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(guan)連接件的選擇
a. 主要(yao)根據管道的(de)設(she)計溫度、設(she)計壓力、腐蝕余量等設(she)計條件確定的(de)。分(fen)支的(de)方(fang)法：對于低(di)壓大直徑管則直接(jie)把分(fen)支管焊于主管上，另外多數是利用分(fen)支管件進行分(fen)支。
b. 當從主(zhu)管(guan)(guan)(guan)(guan)(guan)引出(chu)支(zhi)管(guan)(guan)(guan)(guan)(guan)時，支(zhi)管(guan)(guan)(guan)(guan)(guan)直(zhi)(zhi)徑(jing)(jing)(jing)(jing)與主(zhu)管(guan)(guan)(guan)(guan)(guan)直(zhi)(zhi)徑(jing)(jing)(jing)(jing)的比(bi)值(zhi)大(da)(da)于(yu)等于(yu)0.5時，采(cai)用(yong)(yong)(yong)異(yi)徑(jing)(jing)(jing)(jing)三通或等徑(jing)(jing)(jing)(jing)三通，當主(zhu)支(zhi)管(guan)(guan)(guan)(guan)(guan)為等徑(jing)(jing)(jing)(jing)時，應采(cai)用(yong)(yong)(yong)三通。GB50316 規定：公稱壓力大(da)(da)于(yu)或等于(yu)10MPa的管(guan)(guan)(guan)(guan)(guan)道(dao)，主(zhu)支(zhi)管(guan)(guan)(guan)(guan)(guan)為異(yi)徑(jing)(jing)(jing)(jing)時，不宜采(cai)用(yong)(yong)(yong)焊接支(zhi)管(guan)(guan)(guan)(guan)(guan)，宜采(cai)用(yong)(yong)(yong)三通或在主(zhu)管(guan)(guan)(guan)(guan)(guan)上開孔并焊接支(zhi)管(guan)(guan)(guan)(guan)(guan)臺。當主(zhu)管(guan)(guan)(guan)(guan)(guan)直(zhi)(zhi)徑(jing)(jing)(jing)(jing)大(da)(da)于(yu)DN65而支(zhi)管(guan)(guan)(guan)(guan)(guan)直(zhi)(zhi)徑(jing)(jing)(jing)(jing)為DN40及以下(xia)時，根據設計壓力的大(da)(da)小，采(cai)用(yong)(yong)(yong)支(zhi)管(guan)(guan)(guan)(guan)(guan)臺或半管(guan)(guan)(guan)(guan)(guan)接頭。
c. 主管(guan)(guan)(guan)(guan)直(zhi)徑(jing)(jing)(jing)(jing)(jing)小于(yu)(yu)(yu)DN50時，支(zhi)管(guan)(guan)(guan)(guan)小于(yu)(yu)(yu)主管(guan)(guan)(guan)(guan)，則用(yong)異(yi)徑(jing)(jing)(jing)(jing)(jing)三通或(huo)(huo)等(deng)徑(jing)(jing)(jing)(jing)(jing)三通加異(yi)徑(jing)(jing)(jing)(jing)(jing)短管(guan)(guan)(guan)(guan)。設(she)計(ji)壓(ya)力(li)等(deng)于(yu)(yu)(yu)或(huo)(huo)大(da)于(yu)(yu)(yu)2.0MPa、設(she)計(ji)溫度超過250℃以及支(zhi)管(guan)(guan)(guan)(guan)與主管(guan)(guan)(guan)(guan)公(gong)稱直(zhi)徑(jing)(jing)(jing)(jing)(jing)之(zhi)比(bi)大(da)于(yu)(yu)(yu)0.8，或(huo)(huo)承(cheng)受機械振動、壓(ya)力(li)脈(mo)動和溫度急劇變化的(de)(de)管(guan)(guan)(guan)(guan)道分支(zhi)，應采(cai)(cai)用(yong)等(deng)徑(jing)(jing)(jing)(jing)(jing)異(yi)徑(jing)(jing)(jing)(jing)(jing)三通；公(gong)稱直(zhi)徑(jing)(jing)(jing)(jing)(jing)小于(yu)(yu)(yu)或(huo)(huo)等(deng)于(yu)(yu)(yu)40mm的(de)(de)管(guan)(guan)(guan)(guan)道，應采(cai)(cai)用(yong)承(cheng)插焊(han)(han)(han)（或(huo)(huo)螺(luo)紋(wen)）鍛制三通；公(gong)稱直(zhi)徑(jing)(jing)(jing)(jing)(jing)等(deng)于(yu)(yu)(yu)或(huo)(huo)大(da)于(yu)(yu)(yu)50mm的(de)(de)管(guan)(guan)(guan)(guan)道，應采(cai)(cai)用(yong)對(dui)(dui)焊(han)(han)(han)三通、對(dui)(dui)焊(han)(han)(han)加強管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)（對(dui)(dui)焊(han)(han)(han)支(zhi)管(guan)(guan)(guan)(guan)臺(tai)）或(huo)(huo)嵌入式(shi)（鞍型）支(zhi)管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)。