①. 由于各國管(guan)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(lian)接件的選擇

   a. 主要(yao)根據管(guan)道的(de)設(she)計溫度(du)、設(she)計壓力、腐蝕(shi)余量等設(she)計條件確定的(de)。分(fen)(fen)支的(de)方法(fa)：對(dui)于(yu)(yu)低(di)壓大直(zhi)徑管(guan)則直(zhi)接把分(fen)(fen)支管(guan)焊于(yu)(yu)主管(guan)上，另(ling)外(wai)多數是(shi)利用分(fen)(fen)支管(guan)件進行分(fen)(fen)支。

   b. 當從主管(guan)(guan)(guan)(guan)引出支(zhi)管(guan)(guan)(guan)(guan)時，支(zhi)管(guan)(guan)(guan)(guan)直徑(jing)與主管(guan)(guan)(guan)(guan)直徑(jing)的(de)比值大于等(deng)于0.5時，采(cai)用(yong)異徑(jing)三(san)通(tong)或(huo)(huo)等(deng)徑(jing)三(san)通(tong)，當主支(zhi)管(guan)(guan)(guan)(guan)為等(deng)徑(jing)時，應采(cai)用(yong)三(san)通(tong)。GB50316 規(gui)定：公稱壓力大于或(huo)(huo)等(deng)于10MPa的(de)管(guan)(guan)(guan)(guan)道，主支(zhi)管(guan)(guan)(guan)(guan)為異徑(jing)時，不宜采(cai)用(yong)焊(han)接支(zhi)管(guan)(guan)(guan)(guan)，宜采(cai)用(yong)三(san)通(tong)或(huo)(huo)在主管(guan)(guan)(guan)(guan)上開孔并焊(han)接支(zhi)管(guan)(guan)(guan)(guan)臺(tai)。當主管(guan)(guan)(guan)(guan)直徑(jing)大于DN65而支(zhi)管(guan)(guan)(guan)(guan)直徑(jing)為DN40及(ji)以下(xia)時，根據設(she)計(ji)壓力的(de)大小，采(cai)用(yong)支(zhi)管(guan)(guan)(guan)(guan)臺(tai)或(huo)(huo)半管(guan)(guan)(guan)(guan)接頭。

