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(lian)接件的選擇
a. 主要(yao)根(gen)據管道的(de)設計溫(wen)度、設計壓力、腐(fu)蝕余量(liang)等設計條(tiao)件確定的(de)。分(fen)支的(de)方法：對于低(di)壓大直(zhi)徑管則(ze)直(zhi)接把分(fen)支管焊于主管上，另外多(duo)數是利用(yong)分(fen)支管件進行分(fen)支。
b. 當(dang)從主(zhu)管(guan)(guan)引出支(zhi)管(guan)(guan)時(shi)，支(zhi)管(guan)(guan)直(zhi)徑(jing)與主(zhu)管(guan)(guan)直(zhi)徑(jing)的比值大(da)(da)于(yu)等(deng)于(yu)0.5時(shi)，采(cai)用異(yi)徑(jing)三(san)通(tong)或(huo)等(deng)徑(jing)三(san)通(tong)，當(dang)主(zhu)支(zhi)管(guan)(guan)為等(deng)徑(jing)時(shi)，應采(cai)用三(san)通(tong)。GB50316 規(gui)定(ding)：公稱壓力大(da)(da)于(yu)或(huo)等(deng)于(yu)10MPa的管(guan)(guan)道，主(zhu)支(zhi)管(guan)(guan)為異(yi)徑(jing)時(shi)，不宜采(cai)用焊(han)接支(zhi)管(guan)(guan)，宜采(cai)用三(san)通(tong)或(huo)在主(zhu)管(guan)(guan)上開孔并焊(han)接支(zhi)管(guan)(guan)臺。當(dang)主(zhu)管(guan)(guan)直(zhi)徑(jing)大(da)(da)于(yu)DN65而支(zhi)管(guan)(guan)直(zhi)徑(jing)為DN40及(ji)以(yi)下(xia)時(shi)，根據設計壓力的大(da)(da)小，采(cai)用支(zhi)管(guan)(guan)臺或(huo)半管(guan)(guan)接頭(tou)。
c. 主管(guan)(guan)(guan)(guan)(guan)(guan)直徑(jing)(jing)(jing)小(xiao)(xiao)(xiao)于(yu)DN50時(shi)，支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)小(xiao)(xiao)(xiao)于(yu)主管(guan)(guan)(guan)(guan)(guan)(guan)，則(ze)用(yong)(yong)異(yi)徑(jing)(jing)(jing)三(san)通(tong)(tong)(tong)或(huo)(huo)(huo)等(deng)(deng)(deng)徑(jing)(jing)(jing)三(san)通(tong)(tong)(tong)加異(yi)徑(jing)(jing)(jing)短管(guan)(guan)(guan)(guan)(guan)(guan)。設計壓(ya)力等(deng)(deng)(deng)于(yu)或(huo)(huo)(huo)大(da)(da)(da)于(yu)2.0MPa、設計溫度(du)超過(guo)250℃以及(ji)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)與(yu)主管(guan)(guan)(guan)(guan)(guan)(guan)公(gong)(gong)稱直徑(jing)(jing)(jing)之比大(da)(da)(da)于(yu)0.8，或(huo)(huo)(huo)承(cheng)受機械振動、壓(ya)力脈動和溫度(du)急劇變化(hua)的管(guan)(guan)(guan)(guan)(guan)(guan)道分支(zhi)(zhi)(zhi)，應采用(yong)(yong)等(deng)(deng)(deng)徑(jing)(jing)(jing)異(yi)徑(jing)(jing)(jing)三(san)通(tong)(tong)(tong)；公(gong)(gong)稱直徑(jing)(jing)(jing)小(xiao)(xiao)(xiao)于(yu)或(huo)(huo)(huo)等(deng)(deng)(deng)于(yu)40mm的管(guan)(guan)(guan)(guan)(guan)(guan)道，應采用(yong)(yong)承(cheng)插焊(han)(han)(han)(han)（或(huo)(huo)(huo)螺紋(wen)）鍛制三(san)通(tong)(tong)(tong)；公(gong)(gong)稱直徑(jing)(jing)(jing)等(deng)(deng)(deng)于(yu)或(huo)(huo)(huo)大(da)(da)(da)于(yu)50mm的管(guan)(guan)(guan)(guan)(guan)(guan)道，應采用(yong)(yong)對焊(han)(han)(han)(han)三(san)通(tong)(tong)(tong)、對焊(han)(han)(han)(han)加強(qiang)管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)（對焊(han)(han)(han)(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)臺）或(huo)(huo)(huo)嵌入式（鞍型）支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)。支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)通(tong)(tong)(tong)過(guo)加強(qiang)管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)（支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)臺）與(yu)主管(guan)(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)(jie)是指將一(yi)個(ge)螺紋(wen)、承(cheng)插焊(han)(han)(han)(han)或(huo)(huo)(huo)對焊(han)(han)(han)(han)的管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)或(huo)(huo)(huo)半(ban)管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)（支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)臺）直接(jie)(jie)(jie)焊(han)(han)(han)(han)于(yu)主管(guan)(guan)(guan)(guan)(guan)(guan)上而制成(cheng)，螺紋(wen)、承(cheng)插焊(han)(han)(han)(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)臺用(yong)(yong)于(yu)直徑(jing)(jing)(jing)小(xiao)(xiao)(xiao)于(yu)等(deng)(deng)(deng)于(yu)DN40（NPS1/2）的支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)(jie)。螺紋(wen)、承(cheng)插焊(han)(han)(han)(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)臺在任何(he)情況下其額定等(deng)(deng)(deng)級應大(da)(da)(da)于(yu)等(deng)(deng)(deng)于(yu)20001b。
