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(ze)

   a. 主要根據(ju)管道(dao)的設計(ji)溫度、設計(ji)壓力、腐蝕余量等(deng)設計(ji)條(tiao)件確定的。分支(zhi)(zhi)的方法：對于(yu)低(di)壓大(da)直徑(jing)管則直接把分支(zhi)(zhi)管焊于(yu)主管上，另外(wai)多數是利(li)用(yong)分支(zhi)(zhi)管件進行分支(zhi)(zhi)。

   b. 當從主(zhu)管(guan)(guan)引(yin)出支(zhi)(zhi)管(guan)(guan)時，支(zhi)(zhi)管(guan)(guan)直徑(jing)與(yu)主(zhu)管(guan)(guan)直徑(jing)的比值大(da)于(yu)(yu)等(deng)于(yu)(yu)0.5時，采(cai)(cai)用異(yi)徑(jing)三通(tong)(tong)(tong)或等(deng)徑(jing)三通(tong)(tong)(tong)，當主(zhu)支(zhi)(zhi)管(guan)(guan)為(wei)等(deng)徑(jing)時，應采(cai)(cai)用三通(tong)(tong)(tong)。GB50316 規定：公稱壓力大(da)于(yu)(yu)或等(deng)于(yu)(yu)10MPa的管(guan)(guan)道，主(zhu)支(zhi)(zhi)管(guan)(guan)為(wei)異(yi)徑(jing)時，不宜采(cai)(cai)用焊接支(zhi)(zhi)管(guan)(guan)，宜采(cai)(cai)用三通(tong)(tong)(tong)或在主(zhu)管(guan)(guan)上開孔(kong)并焊接支(zhi)(zhi)管(guan)(guan)臺。當主(zhu)管(guan)(guan)直徑(jing)大(da)于(yu)(yu)DN65而支(zhi)(zhi)管(guan)(guan)直徑(jing)為(wei)DN40及以下時，根據設計(ji)壓力的大(da)小，采(cai)(cai)用支(zhi)(zhi)管(guan)(guan)臺或半管(guan)(guan)接頭(tou)。

   c. 主(zhu)管(guan)(guan)(guan)(guan)直(zhi)(zhi)(zhi)徑小(xiao)于(yu)(yu)(yu)DN50時，支(zhi)(zhi)管(guan)(guan)(guan)(guan)小(xiao)于(yu)(yu)(yu)主(zhu)管(guan)(guan)(guan)(guan)，則用(yong)異徑三通(tong)或(huo)等(deng)徑三通(tong)加異徑短(duan)管(guan)(guan)(guan)(guan)。設計壓(ya)力(li)等(deng)于(yu)(yu)(yu)或(huo)大(da)于(yu)(yu)(yu)2.0MPa、設計溫(wen)度超(chao)過(guo)250℃以及支(zhi)(zhi)管(guan)(guan)(guan)(guan)與主(zhu)管(guan)(guan)(guan)(guan)公(gong)稱(cheng)直(zhi)(zhi)(zhi)徑之比大(da)于(yu)(yu)(yu)0.8，或(huo)承受(shou)機械(xie)振動(dong)(dong)、壓(ya)力(li)脈動(dong)(dong)和溫(wen)度急劇變化的(de)管(guan)(guan)(guan)(guan)道分支(zhi)(zhi)，應采用(yong)等(deng)徑異徑三通(tong)；公(gong)稱(cheng)直(zhi)(zhi)(zhi)徑小(xiao)于(yu)(yu)(yu)或(huo)等(deng)于(yu)(yu)(yu)40mm的(de)管(guan)(guan)(guan)(guan)道，應采用(yong)承插(cha)焊(han)（或(huo)螺(luo)紋(wen)）鍛制(zhi)三通(tong)；公(gong)稱(cheng)直(zhi)(zhi)(zhi)徑等(deng)于(yu)(yu)(yu)或(huo)大(da)于(yu)(yu)(yu)50mm的(de)管(guan)(guan)(guan)(guan)道，應采用(yong)對(dui)焊(han)三通(tong)、對(dui)焊(han)加強(qiang)管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)（對(dui)焊(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺）或(huo)嵌(qian)入(ru)式（鞍(an)型）支(zhi)(zhi)管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)。支(zhi)(zhi)管(guan)(guan)(guan)(guan)通(tong)過(guo)加強(qiang)管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)（支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺）與主(zhu)管(guan)(guan)(guan)(guan)連(lian)接(jie)是(shi)指將一個(ge)螺(luo)紋(wen)、承插(cha)焊(han)或(huo)對(dui)焊(han)的(de)管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)或(huo)半管(guan)(guan)(guan)(guan)接(jie)頭(tou)(tou)（支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺）直(zhi)(zhi)(zhi)接(jie)焊(han)于(yu)(yu)(yu)主(zhu)管(guan)(guan)(guan)(guan)上(shang)而(er)制(zhi)成，螺(luo)紋(wen)、承插(cha)焊(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺用(yong)于(yu)(yu)(yu)直(zhi)(zhi)(zhi)徑小(xiao)于(yu)(yu)(yu)等(deng)于(yu)(yu)(yu)DN40（NPS1/2）的(de)支(zhi)(zhi)管(guan)(guan)(guan)(guan)連(lian)接(jie)。螺(luo)紋(wen)、承插(cha)焊(han)支(zhi)(zhi)管(guan)(guan)(guan)(guan)臺在任(ren)何(he)情況下其額定等(deng)級(ji)應大(da)于(yu)(yu)(yu)等(deng)于(yu)(yu)(yu)20001b。

