彎(wan)(wan)(wan)(wan)管(guan)(guan)(guan)(guan)(guan)尺寸由管(guan)(guan)(guan)(guan)(guan)徑(jing)(jing)(jing)、彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)角(jiao)度(du)和彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)半(ban)徑(jing)(jing)(jing)三者確(que)定(ding)(ding)。彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)角(jiao)度(du)根(gen)據圖(tu)紙和施工現場實際情況確(que)定(ding)(ding)，然后制出樣(yang)(yang)板，照樣(yang)(yang)板煨(wei)(wei)制并按(an)樣(yang)(yang)板檢查(cha)煨(wei)(wei)制管(guan)(guan)(guan)(guan)(guan)件彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)角(jiao)度(du)是否符合要求。樣(yang)(yang)板可用圓鋼(gang)煨(wei)(wei)制，圓鋼(gang)的(de)(de)(de)直徑(jing)(jing)(jing)根(gen)據所煨(wei)(wei)管(guan)(guan)(guan)(guan)(guan)徑(jing)(jing)(jing)的(de)(de)(de)大小(xiao)選(xuan)(xuan)用，10-14mm即可。彎(wan)(wan)(wan)(wan)管(guan)(guan)(guan)(guan)(guan)的(de)(de)(de)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)半(ban)徑(jing)(jing)(jing)應(ying)按(an)管(guan)(guan)(guan)(guan)(guan)徑(jing)(jing)(jing)大小(xiao)、設計(ji)要求及有關規(gui)(gui)定(ding)(ding)而定(ding)(ding)。既不(bu)能過(guo)(guo)大，也(ye)末虛選(xuan)(xuan)得太(tai)(tai)小(xiao)。因(yin)為彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)半(ban)徑(jing)(jing)(jing)過(guo)(guo)大，不(bu)但用材料(liao)多，而且管(guan)(guan)(guan)(guan)(guan)子(zi)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)部分所占的(de)(de)(de)地方(fang)也(ye)大，這樣(yang)(yang)會給管(guan)(guan)(guan)(guan)(guan)道裝配帶來困難(nan)；彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)半(ban)徑(jing)(jing)(jing)選(xuan)(xuan)得太(tai)(tai)小(xiao)時，彎(wan)(wan)(wan)(wan)頭(tou)(tou)背部管(guan)(guan)(guan)(guan)(guan)壁由于(yu)過(guo)(guo)分伸長而減薄，使其強度(du)降(jiang)低，而在彎(wan)(wan)(wan)(wan)頭(tou)(tou)里側管(guan)(guan)(guan)(guan)(guan)壁被壓縮，形成皺紋狀態。因(yin)此，一(yi)般規(gui)(gui)定(ding)(ding)：熱煨(wei)(wei)彎(wan)(wan)(wan)(wan)管(guan)(guan)(guan)(guan)(guan)的(de)(de)(de)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)半(ban)徑(jing)(jing)(jing)應(ying)不(bu)小(xiao)于(yu)管(guan)(guan)(guan)(guan)(guan)子(zi)外(wai)徑(jing)(jing)(jing)的(de)(de)(de)3．5倍；冷煨(wei)(wei)彎(wan)(wan)(wan)(wan)管(guan)(guan)(guan)(guan)(guan)的(de)(de)(de)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)半(ban)徑(jing)(jing)(jing)應(ying)不(bu)小(xiao)于(yu)管(guan)(guan)(guan)(guan)(guan)子(zi)外(wai)徑(jing)(jing)(jing)的(de)(de)(de)4倍；焊接彎(wan)(wan)(wan)(wan)頭(tou)(tou)的(de)(de)(de)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)半(ban)徑(jing)(jing)(jing)應(ying)不(bu)小(xiao)于(yu)管(guan)(guan)(guan)(guan)(guan)子(zi)外(wai)徑(jing)(jing)(jing)的(de)(de)(de)1．5倍；沖壓彎(wan)(wan)(wan)(wan)頭(tou)(tou)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)半(ban)徑(jing)(jing)(jing)應(ying)不(bu)小(xiao)于(yu)管(guan)(guan)(guan)(guan)(guan)子(zi)外(wai)徑(jing)(jing)(jing)。