d. 其他支管(guan)(guan)連(lian)接可用直(zhi)接焊(han)接，但必(bi)(bi)須經校核(he)后明確是否增加補(bu)強。直(zhi)接焊(han)接在(zai)(zai)主管(guan)(guan)上的(de)(de)支管(guan)(guan)連(lian)接，不宜用于(yu)有機械振動、壓力脈(mo)動和溫(wen)度(du)急劇變化的(de)(de)部位及(ji)設計溫(wen)度(du)超過425℃的(de)(de)管(guan)(guan)道，當支管(guan)(guan)連(lian)接處承受由(you)于(yu)支管(guan)(guan)熱變形、外載荷及(ji)支架位移等引起的(de)(de)應力時，應對附加載荷在(zai)(zai)支管(guan)(guan)連(lian)接處產生(sheng)的(de)(de)影響(xiang)進(jin)行分析并采取(qu)必(bi)(bi)要的(de)(de)加強措施。
e. 實際(ji)設計過程中，主要依據管(guan)(guan)(guan)(guan)(guan)道等(deng)級中已經確(que)定(ding)(ding)的(de)(de)法蘭(lan)壓力(li)等(deng)級或(huo)(huo)(huo)公稱壓力(li)（PN）來選用支管(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)件(jian)(jian)(jian)。一般情況下，當法蘭(lan)的(de)(de)公稱壓力(li)PN≤2.5MPa時(shi)，支管(guan)(guan)(guan)(guan)(guan)直接(jie)焊(han)(han)接(jie)在(zai)主管(guan)(guan)(guan)(guan)(guan)上；當PN≥4.0MPa時(shi)，則根(gen)據主管(guan)(guan)(guan)(guan)(guan)支管(guan)(guan)(guan)(guan)(guan)公稱直徑的(de)(de)不同按(an)對焊(han)(han)三(san)(san)通、對焊(han)(han)加強(qiang)管(guan)(guan)(guan)(guan)(guan)接(jie)頭(tou)、承(cheng)插(cha)焊(han)(han)或(huo)(huo)(huo)螺(luo)(luo)(luo)(luo)紋(wen)連(lian)接(jie)三(san)(san)通、承(cheng)插(cha)焊(han)(han)或(huo)(huo)(huo)螺(luo)(luo)(luo)(luo)紋(wen)加強(qiang)管(guan)(guan)(guan)(guan)(guan)接(jie)頭(tou)的(de)(de)順序選用。值得注意(yi)的(de)(de)是在(zai)確(que)定(ding)(ding)支管(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)件(jian)(jian)(jian)的(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表(biao)號時(shi)，應根(gen)據管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)與(yu)(yu)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)等(deng)強(qiang)度(du)的(de)(de)原則以(yi)及管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)與(yu)(yu)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)連(lian)接(jie)方式(shi)而(er)定(ding)(ding)。例如，當管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)與(yu)(yu)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)采(cai)用對焊(han)(han)連(lian)接(jie)時(shi)，管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)與(yu)(yu)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表(biao)號應一致；而(er)當管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)與(yu)(yu)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)采(cai)用承(cheng)插(cha)焊(han)(han)或(huo)(huo)(huo)螺(luo)(luo)(luo)(luo)紋(wen)連(lian)接(jie)時(shi)，標準的(de)(de)承(cheng)插(cha)焊(han)(han)和螺(luo)(luo)(luo)(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表(biao)號只(zhi)有Sch80、Sch60、XXS，最低的(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表(biao)號就(jiu)是Sch80，也就(jiu)是說只(zhi)要當承(cheng)插(cha)焊(han)(han)或(huo)(huo)(huo)螺(luo)(luo)(luo)(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)所連(lian)接(jie)的(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表(biao)號不大(da)于(yu)Sch80時(shi)，承(cheng)插(cha)焊(han)(han)或(huo)(huo)(huo)螺(luo)(luo)(luo)(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表(biao)號就(jiu)選Sch80。而(er)當所連(lian)接(jie)的(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表(biao)號大(da)于(yu)Sch80時(shi)，承(cheng)插(cha)焊(han)(han)或(huo)(huo)(huo)螺(luo)(luo)(luo)(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表(biao)號就(jiu)選Sch60或(huo)(huo)(huo)XXS。
f. 當對焊(han)三通主(zhu)管(guan)(guan)、支管(guan)(guan)所(suo)連(lian)(lian)接的管(guan)(guan)子(zi)(zi)的管(guan)(guan)子(zi)(zi)表(biao)號(hao)不(bu)同(tong)時，應(ying)注(zhu)意(yi)三通主(zhu)管(guan)(guan)、支管(guan)(guan)端部的管(guan)(guan)子(zi)(zi)表(biao)號(hao)應(ying)分別與其所(suo)連(lian)(lian)接的管(guan)(guan)子(zi)(zi)的管(guan)(guan)子(zi)(zi)表(biao)號(hao)相同(tong)，這樣就非(fei)常方便管(guan)(guan)道施工(gong)，管(guan)(guan)件不(bu)必現(xian)場(chang)再打(da)坡口。
③. 分(fen)支管與主管連接的(de)管件(jian)選擇(ze)見(jian)表(biao)16.71。
