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
a. 主(zhu)要(yao)根據管(guan)(guan)道的設計溫(wen)度(du)、設計壓力、腐(fu)蝕余量等設計條件確定的。分(fen)(fen)(fen)支(zhi)的方法：對于(yu)低壓大直(zhi)徑(jing)管(guan)(guan)則直(zhi)接把分(fen)(fen)(fen)支(zhi)管(guan)(guan)焊于(yu)主(zhu)管(guan)(guan)上(shang)，另(ling)外多數是利(li)用(yong)分(fen)(fen)(fen)支(zhi)管(guan)(guan)件進行分(fen)(fen)(fen)支(zhi)。
b. 當(dang)從(cong)主管(guan)(guan)(guan)引出支管(guan)(guan)(guan)時(shi)(shi)，支管(guan)(guan)(guan)直徑(jing)(jing)與(yu)主管(guan)(guan)(guan)直徑(jing)(jing)的比值大于(yu)(yu)(yu)等(deng)于(yu)(yu)(yu)0.5時(shi)(shi)，采(cai)(cai)用異(yi)徑(jing)(jing)三(san)通(tong)或等(deng)徑(jing)(jing)三(san)通(tong)，當(dang)主支管(guan)(guan)(guan)為(wei)等(deng)徑(jing)(jing)時(shi)(shi)，應(ying)采(cai)(cai)用三(san)通(tong)。GB50316 規定：公稱壓力大于(yu)(yu)(yu)或等(deng)于(yu)(yu)(yu)10MPa的管(guan)(guan)(guan)道(dao)，主支管(guan)(guan)(guan)為(wei)異(yi)徑(jing)(jing)時(shi)(shi)，不宜采(cai)(cai)用焊接支管(guan)(guan)(guan)，宜采(cai)(cai)用三(san)通(tong)或在主管(guan)(guan)(guan)上開孔并(bing)焊接支管(guan)(guan)(guan)臺(tai)。當(dang)主管(guan)(guan)(guan)直徑(jing)(jing)大于(yu)(yu)(yu)DN65而支管(guan)(guan)(guan)直徑(jing)(jing)為(wei)DN40及以下時(shi)(shi)，根據(ju)設計(ji)壓力的大小，采(cai)(cai)用支管(guan)(guan)(guan)臺(tai)或半管(guan)(guan)(guan)接頭。
c. 主(zhu)(zhu)管(guan)(guan)(guan)直(zhi)徑(jing)(jing)(jing)小于(yu)(yu)(yu)(yu)DN50時，支(zhi)管(guan)(guan)(guan)小于(yu)(yu)(yu)(yu)主(zhu)(zhu)管(guan)(guan)(guan)，則用(yong)異(yi)徑(jing)(jing)(jing)三(san)(san)通或等(deng)(deng)(deng)徑(jing)(jing)(jing)三(san)(san)通加異(yi)徑(jing)(jing)(jing)短管(guan)(guan)(guan)。設(she)計壓(ya)(ya)力等(deng)(deng)(deng)于(yu)(yu)(yu)(yu)或大于(yu)(yu)(yu)(yu)2.0MPa、設(she)計溫度(du)超過250℃以(yi)及支(zhi)管(guan)(guan)(guan)與主(zhu)(zhu)管(guan)(guan)(guan)公(gong)稱直(zhi)徑(jing)(jing)(jing)之比大于(yu)(yu)(yu)(yu)0.8，或承(cheng)受(shou)機械振動(dong)、壓(ya)(ya)力脈動(dong)和溫度(du)急劇變(bian)化(hua)的(de)(de)(de)管(guan)(guan)(guan)道分(fen)支(zhi)，應(ying)采(cai)用(yong)等(deng)(deng)(deng)徑(jing)(jing)(jing)異(yi)徑(jing)(jing)(jing)三(san)(san)通；公(gong)稱直(zhi)徑(jing)(jing)(jing)小于(yu)(yu)(yu)(yu)或等(deng)(deng)(deng)于(yu)(yu)(yu)(yu)40mm的(de)(de)(de)管(guan)(guan)(guan)道，應(ying)采(cai)用(yong)承(cheng)插焊(han)（或螺(luo)紋）鍛制(zhi)(zhi)三(san)(san)通；公(gong)稱直(zhi)徑(jing)(jing)(jing)等(deng)(deng)(deng)于(yu)(yu)(yu)(yu)或大于(yu)(yu)(yu)(yu)50mm的(de)(de)(de)管(guan)(guan)(guan)道，應(ying)采(cai)用(yong)對(dui)焊(han)三(san)(san)通、對(dui)焊(han)加強管(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)（對(dui)焊(han)支(zhi)管(guan)(guan)(guan)臺）或嵌入(ru)式（鞍型）支(zhi)管(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)。