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(xuan)擇(ze)
a. 主要根據管(guan)道的(de)(de)設計(ji)溫(wen)度、設計(ji)壓力、腐(fu)蝕余量等設計(ji)條件確定(ding)的(de)(de)。分(fen)支(zhi)的(de)(de)方(fang)法：對于低(di)壓大直(zhi)(zhi)徑管(guan)則直(zhi)(zhi)接(jie)把分(fen)支(zhi)管(guan)焊于主管(guan)上，另外(wai)多數(shu)是利用(yong)分(fen)支(zhi)管(guan)件進行分(fen)支(zhi)。
b. 當從主管(guan)(guan)引出(chu)支(zhi)(zhi)管(guan)(guan)時(shi)(shi)(shi)，支(zhi)(zhi)管(guan)(guan)直徑(jing)(jing)與(yu)主管(guan)(guan)直徑(jing)(jing)的比(bi)值大(da)于(yu)等于(yu)0.5時(shi)(shi)(shi)，采(cai)用異徑(jing)(jing)三(san)通(tong)或(huo)等徑(jing)(jing)三(san)通(tong)，當主支(zhi)(zhi)管(guan)(guan)為等徑(jing)(jing)時(shi)(shi)(shi)，應采(cai)用三(san)通(tong)。GB50316 規定：公(gong)稱(cheng)壓力大(da)于(yu)或(huo)等于(yu)10MPa的管(guan)(guan)道，主支(zhi)(zhi)管(guan)(guan)為異徑(jing)(jing)時(shi)(shi)(shi)，不(bu)宜采(cai)用焊接支(zhi)(zhi)管(guan)(guan)，宜采(cai)用三(san)通(tong)或(huo)在(zai)主管(guan)(guan)上開孔并焊接支(zhi)(zhi)管(guan)(guan)臺(tai)。當主管(guan)(guan)直徑(jing)(jing)大(da)于(yu)DN65而支(zhi)(zhi)管(guan)(guan)直徑(jing)(jing)為DN40及以下時(shi)(shi)(shi)，根據設計(ji)壓力的大(da)小(xiao)，采(cai)用支(zhi)(zhi)管(guan)(guan)臺(tai)或(huo)半(ban)管(guan)(guan)接頭(tou)。
c. 主管(guan)(guan)(guan)(guan)直(zhi)(zhi)徑(jing)(jing)小于(yu)(yu)(yu)DN50時，支(zhi)(zhi)管(guan)(guan)(guan)(guan)小于(yu)(yu)(yu)主管(guan)(guan)(guan)(guan)，則用異(yi)徑(jing)(jing)三(san)通(tong)或(huo)(huo)等徑(jing)(jing)三(san)通(tong)加(jia)(jia)異(yi)徑(jing)(jing)短(duan)管(guan)(guan)(guan)(guan)。設計壓力(li)等于(yu)(yu)(yu)或(huo)(huo)大于(yu)(yu)(yu)2.0MPa、設計溫(wen)度超過250℃以及支(zhi)(zhi)管(guan)(guan)(guan)(guan)與主管(guan)(guan)(guan)(guan)公稱(cheng)(cheng)直(zhi)(zhi)徑(jing)(jing)之(zhi)比大于(yu)(yu)(yu)0.8，或(huo)(huo)承受機械振動、壓力(li)脈動和溫(wen)度急劇變化的(de)(de)管(guan)(guan)(guan)(guan)道(dao)分(fen)支(zhi)(zhi)，應采(cai)用等徑(jing)(jing)異(yi)徑(jing)(jing)三(san)通(tong)；公稱(cheng)(cheng)直(zhi)(zhi)徑(jing)(jing)小于(yu)(yu)(yu)或(huo)(huo)等于(yu)(yu)(yu)40mm的(de)(de)管(guan)(guan)(guan)(guan)道(dao)，應采(cai)用承插焊(han)（或(huo)(huo)螺紋(wen)）鍛制三(san)通(tong)；公稱(cheng)(cheng)直(zhi)(zhi)徑(jing)(jing)等于(yu)(yu)(yu)或(huo)(huo)大于(yu)(yu)(yu)50mm的(de)(de)管(guan)(guan)(guan)(guan)道(dao)，應采(cai)用對焊(han)三(san)通(tong)、對焊(han)加(jia)(jia)強管(guan)(guan)(guan)(guan)接(jie)頭（對焊(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)(tai)）或(huo)(huo)嵌入式(shi)（鞍型）支(zhi)(zhi)管(guan)(guan)(guan)(guan)接(jie)頭。支(zhi)(zhi)管(guan)(guan)(guan)(guan)通(tong)過加(jia)(jia)強管(guan)(guan)(guan)(guan)接(jie)頭（支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)(tai)）與主管(guan)(guan)(guan)(guan)連(lian)接(jie)是指將一個螺紋(wen)、承插焊(han)或(huo)(huo)對焊(han)的(de)(de)管(guan)(guan)(guan)(guan)接(jie)頭或(huo)(huo)半管(guan)(guan)(guan)(guan)接(jie)頭（支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)(tai)）直(zhi)(zhi)接(jie)焊(han)于(yu)(yu)(yu)主管(guan)(guan)(guan)(guan)上而制成，螺紋(wen)、承插焊(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)(tai)用于(yu)(yu)(yu)直(zhi)(zhi)徑(jing)(jing)小于(yu)(yu)(yu)等于(yu)(yu)(yu)DN40（NPS1/2）的(de)(de)支(zhi)(zhi)管(guan)(guan)(guan)(guan)連(lian)接(jie)。螺紋(wen)、承插焊(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)(tai)在任何情況下(xia)其額定等級應大于(yu)(yu)(yu)等于(yu)(yu)(yu)20001b。
d. 其他支管(guan)(guan)(guan)連接(jie)(jie)可用直(zhi)接(jie)(jie)焊(han)接(jie)(jie)，但必(bi)須經校核(he)后(hou)明確是(shi)否增(zeng)加補強(qiang)(qiang)。直(zhi)接(jie)(jie)焊(han)接(jie)(jie)在(zai)主(zhu)管(guan)(guan)(guan)上的(de)支管(guan)(guan)(guan)連接(jie)(jie)，不(bu)宜用于(yu)有機(ji)械振(zhen)動、壓力(li)脈(mo)動和溫度(du)急(ji)劇變化的(de)部位(wei)及設計溫度(du)超過425℃的(de)管(guan)(guan)(guan)道，當支管(guan)(guan)(guan)連接(jie)(jie)處承(cheng)受(shou)由于(yu)支管(guan)(guan)(guan)熱變形、外載荷(he)及支架位(wei)移等引起的(de)應力(li)時，應對附加載荷(he)在(zai)支管(guan)(guan)(guan)連接(jie)(jie)處產生的(de)影響進行分析并(bing)采取必(bi)要的(de)加強(qiang)(qiang)措(cuo)施。
