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. 支管連接件的選擇
a. 主要根據管(guan)道的設(she)計溫度(du)、設(she)計壓力、腐蝕余量等設(she)計條(tiao)件確定的。分支(zhi)的方法：對于低壓大(da)直徑管(guan)則(ze)直接把分支(zhi)管(guan)焊于主管(guan)上(shang)，另外多數是利用分支(zhi)管(guan)件進(jin)行分支(zhi)。
b. 當(dang)從主(zhu)(zhu)管(guan)引出支(zhi)(zhi)(zhi)(zhi)管(guan)時(shi)，支(zhi)(zhi)(zhi)(zhi)管(guan)直(zhi)徑(jing)(jing)(jing)與(yu)主(zhu)(zhu)管(guan)直(zhi)徑(jing)(jing)(jing)的比值大于等(deng)于0.5時(shi)，采(cai)(cai)用(yong)異徑(jing)(jing)(jing)三(san)通或(huo)等(deng)徑(jing)(jing)(jing)三(san)通，當(dang)主(zhu)(zhu)支(zhi)(zhi)(zhi)(zhi)管(guan)為(wei)等(deng)徑(jing)(jing)(jing)時(shi)，應采(cai)(cai)用(yong)三(san)通。GB50316 規(gui)定：公(gong)稱壓力大于或(huo)等(deng)于10MPa的管(guan)道，主(zhu)(zhu)支(zhi)(zhi)(zhi)(zhi)管(guan)為(wei)異徑(jing)(jing)(jing)時(shi)，不(bu)宜采(cai)(cai)用(yong)焊接支(zhi)(zhi)(zhi)(zhi)管(guan)，宜采(cai)(cai)用(yong)三(san)通或(huo)在主(zhu)(zhu)管(guan)上開孔并(bing)焊接支(zhi)(zhi)(zhi)(zhi)管(guan)臺。當(dang)主(zhu)(zhu)管(guan)直(zhi)徑(jing)(jing)(jing)大于DN65而支(zhi)(zhi)(zhi)(zhi)管(guan)直(zhi)徑(jing)(jing)(jing)為(wei)DN40及(ji)以下(xia)時(shi)，根據設計壓力的大小，采(cai)(cai)用(yong)支(zhi)(zhi)(zhi)(zhi)管(guan)臺或(huo)半管(guan)接頭(tou)。
c. 主(zhu)(zhu)(zhu)管(guan)(guan)(guan)(guan)直(zhi)徑(jing)小于(yu)(yu)(yu)DN50時，支(zhi)管(guan)(guan)(guan)(guan)小于(yu)(yu)(yu)主(zhu)(zhu)(zhu)管(guan)(guan)(guan)(guan)，則(ze)用(yong)異徑(jing)三(san)(san)(san)通(tong)或(huo)(huo)(huo)等(deng)(deng)徑(jing)三(san)(san)(san)通(tong)加異徑(jing)短(duan)管(guan)(guan)(guan)(guan)。設計(ji)壓力等(deng)(deng)于(yu)(yu)(yu)或(huo)(huo)(huo)大于(yu)(yu)(yu)2.0MPa、設計(ji)溫(wen)度(du)超過250℃以及(ji)支(zhi)管(guan)(guan)(guan)(guan)與主(zhu)(zhu)(zhu)管(guan)(guan)(guan)(guan)公稱直(zhi)徑(jing)之比大于(yu)(yu)(yu)0.8，或(huo)(huo)(huo)承(cheng)受機械(xie)振動、壓力脈動和溫(wen)度(du)急劇變化的(de)(de)管(guan)(guan)(guan)(guan)道(dao)分支(zhi)，應(ying)采(cai)用(yong)等(deng)(deng)徑(jing)異徑(jing)三(san)(san)(san)通(tong)；公稱直(zhi)徑(jing)小于(yu)(yu)(yu)或(huo)(huo)(huo)等(deng)(deng)于(yu)(yu)(yu)40mm的(de)(de)管(guan)(guan)(guan)(guan)道(dao)，應(ying)采(cai)用(yong)承(cheng)插(cha)(cha)焊（或(huo)(huo)(huo)螺紋）鍛制三(san)(san)(san)通(tong)；公稱直(zhi)徑(jing)等(deng)(deng)于(yu)(yu)(yu)或(huo)(huo)(huo)大于(yu)(yu)(yu)50mm的(de)(de)管(guan)(guan)(guan)(guan)道(dao)，應(ying)采(cai)用(yong)對焊三(san)(san)(san)通(tong)、對焊加強(qiang)(qiang)管(guan)(guan)(guan)(guan)接(jie)頭（對焊支(zhi)管(guan)(guan)(guan)(guan)臺(tai)）或(huo)(huo)(huo)嵌入式（鞍型(xing)）支(zhi)管(guan)(guan)(guan)(guan)接(jie)頭。