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(guan)連接件的選擇
a. 主要(yao)根據管(guan)(guan)道的設計(ji)溫度、設計(ji)壓(ya)力、腐蝕余量(liang)等設計(ji)條(tiao)件(jian)確(que)定的。分支的方法(fa)：對于低壓(ya)大直徑管(guan)(guan)則(ze)直接把分支管(guan)(guan)焊于主管(guan)(guan)上，另外多數(shu)是(shi)利(li)用分支管(guan)(guan)件(jian)進行(xing)分支。
b. 當(dang)從主(zhu)管(guan)(guan)(guan)(guan)引出支(zhi)(zhi)管(guan)(guan)(guan)(guan)時，支(zhi)(zhi)管(guan)(guan)(guan)(guan)直徑(jing)(jing)(jing)與主(zhu)管(guan)(guan)(guan)(guan)直徑(jing)(jing)(jing)的(de)比值大(da)于(yu)(yu)等(deng)于(yu)(yu)0.5時，采(cai)(cai)用異徑(jing)(jing)(jing)三(san)通(tong)或(huo)(huo)等(deng)徑(jing)(jing)(jing)三(san)通(tong)，當(dang)主(zhu)支(zhi)(zhi)管(guan)(guan)(guan)(guan)為(wei)(wei)等(deng)徑(jing)(jing)(jing)時，應采(cai)(cai)用三(san)通(tong)。GB50316 規定：公(gong)稱壓(ya)力(li)大(da)于(yu)(yu)或(huo)(huo)等(deng)于(yu)(yu)10MPa的(de)管(guan)(guan)(guan)(guan)道，主(zhu)支(zhi)(zhi)管(guan)(guan)(guan)(guan)為(wei)(wei)異徑(jing)(jing)(jing)時，不宜(yi)采(cai)(cai)用焊接支(zhi)(zhi)管(guan)(guan)(guan)(guan)，宜(yi)采(cai)(cai)用三(san)通(tong)或(huo)(huo)在主(zhu)管(guan)(guan)(guan)(guan)上(shang)開孔并焊接支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺。當(dang)主(zhu)管(guan)(guan)(guan)(guan)直徑(jing)(jing)(jing)大(da)于(yu)(yu)DN65而支(zhi)(zhi)管(guan)(guan)(guan)(guan)直徑(jing)(jing)(jing)為(wei)(wei)DN40及以下時，根據設計壓(ya)力(li)的(de)大(da)小(xiao)，采(cai)(cai)用支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺或(huo)(huo)半管(guan)(guan)(guan)(guan)接頭。
c. 主管(guan)(guan)(guan)(guan)直(zhi)徑(jing)(jing)(jing)(jing)(jing)(jing)小(xiao)于(yu)DN50時，支(zhi)(zhi)管(guan)(guan)(guan)(guan)小(xiao)于(yu)主管(guan)(guan)(guan)(guan)，則用異徑(jing)(jing)(jing)(jing)(jing)(jing)三(san)(san)通(tong)或(huo)(huo)等(deng)(deng)徑(jing)(jing)(jing)(jing)(jing)(jing)三(san)(san)通(tong)加異徑(jing)(jing)(jing)(jing)(jing)(jing)短管(guan)(guan)(guan)(guan)。設計壓力(li)等(deng)(deng)于(yu)或(huo)(huo)大(da)于(yu)2.0MPa、設計溫(wen)度(du)超過250℃以及支(zhi)(zhi)管(guan)(guan)(guan)(guan)與(yu)主管(guan)(guan)(guan)(guan)公稱(cheng)(cheng)直(zhi)徑(jing)(jing)(jing)(jing)(jing)(jing)之比大(da)于(yu)0.8，或(huo)(huo)承受機械振動、壓力(li)脈動和溫(wen)度(du)急(ji)劇變化的(de)管(guan)(guan)(guan)(guan)道分(fen)支(zhi)(zhi)，應(ying)(ying)采(cai)用等(deng)(deng)徑(jing)(jing)(jing)(jing)(jing)(jing)異徑(jing)(jing)(jing)(jing)(jing)(jing)三(san)(san)通(tong)；公稱(cheng)(cheng)直(zhi)徑(jing)(jing)(jing)(jing)(jing)(jing)小(xiao)于(yu)或(huo)(huo)等(deng)(deng)于(yu)40mm的(de)管(guan)(guan)(guan)(guan)道，應(ying)(ying)采(cai)用承插(cha)焊(han)(han)（或(huo)(huo)螺紋）鍛制三(san)(san)通(tong)；公稱(cheng)(cheng)直(zhi)徑(jing)(jing)(jing)(jing)(jing)(jing)等(deng)(deng)于(yu)或(huo)(huo)大(da)于(yu)50mm的(de)管(guan)(guan)(guan)(guan)道，應(ying)(ying)采(cai)用對焊(han)(han)三(san)(san)通(tong)、對焊(han)(han)加強管(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)(tou)（對焊(han)(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)）或(huo)(huo)嵌入式（鞍型）支(zhi)(zhi)管(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)(tou)。