支(zhi)管(guan)(guan)(guan)通過加強管(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)（支(zhi)管(guan)(guan)(guan)臺）與主(zhu)(zhu)管(guan)(guan)(guan)連(lian)接(jie)(jie)(jie)是指將一個螺(luo)紋、承(cheng)插焊(han)或對(dui)焊(han)的(de)(de)(de)管(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)或半(ban)管(guan)(guan)(guan)接(jie)(jie)(jie)頭(tou)（支(zhi)管(guan)(guan)(guan)臺）直(zhi)接(jie)(jie)(jie)焊(han)于(yu)(yu)(yu)(yu)主(zhu)(zhu)管(guan)(guan)(guan)上而制(zhi)(zhi)成，螺(luo)紋、承(cheng)插焊(han)支(zhi)管(guan)(guan)(guan)臺用(yong)于(yu)(yu)(yu)(yu)直(zhi)徑(jing)(jing)(jing)小于(yu)(yu)(yu)(yu)等(deng)(deng)(deng)于(yu)(yu)(yu)(yu)DN40（NPS1/2）的(de)(de)(de)支(zhi)管(guan)(guan)(guan)連(lian)接(jie)(jie)(jie)。螺(luo)紋、承(cheng)插焊(han)支(zhi)管(guan)(guan)(guan)臺在任何情況下其額定等(deng)(deng)(deng)級(ji)應(ying)大于(yu)(yu)(yu)(yu)等(deng)(deng)(deng)于(yu)(yu)(yu)(yu)20001b。
d. 其(qi)他支(zhi)管(guan)(guan)(guan)連(lian)(lian)接可用直(zhi)接焊(han)接，但必須經校(xiao)核(he)后明(ming)確是(shi)否增加(jia)(jia)補強(qiang)(qiang)。直(zhi)接焊(han)接在主(zhu)管(guan)(guan)(guan)上的(de)支(zhi)管(guan)(guan)(guan)連(lian)(lian)接，不宜用于(yu)有機械振動、壓力(li)脈動和(he)溫度急劇變化的(de)部位(wei)(wei)及設計溫度超過425℃的(de)管(guan)(guan)(guan)道(dao)，當(dang)支(zhi)管(guan)(guan)(guan)連(lian)(lian)接處承(cheng)受由于(yu)支(zhi)管(guan)(guan)(guan)熱變形(xing)、外載荷及支(zhi)架位(wei)(wei)移等引(yin)起的(de)應力(li)時，應對附加(jia)(jia)載荷在支(zhi)管(guan)(guan)(guan)連(lian)(lian)接處產(chan)生(sheng)的(de)影響進行(xing)分析(xi)并采(cai)取必要(yao)的(de)加(jia)(jia)強(qiang)(qiang)措(cuo)施。
e. 實際設計(ji)過程(cheng)中，主(zhu)要(yao)依據管(guan)(guan)(guan)(guan)(guan)(guan)道等(deng)級(ji)中已經(jing)確定的(de)(de)(de)(de)(de)(de)法蘭(lan)壓力等(deng)級(ji)或(huo)(huo)(huo)公(gong)稱壓力（PN）來選(xuan)用(yong)支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)連(lian)(lian)接(jie)(jie)(jie)件(jian)(jian)。一(yi)(yi)般情況下，當(dang)法蘭(lan)的(de)(de)(de)(de)(de)(de)公(gong)稱壓力PN≤2.5MPa時，支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)直接(jie)(jie)(jie)焊接(jie)(jie)(jie)在主(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)上；當(dang)PN≥4.0MPa時，則根據主(zhu)管(guan)(guan)(guan)(guan)(guan)(guan)支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)公(gong)稱直徑(jing)的(de)(de)(de)(de)(de)(de)