支(zhi)管(guan)(guan)(guan)(guan)通(tong)過加強(qiang)(qiang)管(guan)(guan)(guan)(guan)接(jie)頭（支(zhi)管(guan)(guan)(guan)(guan)臺(tai)）與主(zhu)(zhu)(zhu)管(guan)(guan)(guan)(guan)連(lian)接(jie)是(shi)指(zhi)將一個(ge)螺紋、承(cheng)插(cha)(cha)焊或(huo)(huo)(huo)對焊的(de)(de)管(guan)(guan)(guan)(guan)接(jie)頭或(huo)(huo)(huo)半管(guan)(guan)(guan)(guan)接(jie)頭（支(zhi)管(guan)(guan)(guan)(guan)臺(tai)）直(zhi)接(jie)焊于(yu)(yu)(yu)主(zhu)(zhu)(zhu)管(guan)(guan)(guan)(guan)上而制成(cheng)，螺紋、承(cheng)插(cha)(cha)焊支(zhi)管(guan)(guan)(guan)(guan)臺(tai)用(yong)于(yu)(yu)(yu)直(zhi)徑(jing)小于(yu)(yu)(yu)等(deng)(deng)于(yu)(yu)(yu)DN40（NPS1/2）的(de)(de)支(zhi)管(guan)(guan)(guan)(guan)連(lian)接(jie)。螺紋、承(cheng)插(cha)(cha)焊支(zhi)管(guan)(guan)(guan)(guan)臺(tai)在任何情(qing)況(kuang)下其(qi)額定等(deng)(deng)級應(ying)大于(yu)(yu)(yu)等(deng)(deng)于(yu)(yu)(yu)20001b。
d. 其(qi)他支(zhi)管(guan)(guan)連(lian)接(jie)(jie)可用直接(jie)(jie)焊(han)接(jie)(jie)，但必須經校核后明確是否增加補強(qiang)。直接(jie)(jie)焊(han)接(jie)(jie)在(zai)主管(guan)(guan)上的(de)支(zhi)管(guan)(guan)連(lian)接(jie)(jie)，不宜用于有機(ji)械振(zhen)動(dong)、壓(ya)力脈動(dong)和溫度急(ji)劇變化(hua)的(de)部(bu)位及(ji)設計溫度超過425℃的(de)管(guan)(guan)道，當支(zhi)管(guan)(guan)連(lian)接(jie)(jie)處(chu)承受(shou)由(you)于支(zhi)管(guan)(guan)熱變形、外載(zai)荷及(ji)支(zhi)架位移等(deng)引起的(de)應力時，應對附加載(zai)荷在(zai)支(zhi)管(guan)(guan)連(lian)接(jie)(jie)處(chu)產生的(de)影響(xiang)進行分析(xi)并采取必要的(de)加強(qiang)措施。
e. 實際設(she)計過程中(zhong)，主要依據管(guan)(guan)(guan)(guan)道(dao)等(deng)(deng)級中(zhong)已經確(que)定的(de)(de)(de)(de)(de)(de)法蘭(lan)壓力等(deng)(deng)級或(huo)公稱壓力（PN）來選用支(zhi)(zhi)管(guan)(guan)(guan)(guan)連(lian)(lian)(lian)(lian)接(jie)(jie)(jie)(jie)件(jian)(jian)(jian)。一(yi)般(ban)情況下，當(dang)法蘭(lan)的(de)(de)(de)(de)(de)(de)公稱壓力PN≤2.5MPa時(shi)(shi)，支(zhi)(zhi)管(guan)(guan)(guan)(guan)直接(jie)(jie)(jie)(jie)焊(han)(han)接(jie)(jie)(jie)(jie)在(zai)主管(guan)(guan)(guan)(guan)上；當(dang)PN≥4.0MPa時(shi)(shi)，則根據主管(guan)(guan)(guan)(guan)支(zhi)(zhi)管(guan)(guan)(guan)(guan)公稱直徑的(de)(de)(de)(de)(de)(de)不(bu)同按對焊(han)(han)三通、對焊(han)(han)加(jia)強(qiang)管(guan)(guan)(guan)(guan)接(jie)(jie)(jie)(jie)頭、承(cheng)(cheng)(cheng)插(cha)焊(han)(han)或(huo)螺(luo)紋(wen)(wen)連(lian)(lian)(lian)(lian)接(jie)(jie)(jie)(jie)三通、承(cheng)(cheng)(cheng)插(cha)焊(han)(han)或(huo)螺(luo)紋(wen)(wen)加(jia)強(qiang)管(guan)(guan)(guan)(guan)接(jie)(jie)(jie)(jie)頭的(de)(de)(de)(de)(de)(de)順(shun)序選用。