   c. 主(zhu)管(guan)(guan)(guan)(guan)直(zhi)徑(jing)(jing)(jing)小于(yu)(yu)DN50時，支(zhi)(zhi)管(guan)(guan)(guan)(guan)小于(yu)(yu)主(zhu)管(guan)(guan)(guan)(guan)，則用(yong)(yong)異(yi)徑(jing)(jing)(jing)三(san)通(tong)或(huo)(huo)(huo)等(deng)(deng)(deng)徑(jing)(jing)(jing)三(san)通(tong)加(jia)異(yi)徑(jing)(jing)(jing)短管(guan)(guan)(guan)(guan)。設計壓力(li)等(deng)(deng)(deng)于(yu)(yu)或(huo)(huo)(huo)大(da)于(yu)(yu)2.0MPa、設計溫度超過250℃以及支(zhi)(zhi)管(guan)(guan)(guan)(guan)與主(zhu)管(guan)(guan)(guan)(guan)公(gong)稱直(zhi)徑(jing)(jing)(jing)之比大(da)于(yu)(yu)0.8，或(huo)(huo)(huo)承(cheng)受機械振動、壓力(li)脈(mo)動和溫度急劇(ju)變(bian)化(hua)的(de)管(guan)(guan)(guan)(guan)道(dao)分(fen)支(zhi)(zhi)，應(ying)采(cai)用(yong)(yong)等(deng)(deng)(deng)徑(jing)(jing)(jing)異(yi)徑(jing)(jing)(jing)三(san)通(tong)；公(gong)稱直(zhi)徑(jing)(jing)(jing)小于(yu)(yu)或(huo)(huo)(huo)等(deng)(deng)(deng)于(yu)(yu)40mm的(de)管(guan)(guan)(guan)(guan)道(dao)，應(ying)采(cai)用(yong)(yong)承(cheng)插焊(han)(han)（或(huo)(huo)(huo)螺紋(wen)(wen)）鍛制三(san)通(tong)；公(gong)稱直(zhi)徑(jing)(jing)(jing)等(deng)(deng)(deng)于(yu)(yu)或(huo)(huo)(huo)大(da)于(yu)(yu)50mm的(de)管(guan)(guan)(guan)(guan)道(dao)，應(ying)采(cai)用(yong)(yong)對焊(han)(han)三(san)通(tong)、對焊(han)(han)加(jia)強管(guan)(guan)(guan)(guan)接頭（對焊(han)(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺）或(huo)(huo)(huo)嵌(qian)入式（鞍型）支(zhi)(zhi)管(guan)(guan)(guan)(guan)接頭。支(zhi)(zhi)管(guan)(guan)(guan)(guan)通(tong)過加(jia)強管(guan)(guan)(guan)(guan)接頭（支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺）與主(zhu)管(guan)(guan)(guan)(guan)連(lian)接是指將一個螺紋(wen)(wen)、承(cheng)插焊(han)(han)或(huo)(huo)(huo)對焊(han)(han)的(de)管(guan)(guan)(guan)(guan)接頭或(huo)(huo)(huo)半管(guan)(guan)(guan)(guan)接頭（支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺）直(zhi)接焊(han)(han)于(yu)(yu)主(zhu)管(guan)(guan)(guan)(guan)上而制成，螺紋(wen)(wen)、承(cheng)插焊(han)(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺用(yong)(yong)于(yu)(yu)直(zhi)徑(jing)(jing)(jing)小于(yu)(yu)等(deng)(deng)(deng)于(yu)(yu)DN40（NPS1/2）的(de)支(zhi)(zhi)管(guan)(guan)(guan)(guan)連(lian)接。螺紋(wen)(wen)、承(cheng)插焊(han)(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺在任何情況下其額(e)定等(deng)(deng)(deng)級應(ying)大(da)于(yu)(yu)等(deng)(deng)(deng)于(yu)(yu)20001b。

   d. 其(qi)他支(zhi)(zhi)管(guan)連(lian)接(jie)可用直接(jie)焊接(jie)，但必須(xu)經校核后明(ming)確是否(fou)增加(jia)補強(qiang)。直接(jie)焊接(jie)在主(zhu)管(guan)上的(de)支(zhi)(zhi)管(guan)連(lian)接(jie)，不(bu)宜(yi)用于(yu)(yu)有機械振動(dong)、壓力脈(mo)動(dong)和溫度急劇變(bian)化的(de)部位及設計溫度超(chao)過425℃的(de)管(guan)道，當支(zhi)(zhi)管(guan)連(lian)接(jie)處承受由于(yu)(yu)支(zhi)(zhi)管(guan)熱變(bian)形、外載(zai)荷(he)及支(zhi)(zhi)架位移等引起的(de)應力時，應對(dui)附加(jia)載(zai)荷(he)在支(zhi)(zhi)管(guan)連(lian)接(jie)處產(chan)生(sheng)的(de)影(ying)響進(jin)行分(fen)析(xi)并采取必要的(de)加(jia)強(qiang)措施。

