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(de)選擇
a. 主(zhu)要根據(ju)管(guan)道的設計溫(wen)度、設計壓力、腐(fu)蝕(shi)余量等設計條件確定(ding)的。分(fen)(fen)支的方法：對于低壓大(da)直(zhi)徑管(guan)則直(zhi)接把(ba)分(fen)(fen)支管(guan)焊于主(zhu)管(guan)上(shang)，另外多數是利用分(fen)(fen)支管(guan)件進行分(fen)(fen)支。
b. 當從主(zhu)(zhu)管(guan)(guan)引出支(zhi)(zhi)(zhi)管(guan)(guan)時(shi)，支(zhi)(zhi)(zhi)管(guan)(guan)直(zhi)徑(jing)(jing)與(yu)主(zhu)(zhu)管(guan)(guan)直(zhi)徑(jing)(jing)的比值大于(yu)等于(yu)0.5時(shi)，采(cai)用異(yi)徑(jing)(jing)三通(tong)或(huo)等徑(jing)(jing)三通(tong)，當主(zhu)(zhu)支(zhi)(zhi)(zhi)管(guan)(guan)為(wei)(wei)等徑(jing)(jing)時(shi)，應(ying)采(cai)用三通(tong)。GB50316 規(gui)定：公稱壓(ya)力(li)大于(yu)或(huo)等于(yu)10MPa的管(guan)(guan)道，主(zhu)(zhu)支(zhi)(zhi)(zhi)管(guan)(guan)為(wei)(wei)異(yi)徑(jing)(jing)時(shi)，不宜采(cai)用焊(han)接支(zhi)(zhi)(zhi)管(guan)(guan)，宜采(cai)用三通(tong)或(huo)在主(zhu)(zhu)管(guan)(guan)上開孔并焊(han)接支(zhi)(zhi)(zhi)管(guan)(guan)臺。當主(zhu)(zhu)管(guan)(guan)直(zhi)徑(jing)(jing)大于(yu)DN65而支(zhi)(zhi)(zhi)管(guan)(guan)直(zhi)徑(jing)(jing)為(wei)(wei)DN40及以(yi)下時(shi)，根據設計壓(ya)力(li)的大小，采(cai)用支(zhi)(zhi)(zhi)管(guan)(guan)臺或(huo)半管(guan)(guan)接頭。
c. 主(zhu)(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)直(zhi)徑(jing)(jing)(jing)小(xiao)(xiao)于(yu)DN50時，支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)小(xiao)(xiao)于(yu)主(zhu)(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)，則(ze)用(yong)異徑(jing)(jing)(jing)三(san)通(tong)(tong)或(huo)(huo)等(deng)(deng)徑(jing)(jing)(jing)三(san)通(tong)(tong)加(jia)(jia)異徑(jing)(jing)(jing)短管(guan)(guan)(guan)(guan)(guan)。設計壓力等(deng)(deng)于(yu)或(huo)(huo)大于(yu)2.0MPa、設計溫(wen)度(du)(du)超過250℃以及(ji)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)與主(zhu)(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)公稱直(zhi)徑(jing)(jing)(jing)之比大于(yu)0.8，或(huo)(huo)承受機械振動(dong)、壓力脈動(dong)和溫(wen)度(du)(du)急劇變化的(de)(de)管(guan)(guan)(guan)(guan)(guan)道分支(zhi)(zhi)(zhi)，應采(cai)用(yong)等(deng)(deng)徑(jing)(jing)(jing)異徑(jing)(jing)(jing)三(san)通(tong)(tong)；公稱直(zhi)徑(jing)(jing)(jing)小(xiao)(xiao)于(yu)或(huo)(huo)等(deng)(deng)于(yu)40mm的(de)(de)管(guan)(guan)(guan)(guan)(guan)道，應采(cai)用(yong)承插(cha)焊(han)(han)(han)（或(huo)(huo)螺(luo)(luo)紋）鍛制(zhi)三(san)通(tong)(tong)；公稱直(zhi)徑(jing)(jing)(jing)等(deng)(deng)于(yu)或(huo)(huo)大于(yu)50mm的(de)(de)管(guan)(guan)(guan)(guan)(guan)道，應采(cai)用(yong)對(dui)焊(han)(han)(han)三(san)通(tong)(tong)、對(dui)焊(han)(han)(han)加(jia)(jia)強(qiang)管(guan)(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)（對(dui)焊(han)(han)(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)）或(huo)(huo)嵌入式（鞍(an)型）支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)。支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)通(tong)(tong)過加(jia)(jia)強(qiang)管(guan)(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)（支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)）與主(zhu)(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)連接(jie)是指將(jiang)一個螺(luo)(luo)紋、承插(cha)焊(han)(han)(han)或(huo)(huo)對(dui)焊(han)(han)(han)的(de)(de)管(guan)(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)或(huo)(huo)半管(guan)(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)（支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)）直(zhi)接(jie)焊(han)(han)(han)于(yu)主(zhu)(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)上而制(zhi)成，螺(luo)(luo)紋、承插(cha)焊(han)(han)(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)用(yong)于(yu)直(zhi)徑(jing)(jing)(jing)小(xiao)(xiao)于(yu)等(deng)(deng)于(yu)DN40（NPS1/2）的(de)(de)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)連接(jie)。螺(luo)(luo)紋、承插(cha)焊(han)(han)(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)在任何情況下其(qi)額定等(deng)(deng)級應大于(yu)等(deng)(deng)于(yu)20001b。
