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(de)選擇
a. 主要根據(ju)管(guan)(guan)道的(de)設(she)計(ji)溫度、設(she)計(ji)壓力、腐蝕余量等設(she)計(ji)條件確定的(de)。分(fen)(fen)(fen)支(zhi)的(de)方法：對(dui)于(yu)低(di)壓大直徑(jing)管(guan)(guan)則直接把分(fen)(fen)(fen)支(zhi)管(guan)(guan)焊于(yu)主管(guan)(guan)上，另(ling)外多數是利用分(fen)(fen)(fen)支(zhi)管(guan)(guan)件進行分(fen)(fen)(fen)支(zhi)。
b. 當從主(zhu)(zhu)管(guan)(guan)(guan)引出支(zhi)管(guan)(guan)(guan)時(shi)，支(zhi)管(guan)(guan)(guan)直(zhi)徑與主(zhu)(zhu)管(guan)(guan)(guan)直(zhi)徑的比值(zhi)大于等于0.5時(shi)，采(cai)用(yong)(yong)異徑三(san)通(tong)或(huo)等徑三(san)通(tong)，當主(zhu)(zhu)支(zhi)管(guan)(guan)(guan)為(wei)等徑時(shi)，應采(cai)用(yong)(yong)三(san)通(tong)。GB50316 規定：公(gong)稱壓力(li)大于或(huo)等于10MPa的管(guan)(guan)(guan)道，主(zhu)(zhu)支(zhi)管(guan)(guan)(guan)為(wei)異徑時(shi)，不宜采(cai)用(yong)(yong)焊(han)(han)接(jie)(jie)支(zhi)管(guan)(guan)(guan)，宜采(cai)用(yong)(yong)三(san)通(tong)或(huo)在(zai)主(zhu)(zhu)管(guan)(guan)(guan)上開(kai)孔并焊(han)(han)接(jie)(jie)支(zhi)管(guan)(guan)(guan)臺(tai)。當主(zhu)(zhu)管(guan)(guan)(guan)直(zhi)徑大于DN65而支(zhi)管(guan)(guan)(guan)直(zhi)徑為(wei)DN40及以下時(shi)，根據設計(ji)壓力(li)的大小，采(cai)用(yong)(yong)支(zhi)管(guan)(guan)(guan)臺(tai)或(huo)半管(guan)(guan)(guan)接(jie)(jie)頭(tou)。
c. 主(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)直徑(jing)(jing)(jing)小(xiao)于(yu)(yu)(yu)DN50時，支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)小(xiao)于(yu)(yu)(yu)主(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)，則用異(yi)徑(jing)(jing)(jing)三(san)(san)通(tong)或(huo)(huo)等(deng)(deng)徑(jing)(jing)(jing)三(san)(san)通(tong)加(jia)(jia)異(yi)徑(jing)(jing)(jing)短(duan)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)。設計壓力等(deng)(deng)于(yu)(yu)(yu)或(huo)(huo)大(da)于(yu)(yu)(yu)2.0MPa、設計溫度超過250℃以及支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)與主(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)公(gong)稱(cheng)直徑(jing)(jing)(jing)之比大(da)于(yu)(yu)(yu)0.8，或(huo)(huo)承受機(ji)械振(zhen)動、壓力脈動和溫度急劇變化的(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)道(dao)分支(zhi)(zhi)(zhi)(zhi)，應采(cai)用等(deng)(deng)徑(jing)(jing)(jing)異(yi)徑(jing)(jing)(jing)三(san)(san)通(tong)；公(gong)稱(cheng)直徑(jing)(jing)(jing)小(xiao)于(yu)(yu)(yu)或(huo)(huo)等(deng)(deng)于(yu)(yu)(yu)40mm的(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)道(dao)，應采(cai)用承插焊(han)（或(huo)(huo)螺(luo)(luo)(luo)(luo)紋）鍛制三(san)(san)通(tong)；公(gong)稱(cheng)直徑(jing)(jing)(jing)等(deng)(deng)于(yu)(yu)(yu)或(huo)(huo)大(da)于(yu)(yu)(yu)50mm的(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)道(dao)，應采(cai)用對(dui)(dui)(dui)焊(han)三(san)(san)通(tong)、對(dui)(dui)(dui)焊(han)加(jia)(jia)強管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)頭（對(dui)(dui)(dui)焊(han)支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)）或(huo)(huo)嵌入式（鞍型）支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)頭。支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)通(tong)過加(jia)(jia)強管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)頭（支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)）與主(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)連接(jie)是指將一個螺(luo)(luo)(luo)(luo)紋、承插焊(han)或(huo)(huo)對(dui)(dui)(dui)焊(han)的(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)頭或(huo)(huo)半管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)接(jie)頭（支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)）直接(jie)焊(han)于(yu)(yu)(yu)主(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)上(shang)而制成(cheng)，螺(luo)(luo)(luo)(luo)紋、承插焊(han)支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)用于(yu)(yu)(yu)直徑(jing)(jing)(jing)小(xiao)于(yu)(yu)(yu)等(deng)(deng)于(yu)(yu)(yu)DN40（NPS1/2）的(de)(de)支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)連接(jie)。螺(luo)(luo)(luo)(luo)紋、承插焊(han)支(zhi)(zhi)(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)(guan)臺(tai)(tai)在任何情況下其額定等(deng)(deng)級(ji)應大(da)于(yu)(yu)(yu)等(deng)(deng)于(yu)(yu)(yu)20001b。
