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. 支管連接件的(de)選擇

   a. 主(zhu)要根據管道的(de)(de)設計溫度、設計壓力、腐蝕余量等(deng)設計條件確定(ding)的(de)(de)。分支的(de)(de)方(fang)法：對于低壓大直(zhi)徑管則直(zhi)接把分支管焊于主(zhu)管上，另(ling)外多數是利(li)用(yong)分支管件進行分支。

   b. 當(dang)(dang)從(cong)主管(guan)(guan)(guan)(guan)(guan)(guan)引出支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)時(shi)，支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)直(zhi)徑(jing)與主管(guan)(guan)(guan)(guan)(guan)(guan)直(zhi)徑(jing)的比值大(da)于(yu)等于(yu)0.5時(shi)，采(cai)用(yong)(yong)異(yi)徑(jing)三通(tong)(tong)或(huo)等徑(jing)三通(tong)(tong)，當(dang)(dang)主支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)為(wei)等徑(jing)時(shi)，應采(cai)用(yong)(yong)三通(tong)(tong)。GB50316 規定(ding)：公稱壓力(li)大(da)于(yu)或(huo)等于(yu)10MPa的管(guan)(guan)(guan)(guan)(guan)(guan)道，主支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)為(wei)異(yi)徑(jing)時(shi)，不(bu)宜采(cai)用(yong)(yong)焊接(jie)(jie)支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)，宜采(cai)用(yong)(yong)三通(tong)(tong)或(huo)在主管(guan)(guan)(guan)(guan)(guan)(guan)上(shang)開(kai)孔(kong)并(bing)焊接(jie)(jie)支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)臺。當(dang)(dang)主管(guan)(guan)(guan)(guan)(guan)(guan)直(zhi)徑(jing)大(da)于(yu)DN65而支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)直(zhi)徑(jing)為(wei)DN40及(ji)以(yi)下時(shi)，根據設計(ji)壓力(li)的大(da)小，采(cai)用(yong)(yong)支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)臺或(huo)半管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭。

   c. 主(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)直(zhi)(zhi)(zhi)徑(jing)(jing)(jing)小(xiao)(xiao)(xiao)于(yu)(yu)DN50時，支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)小(xiao)(xiao)(xiao)于(yu)(yu)主(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)，則用(yong)(yong)異(yi)徑(jing)(jing)(jing)三(san)通(tong)(tong)(tong)或等(deng)徑(jing)(jing)(jing)三(san)通(tong)(tong)(tong)加(jia)異(yi)徑(jing)(jing)(jing)短(duan)管(guan)(guan)(guan)(guan)(guan)。設(she)計壓(ya)力(li)等(deng)于(yu)(yu)或大(da)(da)于(yu)(yu)2.0MPa、設(she)計溫(wen)度超過(guo)250℃以(yi)及(ji)支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)與(yu)主(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)公稱直(zhi)(zhi)(zhi)徑(jing)(jing)(jing)之比大(da)(da)于(yu)(yu)0.8，或承(cheng)(cheng)受機械振動、壓(ya)力(li)脈動和溫(wen)度急劇(ju)變化的(de)管(guan)(guan)(guan)(guan)(guan)道分支(zhi)(zhi)，應(ying)(ying)采(cai)(cai)用(yong)(yong)等(deng)徑(jing)(jing)(jing)異(yi)徑(jing)(jing)(jing)三(san)通(tong)(tong)(tong)；公稱直(zhi)(zhi)(zhi)徑(jing)(jing)(jing)小(xiao)(xiao)(xiao)于(yu)(yu)或等(deng)于(yu)(yu)40mm的(de)管(guan)(guan)(guan)(guan)(guan)道，應(ying)(ying)采(cai)(cai)用(yong)(yong)承(cheng)(cheng)插(cha)(cha)焊(han)(han)（或螺(luo)紋(wen)(wen)(wen)）鍛(duan)制(zhi)三(san)通(tong)(tong)(tong)；公稱直(zhi)(zhi)(zhi)徑(jing)(jing)(jing)等(deng)于(yu)(yu)或大(da)(da)于(yu)(yu)50mm的(de)管(guan)(guan)(guan)(guan)(guan)道，應(ying)(ying)采(cai)(cai)用(yong)(yong)對(dui)焊(han)(han)三(san)通(tong)(tong)(tong)、對(dui)焊(han)(han)加(jia)強(qiang)管(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)（對(dui)焊(han)(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)）或嵌入(ru)式（鞍(an)型）支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)。支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)通(tong)(tong)(tong)過(guo)加(jia)強(qiang)管(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)（支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)）與(yu)主(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)是指將一(yi)個(ge)螺(luo)紋(wen)(wen)(wen)、承(cheng)(cheng)插(cha)(cha)焊(han)(han)或對(dui)焊(han)(han)的(de)管(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)或半管(guan)(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)（支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)）直(zhi)(zhi)(zhi)接(jie)(jie)焊(han)(han)于(yu)(yu)主(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)上而制(zhi)成，螺(luo)紋(wen)(wen)(wen)、承(cheng)(cheng)插(cha)(cha)焊(han)(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)用(yong)(yong)于(yu)(yu)直(zhi)(zhi)(zhi)徑(jing)(jing)(jing)小(xiao)(xiao)(xiao)于(yu)(yu)等(deng)于(yu)(yu)DN40（NPS1/2）的(de)支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)。螺(luo)紋(wen)(wen)(wen)、承(cheng)(cheng)插(cha)(cha)焊(han)(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)在(zai)任何情況下(xia)其額定等(deng)級應(ying)(ying)大(da)(da)于(yu)(yu)等(deng)于(yu)(yu)20001b。

