guan)(guan)直(zhi)(zhi)(zhi)徑(jing)(jing)(jing)與主(zhu)管(guan)(guan)(guan)直(zhi)(zhi)(zhi)徑(jing)(jing)(jing)的(de)比值大于(yu)(yu)等(deng)于(yu)(yu)0.5時(shi)，采(cai)用異徑(jing)(jing)(jing)三通(tong)(tong)(tong)或(huo)(huo)等(deng)徑(jing)(jing)(jing)三通(tong)(tong)(tong)，當主(zhu)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)為等(deng)徑(jing)(jing)(jing)時(shi)，應采(cai)用三通(tong)(tong)(tong)。GB50316 規定：公稱壓力(li)大于(yu)(yu)或(huo)(huo)等(deng)于(yu)(yu)10MPa的(de)管(guan)(guan)(guan)道，主(zhu)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)為異徑(jing)(jing)(jing)時(shi)，不宜采(cai)用焊(han)接支(zhi)(zhi)(zhi)管(guan)(guan)(guan)，宜采(cai)用三通(tong)(tong)(tong)或(huo)(huo)在(zai)主(zhu)管(guan)(guan)(guan)上開孔并焊(han)接支(zhi)(zhi)(zhi)管(guan)(guan)(guan)臺。當主(zhu)管(guan)(guan)(guan)直(zhi)(zhi)(zhi)徑(jing)(jing)(jing)大于(yu)(yu)DN65而支(zhi)(zhi)(zhi)管(guan)(guan)(guan)直(zhi)(zhi)(zhi)徑(jing)(jing)(jing)為DN40及以下時(shi)，根據設計壓力(li)的(de)大小，采(cai)用支(zhi)(zhi)(zhi)管(guan)(guan)(guan)臺或(huo)(huo)半管(guan)(guan)(guan)接頭。
c. 主(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)直徑(jing)(jing)(jing)小(xiao)于(yu)(yu)(yu)DN50時，支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)小(xiao)于(yu)(yu)(yu)主(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)，則用(yong)(yong)(yong)異徑(jing)(jing)(jing)三(san)通(tong)或(huo)(huo)等(deng)徑(jing)(jing)(jing)三(san)通(tong)加(jia)異徑(jing)(jing)(jing)短管(guan)(guan)(guan)(guan)(guan)(guan)(guan)。設(she)計(ji)壓(ya)力(li)等(deng)于(yu)(yu)(yu)或(huo)(huo)大于(yu)(yu)(yu)2.0MPa、設(she)計(ji)溫(wen)度超過250℃以及支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)與主(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)公稱(cheng)直徑(jing)(jing)(jing)之比大于(yu)(yu)(yu)0.8，或(huo)(huo)承(cheng)受機械振(zhen)動、壓(ya)力(li)脈(mo)動和(he)溫(wen)度急劇變化(hua)的管(guan)(guan)(guan)(guan)(guan)(guan)(guan)道分(fen)支(zhi)(zhi)(zhi)，應(ying)采(cai)用(yong)(yong)(yong)等(deng)徑(jing)(jing)(jing)異徑(jing)(jing)(jing)三(san)通(tong)；公稱(cheng)直徑(jing)(jing)(jing)小(xiao)于(yu)(yu)(yu)或(huo)(huo)等(deng)于(yu)(yu)(yu)40mm的管(guan)(guan)(guan)(guan)(guan)(guan)(guan)道，應(ying)采(cai)用(yong)(yong)(yong)承(cheng)插(cha)焊(han)（或(huo)(huo)螺(luo)紋(wen)）鍛(duan)制(zhi)(zhi)三(san)通(tong)；公稱(cheng)直徑(jing)(jing)(jing)等(deng)于(yu)(yu)(yu)或(huo)(huo)大于(yu)(yu)(yu)50mm的管(guan)(guan)(guan)(guan)(guan)(guan)(guan)道，應(ying)采(cai)用(yong)(yong)(yong)對(dui)焊(han)三(san)通(tong)、對(dui)焊(han)加(jia)強(qiang)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭（對(dui)焊(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)）或(huo)(huo)嵌入式(shi)（鞍型）支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭。支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)通(tong)過加(jia)強(qiang)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭（支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)）與主(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)是指(zhi)將(jiang)一個螺(luo)紋(wen)、承(cheng)插(cha)焊(han)或(huo)(huo)對(dui)焊(han)的管(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭或(huo)(huo)半管(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭（支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)）直接(jie)(jie)焊(han)于(yu)(yu)(yu)主(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)上(shang)而制(zhi)(zhi)成，螺(luo)紋(wen)、承(cheng)插(cha)焊(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)用(yong)(yong)(yong)于(yu)(yu)(yu)直徑(jing)(jing)(jing)小(xiao)于(yu)(yu)(yu)等(deng)于(yu)(yu)(yu)DN40（NPS1/2）的支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)。螺(luo)紋(wen)、承(cheng)插(cha)焊(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)在任何(he)情況下其(qi)額定等(deng)級(ji)應(ying)大于(yu)(yu)(yu)等(deng)于(yu)(yu)(yu)20001b。
