①. 由于各國管件(jian)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(jie)件的選擇
a. 主要(yao)根據(ju)管(guan)道的設(she)計(ji)溫度、設(she)計(ji)壓(ya)(ya)力、腐蝕余量等(deng)設(she)計(ji)條件(jian)確定的。分支(zhi)(zhi)的方法：對于低壓(ya)(ya)大直(zhi)徑管(guan)則直(zhi)接(jie)把(ba)分支(zhi)(zhi)管(guan)焊(han)于主管(guan)上，另(ling)外多(duo)數是利用分支(zhi)(zhi)管(guan)件(jian)進(jin)行分支(zhi)(zhi)。
b. 當(dang)(dang)從主(zhu)(zhu)管(guan)(guan)引出(chu)支(zhi)(zhi)(zhi)管(guan)(guan)時(shi)，支(zhi)(zhi)(zhi)管(guan)(guan)直(zhi)徑(jing)與主(zhu)(zhu)管(guan)(guan)直(zhi)徑(jing)的比(bi)值大(da)于等(deng)于0.5時(shi)，采用異徑(jing)三(san)(san)通或(huo)等(deng)徑(jing)三(san)(san)通，當(dang)(dang)主(zhu)(zhu)支(zhi)(zhi)(zhi)管(guan)(guan)為等(deng)徑(jing)時(shi)，應采用三(san)(san)通。GB50316 規定：公稱壓(ya)力(li)大(da)于或(huo)等(deng)于10MPa的管(guan)(guan)道，主(zhu)(zhu)支(zhi)(zhi)(zhi)管(guan)(guan)為異徑(jing)時(shi)，不宜采用焊接(jie)支(zhi)(zhi)(zhi)管(guan)(guan)，宜采用三(san)(san)通或(huo)在主(zhu)(zhu)管(guan)(guan)上開孔并焊接(jie)支(zhi)(zhi)(zhi)管(guan)(guan)臺。當(dang)(dang)主(zhu)(zhu)管(guan)(guan)直(zhi)徑(jing)大(da)于DN65而支(zhi)(zhi)(zhi)管(guan)(guan)直(zhi)徑(jing)為DN40及以下時(shi)，根據設計壓(ya)力(li)的大(da)小，采用支(zhi)(zhi)(zhi)管(guan)(guan)臺或(huo)半管(guan)(guan)接(jie)頭(tou)。
c. 主管(guan)(guan)(guan)(guan)(guan)直(zhi)徑小(xiao)(xiao)于(yu)(yu)DN50時，支管(guan)(guan)(guan)(guan)(guan)小(xiao)(xiao)于(yu)(yu)主管(guan)(guan)(guan)(guan)(guan)，則(ze)用(yong)異徑三(san)(san)(san)通(tong)或等(deng)(deng)徑三(san)(san)(san)通(tong)加異徑短(duan)管(guan)(guan)(guan)(guan)(guan)。設計(ji)壓力(li)(li)等(deng)(deng)于(yu)(yu)或大于(yu)(yu)2.0MPa、設計(ji)溫度(du)超過250℃以及支管(guan)(guan)(guan)(guan)(guan)與(yu)主管(guan)(guan)(guan)(guan)(guan)公(gong)(gong)稱(cheng)直(zhi)徑之比(bi)大于(yu)(yu)0.8，或承(cheng)受機械(xie)振動(dong)、壓力(li)(li)脈動(dong)和溫度(du)急劇(ju)變化的(de)管(guan)(guan)(guan)(guan)(guan)道分支，應(ying)采用(yong)等(deng)(deng)徑異徑三(san)(san)(san)通(tong)；公(gong)(gong)稱(cheng)直(zhi)徑小(xiao)(xiao)于(yu)(yu)或等(deng)(deng)于(yu)(yu)40mm的(de)管(guan)(guan)(guan)(guan)(guan)道，應(ying)采用(yong)承(cheng)插焊（或螺(luo)紋(wen)(wen)）鍛制三(san)(san)(san)通(tong)；公(gong)(gong)稱(cheng)直(zhi)徑等(deng)(deng)于(yu)(yu)或大于(yu)(yu)50mm的(de)管(guan)(guan)(guan)(guan)(guan)道，應(ying)采用(yong)對焊三(san)(san)(san)通(tong)、對焊加強管(guan)(guan)(guan)(guan)(guan)接(jie)頭(tou)（對焊支管(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)）或嵌入式（鞍型）支管(guan)(guan)(guan)(guan)(guan)接(jie)頭(tou)。支管(guan)(guan)(guan)(guan)(guan)通(tong)過加強管(guan)(guan)(guan)(guan)(guan)接(jie)頭(tou)（支管(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)）與(yu)主管(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)是(shi)指將(jiang)一(yi)個(ge)螺(luo)紋(wen)(wen)、承(cheng)插焊或對焊的(de)管(guan)(guan)(guan)(guan)(guan)接(jie)頭(tou)或半管(guan)(guan)(guan)(guan)(guan)接(jie)頭(tou)（支管(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)）直(zhi)接(jie)焊于(yu)(yu)主管(guan)(guan)(guan)(guan)(guan)上而制成，螺(luo)紋(wen)(wen)、承(cheng)插焊支管(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)用(yong)于(yu)(yu)直(zhi)徑小(xiao)(xiao)于(yu)(yu)等(deng)(deng)于(yu)(yu)DN40（NPS1/2）的(de)支管(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)。螺(luo)紋(wen)(wen)、承(cheng)插焊支管(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)在任何情(qing)況下其額定等(deng)(deng)級應(ying)大于(yu)(yu)等(deng)(deng)于(yu)(yu)20001b。