   e. 實際(ji)設計過程中，主(zhu)要依據管(guan)(guan)(guan)道等級中已經確定(ding)(ding)(ding)的(de)法蘭壓力等級或(huo)公(gong)稱(cheng)(cheng)壓力（PN）來選(xuan)用(yong)支管(guan)(guan)(guan)連(lian)(lian)接(jie)(jie)(jie)件(jian)(jian)。一般情況下，當(dang)法蘭的(de)公(gong)稱(cheng)(cheng)壓力PN≤2.5MPa時(shi)，支管(guan)(guan)(guan)直接(jie)(jie)(jie)焊(han)(han)(han)接(jie)(jie)(jie)在主(zhu)管(guan)(guan)(guan)上；當(dang)PN≥4.0MPa時(shi)，則根據主(zhu)管(guan)(guan)(guan)支管(guan)(guan)(guan)公(gong)稱(cheng)(cheng)直徑的(de)不同按對(dui)焊(han)(han)(han)三通(tong)、對(dui)焊(han)(han)(han)加強(qiang)管(guan)(guan)(guan)接(jie)(jie)(jie)頭、承(cheng)插(cha)(cha)焊(han)(han)(han)或(huo)螺紋(wen)連(lian)(lian)接(jie)(jie)(jie)三通(tong)、承(cheng)插(cha)(cha)焊(han)(han)(han)或(huo)螺紋(wen)加強(qiang)管(guan)(guan)(guan)接(jie)(jie)(jie)頭的(de)順序選(xuan)用(yong)。值得(de)注意的(de)是在確定(ding)(ding)(ding)支管(guan)(guan)(guan)連(lian)(lian)接(jie)(jie)(jie)件(jian)(jian)的(de)管(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)(hao)時(shi)，應(ying)根據管(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)件(jian)(jian)等強(qiang)度的(de)原則以及管(guan)(guan)(guan)件(jian)(jian)與管(guan)(guan)(guan)子(zi)(zi)(zi)連(lian)(lian)接(jie)(jie)(jie)方(fang)式而定(ding)(ding)(ding)。例如，當(dang)管(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)件(jian)(jian)采用(yong)對(dui)焊(han)(han)(han)連(lian)(lian)接(jie)(jie)(jie)時(shi)，管(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)件(jian)(jian)的(de)管(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)(hao)應(ying)一致；而當(dang)管(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)件(jian)(jian)采用(yong)承(cheng)插(cha)(cha)焊(han)(han)(han)或(huo)螺紋(wen)連(lian)(lian)接(jie)(jie)(jie)時(shi)，標準的(de)承(cheng)插(cha)(cha)焊(han)(han)(han)和螺紋(wen)管(guan)(guan)(guan)件(jian)(jian)的(de)管(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)(hao)只有Sch80、Sch60、XXS，最低的(de)管(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)(hao)就(jiu)是Sch80，也就(jiu)是說(shuo)只要當(dang)承(cheng)插(cha)(cha)焊(han)(han)(han)或(huo)螺紋(wen)管(guan)(guan)(guan)件(jian)(jian)所連(lian)(lian)接(jie)(jie)(jie)的(de)管(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)(hao)不大于(yu)Sch80時(shi)，承(cheng)插(cha)(cha)焊(han)(han)(han)或(huo)螺紋(wen)管(guan)(guan)(guan)件(jian)(jian)的(de)管(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)(hao)就(jiu)選(xuan)Sch80。而當(dang)所連(lian)(lian)接(jie)(jie)(jie)的(de)管(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)(hao)大于(yu)Sch80時(shi)，承(cheng)插(cha)(cha)焊(han)(han)(han)或(huo)螺紋(wen)管(guan)(guan)(guan)件(jian)(jian)的(de)管(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)(hao)就(jiu)選(xuan)Sch60或(huo)XXS。

   f. 當對焊(han)三通主管(guan)(guan)、支管(guan)(guan)所連(lian)接(jie)的管(guan)(guan)子(zi)的管(guan)(guan)子(zi)表號不(bu)(bu)同時(shi)，應注意三通主管(guan)(guan)、支管(guan)(guan)端部的管(guan)(guan)子(zi)表號應分(fen)別(bie)與其所連(lian)接(jie)的管(guan)(guan)子(zi)的管(guan)(guan)子(zi)表號相(xiang)同，這樣就非常方(fang)便(bian)管(guan)(guan)道施工，管(guan)(guan)件不(bu)(bu)必現場再打坡口。

 ③. 分支管與主管連接的管件選擇見表16.71。