d. 其他支(zhi)管連(lian)接可(ke)用(yong)直接焊(han)接，但必須(xu)經校核(he)后明(ming)確是否增加補強。直接焊(han)接在主(zhu)管上的(de)(de)(de)支(zhi)管連(lian)接，不宜用(yong)于有機械振(zhen)動(dong)、壓(ya)力(li)脈動(dong)和溫度急劇變(bian)化的(de)(de)(de)部位及(ji)設計溫度超(chao)過425℃的(de)(de)(de)管道，當支(zhi)管連(lian)接處承受(shou)由于支(zhi)管熱變(bian)形、外載荷及(ji)支(zhi)架位移等(deng)引起的(de)(de)(de)應力(li)時(shi)，應對附加載荷在支(zhi)管連(lian)接處產生的(de)(de)(de)影響進行分(fen)析并采取必要(yao)的(de)(de)(de)加強措施。
e. 實際設計過(guo)程中，主要依據管(guan)(guan)(guan)(guan)(guan)(guan)道等(deng)級中已(yi)經(jing)確定(ding)的(de)(de)(de)(de)法(fa)蘭壓(ya)力等(deng)級或(huo)(huo)(huo)公稱(cheng)(cheng)壓(ya)力（PN）來選用支管(guan)(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)(jie)件(jian)。一般(ban)情況下(xia)，當(dang)法(fa)蘭的(de)(de)(de)(de)公稱(cheng)(cheng)壓(ya)力PN≤2.5MPa時，支管(guan)(guan)(guan)(guan)(guan)(guan)直接(jie)(jie)(jie)焊(han)(han)(han)(han)接(jie)(jie)(jie)在主管(guan)(guan)(guan)(guan)(guan)(guan)上；當(dang)PN≥4.0MPa時，則(ze)根(gen)據主管(guan)(guan)(guan)(guan)(guan)(guan)支管(guan)(guan)(guan)(guan)(guan)(guan)公稱(cheng)(cheng)直徑的(de)(de)(de)(de)不同按對(dui)焊(han)(han)(han)(han)三(san)通(tong)、對(dui)焊(han)(han)(han)(han)加強管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)、承(cheng)插(cha)(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)(huo)螺(luo)(luo)紋(wen)連(lian)接(jie)(jie)(jie)三(san)通(tong)、承(cheng)插(cha)(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)(huo)螺(luo)(luo)紋(wen)加強管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)的(de)(de)(de)(de)順序選用。值得(de)注意的(de)(de)(de)(de)是在確定(ding)支管(guan)(guan)(guan)(guan)(guan)(guan)連(lian)接(jie)(jie)(jie)件(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)號(hao)時，應(ying)根(gen)據管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)與(yu)(yu)(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)等(deng)強度的(de)(de)(de)(de)原則(ze)以及管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)與(yu)(yu)(yu)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)連(lian)接(jie)(jie)(jie)方式而定(ding)。例(li)如，當(dang)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)與(yu)(yu)(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)采用對(dui)焊(han)(han)(han)(han)連(lian)接(jie)(jie)(jie)時，管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)與(yu)(yu)(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)號(hao)應(ying)一致(zhi)；而當(dang)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)與(yu)(yu)(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)采用承(cheng)插(cha)(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)(huo)螺(luo)(luo)紋(wen)連(lian)接(jie)(jie)(jie)時，標準的(de)(de)(de)(de)承(cheng)插(cha)(cha)(cha)焊(han)(han)(han)(han)和螺(luo)(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)號(hao)只(zhi)有(you)Sch80、Sch60、XXS，最(zui)低的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)號(hao)就是Sch80，也就是說(shuo)只(zhi)要當(dang)承(cheng)插(cha)(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)(huo)螺(luo)(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)所(suo)連(lian)接(jie)(jie)(jie)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)號(hao)不大(da)于(yu)Sch80時，承(cheng)插(cha)(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)(huo)螺(luo)(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)號(hao)就選Sch80。而當(dang)所(suo)連(lian)接(jie)(jie)(jie)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)號(hao)大(da)于(yu)Sch80時，承(cheng)插(cha)(cha)(cha)焊(han)(han)(han)(han)或(huo)(huo)(huo)螺(luo)(luo)紋(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)號(hao)就選Sch60或(huo)(huo)(huo)XXS。
f. 當(dang)對焊三通主管、支管所連接的管子(zi)(zi)的管子(zi)(zi)表號不同時，應(ying)注意三通主管、支管端部的管子(zi)(zi)表號應(ying)分別與其所連接的管子(zi)(zi)的管子(zi)(zi)表號相同，這(zhe)樣就非(fei)常方便(bian)管道施工(gong)，管件不必現場再打坡口。
③. 分支管與主(zhu)管連接的(de)管件選擇見表16.71。