d. 其他支管(guan)(guan)(guan)(guan)連接(jie)可用直(zhi)接(jie)焊接(jie)，但(dan)必(bi)須經校核(he)后(hou)明(ming)確(que)是(shi)否(fou)增加(jia)補(bu)強。直(zhi)接(jie)焊接(jie)在主管(guan)(guan)(guan)(guan)上的(de)支管(guan)(guan)(guan)(guan)連接(jie)，不宜用于(yu)有(you)機(ji)械振動、壓力脈動和溫(wen)度(du)急劇(ju)變(bian)化的(de)部位(wei)及設計(ji)溫(wen)度(du)超過425℃的(de)管(guan)(guan)(guan)(guan)道，當支管(guan)(guan)(guan)(guan)連接(jie)處(chu)承(cheng)受由于(yu)支管(guan)(guan)(guan)(guan)熱變(bian)形(xing)、外載荷(he)及支架位(wei)移等引(yin)起的(de)應(ying)力時，應(ying)對附加(jia)載荷(he)在支管(guan)(guan)(guan)(guan)連接(jie)處(chu)產生(sheng)的(de)影響進行分析(xi)并采(cai)取必(bi)要(yao)的(de)加(jia)強措施。
e. 實際(ji)設計(ji)過程中，主要依據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)道等(deng)級中已經確定(ding)的(de)法(fa)蘭壓力等(deng)級或(huo)(huo)(huo)公(gong)稱(cheng)壓力（PN）來選用支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)件(jian)。一般情況下，當(dang)法(fa)蘭的(de)公(gong)稱(cheng)壓力PN≤2.5MPa時(shi)(shi)，支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)直(zhi)接(jie)(jie)焊(han)接(jie)(jie)在(zai)主管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)上(shang)；當(dang)PN≥4.0MPa時(shi)(shi)，則根據(ju)主管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)公(gong)稱(cheng)直(zhi)徑的(de)不(bu)(bu)同(tong)按對焊(han)三通、對焊(han)加強管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭、承(cheng)插(cha)(cha)(cha)(cha)焊(han)或(huo)(huo)(huo)螺(luo)(luo)(luo)紋連(lian)接(jie)(jie)三通、承(cheng)插(cha)(cha)(cha)(cha)焊(han)或(huo)(huo)(huo)螺(luo)(luo)(luo)紋加強管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭的(de)順序選用。值得注意的(de)是在(zai)確定(ding)支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)件(jian)的(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)(biao)號(hao)時(shi)(shi)，應根據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)等(deng)強度的(de)原(yuan)則以及管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)連(lian)接(jie)(jie)方式而定(ding)。例(li)如(ru)，當(dang)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)采用對焊(han)連(lian)接(jie)(jie)時(shi)(shi)，管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)的(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)(biao)號(hao)應一致(zhi)；而當(dang)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)采用承(cheng)插(cha)(cha)(cha)(cha)焊(han)或(huo)(huo)(huo)螺(luo)(luo)(luo)紋連(lian)接(jie)(jie)時(shi)(shi)，標準的(de)承(cheng)插(cha)(cha)(cha)(cha)焊(han)和螺(luo)(luo)(luo)紋管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)的(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)(biao)號(hao)只有Sch80、Sch60、XXS，最(zui)低(di)的(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)(biao)號(hao)就(jiu)是Sch80，也就(jiu)是說只要當(dang)承(cheng)插(cha)(cha)(cha)(cha)焊(han)或(huo)(huo)(huo)螺(luo)(luo)(luo)紋管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)所連(lian)接(jie)(jie)的(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)(biao)號(hao)不(bu)(bu)大于Sch80時(shi)(shi)，承(cheng)插(cha)(cha)(cha)(cha)焊(han)或(huo)(huo)(huo)螺(luo)(luo)(luo)紋管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)的(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)(biao)號(hao)就(jiu)選Sch80。而當(dang)所連(lian)接(jie)(jie)的(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)(biao)號(hao)大于Sch80時(shi)(shi)，承(cheng)插(cha)(cha)(cha)(cha)焊(han)或(huo)(huo)(huo)螺(luo)(luo)(luo)紋管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)的(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)(biao)號(hao)就(jiu)選Sch60或(huo)(huo)(huo)XXS。
f. 當對焊(han)三通主(zhu)管(guan)、支管(guan)所(suo)連接的管(guan)子(zi)的管(guan)子(zi)表號不同時，應注意三通主(zhu)管(guan)、支管(guan)端部(bu)的管(guan)子(zi)表號應分別與其所(suo)連接的管(guan)子(zi)的管(guan)子(zi)表號相同，這樣就非(fei)常方便管(guan)道施工，管(guan)件不必(bi)現場再(zai)打坡口(kou)。
③. 分支(zhi)管(guan)與主管(guan)連接的管(guan)件選擇見表16.71。