支(zhi)(zhi)管(guan)(guan)(guan)(guan)通(tong)過加強管(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)(tou)（支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)）與(yu)主管(guan)(guan)(guan)(guan)連接(jie)(jie)是指將一個螺紋、承插(cha)焊(han)(han)或(huo)(huo)對焊(han)(han)的(de)管(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)(tou)或(huo)(huo)半(ban)管(guan)(guan)(guan)(guan)接(jie)(jie)頭(tou)(tou)（支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)）直(zhi)接(jie)(jie)焊(han)(han)于(yu)主管(guan)(guan)(guan)(guan)上(shang)而制成，螺紋、承插(cha)焊(han)(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)用于(yu)直(zhi)徑(jing)(jing)(jing)(jing)(jing)(jing)小(xiao)于(yu)等(deng)(deng)于(yu)DN40（NPS1/2）的(de)支(zhi)(zhi)管(guan)(guan)(guan)(guan)連接(jie)(jie)。螺紋、承插(cha)焊(han)(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺(tai)在任何情況下其額定等(deng)(deng)級(ji)應(ying)(ying)大(da)于(yu)等(deng)(deng)于(yu)20001b。
d. 其他支管(guan)(guan)連(lian)接(jie)(jie)可用(yong)(yong)直(zhi)接(jie)(jie)焊接(jie)(jie)，但必須經校核后明確是否增(zeng)加(jia)(jia)補(bu)強。直(zhi)接(jie)(jie)焊接(jie)(jie)在主管(guan)(guan)上(shang)的(de)支管(guan)(guan)連(lian)接(jie)(jie)，不(bu)宜用(yong)(yong)于有機械振動、壓力脈動和溫度急劇變化的(de)部位(wei)及設計溫度超過425℃的(de)管(guan)(guan)道(dao)，當支管(guan)(guan)連(lian)接(jie)(jie)處承受由于支管(guan)(guan)熱變形、外載荷(he)及支架位(wei)移等引起的(de)應力時，應對附加(jia)(jia)載荷(he)在支管(guan)(guan)連(lian)接(jie)(jie)處產生的(de)影響進行分析并采取必要的(de)加(jia)(jia)強措施。
e. 實際設(she)計過程中，主要依據(ju)(ju)管(guan)(guan)(guan)(guan)道等(deng)級中已(yi)經確定(ding)的(de)(de)(de)(de)(de)法蘭(lan)(lan)壓力(li)等(deng)級或(huo)(huo)公稱壓力(li)（PN）來選用(yong)支(zhi)管(guan)(guan)(guan)(guan)連(lian)(lian)(lian)(lian)接(jie)(jie)件(jian)。一般情況下(xia)，當(dang)法蘭(lan)(lan)的(de)(de)(de)(de)(de)公稱壓力(li)PN≤2.5MPa時(shi)(shi)，支(zhi)管(guan)(guan)(guan)(guan)直(zhi)接(jie)(jie)焊(han)(han)接(jie)(jie)在(zai)(zai)主管(guan)(guan)(guan)(guan)上(shang)；當(dang)PN≥4.0MPa時(shi)(shi)，則根據(ju)(ju)主管(guan)(guan)(guan)(guan)支(zhi)管(guan)(guan)(guan)(guan)公稱直(zhi)徑的(de)(de)(de)(de)(de)不同按(an)對焊(han)(han)三通、對焊(han)(han)加強管(guan)(guan)(guan)(guan)接(jie)(jie)頭、承(cheng)(cheng)插(cha)焊(han)(han)或(huo)(huo)螺(luo)(luo)紋(wen)連(lian)(lian)(lian)(lian)接(jie)(jie)三通、承(cheng)(cheng)插(cha)焊(han)(han)或(huo)(huo)螺(luo)(luo)紋(wen)加強管(guan)(guan)(guan)(guan)接(jie)(jie)頭的(de)(de)(de)(de)(de)順序選用(yong)。