不同按(an)對(dui)焊三(san)通、對(dui)焊加(jia)強(qiang)管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)頭、承(cheng)(cheng)(cheng)插焊或(huo)(huo)(huo)螺(luo)(luo)紋連(lian)(lian)接(jie)(jie)(jie)三(san)通、承(cheng)(cheng)(cheng)插焊或(huo)(huo)(huo)螺(luo)(luo)紋加(jia)強(qiang)管(guan)(guan)(guan)(guan)(guan)(guan)接(jie)(jie)(jie)頭的(de)(de)(de)(de)(de)(de)順(shun)序選(xuan)用(yong)。值得注(zhu)意的(de)(de)(de)(de)(de)(de)是(shi)在確定支(zhi)管(guan)(guan)(guan)(guan)(guan)(guan)連(lian)(lian)接(jie)(jie)(jie)件(jian)(jian)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號時，應根據管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)等(deng)強(qiang)度的(de)(de)(de)(de)(de)(de)原則以(yi)及管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)連(lian)(lian)接(jie)(jie)(jie)方式(shi)而(er)定。例如(ru)，當(dang)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)采用(yong)對(dui)焊連(lian)(lian)接(jie)(jie)(jie)時，管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號應一(yi)(yi)致；而(er)當(dang)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)采用(yong)承(cheng)(cheng)(cheng)插焊或(huo)(huo)(huo)螺(luo)(luo)紋連(lian)(lian)接(jie)(jie)(jie)時，標準的(de)(de)(de)(de)(de)(de)承(cheng)(cheng)(cheng)插焊和螺(luo)(luo)紋管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號只有(you)Sch80、Sch60、XXS，最(zui)低的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號就是(shi)Sch80，也就是(shi)說只要(yao)當(dang)承(cheng)(cheng)(cheng)插焊或(huo)(huo)(huo)螺(luo)(luo)紋管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)所連(lian)(lian)接(jie)(jie)(jie)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號不大于(yu)Sch80時，承(cheng)(cheng)(cheng)插焊或(huo)(huo)(huo)螺(luo)(luo)紋管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號就選(xuan)Sch80。而(er)當(dang)所連(lian)(lian)接(jie)(jie)(jie)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號大于(yu)Sch80時，承(cheng)(cheng)(cheng)插焊或(huo)(huo)(huo)螺(luo)(luo)紋管(guan)(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)號就選(xuan)Sch60或(huo)(huo)(huo)XXS。
f. 當對焊三(san)通主(zhu)管(guan)、支管(guan)所(suo)連接的(de)(de)管(guan)子(zi)(zi)的(de)(de)管(guan)子(zi)(zi)表(biao)號(hao)不同時，應注意三(san)通主(zhu)管(guan)、支管(guan)端部的(de)(de)管(guan)子(zi)(zi)表(biao)號(hao)應分別與其所(suo)連接的(de)(de)管(guan)子(zi)(zi)的(de)(de)管(guan)子(zi)(zi)表(biao)號(hao)相同，這樣(yang)就非常(chang)方便(bian)管(guan)道(dao)施工，管(guan)件不必現場再打坡口(kou)。
③. 分支管與主管連接的管件選擇(ze)見表(biao)16.71。
