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(zhi)管連接件的(de)選擇

   a. 主要根據管(guan)道的(de)設計溫(wen)度、設計壓力、腐(fu)蝕(shi)余量(liang)等設計條件(jian)確定的(de)。分(fen)(fen)(fen)支的(de)方法：對于低壓大(da)直(zhi)徑(jing)管(guan)則(ze)直(zhi)接(jie)把分(fen)(fen)(fen)支管(guan)焊于主管(guan)上，另(ling)外多(duo)數是利用分(fen)(fen)(fen)支管(guan)件(jian)進行分(fen)(fen)(fen)支。

   b. 當(dang)從主管(guan)(guan)引出支(zhi)(zhi)管(guan)(guan)時(shi)，支(zhi)(zhi)管(guan)(guan)直徑(jing)(jing)與主管(guan)(guan)直徑(jing)(jing)的比值大于(yu)等(deng)(deng)于(yu)0.5時(shi)，采(cai)(cai)(cai)用(yong)異徑(jing)(jing)三(san)通(tong)或(huo)等(deng)(deng)徑(jing)(jing)三(san)通(tong)，當(dang)主支(zhi)(zhi)管(guan)(guan)為等(deng)(deng)徑(jing)(jing)時(shi)，應采(cai)(cai)(cai)用(yong)三(san)通(tong)。GB50316 規(gui)定：公稱壓力(li)大于(yu)或(huo)等(deng)(deng)于(yu)10MPa的管(guan)(guan)道，主支(zhi)(zhi)管(guan)(guan)為異徑(jing)(jing)時(shi)，不宜(yi)采(cai)(cai)(cai)用(yong)焊接支(zhi)(zhi)管(guan)(guan)，宜(yi)采(cai)(cai)(cai)用(yong)三(san)通(tong)或(huo)在主管(guan)(guan)上開孔(kong)并(bing)焊接支(zhi)(zhi)管(guan)(guan)臺。當(dang)主管(guan)(guan)直徑(jing)(jing)大于(yu)DN65而支(zhi)(zhi)管(guan)(guan)直徑(jing)(jing)為DN40及(ji)以下(xia)時(shi)，根據設計壓力(li)的大小，采(cai)(cai)(cai)用(yong)支(zhi)(zhi)管(guan)(guan)臺或(huo)半管(guan)(guan)接頭。

   c. 主(zhu)管(guan)(guan)(guan)(guan)直徑(jing)(jing)(jing)(jing)小(xiao)于(yu)(yu)DN50時(shi)，支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)小(xiao)于(yu)(yu)主(zhu)管(guan)(guan)(guan)(guan)，則(ze)用異徑(jing)(jing)(jing)(jing)三(san)通(tong)或(huo)(huo)等(deng)(deng)徑(jing)(jing)(jing)(jing)三(san)通(tong)加(jia)異徑(jing)(jing)(jing)(jing)短管(guan)(guan)(guan)(guan)。設計(ji)壓(ya)力等(deng)(deng)于(yu)(yu)或(huo)(huo)大于(yu)(yu)2.0MPa、設計(ji)溫度(du)(du)超過250℃以及支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)與主(zhu)管(guan)(guan)(guan)(guan)公稱(cheng)直徑(jing)(jing)(jing)(jing)之(zhi)比(bi)大于(yu)(yu)0.8，或(huo)(huo)承(cheng)受機械振(zhen)動、壓(ya)力脈(mo)動和(he)溫度(du)(du)急劇變化(hua)的(de)管(guan)(guan)(guan)(guan)道(dao)分(fen)支(zhi)(zhi)(zhi)，應(ying)采用等(deng)(deng)徑(jing)(jing)(jing)(jing)異徑(jing)(jing)(jing)(jing)三(san)通(tong)；公稱(cheng)直徑(jing)(jing)(jing)(jing)小(xiao)于(yu)(yu)或(huo)(huo)等(deng)(deng)于(yu)(yu)40mm的(de)管(guan)(guan)(guan)(guan)道(dao)，應(ying)采用承(cheng)插焊(han)(han)(han)(han)（或(huo)(huo)螺(luo)(luo)紋(wen)(wen)）鍛制三(san)通(tong)；公稱(cheng)直徑(jing)(jing)(jing)(jing)等(deng)(deng)于(yu)(yu)或(huo)(huo)大于(yu)(yu)50mm的(de)管(guan)(guan)(guan)(guan)道(dao)，應(ying)采用對(dui)焊(han)(han)(han)(han)三(san)通(tong)、對(dui)焊(han)(han)(han)(han)加(jia)強管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)（對(dui)焊(han)(han)(han)(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)(tai)）或(huo)(huo)嵌入式（鞍型）支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)。支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)通(tong)過加(jia)強管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)（支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)(tai)）與主(zhu)管(guan)(guan)(guan)(guan)連接(jie)是(shi)指將一個螺(luo)(luo)紋(wen)(wen)、承(cheng)插焊(han)(han)(han)(han)或(huo)(huo)對(dui)焊(han)(han)(han)(han)的(de)管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)或(huo)(huo)半管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)（支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)(tai)）直接(jie)焊(han)(han)(han)(han)于(yu)(yu)主(zhu)管(guan)(guan)(guan)(guan)上而制成(cheng)，螺(luo)(luo)紋(wen)(wen)、承(cheng)插焊(han)(han)(han)(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)(tai)用于(yu)(yu)直徑(jing)(jing)(jing)(jing)小(xiao)于(yu)(yu)等(deng)(deng)于(yu)(yu)DN40（NPS1/2）的(de)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)連接(jie)。螺(luo)(luo)紋(wen)(wen)、承(cheng)插焊(han)(han)(han)(han)支(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)(tai)在任何情(qing)況下其額定等(deng)(deng)級應(ying)大于(yu)(yu)等(deng)(deng)于(yu)(yu)20001b。

