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(zhi)管連接件的選擇
a. 主要(yao)根據管(guan)道的(de)設計(ji)溫度、設計(ji)壓力、腐(fu)蝕余量等設計(ji)條件(jian)確定的(de)。分支的(de)方法：對于(yu)低(di)壓大直(zhi)徑管(guan)則直(zhi)接把分支管(guan)焊于(yu)主管(guan)上，另外(wai)多數是利用分支管(guan)件(jian)進行分支。
b. 當從(cong)主管(guan)(guan)引出支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)時(shi)(shi)(shi)，支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)直(zhi)徑(jing)(jing)與主管(guan)(guan)直(zhi)徑(jing)(jing)的比值大于(yu)等(deng)于(yu)0.5時(shi)(shi)(shi)，采(cai)(cai)用(yong)(yong)異徑(jing)(jing)三通(tong)或(huo)等(deng)徑(jing)(jing)三通(tong)，當主支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)為(wei)等(deng)徑(jing)(jing)時(shi)(shi)(shi)，應(ying)采(cai)(cai)用(yong)(yong)三通(tong)。GB50316 規(gui)定：公(gong)稱(cheng)壓力大于(yu)或(huo)等(deng)于(yu)10MPa的管(guan)(guan)道(dao)，主支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)為(wei)異徑(jing)(jing)時(shi)(shi)(shi)，不宜采(cai)(cai)用(yong)(yong)焊接(jie)支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)，宜采(cai)(cai)用(yong)(yong)三通(tong)或(huo)在(zai)主管(guan)(guan)上開孔(kong)并(bing)焊接(jie)支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)臺(tai)。當主管(guan)(guan)直(zhi)徑(jing)(jing)大于(yu)DN65而支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)直(zhi)徑(jing)(jing)為(wei)DN40及以下時(shi)(shi)(shi)，根(gen)據設(she)計壓力的大小，采(cai)(cai)用(yong)(yong)支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)臺(tai)或(huo)半管(guan)(guan)接(jie)頭。
c. 主管(guan)(guan)(guan)(guan)(guan)(guan)直(zhi)(zhi)徑(jing)(jing)小于(yu)(yu)DN50時，支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)小于(yu)(yu)主管(guan)(guan)(guan)(guan)(guan)(guan)，則用(yong)(yong)異(yi)徑(jing)(jing)三(san)(san)通或(huo)(huo)(huo)等徑(jing)(jing)三(san)(san)通加(jia)異(yi)徑(jing)(jing)短管(guan)(guan)(guan)(guan)(guan)(guan)。設計(ji)壓力(li)等于(yu)(yu)或(huo)(huo)(huo)大于(yu)(yu)2.0MPa、設計(ji)溫度超(chao)過250℃以及支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)與(yu)主管(guan)(guan)(guan)(guan)(guan)(guan)公稱直(zhi)(zhi)徑(jing)(jing)之比大于(yu)(yu)0.8，或(huo)(huo)(huo)承受(shou)機械振動、壓力(li)脈(mo)動和溫度急劇變化的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)道分支(zhi)(zhi)(zhi)，應(ying)(ying)采(cai)用(yong)(yong)等徑(jing)(jing)異(yi)徑(jing)(jing)三(san)(san)通；公稱直(zhi)(zhi)徑(jing)(jing)小于(yu)(yu)或(huo)(huo)(huo)等于(yu)(yu)40mm的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)道，應(ying)(ying)采(cai)用(yong)(yong)承插焊(han)（或(huo)(huo)(huo)螺(luo)(luo)紋）鍛制三(san)(san)通；公稱直(zhi)(zhi)徑(jing)(jing)等于(yu)(yu)或(huo)(huo)(huo)大于(yu)(yu)50mm的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)道，應(ying)(ying)采(cai)用(yong)(yong)對焊(han)三(san)(san)通、對焊(han)加(jia)強管(guan)(guan)(guan)(guan)(guan)(guan)接頭（對焊(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)）或(huo)(huo)(huo)嵌(qian)入式（鞍(an)型）支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)接頭。支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)通過加(jia)強管(guan)(guan)(guan)(guan)(guan)(guan)接頭（支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)）與(yu)主管(guan)(guan)(guan)(guan)(guan)(guan)連接是指將(jiang)一(yi)個螺(luo)(luo)紋、承插焊(han)或(huo)(huo)(huo)對焊(han)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)接頭或(huo)(huo)(huo)半(ban)管(guan)(guan)(guan)(guan)(guan)(guan)接頭（支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)）直(zhi)(zhi)接焊(han)于(yu)(yu)主管(guan)(guan)(guan)(guan)(guan)(guan)上而制成，螺(luo)(luo)紋、承插焊(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)用(yong)(yong)于(yu)(yu)直(zhi)(zhi)徑(jing)(jing)小于(yu)(yu)等于(yu)(yu)DN40（NPS1/2）的(de)(de)(de)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)連接。螺(luo)(luo)紋、承插焊(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)在任何(he)情況下其額定等級應(ying)(ying)大于(yu)(yu)等于(yu)(yu)20001b。