   d. 其他支(zhi)管連接(jie)(jie)(jie)(jie)可(ke)用直接(jie)(jie)(jie)(jie)焊接(jie)(jie)(jie)(jie)，但必須經校核后明(ming)確是(shi)否增(zeng)加(jia)補強。直接(jie)(jie)(jie)(jie)焊接(jie)(jie)(jie)(jie)在主管上的支(zhi)管連接(jie)(jie)(jie)(jie)，不(bu)宜用于有機(ji)械振動、壓力脈(mo)動和(he)溫度(du)急劇(ju)變(bian)化的部位(wei)及設計溫度(du)超過425℃的管道(dao)，當支(zhi)管連接(jie)(jie)(jie)(jie)處承受由于支(zhi)管熱變(bian)形、外載荷(he)及支(zhi)架位(wei)移等引起的應力時，應對附加(jia)載荷(he)在支(zhi)管連接(jie)(jie)(jie)(jie)處產生的影響(xiang)進行(xing)分析并采取必要的加(jia)強措施。

   e. 實際設計過程中，主(zhu)(zhu)要(yao)依(yi)據(ju)管(guan)(guan)(guan)(guan)(guan)道等(deng)級中已(yi)經(jing)確(que)定的(de)(de)(de)法蘭壓力(li)等(deng)級或(huo)公稱壓力(li)（PN）來選(xuan)用(yong)支(zhi)管(guan)(guan)(guan)(guan)(guan)連(lian)(lian)接件(jian)(jian)。一(yi)般情況下(xia)，當(dang)(dang)法蘭的(de)(de)(de)公稱壓力(li)PN≤2.5MPa時(shi)，支(zhi)管(guan)(guan)(guan)(guan)(guan)直接焊(han)(han)(han)接在主(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)上；當(dang)(dang)PN≥4.0MPa時(shi)，則(ze)根據(ju)主(zhu)(zhu)管(guan)(guan)(guan)(guan)(guan)支(zhi)管(guan)(guan)(guan)(guan)(guan)公稱直徑的(de)(de)(de)不同按對焊(han)(han)(han)三通、對焊(han)(han)(han)加(jia)強管(guan)(guan)(guan)(guan)(guan)接頭、承插(cha)焊(han)(han)(han)或(huo)螺(luo)紋(wen)(wen)(wen)連(lian)(lian)接三通、承插(cha)焊(han)(han)(han)或(huo)螺(luo)紋(wen)(wen)(wen)加(jia)強管(guan)(guan)(guan)(guan)(guan)接頭的(de)(de)(de)順序選(xuan)用(yong)。值得注意的(de)(de)(de)是(shi)在確(que)定支(zhi)管(guan)(guan)(guan)(guan)(guan)連(lian)(lian)接件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)時(shi)，應根據(ju)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)等(deng)強度(du)的(de)(de)(de)原則(ze)以及(ji)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)與(yu)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)連(lian)(lian)接方(fang)式(shi)而定。例如，當(dang)(dang)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)采用(yong)對焊(han)(han)(han)連(lian)(lian)接時(shi)，管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)應一(yi)致；而當(dang)(dang)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)與(yu)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)采用(yong)承插(cha)焊(han)(han)(han)或(huo)螺(luo)紋(wen)(wen)(wen)連(lian)(lian)接時(shi)，標準的(de)(de)(de)承插(cha)焊(han)(han)(han)和螺(luo)紋(wen)(wen)(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)只有Sch80、Sch60、XXS，最低(di)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)就(jiu)(jiu)是(shi)Sch80，也(ye)就(jiu)(jiu)是(shi)說只要(yao)當(dang)(dang)承插(cha)焊(han)(han)(han)或(huo)螺(luo)紋(wen)(wen)(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)所連(lian)(lian)接的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)不大于Sch80時(shi)，承插(cha)焊(han)(han)(han)或(huo)螺(luo)紋(wen)(wen)(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)就(jiu)(jiu)選(xuan)Sch80。而當(dang)(dang)所連(lian)(lian)接的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)大于Sch80時(shi)，承插(cha)焊(han)(han)(han)或(huo)螺(luo)紋(wen)(wen)(wen)管(guan)(guan)(guan)(guan)(guan)件(jian)(jian)的(de)(de)(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)表號(hao)(hao)就(jiu)(jiu)選(xuan)Sch60或(huo)XXS。

   f. 當(dang)對焊三通(tong)主(zhu)管(guan)(guan)、支(zhi)管(guan)(guan)所(suo)連接(jie)的(de)管(guan)(guan)子(zi)的(de)管(guan)(guan)子(zi)表號不同時，應注意三通(tong)主(zhu)管(guan)(guan)、支(zhi)管(guan)(guan)端部的(de)管(guan)(guan)子(zi)表號應分別與其所(suo)連接(jie)的(de)管(guan)(guan)子(zi)的(de)管(guan)(guan)子(zi)表號相同，這樣就非常(chang)方便(bian)管(guan)(guan)道(dao)施工，管(guan)(guan)件不必現場(chang)再(zai)打坡口。

 ③. 分支管與主管連(lian)接(jie)的管件選擇(ze)見(jian)表16.71。