   d. 其(qi)他支管(guan)連(lian)(lian)接(jie)(jie)可(ke)用直接(jie)(jie)焊接(jie)(jie)，但必(bi)須經(jing)校核后明(ming)確是否增加補強(qiang)。直接(jie)(jie)焊接(jie)(jie)在主管(guan)上的(de)(de)支管(guan)連(lian)(lian)接(jie)(jie)，不宜用于有機械振動(dong)、壓力(li)脈動(dong)和(he)溫度(du)急劇變化的(de)(de)部位(wei)及設計溫度(du)超過425℃的(de)(de)管(guan)道(dao)，當支管(guan)連(lian)(lian)接(jie)(jie)處(chu)承受由于支管(guan)熱變形、外載荷(he)及支架(jia)位(wei)移等引起的(de)(de)應力(li)時，應對附加載荷(he)在支管(guan)連(lian)(lian)接(jie)(jie)處(chu)產生的(de)(de)影響進行分析并采(cai)取必(bi)要(yao)的(de)(de)加強(qiang)措(cuo)施(shi)。

   e. 實際(ji)設計過(guo)程中，主要依據管(guan)(guan)(guan)(guan)(guan)道(dao)等級中已經確定(ding)的(de)(de)(de)法(fa)蘭壓力等級或(huo)(huo)公稱壓力（PN）來選用支(zhi)管(guan)(guan)(guan)(guan)(guan)連(lian)(lian)接(jie)(jie)(jie)件(jian)。一般情況下，當(dang)法(fa)蘭的(de)(de)(de)公稱壓力PN≤2.5MPa時，支(zhi)管(guan)(guan)(guan)(guan)(guan)直接(jie)(jie)(jie)焊(han)接(jie)(jie)(jie)在(zai)主管(guan)(guan)(guan)(guan)(guan)上；當(dang)PN≥4.0MPa時，則根據主管(guan)(guan)(guan)(guan)(guan)支(zhi)管(guan)(guan)(guan)(guan)(guan)公稱直徑(jing)的(de)(de)(de)不(bu)同按對(dui)焊(han)三(san)通、對(dui)焊(han)加(jia)強管(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)、承(cheng)(cheng)插焊(han)或(huo)(huo)螺(luo)紋(wen)連(lian)(lian)接(jie)(jie)(jie)三(san)通、承(cheng)(cheng)插焊(han)或(huo)(huo)螺(luo)紋(wen)加(jia)強管(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)的(de)(de)(de)順序選用。值(zhi)得(de)注意的(de)(de)(de)是在(zai)確定(ding)支(zhi)管(guan)(guan)(guan)(guan)(guan)連(lian)(lian)接(jie)(jie)(jie)件(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號時，應根據管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)與管(guan)(guan)(guan)(guan)(guan)件(jian)等強度的(de)(de)(de)原則以及管(guan)(guan)(guan)(guan)(guan)件(jian)與管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)連(lian)(lian)接(jie)(jie)(jie)方式而定(ding)。例如，當(dang)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)與管(guan)(guan)(guan)(guan)(guan)件(jian)采用對(dui)焊(han)連(lian)(lian)接(jie)(jie)(jie)時，管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)與管(guan)(guan)(guan)(guan)(guan)件(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號應一致；而當(dang)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)與管(guan)(guan)(guan)(guan)(guan)件(jian)采用承(cheng)(cheng)插焊(han)或(huo)(huo)螺(luo)紋(wen)連(lian)(lian)接(jie)(jie)(jie)時，標(biao)準(zhun)的(de)(de)(de)承(cheng)(cheng)插焊(han)和(he)螺(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號只有Sch80、Sch60、XXS，最低(di)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號就是Sch80，也(ye)就是說只要當(dang)承(cheng)(cheng)插焊(han)或(huo)(huo)螺(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)所(suo)連(lian)(lian)接(jie)(jie)(jie)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號不(bu)大于Sch80時，承(cheng)(cheng)插焊(han)或(huo)(huo)螺(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號就選Sch80。而當(dang)所(suo)連(lian)(lian)接(jie)(jie)(jie)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號大于Sch80時，承(cheng)(cheng)插焊(han)或(huo)(huo)螺(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號就選Sch60或(huo)(huo)XXS。

   f. 當(dang)對焊三(san)通主(zhu)管(guan)(guan)(guan)(guan)(guan)、支(zhi)管(guan)(guan)(guan)(guan)(guan)所連(lian)接的管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)的管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號(hao)不同(tong)時，應注意三(san)通主(zhu)管(guan)(guan)(guan)(guan)(guan)、支(zhi)管(guan)(guan)(guan)(guan)(guan)端部的管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號(hao)應分別(bie)與(yu)其所連(lian)接的管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)的管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號(hao)相(xiang)同(tong)，這樣就非常方便(bian)管(guan)(guan)(guan)(guan)(guan)道施(shi)工，管(guan)(guan)(guan)(guan)(guan)件不必現場(chang)再打坡口。

 ③. 分支管與主管連接的管件選擇見表16.71。