鉛管因質軟(ruan)且重,故經(jing)過搬運、裝卸之后一般均產生變形,所以鉛管在(zai)安裝前(qian)均應(ying)調直和校圓。
鉛管(guan)調直(zhi)時,鉛管(guan)應放(fang)在(zai)鋪(pu)有木板的平臺上用(yong)木榔頭輕輕敲打調直(zhi)。為了(le)便于檢査和操作,常把鉛管(guan)緊貼在(zai)角鋼或槽(cao)鋼內(nei)側的翼上,根(gen)據(ju)管(guan)子(zi)和型鋼的間隙拍打調直(zhi)。
鉛(qian)管(guan)(guan)(guan)除調直(zhi)外,還需校(xiao)(xiao)圓(yuan)(yuan)。直(zhi)徑(jing)大于DN50mm的鉛(qian)管(guan)(guan)(guan)校(xiao)(xiao)圓(yuan)(yuan),可用一(yi)根外徑(jing)小于鉛(qian)管(guan)(guan)(guan)內徑(jing)的鋼管(guan)(guan)(guan)(管(guan)(guan)(guan)端最好制(zhi)成一(yi)半(ban)球形封頭(tou))穿在鉛(qian)管(guan)(guan)(guan)內,并把鋼管(guan)(guan)(guan)的兩端放(fang)在支撐架上(shang), 然后(hou)用木錘(chui)敲打(da)鉛(qian)管(guan)(guan)(guan)被(bei)壓扁的地方(fang),邊(bian)打(da)邊(bian)轉(zhuan)動(dong)管(guan)(guan)(guan)子,直(zhi)到將管(guan)(guan)(guan)子校(xiao)(xiao)圓(yuan)(yuan)為止。
鉛(qian)管校圓(yuan)(yuan)的方法還有用硬(ying)木制成的外徑與鉛(qian)管內徑相同(tong)的圓(yuan)(yuan)柱形胎(tai)(tai)具,將頭(tou)部削圓(yuan)(yuan), 穿上繩子,用繩將胎(tai)(tai)具拉進管內,使變形部位(wei)隨胎(tai)(tai)具而撐圓(yuan)(yuan)。
鉛管直徑不大于DN50mm的鉛管校圓(yuan),可將鉛管兩(liang)端堵塞,在管內(nei)通(tong)入壓力為0.3~0.4MPa的壓縮(suo)空氣,然后用焊炬(ju)對壓扁的地方(fang)加熱(re)(re),管內(nei)的壓縮(suo)空氣把管子脹圓(yuan),加熱(re)(re)時,要(yao)注意(yi)使加熱(re)(re)部分受(shou)熱(re)(re)均勻,升(sheng)溫不要(yao)太快,當管子被脹圓(yuan)時,應立(li)即停止加熱(re)(re)。