e. 實際設(she)計(ji)過程中，主要(yao)依據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)道等(deng)級中已經確定的(de)(de)(de)(de)法(fa)蘭壓(ya)力(li)(li)等(deng)級或(huo)公(gong)(gong)稱壓(ya)力(li)(li)（PN）來選(xuan)用(yong)支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)連接(jie)(jie)(jie)(jie)件(jian)(jian)(jian)(jian)(jian)。一(yi)般情況下，當(dang)(dang)法(fa)蘭的(de)(de)(de)(de)公(gong)(gong)稱壓(ya)力(li)(li)PN≤2.5MPa時，支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)直(zhi)接(jie)(jie)(jie)(jie)焊(han)接(jie)(jie)(jie)(jie)在主管(guan)(guan)(guan)(guan)(guan)(guan)上；當(dang)(dang)PN≥4.0MPa時，則根(gen)據(ju)主管(guan)(guan)(guan)(guan)(guan)(guan)支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)公(gong)(gong)稱直(zhi)徑的(de)(de)(de)(de)不同(tong)按對焊(han)三通、對焊(han)加強管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)(jie)頭、承(cheng)插(cha)(cha)焊(han)或(huo)螺(luo)紋(wen)(wen)連接(jie)(jie)(jie)(jie)三通、承(cheng)插(cha)(cha)焊(han)或(huo)螺(luo)紋(wen)(wen)加強管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)(jie)頭的(de)(de)(de)(de)順序選(xuan)用(yong)。值(zhi)得注意的(de)(de)(de)(de)是(shi)(shi)在確定支(zhi)(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)連接(jie)(jie)(jie)(jie)件(jian)(jian)(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)(biao)號(hao)(hao)時，應根(gen)據(ju)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)等(deng)強度的(de)(de)(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)連接(jie)(jie)(jie)(jie)方式而定。例如，當(dang)(dang)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)采用(yong)對焊(han)連接(jie)(jie)(jie)(jie)時，管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)(biao)號(hao)(hao)應一(yi)致(zhi)；而當(dang)(dang)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)采用(yong)承(cheng)插(cha)(cha)焊(han)或(huo)螺(luo)紋(wen)(wen)連接(jie)(jie)(jie)(jie)時，標準的(de)(de)(de)(de)承(cheng)插(cha)(cha)焊(han)和螺(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)(biao)號(hao)(hao)只(zhi)有Sch80、Sch60、XXS，最低的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)(biao)號(hao)(hao)就(jiu)(jiu)是(shi)(shi)Sch80，也就(jiu)(jiu)是(shi)(shi)說(shuo)只(zhi)要(yao)當(dang)(dang)承(cheng)插(cha)(cha)焊(han)或(huo)螺(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)所連接(jie)(jie)(jie)(jie)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)(biao)號(hao)(hao)不大于(yu)Sch80時，承(cheng)插(cha)(cha)焊(han)或(huo)螺(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)(biao)號(hao)(hao)就(jiu)(jiu)選(xuan)Sch80。而當(dang)(dang)所連接(jie)(jie)(jie)(jie)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)(biao)號(hao)(hao)大于(yu)Sch80時，承(cheng)插(cha)(cha)焊(han)或(huo)螺(luo)紋(wen)(wen)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)(jian)(jian)(jian)的(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)表(biao)(biao)號(hao)(hao)就(jiu)(jiu)選(xuan)Sch60或(huo)XXS。
f. 當對焊(han)三(san)通主管(guan)(guan)(guan)(guan)、支管(guan)(guan)(guan)(guan)所連(lian)接(jie)的管(guan)(guan)(guan)(guan)子(zi)的管(guan)(guan)(guan)(guan)子(zi)表號不(bu)同(tong)時，應(ying)注意三(san)通主管(guan)(guan)(guan)(guan)、支管(guan)(guan)(guan)(guan)端部(bu)的管(guan)(guan)(guan)(guan)子(zi)表號應(ying)分(fen)別與其(qi)所連(lian)接(jie)的管(guan)(guan)(guan)(guan)子(zi)的管(guan)(guan)(guan)(guan)子(zi)表號相同(tong)，這(zhe)樣就非常方便管(guan)(guan)(guan)(guan)道施工(gong)，管(guan)(guan)(guan)(guan)件不(bu)必(bi)現(xian)場再打坡口(kou)。
③. 分支管(guan)與(yu)主管(guan)連接的管(guan)件選擇(ze)見表16.71。
