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(jian)的選擇
a. 主(zhu)要根據管道的(de)(de)設計(ji)(ji)溫度、設計(ji)(ji)壓力、腐蝕余(yu)量等設計(ji)(ji)條件(jian)(jian)確定的(de)(de)。分(fen)支(zhi)(zhi)的(de)(de)方法：對于低壓大直徑管則直接把分(fen)支(zhi)(zhi)管焊(han)于主(zhu)管上(shang)，另(ling)外(wai)多數是利用分(fen)支(zhi)(zhi)管件(jian)(jian)進行分(fen)支(zhi)(zhi)。
b. 當(dang)從主(zhu)管(guan)(guan)(guan)(guan)引出(chu)支(zhi)(zhi)管(guan)(guan)(guan)(guan)時(shi)，支(zhi)(zhi)管(guan)(guan)(guan)(guan)直徑(jing)與(yu)主(zhu)管(guan)(guan)(guan)(guan)直徑(jing)的比值大(da)于(yu)(yu)等于(yu)(yu)0.5時(shi)，采(cai)用異徑(jing)三通或等徑(jing)三通，當(dang)主(zhu)支(zhi)(zhi)管(guan)(guan)(guan)(guan)為(wei)等徑(jing)時(shi)，應(ying)采(cai)用三通。GB50316 規定(ding)：公稱壓力大(da)于(yu)(yu)或等于(yu)(yu)10MPa的管(guan)(guan)(guan)(guan)道(dao)，主(zhu)支(zhi)(zhi)管(guan)(guan)(guan)(guan)為(wei)異徑(jing)時(shi)，不宜(yi)采(cai)用焊接(jie)支(zhi)(zhi)管(guan)(guan)(guan)(guan)，宜(yi)采(cai)用三通或在主(zhu)管(guan)(guan)(guan)(guan)上開孔并焊接(jie)支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺。當(dang)主(zhu)管(guan)(guan)(guan)(guan)直徑(jing)大(da)于(yu)(yu)DN65而支(zhi)(zhi)管(guan)(guan)(guan)(guan)直徑(jing)為(wei)DN40及(ji)以下(xia)時(shi)，根據設(she)計壓力的大(da)小(xiao)，采(cai)用支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺或半管(guan)(guan)(guan)(guan)接(jie)頭。
c. 主(zhu)管(guan)(guan)(guan)(guan)(guan)直(zhi)徑(jing)(jing)小(xiao)(xiao)于(yu)(yu)(yu)(yu)DN50時，支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)小(xiao)(xiao)于(yu)(yu)(yu)(yu)主(zhu)管(guan)(guan)(guan)(guan)(guan)，則(ze)用(yong)(yong)異(yi)徑(jing)(jing)三(san)通或(huo)(huo)(huo)等徑(jing)(jing)三(san)通加異(yi)徑(jing)(jing)短管(guan)(guan)(guan)(guan)(guan)。設計壓力等于(yu)(yu)(yu)(yu)或(huo)(huo)(huo)大于(yu)(yu)(yu)(yu)2.0MPa、設計溫(wen)度(du)超過250℃以(yi)及支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)與(yu)主(zhu)管(guan)(guan)(guan)(guan)(guan)公稱(cheng)直(zhi)徑(jing)(jing)之比大于(yu)(yu)(yu)(yu)0.8，或(huo)(huo)(huo)承(cheng)受機械振(zhen)動(dong)、壓力脈動(dong)和(he)溫(wen)度(du)急劇變化的(de)(de)管(guan)(guan)(guan)(guan)(guan)道(dao)分支(zhi)(zhi)(zhi)(zhi)，應(ying)采(cai)用(yong)(yong)等徑(jing)(jing)異(yi)徑(jing)(jing)三(san)通；公稱(cheng)直(zhi)徑(jing)(jing)小(xiao)(xiao)于(yu)(yu)(yu)(yu)或(huo)(huo)(huo)等于(yu)(yu)(yu)(yu)40mm的(de)(de)管(guan)(guan)(guan)(guan)(guan)道(dao)，應(ying)采(cai)用(yong)(yong)承(cheng)插(cha)焊(han)（或(huo)(huo)(huo)螺紋(wen)）鍛制三(san)通；公稱(cheng)直(zhi)徑(jing)(jing)等于(yu)(yu)(yu)(yu)或(huo)(huo)(huo)大于(yu)(yu)(yu)(yu)50mm的(de)(de)管(guan)(guan)(guan)(guan)(guan)道(dao)，應(ying)采(cai)用(yong)(yong)對(dui)焊(han)三(san)通、對(dui)焊(han)加強管(guan)(guan)(guan)(guan)(guan)接頭（對(dui)焊(han)支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)）或(huo)(huo)(huo)嵌入式（鞍型）支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)接頭。支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)通過加強管(guan)(guan)(guan)(guan)(guan)接頭（支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)）與(yu)主(zhu)管(guan)(guan)(guan)(guan)(guan)連(lian)接是指將一個螺紋(wen)、承(cheng)插(cha)焊(han)或(huo)(huo)(huo)對(dui)焊(han)的(de)(de)管(guan)(guan)(guan)(guan)(guan)接頭或(huo)(huo)(huo)半管(guan)(guan)(guan)(guan)(guan)接頭（支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)）直(zhi)接焊(han)于(yu)(yu)(yu)(yu)主(zhu)管(guan)(guan)(guan)(guan)(guan)上而制成，螺紋(wen)、承(cheng)插(cha)焊(han)支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)用(yong)(yong)于(yu)(yu)(yu)(yu)直(zhi)徑(jing)(jing)小(xiao)(xiao)于(yu)(yu)(yu)(yu)等于(yu)(yu)(yu)(yu)DN40（NPS1/2）的(de)(de)支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)連(lian)接。螺紋(wen)、承(cheng)插(cha)焊(han)支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)在任何情況下其額定(ding)等級應(ying)大于(yu)(yu)(yu)(yu)等于(yu)(yu)(yu)(yu)20001b。
d. 其他支(zhi)管(guan)連(lian)接(jie)可(ke)用(yong)直接(jie)焊接(jie)，但(dan)必(bi)須經校核后明確是否增加補(bu)強(qiang)(qiang)。直接(jie)焊接(jie)在(zai)主(zhu)管(guan)上的(de)(de)支(zhi)管(guan)連(lian)接(jie)，不宜用(yong)于(yu)有(you)機械振動、壓力脈動和溫度急(ji)劇變(bian)化的(de)(de)部位(wei)及設(she)計溫度超過425℃的(de)(de)管(guan)道，當支(zhi)管(guan)連(lian)接(jie)處(chu)承受由(you)于(yu)支(zhi)管(guan)熱變(bian)形、外載荷及支(zhi)架位(wei)移等引起(qi)的(de)(de)應力時，應對附(fu)加載荷在(zai)支(zhi)管(guan)連(lian)接(jie)處(chu)產生的(de)(de)影響進(jin)行分析并采取必(bi)要(yao)的(de)(de)加強(qiang)(qiang)措施。