d. 其他支(zhi)管(guan)連接(jie)(jie)(jie)可用(yong)直接(jie)(jie)(jie)焊接(jie)(jie)(jie)，但必(bi)須經校核后明(ming)確是否增加補強(qiang)。直接(jie)(jie)(jie)焊接(jie)(jie)(jie)在主管(guan)上的(de)(de)支(zhi)管(guan)連接(jie)(jie)(jie)，不宜用(yong)于(yu)有機(ji)械振動、壓(ya)力脈動和溫度急(ji)劇變化的(de)(de)部位(wei)及設計(ji)溫度超(chao)過(guo)425℃的(de)(de)管(guan)道(dao)，當支(zhi)管(guan)連接(jie)(jie)(jie)處承受由于(yu)支(zhi)管(guan)熱變形、外載荷及支(zhi)架位(wei)移等引(yin)起(qi)的(de)(de)應力時，應對附加載荷在支(zhi)管(guan)連接(jie)(jie)(jie)處產生(sheng)的(de)(de)影響(xiang)進行(xing)分析并采取(qu)必(bi)要的(de)(de)加強(qiang)措(cuo)施(shi)。
e. 實際設計過程中，主(zhu)要依據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)道等(deng)級中已經確定(ding)(ding)的(de)(de)(de)法(fa)蘭壓(ya)力(li)等(deng)級或(huo)(huo)公(gong)稱(cheng)壓(ya)力(li)（PN）來選(xuan)(xuan)用支管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)連接(jie)件(jian)(jian)(jian)。一(yi)般(ban)情況下，當(dang)法(fa)蘭的(de)(de)(de)公(gong)稱(cheng)壓(ya)力(li)PN≤2.5MPa時(shi)(shi)(shi)(shi)，支管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)直(zhi)接(jie)焊(han)(han)(han)接(jie)在主(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)上；當(dang)PN≥4.0MPa時(shi)(shi)(shi)(shi)，則根據(ju)主(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)支管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)公(gong)稱(cheng)直(zhi)徑(jing)的(de)(de)(de)不同按對焊(han)(han)(han)三通、對焊(han)(han)(han)加強(qiang)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)頭、承(cheng)(cheng)插焊(han)(han)(han)或(huo)(huo)螺(luo)紋(wen)連接(jie)三通、承(cheng)(cheng)插焊(han)(han)(han)或(huo)(huo)螺(luo)紋(wen)加強(qiang)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)頭的(de)(de)(de)順序選(xuan)(xuan)用。值得注意的(de)(de)(de)是在確定(ding)(ding)支管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)連接(jie)件(jian)(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)(zi)表號(hao)時(shi)(shi)(shi)(shi)，應根據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)等(deng)強(qiang)度的(de)(de)(de)原則以(yi)及管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)(zi)連接(jie)方式而定(ding)(ding)。例如，當(dang)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)采用對焊(han)(han)(han)連接(jie)時(shi)(shi)(shi)(shi)，管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)(zi)表號(hao)應一(yi)致；而當(dang)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)采用承(cheng)(cheng)插焊(han)(han)(han)或(huo)(huo)螺(luo)紋(wen)連接(jie)時(shi)(shi)(shi)(shi)，標準(zhun)的(de)(de)(de)承(cheng)(cheng)插焊(han)(han)(han)和螺(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)(zi)表號(hao)只(zhi)有(you)Sch80、Sch60、XXS，最低的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)(zi)表號(hao)就(jiu)是Sch80，也就(jiu)是說只(zhi)要當(dang)承(cheng)(cheng)插焊(han)(han)(han)或(huo)(huo)螺(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)所(suo)連接(jie)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)(zi)表號(hao)不大于Sch80時(shi)(shi)(shi)(shi)，承(cheng)(cheng)插焊(han)(han)(han)或(huo)(huo)螺(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)(zi)表號(hao)就(jiu)選(xuan)(xuan)Sch80。而當(dang)所(suo)連接(jie)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)(zi)表號(hao)大于Sch80時(shi)(shi)(shi)(shi)，承(cheng)(cheng)插焊(han)(han)(han)或(huo)(huo)螺(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)(zi)表號(hao)就(jiu)選(xuan)(xuan)Sch60或(huo)(huo)XXS。
f. 當(dang)對焊三(san)通主管(guan)(guan)、支管(guan)(guan)所連(lian)接的(de)管(guan)(guan)子(zi)(zi)(zi)的(de)管(guan)(guan)子(zi)(zi)(zi)表(biao)號不同(tong)時，應注(zhu)意三(san)通主管(guan)(guan)、支管(guan)(guan)端部(bu)的(de)管(guan)(guan)子(zi)(zi)(zi)表(biao)號應分(fen)別與其(qi)所連(lian)接的(de)管(guan)(guan)子(zi)(zi)(zi)的(de)管(guan)(guan)子(zi)(zi)(zi)表(biao)號相同(tong)，這樣就非(fei)常(chang)方便管(guan)(guan)道(dao)施(shi)工，管(guan)(guan)件不必(bi)現場再打坡口。
③. 分(fen)支管(guan)與主管(guan)連接的管(guan)件選擇見表(biao)16.71。