   d. 其他支(zhi)管(guan)(guan)連(lian)(lian)接(jie)可用直接(jie)焊(han)接(jie)，但必須經(jing)校核后明(ming)確是否增加補強(qiang)。直接(jie)焊(han)接(jie)在主管(guan)(guan)上的(de)(de)支(zhi)管(guan)(guan)連(lian)(lian)接(jie)，不(bu)宜用于(yu)有機(ji)械振動、壓力(li)脈動和溫(wen)度急(ji)劇變化的(de)(de)部位及設(she)計溫(wen)度超(chao)過(guo)425℃的(de)(de)管(guan)(guan)道，當支(zhi)管(guan)(guan)連(lian)(lian)接(jie)處承受由于(yu)支(zhi)管(guan)(guan)熱(re)變形、外載荷(he)及支(zhi)架(jia)位移(yi)等引起的(de)(de)應力(li)時，應對附加載荷(he)在支(zhi)管(guan)(guan)連(lian)(lian)接(jie)處產(chan)生的(de)(de)影(ying)響(xiang)進行(xing)分析并采(cai)取必要的(de)(de)加強(qiang)措施。

   e. 實際設計過程中，主(zhu)要依據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)道等(deng)級(ji)中已經確定(ding)(ding)的(de)(de)(de)(de)法蘭壓力等(deng)級(ji)或(huo)公(gong)(gong)稱(cheng)壓力（PN）來(lai)選(xuan)(xuan)用支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)連(lian)(lian)接(jie)件(jian)(jian)(jian)(jian)。一般情況下，當(dang)法蘭的(de)(de)(de)(de)公(gong)(gong)稱(cheng)壓力PN≤2.5MPa時，支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)直接(jie)焊接(jie)在主(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)上；當(dang)PN≥4.0MPa時，則根(gen)據(ju)主(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)公(gong)(gong)稱(cheng)直徑的(de)(de)(de)(de)不同按對焊三通、對焊加強管(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)頭、承插(cha)(cha)焊或(huo)螺(luo)(luo)紋(wen)(wen)(wen)連(lian)(lian)接(jie)三通、承插(cha)(cha)焊或(huo)螺(luo)(luo)紋(wen)(wen)(wen)加強管(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)頭的(de)(de)(de)(de)順序選(xuan)(xuan)用。值得注意的(de)(de)(de)(de)是(shi)在確定(ding)(ding)支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)連(lian)(lian)接(jie)件(jian)(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)號(hao)(hao)時，應根(gen)據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)等(deng)強度的(de)(de)(de)(de)原則以及管(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)與管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)連(lian)(lian)接(jie)方式而(er)定(ding)(ding)。例如，當(dang)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)采用對焊連(lian)(lian)接(jie)時，管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)號(hao)(hao)應一致；而(er)當(dang)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)采用承插(cha)(cha)焊或(huo)螺(luo)(luo)紋(wen)(wen)(wen)連(lian)(lian)接(jie)時，標準的(de)(de)(de)(de)承插(cha)(cha)焊和螺(luo)(luo)紋(wen)(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)號(hao)(hao)只有(you)Sch80、Sch60、XXS，最(zui)低的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)號(hao)(hao)就是(shi)Sch80，也(ye)就是(shi)說只要當(dang)承插(cha)(cha)焊或(huo)螺(luo)(luo)紋(wen)(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)所連(lian)(lian)接(jie)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)號(hao)(hao)不大于(yu)Sch80時，承插(cha)(cha)焊或(huo)螺(luo)(luo)紋(wen)(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)號(hao)(hao)就選(xuan)(xuan)Sch80。而(er)當(dang)所連(lian)(lian)接(jie)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)號(hao)(hao)大于(yu)Sch80時，承插(cha)(cha)焊或(huo)螺(luo)(luo)紋(wen)(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)(biao)號(hao)(hao)就選(xuan)(xuan)Sch60或(huo)XXS。

   f. 當對(dui)焊三(san)通主管(guan)、支管(guan)所連接的(de)管(guan)子的(de)管(guan)子表號(hao)不同時，應(ying)注意三(san)通主管(guan)、支管(guan)端(duan)部(bu)的(de)管(guan)子表號(hao)應(ying)分別(bie)與其所連接的(de)管(guan)子的(de)管(guan)子表號(hao)相同，這樣就非常(chang)方便管(guan)道施工，管(guan)件不必現(xian)場再打(da)坡(po)口。

 ③. 分支管(guan)(guan)與主管(guan)(guan)連(lian)接(jie)的管(guan)(guan)件選(xuan)擇見(jian)表16.71。