‌  同(tong)心(xin)大(dai)小(xiao)頭(tou)又(you)叫(jiao)同(tong)心(xin)異(yi)徑(jing)管(guan)是(shi)管(guan)道(dao)變(bian)徑(jing)配(pei)件(jian)之(zhi)一(yi)，在(zai)管(guan)道(dao)施(shi)工(gong)中(zhong)用(yong)於(yu)兩(liang)種(zhong)不(bu)同(tong)管(guan)徑(jing)的(di)連(lian)接(jie),按(an)照(zhao)形(xing)狀(zhuang)的(di)不(bu)同(tong)可(ke)以(yi)分(fen)為(wei)RC同(tong)心(xin)大(dai)小(xiao)頭(tou)和(hu)RE偏(pian)心(xin)大(dai)小(xiao)頭(tou)。同(tong)心(xin)大(dai)小(xiao)頭(tou)是(shi)用(yong)於(yu)管(guan)道(dao)變(bian)徑(jing)處(chu)的(di)一(yi)種(zhong)管(guan)件(jian),通(tong)常(chang)采(cai)用(yong)的(di)成(cheng)形(xing)工(gong)藝(yi)為(wei)縮(suo)徑(jing)壓(ya)製(zhi)、擴(kuo)徑(jing)壓(ya)製(zhi)或(huo)縮(suo)徑(jing)加(jia)擴(kuo)徑(jing)壓(ya)製(zhi)，對(dui)某(mou)些(xie)小(xiao)規(gui)格(ge)的(di)異(yi)徑(jing)管(guan)也(ye)可(ke)采(cai)用(yong)衝(chong)壓(ya)成(cheng)形(xing)。同(tong)心(xin)大(dai)小(xiao)頭(tou)應(ying)用(yong)：當(dang)管(guan)道(dao)中(zhong)流(liu)體(ti)的(di)流(liu)量(liang)有(you)變(bian)化(hua)時(shi),比(bi)如(ru)增(zeng)大(dai)或(huo)減(jian)少(shao),流(liu)速(su)要(yao)求(qiu)變(bian)化(hua)不(bu)大(dai)時(shi),均(jun)需(xu)采(cai)用(yong)異(yi)徑(jing)管(guan)；在(zai)泵(beng)的(di)進(jin)口(kou),為(wei)了(liao)防(fang)止(zhi)汽(qi)蝕(shi)，需(xu)要(yao)采(cai)用(yong)異(yi)徑(jing)管(guan)；與(yu)儀(yi)表(biao),如(ru)流(liu)量(liang)計(ji)、調(diao)節(jie)閥(fa)的(di)接(jie)頭(tou)處(chu),為(wei)了(liao)與(yu)儀(yi)表(biao)的(di)接(jie)頭(tou)配(pei)合(ge),也(ye)需(xu)采(cai)用(yong)異(yi)徑(jing)管(guan)。目(mu)前(qian)大(dai)部(bu)分(fen)管(guan)網(wang)需(xu)要(yao)用(yong)到(dao)異(yi)徑(jing)管(guan)大(dai)小(xiao)頭(tou)，主(zhu)要(yao)用(yong)在(zai)石(dan)油(you)、化(hua)工(gong)、天(tian)然(ran)氣(qi)、蒸(zheng)汽(qi)管(guan)網(wang)，液(ye)壓(ya)機(ji)械(xie)等(deng)。