值得(de)注(zhu)意的(de)(de)(de)(de)(de)(de)是在(zai)確(que)定支(zhi)(zhi)管(guan)(guan)(guan)(guan)連(lian)(lian)(lian)(lian)接(jie)(jie)(jie)(jie)件(jian)(jian)(jian)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)時(shi)(shi)，應根據管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)等(deng)(deng)強(qiang)度的(de)(de)(de)(de)(de)(de)原則以及管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)與(yu)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)連(lian)(lian)(lian)(lian)接(jie)(jie)(jie)(jie)方(fang)式(shi)而(er)定。例如，當(dang)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)采(cai)(cai)用對焊(han)(han)連(lian)(lian)(lian)(lian)接(jie)(jie)(jie)(jie)時(shi)(shi)，管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)應一(yi)致；而(er)當(dang)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)采(cai)(cai)用承(cheng)(cheng)(cheng)插(cha)焊(han)(han)或(huo)螺(luo)紋(wen)(wen)連(lian)(lian)(lian)(lian)接(jie)(jie)(jie)(jie)時(shi)(shi)，標準的(de)(de)(de)(de)(de)(de)承(cheng)(cheng)(cheng)插(cha)焊(han)(han)和螺(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)只有Sch80、Sch60、XXS，最低的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)就是Sch80，也就是說只要當(dang)承(cheng)(cheng)(cheng)插(cha)焊(han)(han)或(huo)螺(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)所(suo)連(lian)(lian)(lian)(lian)接(jie)(jie)(jie)(jie)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)不(bu)大于Sch80時(shi)(shi)，承(cheng)(cheng)(cheng)插(cha)焊(han)(han)或(huo)螺(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)就選Sch80。而(er)當(dang)所(suo)連(lian)(lian)(lian)(lian)接(jie)(jie)(jie)(jie)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)大于Sch80時(shi)(shi)，承(cheng)(cheng)(cheng)插(cha)焊(han)(han)或(huo)螺(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)件(jian)(jian)(jian)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號(hao)就選Sch60或(huo)XXS。
f. 當對(dui)焊三(san)通(tong)主(zhu)管(guan)、支管(guan)所連接的(de)管(guan)子(zi)的(de)管(guan)子(zi)表號不同時，應注意(yi)三(san)通(tong)主(zhu)管(guan)、支管(guan)端部的(de)管(guan)子(zi)表號應分(fen)別與(yu)其所連接的(de)管(guan)子(zi)的(de)管(guan)子(zi)表號相同，這(zhe)樣就(jiu)非(fei)常(chang)方便管(guan)道(dao)施工，管(guan)件不必現(xian)場再打坡口。
③. 分支管(guan)與主管(guan)連接的管(guan)件選(xuan)擇見表16.71。
