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(guan)連接件(jian)的選擇

   a. 主要根據管(guan)(guan)道的設(she)計(ji)溫度、設(she)計(ji)壓力、腐蝕余量(liang)等設(she)計(ji)條件確定的。分(fen)支(zhi)的方法：對(dui)于低壓大直徑管(guan)(guan)則(ze)直接(jie)把分(fen)支(zhi)管(guan)(guan)焊于主管(guan)(guan)上，另外多(duo)數是(shi)利用分(fen)支(zhi)管(guan)(guan)件進行分(fen)支(zhi)。

   b. 當(dang)從主(zhu)管(guan)(guan)(guan)引(yin)出(chu)支(zhi)(zhi)管(guan)(guan)(guan)時(shi)，支(zhi)(zhi)管(guan)(guan)(guan)直(zhi)(zhi)徑(jing)與主(zhu)管(guan)(guan)(guan)直(zhi)(zhi)徑(jing)的比值大(da)于(yu)等(deng)于(yu)0.5時(shi)，采用(yong)(yong)異徑(jing)三通(tong)或(huo)等(deng)徑(jing)三通(tong)，當(dang)主(zhu)支(zhi)(zhi)管(guan)(guan)(guan)為(wei)等(deng)徑(jing)時(shi)，應(ying)采用(yong)(yong)三通(tong)。GB50316 規定：公稱壓力大(da)于(yu)或(huo)等(deng)于(yu)10MPa的管(guan)(guan)(guan)道，主(zhu)支(zhi)(zhi)管(guan)(guan)(guan)為(wei)異徑(jing)時(shi)，不宜(yi)(yi)采用(yong)(yong)焊接(jie)支(zhi)(zhi)管(guan)(guan)(guan)，宜(yi)(yi)采用(yong)(yong)三通(tong)或(huo)在主(zhu)管(guan)(guan)(guan)上開孔并焊接(jie)支(zhi)(zhi)管(guan)(guan)(guan)臺。當(dang)主(zhu)管(guan)(guan)(guan)直(zhi)(zhi)徑(jing)大(da)于(yu)DN65而支(zhi)(zhi)管(guan)(guan)(guan)直(zhi)(zhi)徑(jing)為(wei)DN40及以下(xia)時(shi)，根(gen)據設計壓力的大(da)小，采用(yong)(yong)支(zhi)(zhi)管(guan)(guan)(guan)臺或(huo)半管(guan)(guan)(guan)接(jie)頭。

   c. 主(zhu)(zhu)管(guan)(guan)(guan)(guan)直(zhi)徑(jing)(jing)(jing)小(xiao)(xiao)于(yu)(yu)DN50時，支管(guan)(guan)(guan)(guan)小(xiao)(xiao)于(yu)(yu)主(zhu)(zhu)管(guan)(guan)(guan)(guan)，則(ze)用(yong)異徑(jing)(jing)(jing)三通(tong)或(huo)(huo)等(deng)徑(jing)(jing)(jing)三通(tong)加異徑(jing)(jing)(jing)短(duan)管(guan)(guan)(guan)(guan)。設(she)計(ji)(ji)壓力等(deng)于(yu)(yu)或(huo)(huo)大于(yu)(yu)2.0MPa、設(she)計(ji)(ji)溫度超(chao)過250℃以及支管(guan)(guan)(guan)(guan)與主(zhu)(zhu)管(guan)(guan)(guan)(guan)公稱直(zhi)徑(jing)(jing)(jing)之比大于(yu)(yu)0.8，或(huo)(huo)承(cheng)受(shou)機械振動、壓力脈(mo)動和溫度急(ji)劇變(bian)化的管(guan)(guan)(guan)(guan)道分支，應(ying)(ying)采(cai)用(yong)等(deng)徑(jing)(jing)(jing)異徑(jing)(jing)(jing)三通(tong)；公稱直(zhi)徑(jing)(jing)(jing)小(xiao)(xiao)于(yu)(yu)或(huo)(huo)等(deng)于(yu)(yu)40mm的管(guan)(guan)(guan)(guan)道，應(ying)(ying)采(cai)用(yong)承(cheng)插焊(han)（或(huo)(huo)螺(luo)紋）鍛制三通(tong)；公稱直(zhi)徑(jing)(jing)(jing)等(deng)于(yu)(yu)或(huo)(huo)大于(yu)(yu)50mm的管(guan)(guan)(guan)(guan)道，應(ying)(ying)采(cai)用(yong)對(dui)(dui)焊(han)三通(tong)、對(dui)(dui)焊(han)加強管(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)（對(dui)(dui)焊(han)支管(guan)(guan)(guan)(guan)臺）或(huo)(huo)嵌入(ru)式（鞍型）支管(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)。支管(guan)(guan)(guan)(guan)通(tong)過加強管(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)（支管(guan)(guan)(guan)(guan)臺）與主(zhu)(zhu)管(guan)(guan)(guan)(guan)連接(jie)(jie)是(shi)指(zhi)將一個螺(luo)紋、承(cheng)插焊(han)或(huo)(huo)對(dui)(dui)焊(han)的管(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)或(huo)(huo)半管(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)（支管(guan)(guan)(guan)(guan)臺）直(zhi)接(jie)(jie)焊(han)于(yu)(yu)主(zhu)(zhu)管(guan)(guan)(guan)(guan)上而(er)制成，螺(luo)紋、承(cheng)插焊(han)支管(guan)(guan)(guan)(guan)臺用(yong)于(yu)(yu)直(zhi)徑(jing)(jing)(jing)小(xiao)(xiao)于(yu)(yu)等(deng)于(yu)(yu)DN40（NPS1/2）的支管(guan)(guan)(guan)(guan)連接(jie)(jie)。螺(luo)紋、承(cheng)插焊(han)支管(guan)(guan)(guan)(guan)臺在任何情況下(xia)其額定(ding)等(deng)級應(ying)(ying)大于(yu)(yu)等(deng)于(yu)(yu)20001b。