d. 其(qi)他支管連(lian)接(jie)(jie)(jie)可用(yong)直(zhi)接(jie)(jie)(jie)焊接(jie)(jie)(jie)，但(dan)必須(xu)經校核后明確是否增加(jia)補強。直(zhi)接(jie)(jie)(jie)焊接(jie)(jie)(jie)在主管上的(de)(de)支管連(lian)接(jie)(jie)(jie)，不宜用(yong)于有機械振(zhen)動、壓(ya)力脈動和溫度(du)急劇變(bian)化的(de)(de)部位及(ji)設計溫度(du)超過425℃的(de)(de)管道，當支管連(lian)接(jie)(jie)(jie)處承受由于支管熱變(bian)形、外載荷及(ji)支架位移等引起的(de)(de)應力時，應對附加(jia)載荷在支管連(lian)接(jie)(jie)(jie)處產生的(de)(de)影響進(jin)行分析并采取必要(yao)的(de)(de)加(jia)強措施。
e. 實際設計過程(cheng)中(zhong)，主要依據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)道等(deng)級中(zhong)已經確定的(de)(de)(de)法蘭(lan)(lan)壓(ya)(ya)力(li)等(deng)級或公稱壓(ya)(ya)力(li)（PN）來(lai)選用支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)(jie)件(jian)(jian)。一般情況下，當(dang)法蘭(lan)(lan)的(de)(de)(de)公稱壓(ya)(ya)力(li)PN≤2.5MPa時(shi)(shi)(shi)，支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)直接(jie)(jie)(jie)焊接(jie)(jie)(jie)在主管(guan)(guan)(guan)(guan)(guan)(guan)上；當(dang)PN≥4.0MPa時(shi)(shi)(shi)，則根據(ju)主管(guan)(guan)(guan)(guan)(guan)(guan)支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)公稱直徑的(de)(de)(de)不同按對(dui)焊三通、對(dui)焊加強(qiang)管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)、承(cheng)(cheng)(cheng)插(cha)焊或螺(luo)紋(wen)(wen)(wen)連(lian)接(jie)(jie)(jie)三通、承(cheng)(cheng)(cheng)插(cha)焊或螺(luo)紋(wen)(wen)(wen)加強(qiang)管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)的(de)(de)(de)順序選用。值得注意的(de)(de)(de)是在確定支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)(jie)件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)(hao)(hao)時(shi)(shi)(shi)，應根據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)等(deng)強(qiang)度的(de)(de)(de)原(yuan)則以及(ji)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)連(lian)接(jie)(jie)(jie)方式而(er)定。例如(ru)，當(dang)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)采(cai)用對(dui)焊連(lian)接(jie)(jie)(jie)時(shi)(shi)(shi)，管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(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)(zi)(zi)(zi)表號(hao)(hao)(hao)(hao)應一致；而(er)當(dang)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)采(cai)用承(cheng)(cheng)(cheng)插(cha)焊或螺(luo)紋(wen)(wen)(wen)連(lian)接(jie)(jie)(jie)時(shi)(shi)(shi)，標(biao)準(zhun)的(de)(de)(de)承(cheng)(cheng)(cheng)插(cha)焊和螺(luo)紋(wen)(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)(hao)(hao)只有Sch80、Sch60、XXS，最低的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)(hao)(hao)就(jiu)是Sch80，也就(jiu)是說只要當(dang)承(cheng)(cheng)(cheng)插(cha)焊或螺(luo)紋(wen)(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)所連(lian)接(jie)(jie)(jie)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)(hao)(hao)不大(da)于(yu)(yu)Sch80時(shi)(shi)(shi)，承(cheng)(cheng)(cheng)插(cha)焊或螺(luo)紋(wen)(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)(hao)(hao)就(jiu)選Sch80。而(er)當(dang)所連(lian)接(jie)(jie)(jie)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)(hao)(hao)大(da)于(yu)(yu)Sch80時(shi)(shi)(shi)，承(cheng)(cheng)(cheng)插(cha)焊或螺(luo)紋(wen)(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)(hao)(hao)就(jiu)選Sch60或XXS。
f. 當對焊三(san)通主管(guan)(guan)、支(zhi)管(guan)(guan)所(suo)連接的(de)管(guan)(guan)子(zi)的(de)管(guan)(guan)子(zi)表(biao)號不同時，應注意三(san)通主管(guan)(guan)、支(zhi)管(guan)(guan)端部(bu)的(de)管(guan)(guan)子(zi)表(biao)號應分別與其所(suo)連接的(de)管(guan)(guan)子(zi)的(de)管(guan)(guan)子(zi)表(biao)號相同，這樣就非常方便管(guan)(guan)道施工(gong)，管(guan)(guan)件不必現場再(zai)打(da)坡口。
③. 分支管與主(zhu)管連接的管件選擇見表(biao)16.71。