e. 實際設計過程中，主(zhu)要依據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)道(dao)等(deng)(deng)級中已經確定(ding)的(de)(de)法(fa)蘭壓(ya)力等(deng)(deng)級或(huo)(huo)公稱(cheng)壓(ya)力（PN）來選(xuan)(xuan)用(yong)支管(guan)(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)(jie)(jie)件(jian)(jian)(jian)(jian)(jian)。一般情況(kuang)下，當法(fa)蘭的(de)(de)公稱(cheng)壓(ya)力PN≤2.5MPa時(shi)，支管(guan)(guan)(guan)(guan)(guan)(guan)直接(jie)(jie)(jie)(jie)焊(han)(han)(han)(han)接(jie)(jie)(jie)(jie)在主(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)上；當PN≥4.0MPa時(shi)，則根據(ju)主(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)支管(guan)(guan)(guan)(guan)(guan)(guan)公稱(cheng)直徑的(de)(de)不同按對(dui)焊(han)(han)(han)(han)三通(tong)、對(dui)焊(han)(han)(han)(han)加(jia)強(qiang)管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)(jie)頭(tou)(tou)、承(cheng)插(cha)(cha)(cha)(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)螺(luo)(luo)紋(wen)(wen)連(lian)接(jie)(jie)(jie)(jie)三通(tong)、承(cheng)插(cha)(cha)(cha)(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)螺(luo)(luo)紋(wen)(wen)加(jia)強(qiang)管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)(jie)頭(tou)(tou)的(de)(de)順序選(xuan)(xuan)用(yong)。值得(de)注意的(de)(de)是在確定(ding)支管(guan)(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)(jie)(jie)件(jian)(jian)(jian)(jian)(jian)的(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)(biao)號(hao)時(shi)，應根據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)等(deng)(deng)強(qiang)度的(de)(de)原則以及管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)連(lian)接(jie)(jie)(jie)(jie)方式(shi)而定(ding)。例如，當管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)采用(yong)對(dui)焊(han)(han)(han)(han)連(lian)接(jie)(jie)(jie)(jie)時(shi)，管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)的(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)(biao)號(hao)應一致；而當管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)采用(yong)承(cheng)插(cha)(cha)(cha)(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)螺(luo)(luo)紋(wen)(wen)連(lian)接(jie)(jie)(jie)(jie)時(shi)，標準的(de)(de)承(cheng)插(cha)(cha)(cha)(cha)(cha)焊(han)(han)(han)(han)和螺(luo)(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)的(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)(biao)號(hao)只(zhi)有Sch80、Sch60、XXS，最低的(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)(biao)號(hao)就是Sch80，也就是說只(zhi)要當承(cheng)插(cha)(cha)(cha)(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)螺(luo)(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)所(suo)連(lian)接(jie)(jie)(jie)(jie)的(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)(biao)號(hao)不大于Sch80時(shi)，承(cheng)插(cha)(cha)(cha)(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)螺(luo)(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)的(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)(biao)號(hao)就選(xuan)(xuan)Sch80。而當所(suo)連(lian)接(jie)(jie)(jie)(jie)的(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)(biao)號(hao)大于Sch80時(shi)，承(cheng)插(cha)(cha)(cha)(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)螺(luo)(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)的(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)(biao)號(hao)就選(xuan)(xuan)Sch60或(huo)(huo)XXS。
f. 當對焊(han)三通主(zhu)管(guan)(guan)(guan)、支管(guan)(guan)(guan)所(suo)連接(jie)的(de)管(guan)(guan)(guan)子(zi)的(de)管(guan)(guan)(guan)子(zi)表(biao)號(hao)不同時，應(ying)注意三通主(zhu)管(guan)(guan)(guan)、支管(guan)(guan)(guan)端部的(de)管(guan)(guan)(guan)子(zi)表(biao)號(hao)應(ying)分別與其所(suo)連接(jie)的(de)管(guan)(guan)(guan)子(zi)的(de)管(guan)(guan)(guan)子(zi)表(biao)號(hao)相同，這樣就非常方便管(guan)(guan)(guan)道(dao)施工，管(guan)(guan)(guan)件不必現場再打坡(po)口。
③. 分(fen)支管與主管連接的管件(jian)選擇見(jian)表16.71。