   d. 其他支管(guan)連(lian)接可用直(zhi)接焊接，但必須經校(xiao)核后明確(que)是否增加補(bu)強(qiang)。直(zhi)接焊接在主管(guan)上(shang)的(de)支管(guan)連(lian)接，不宜(yi)用于有機械(xie)振(zhen)動、壓力(li)脈動和溫(wen)度(du)急劇變化的(de)部(bu)位及(ji)設計溫(wen)度(du)超過425℃的(de)管(guan)道，當支管(guan)連(lian)接處承受由于支管(guan)熱(re)變形(xing)、外載(zai)荷及(ji)支架位移等(deng)引起(qi)的(de)應(ying)力(li)時，應(ying)對附加載(zai)荷在支管(guan)連(lian)接處產生的(de)影響(xiang)進行分(fen)析并(bing)采取必要的(de)加強(qiang)措(cuo)施。

   e. 實(shi)際設計過程中，主要依據管(guan)(guan)(guan)(guan)道(dao)等(deng)級中已(yi)經確(que)定(ding)的(de)(de)(de)(de)法蘭壓(ya)力(li)(li)等(deng)級或(huo)(huo)公(gong)稱(cheng)壓(ya)力(li)(li)（PN）來選用支管(guan)(guan)(guan)(guan)連(lian)接件(jian)(jian)(jian)。一般(ban)情況下(xia)，當(dang)(dang)(dang)(dang)法蘭的(de)(de)(de)(de)公(gong)稱(cheng)壓(ya)力(li)(li)PN≤2.5MPa時(shi)(shi)，支管(guan)(guan)(guan)(guan)直接焊(han)(han)(han)(han)接在主管(guan)(guan)(guan)(guan)上；當(dang)(dang)(dang)(dang)PN≥4.0MPa時(shi)(shi)，則根(gen)據主管(guan)(guan)(guan)(guan)支管(guan)(guan)(guan)(guan)公(gong)稱(cheng)直徑的(de)(de)(de)(de)不同按對(dui)焊(han)(han)(han)(han)三通、對(dui)焊(han)(han)(han)(han)加強(qiang)管(guan)(guan)(guan)(guan)接頭、承(cheng)(cheng)插(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)螺(luo)紋連(lian)接三通、承(cheng)(cheng)插(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)螺(luo)紋加強(qiang)管(guan)(guan)(guan)(guan)接頭的(de)(de)(de)(de)順序選用。值得(de)注意(yi)的(de)(de)(de)(de)是在確(que)定(ding)支管(guan)(guan)(guan)(guan)連(lian)接件(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)表號(hao)時(shi)(shi)，應(ying)根(gen)據管(guan)(guan)(guan)(guan)子(zi)(zi)與(yu)(yu)管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)等(deng)強(qiang)度的(de)(de)(de)(de)原(yuan)則以及(ji)管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)與(yu)(yu)管(guan)(guan)(guan)(guan)子(zi)(zi)連(lian)接方式而定(ding)。例如，當(dang)(dang)(dang)(dang)管(guan)(guan)(guan)(guan)子(zi)(zi)與(yu)(yu)管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)采用對(dui)焊(han)(han)(han)(han)連(lian)接時(shi)(shi)，管(guan)(guan)(guan)(guan)子(zi)(zi)與(yu)(yu)管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)表號(hao)應(ying)一致；而當(dang)(dang)(dang)(dang)管(guan)(guan)(guan)(guan)子(zi)(zi)與(yu)(yu)管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)采用承(cheng)(cheng)插(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)螺(luo)紋連(lian)接時(shi)(shi)，標準的(de)(de)(de)(de)承(cheng)(cheng)插(cha)(cha)焊(han)(han)(han)(han)和螺(luo)紋管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)表號(hao)只(zhi)有Sch80、Sch60、XXS，最低的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)表號(hao)就是Sch80，也就是說(shuo)只(zhi)要當(dang)(dang)(dang)(dang)承(cheng)(cheng)插(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)螺(luo)紋管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)所連(lian)接的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)表號(hao)不大于Sch80時(shi)(shi)，承(cheng)(cheng)插(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)螺(luo)紋管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)表號(hao)就選Sch80。而當(dang)(dang)(dang)(dang)所連(lian)接的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)表號(hao)大于Sch80時(shi)(shi)，承(cheng)(cheng)插(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)螺(luo)紋管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)表號(hao)就選Sch60或(huo)(huo)XXS。

   f. 當(dang)對焊三通主管(guan)(guan)(guan)、支管(guan)(guan)(guan)所(suo)連(lian)接(jie)的管(guan)(guan)(guan)子的管(guan)(guan)(guan)子表號(hao)不同時，應(ying)注(zhu)意(yi)三通主管(guan)(guan)(guan)、支管(guan)(guan)(guan)端部的管(guan)(guan)(guan)子表號(hao)應(ying)分別(bie)與(yu)其所(suo)連(lian)接(jie)的管(guan)(guan)(guan)子的管(guan)(guan)(guan)子表號(hao)相同，這樣就非常方便(bian)管(guan)(guan)(guan)道施工，管(guan)(guan)(guan)件不必現場(chang)再打坡口。

 ③. 分支管(guan)與主管(guan)連接(jie)的管(guan)件選擇見表16.71。