支(zhi)管(guan)(guan)(guan)(guan)通過加強管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)（支(zhi)管(guan)(guan)(guan)(guan)臺(tai)）與主管(guan)(guan)(guan)(guan)連(lian)接(jie)是指將一(yi)個螺(luo)紋(wen)、承(cheng)插焊(han)(han)(han)或(huo)(huo)對(dui)(dui)焊(han)(han)(han)的(de)(de)管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)或(huo)(huo)半管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)（支(zhi)管(guan)(guan)(guan)(guan)臺(tai)）直(zhi)接(jie)焊(han)(han)(han)于(yu)(yu)(yu)主管(guan)(guan)(guan)(guan)上(shang)而制成，螺(luo)紋(wen)、承(cheng)插焊(han)(han)(han)支(zhi)管(guan)(guan)(guan)(guan)臺(tai)用(yong)于(yu)(yu)(yu)直(zhi)徑(jing)(jing)(jing)(jing)(jing)小于(yu)(yu)(yu)等(deng)于(yu)(yu)(yu)DN40（NPS1/2）的(de)(de)支(zhi)管(guan)(guan)(guan)(guan)連(lian)接(jie)。螺(luo)紋(wen)、承(cheng)插焊(han)(han)(han)支(zhi)管(guan)(guan)(guan)(guan)臺(tai)在任何情況下(xia)其額(e)定等(deng)級應大(da)于(yu)(yu)(yu)等(deng)于(yu)(yu)(yu)20001b。
d. 其他支(zhi)(zhi)管(guan)連(lian)接(jie)可用直接(jie)焊(han)接(jie)，但必(bi)須經校核后明確是(shi)否(fou)增加補強。直接(jie)焊(han)接(jie)在(zai)(zai)主(zhu)管(guan)上(shang)的(de)(de)(de)支(zhi)(zhi)管(guan)連(lian)接(jie)，不宜用于有機械振動、壓力(li)脈動和溫度急劇(ju)變化的(de)(de)(de)部位(wei)及(ji)設計溫度超過425℃的(de)(de)(de)管(guan)道，當(dang)支(zhi)(zhi)管(guan)連(lian)接(jie)處承受(shou)由于支(zhi)(zhi)管(guan)熱變形(xing)、外載荷及(ji)支(zhi)(zhi)架位(wei)移等引起的(de)(de)(de)應(ying)力(li)時，應(ying)對附(fu)加載荷在(zai)(zai)支(zhi)(zhi)管(guan)連(lian)接(jie)處產生(sheng)的(de)(de)(de)影(ying)響進行分析并(bing)采(cai)取必(bi)要(yao)的(de)(de)(de)加強措施(shi)。
e. 實際(ji)設計(ji)過程中，主要依據(ju)管(guan)(guan)(guan)(guan)(guan)道等級(ji)中已經確定的(de)法蘭(lan)壓力等級(ji)或(huo)公稱壓力（PN）來選用(yong)(yong)支管(guan)(guan)(guan)(guan)(guan)連(lian)(lian)接(jie)(jie)件(jian)(jian)(jian)。一般情況(kuang)下(xia)，當(dang)(dang)法蘭(lan)的(de)公稱壓力PN≤2.5MPa時(shi)(shi)(shi)，支管(guan)(guan)(guan)(guan)(guan)直接(jie)(jie)焊(han)(han)接(jie)(jie)在主管(guan)(guan)(guan)(guan)(guan)上；當(dang)(dang)PN≥4.0MPa時(shi)(shi)(shi)，則根(gen)據(ju)主管(guan)(guan)(guan)(guan)(guan)支管(guan)(guan)(guan)(guan)(guan)公稱直徑的(de)不同(tong)按對(dui)(dui)焊(han)(han)三通(tong)、對(dui)(dui)焊(han)(han)加強(qiang)(qiang)(qiang)管(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭、承插(cha)焊(han)(han)或(huo)螺(luo)(luo)紋(wen)(wen)連(lian)(lian)接(jie)(jie)三通(tong)、承插(cha)焊(han)(han)或(huo)螺(luo)(luo)紋(wen)(wen)加強(qiang)(qiang)(qiang)管(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭的(de)順序選用(yong)(yong)。