d. 其他支(zhi)(zhi)管(guan)連接(jie)(jie)(jie)(jie)可用直接(jie)(jie)(jie)(jie)焊接(jie)(jie)(jie)(jie)，但必(bi)須經校核(he)后明確是否增(zeng)加(jia)(jia)補(bu)強。直接(jie)(jie)(jie)(jie)焊接(jie)(jie)(jie)(jie)在主管(guan)上的(de)支(zhi)(zhi)管(guan)連接(jie)(jie)(jie)(jie)，不宜用于(yu)(yu)有機械振動(dong)、壓力脈動(dong)和溫(wen)度急劇(ju)變化的(de)部位及設(she)計溫(wen)度超過425℃的(de)管(guan)道，當支(zhi)(zhi)管(guan)連接(jie)(jie)(jie)(jie)處(chu)承受由(you)于(yu)(yu)支(zhi)(zhi)管(guan)熱變形、外載荷及支(zhi)(zhi)架(jia)位移等引起(qi)的(de)應力時(shi)，應對(dui)附加(jia)(jia)載荷在支(zhi)(zhi)管(guan)連接(jie)(jie)(jie)(jie)處(chu)產生的(de)影(ying)響進行(xing)分析(xi)并采取必(bi)要的(de)加(jia)(jia)強措施。
e. 實(shi)際設(she)計(ji)過程中(zhong)，主要(yao)依據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)道等級(ji)(ji)中(zhong)已經確定的(de)(de)(de)法蘭壓(ya)力等級(ji)(ji)或(huo)(huo)(huo)(huo)(huo)公稱(cheng)(cheng)壓(ya)力（PN）來選用(yong)支管(guan)(guan)(guan)(guan)(guan)(guan)連(lian)(lian)接(jie)件(jian)(jian)。一般情況下，當(dang)(dang)法蘭的(de)(de)(de)公稱(cheng)(cheng)壓(ya)力PN≤2.5MPa時(shi)，支管(guan)(guan)(guan)(guan)(guan)(guan)直接(jie)焊(han)(han)接(jie)在主管(guan)(guan)(guan)(guan)(guan)(guan)上；當(dang)(dang)PN≥4.0MPa時(shi)，則(ze)根據(ju)主管(guan)(guan)(guan)(guan)(guan)(guan)支管(guan)(guan)(guan)(guan)(guan)(guan)公稱(cheng)(cheng)直徑的(de)(de)(de)不(bu)(bu)同按對(dui)焊(han)(han)三通(tong)、對(dui)焊(han)(han)加(jia)強管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)頭、承(cheng)插(cha)焊(han)(han)或(huo)(huo)(huo)(huo)(huo)螺(luo)(luo)紋連(lian)(lian)接(jie)三通(tong)、承(cheng)插(cha)焊(han)(han)或(huo)(huo)(huo)(huo)(huo)螺(luo)(luo)紋加(jia)強管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)頭的(de)(de)(de)順序選用(yong)。值(zhi)得注意的(de)(de)(de)是(shi)(shi)在確定支管(guan)(guan)(guan)(guan)(guan)(guan)連(lian)(lian)接(jie)件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表號(hao)(hao)時(shi)，應根據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)等強度(du)的(de)(de)(de)原則(ze)以及(ji)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)連(lian)(lian)接(jie)方(fang)式(shi)而定。例如，當(dang)(dang)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)采用(yong)對(dui)焊(han)(han)連(lian)(lian)接(jie)時(shi)，管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表號(hao)(hao)應一致；而當(dang)(dang)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)采用(yong)承(cheng)插(cha)焊(han)(han)或(huo)(huo)(huo)(huo)(huo)螺(luo)(luo)紋連(lian)(lian)接(jie)時(shi)，標準的(de)(de)(de)承(cheng)插(cha)焊(han)(han)和螺(luo)(luo)紋管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表號(hao)(hao)只(zhi)有Sch80、Sch60、XXS，最低的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表號(hao)(hao)就(jiu)是(shi)(shi)Sch80，也(ye)就(jiu)是(shi)(shi)說只(zhi)要(yao)當(dang)(dang)承(cheng)插(cha)焊(han)(han)或(huo)(huo)(huo)(huo)(huo)螺(luo)(luo)紋管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)所(suo)連(lian)(lian)接(jie)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表號(hao)(hao)不(bu)(bu)大于(yu)Sch80時(shi)，承(cheng)插(cha)焊(han)(han)或(huo)(huo)(huo)(huo)(huo)螺(luo)(luo)紋管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表號(hao)(hao)就(jiu)選Sch80。而當(dang)(dang)所(suo)連(lian)(lian)接(jie)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表號(hao)(hao)大于(yu)Sch80時(shi)，承(cheng)插(cha)焊(han)(han)或(huo)(huo)(huo)(huo)(huo)螺(luo)(luo)紋管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表號(hao)(hao)就(jiu)選Sch60或(huo)(huo)(huo)(huo)(huo)XXS。
f. 當對焊(han)三通主管(guan)(guan)、支管(guan)(guan)所連接的(de)管(guan)(guan)子(zi)(zi)(zi)的(de)管(guan)(guan)子(zi)(zi)(zi)表號不同(tong)時，應注(zhu)意三通主管(guan)(guan)、支管(guan)(guan)端部的(de)管(guan)(guan)子(zi)(zi)(zi)表號應分別與其所連接的(de)管(guan)(guan)子(zi)(zi)(zi)的(de)管(guan)(guan)子(zi)(zi)(zi)表號相同(tong)，這樣就非(fei)常方(fang)便管(guan)(guan)道施(shi)工(gong)，管(guan)(guan)件不必(bi)現場(chang)再(zai)打(da)坡口(kou)。
③. 分(fen)支管(guan)與主管(guan)連接的(de)管(guan)件(jian)選(xuan)擇見表16.71。