值得注意的(de)(de)(de)(de)(de)是在(zai)(zai)確定(ding)支(zhi)管(guan)(guan)(guan)(guan)連(lian)(lian)(lian)(lian)接(jie)(jie)件(jian)的(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)號(hao)(hao)時(shi)(shi)，應(ying)(ying)根據(ju)(ju)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)(guan)件(jian)等(deng)強度的(de)(de)(de)(de)(de)原則以(yi)及管(guan)(guan)(guan)(guan)件(jian)與管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)連(lian)(lian)(lian)(lian)接(jie)(jie)方式而(er)定(ding)。例(li)如，當(dang)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)(guan)件(jian)采用(yong)對焊(han)(han)連(lian)(lian)(lian)(lian)接(jie)(jie)時(shi)(shi)，管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)(guan)件(jian)的(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)號(hao)(hao)應(ying)(ying)一致；而(er)當(dang)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)與管(guan)(guan)(guan)(guan)件(jian)采用(yong)承(cheng)(cheng)插(cha)焊(han)(han)或(huo)(huo)螺(luo)(luo)紋(wen)連(lian)(lian)(lian)(lian)接(jie)(jie)時(shi)(shi)，標準的(de)(de)(de)(de)(de)承(cheng)(cheng)插(cha)焊(han)(han)和螺(luo)(luo)紋(wen)管(guan)(guan)(guan)(guan)件(jian)的(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)號(hao)(hao)只有Sch80、Sch60、XXS，最(zui)低的(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)號(hao)(hao)就是Sch80，也就是說只要當(dang)承(cheng)(cheng)插(cha)焊(han)(han)或(huo)(huo)螺(luo)(luo)紋(wen)管(guan)(guan)(guan)(guan)件(jian)所連(lian)(lian)(lian)(lian)接(jie)(jie)的(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)號(hao)(hao)不大(da)(da)于Sch80時(shi)(shi)，承(cheng)(cheng)插(cha)焊(han)(han)或(huo)(huo)螺(luo)(luo)紋(wen)管(guan)(guan)(guan)(guan)件(jian)的(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)號(hao)(hao)就選Sch80。而(er)當(dang)所連(lian)(lian)(lian)(lian)接(jie)(jie)的(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)號(hao)(hao)大(da)(da)于Sch80時(shi)(shi)，承(cheng)(cheng)插(cha)焊(han)(han)或(huo)(huo)螺(luo)(luo)紋(wen)管(guan)(guan)(guan)(guan)件(jian)的(de)(de)(de)(de)(de)管(guan)(guan)(guan)(guan)子(zi)(zi)(zi)表(biao)(biao)號(hao)(hao)就選Sch60或(huo)(huo)XXS。
f. 當對焊(han)三通主管(guan)(guan)(guan)、支管(guan)(guan)(guan)所連接(jie)的管(guan)(guan)(guan)子(zi)(zi)的管(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號(hao)不同(tong)時，應(ying)注意三通主管(guan)(guan)(guan)、支管(guan)(guan)(guan)端部的管(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號(hao)應(ying)分(fen)別(bie)與其(qi)所連接(jie)的管(guan)(guan)(guan)子(zi)(zi)的管(guan)(guan)(guan)子(zi)(zi)表(biao)(biao)號(hao)相同(tong)，這(zhe)樣就非常方便管(guan)(guan)(guan)道施工，管(guan)(guan)(guan)件不必現場再打(da)坡(po)口。
③. 分支管(guan)與主管(guan)連接(jie)的管(guan)件選擇見表16.71。