值(zhi)得注意的(de)是在確定支管(guan)(guan)(guan)(guan)(guan)連(lian)(lian)接(jie)(jie)件(jian)(jian)(jian)的(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表號(hao)時(shi)(shi)(shi)，應(ying)根(gen)據(ju)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)等強(qiang)(qiang)(qiang)度(du)的(de)原(yuan)則以及管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)與管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)連(lian)(lian)接(jie)(jie)方式而定。例如(ru)，當(dang)(dang)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)采用(yong)(yong)對(dui)(dui)焊(han)(han)連(lian)(lian)接(jie)(jie)時(shi)(shi)(shi)，管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表號(hao)應(ying)一致；而當(dang)(dang)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)采用(yong)(yong)承插(cha)焊(han)(han)或(huo)螺(luo)(luo)紋(wen)(wen)連(lian)(lian)接(jie)(jie)時(shi)(shi)(shi)，標(biao)準的(de)承插(cha)焊(han)(han)和(he)螺(luo)(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表號(hao)只有Sch80、Sch60、XXS，最低的(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表號(hao)就(jiu)是Sch80，也就(jiu)是說只要當(dang)(dang)承插(cha)焊(han)(han)或(huo)螺(luo)(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)所(suo)連(lian)(lian)接(jie)(jie)的(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表號(hao)不大(da)(da)于(yu)Sch80時(shi)(shi)(shi)，承插(cha)焊(han)(han)或(huo)螺(luo)(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表號(hao)就(jiu)選Sch80。而當(dang)(dang)所(suo)連(lian)(lian)接(jie)(jie)的(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表號(hao)大(da)(da)于(yu)Sch80時(shi)(shi)(shi)，承插(cha)焊(han)(han)或(huo)螺(luo)(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表號(hao)就(jiu)選Sch60或(huo)XXS。
f. 當對焊三通主管(guan)(guan)(guan)(guan)、支(zhi)管(guan)(guan)(guan)(guan)所(suo)連接的(de)管(guan)(guan)(guan)(guan)子(zi)的(de)管(guan)(guan)(guan)(guan)子(zi)表(biao)(biao)號不同時，應(ying)注意(yi)三通主管(guan)(guan)(guan)(guan)、支(zhi)管(guan)(guan)(guan)(guan)端部的(de)管(guan)(guan)(guan)(guan)子(zi)表(biao)(biao)號應(ying)分別與其所(suo)連接的(de)管(guan)(guan)(guan)(guan)子(zi)的(de)管(guan)(guan)(guan)(guan)子(zi)表(biao)(biao)號相(xiang)同，這樣就非常(chang)方便管(guan)(guan)(guan)(guan)道施(shi)工，管(guan)(guan)(guan)(guan)件不必現場(chang)再打(da)坡(po)口。
③. 分支管與主管連(lian)接的管件(jian)選擇(ze)見表(biao)16.71。
