?向(xiang)(xiang)下(xia)(xia)(xia)焊(han)(han)是當(dang)前受歡迎的(de)(de)一種(zhong)焊(han)(han)接(jie)技術(shu)，相(xiang)對于在(zai)立焊(han)(han)式管(guan)道全位置焊(han)(han)接(jie)中采用的(de)(de)“向(xiang)(xiang)上立焊(han)(han)”焊(han)(han)接(jie)工藝(yi)(yi)而言的(de)(de)，是電弧熱源由上而下(xia)(xia)(xia)移動的(de)(de)一種(zhong)焊(han)(han)接(jie)方法。這是一種(zhong)良好的(de)(de)焊(han)(han)接(jie)工藝(yi)(yi)，建(jian)筑電氣焊(han)(han)工，目前主要應用于大直徑(jing)遠距離野外輸(shu)油、輸(shu)氣、輸(shu)水以及輸(shu)送礦物質(zhi)等管(guan)道的(de)(de)焊(han)(han)接(jie)，是一種(zhong)比(bi)較成熟的(de)(de)焊(han)(han)接(jie)工藝(yi)(yi)。下(xia)(xia)(xia)面則來看看向(xiang)(xiang)下(xia)(xia)(xia)焊(han)(han)的(de)(de)技術(shu)優勢：

??向下焊的技術優勢：

??(1)焊(han)(han)接速(su)度(du)快，生產。因該種焊(han)(han)條鐵水濃度(du)低(di)，不淌渣，比由(you)下向 上(shang)施(shi)焊(han)(han)提50％。

??(2)焊(han)接質量好，纖(xian)維素焊(han)條焊(han)接的(de)焊(han)縫根部(bu)成形飽滿，高壓電氣焊(han)工培訓學(xue)校，電弧吹力大，穿透 均(jun)勻，焊(han)道背面成形美觀(guan)，抗風(feng)能力強，適于野外作業。

??(3)減(jian)少焊接(jie)材料的消(xiao)耗，與傳統的由下向上焊接(jie)方法相比焊條(tiao)消(xiao)耗量減(jian)少 20％-30％。

??(4)焊接一次合格率可達 90％以上。

焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)證(zheng)(zheng)，也叫上崗證(zheng)(zheng)，發證(zheng)(zheng)機構是(shi)(shi)(shi)安全(quan)生(sheng)產(chan)監(jian)(jian)督(du)(du)(du)管(guan)理局(ju)，是(shi)(shi)(shi)焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)培(pei)訓(xun)結束(shu)后，上崗的(de)(de)所(suo)需證(zheng)(zheng)書(shu)(shu)，沒有(you)證(zheng)(zheng)書(shu)(shu)不能進行焊(han)(han)(han)(han)接作(zuo)(zuo)業(ye)(ye)。分熔(rong)化焊(han)(han)(han)(han)接與(yu)熱(re)切割(ge)作(zuo)(zuo)業(ye)(ye)、壓(ya)力(li)(li)焊(han)(han)(han)(han)作(zuo)(zuo)業(ye)(ye)、釬焊(han)(han)(han)(han)作(zuo)(zuo)業(ye)(ye)等(deng)，焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)證(zheng)(zheng)書(shu)(shu)帶磁卡(ka)(ka)，。??焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)證(zheng)(zheng)一(yi)般分為三(san)類(lei)：IC卡(ka)(ka)焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)證(zheng)(zheng)，人(ren)(ren)勞局(ju)的(de)(de)職業(ye)(ye)資(zi)(zi)格焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)證(zheng)(zheng)，的(de)(de)特(te)(te)種(zhong)設(she)備(bei)作(zuo)(zuo)業(ye)(ye)人(ren)(ren)員焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)證(zheng)(zheng)。?一(yi)類(lei)是(shi)(shi)(shi)IC卡(ka)(ka)焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)證(zheng)(zheng)：焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)作(zuo)(zuo)業(ye)(ye)須有(you)的(de)(de)焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)證(zheng)(zheng)是(shi)(shi)(shi)各(ge)(ge)省(sheng)安全(quan)生(sheng)產(chan)監(jian)(jian)督(du)(du)(du)管(guan)理局(ju)(簡稱省(sheng))頒發的(de)(de)IC卡(ka)(ka)焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)證(zheng)(zheng)，凡從事焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)作(zuo)(zuo)業(ye)(ye)，這個(ge)IC卡(ka)(ka)焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)證(zheng)(zheng)就(jiu)是(shi)(shi)(shi)須持有(you)的(de)(de)證(zheng)(zheng)件，否則查到(dao)無(wu)證(zheng)(zheng)將會被依法處理。?二類(lei)是(shi)(shi)(shi)焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)證(zheng)(zheng)是(shi)(shi)(shi)職業(ye)(ye)資(zi)(zi)格證(zheng)(zheng)：是(shi)(shi)(shi)由各(ge)(ge)省(sheng)、地市的(de)(de)人(ren)(ren)力(li)(li)資(zi)(zi)源與(yu)社(she)會保障局(ju)（廳）統一(yi)組織考試，濟陽電(dian)氣(qi)焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)，的(de)(de)證(zheng)(zheng)書(shu)(shu)蓋有(you)該(gai)地市職業(ye)(ye)資(zi)(zi)格鑒(jian)定的(de)(de)公章，短(duan)期電(dian)氣(qi)焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)培(pei)訓(xun)中心，證(zheng)(zheng)書(shu)(shu)樣本是(shi)(shi)(shi)統一(yi)的(de)(de)，但是(shi)(shi)(shi)省(sheng)、地市并不是(shi)(shi)(shi)統一(yi)考試。?三(san)類(lei)是(shi)(shi)(shi)壓(ya)力(li)(li)容器焊(han)(han)(han)(han)工(gong)(gong)(gong)(gong)(gong)證(zheng)(zheng)：是(shi)(shi)(shi)中華(hua)人(ren)(ren)民共和國(guo)特(te)(te)種(zhong)設(she)備(bei)作(zuo)(zuo)業(ye)(ye)人(ren)(ren)員證(zheng)(zheng)的(de)(de)一(yi)個(ge)工(gong)(gong)(gong)(gong)(gong)種(zhong)，由國(guo)家質量監(jian)(jian)督(du)(du)(du)檢(jian)(jian)驗檢(jian)(jian)疫總局(ju)監(jian)(jian)制，省(sheng)級(ji)質量技術監(jian)(jian)督(du)(du)(du)部門決定具體(ti)的(de)(de)發證(zheng)(zheng)分級(ji)范圍，負責對考核(he)發證(zheng)(zheng)工(gong)(gong)(gong)(gong)(gong)作(zuo)(zuo)的(de)(de)日常監(jian)(jian)督(du)(du)(du)管(guan)理。

一 、弧焊：

1 保(bao)護氣體種類的(de)變換；

2 保護氣(qi)體(ti)流量(liang)增加 25％以上或減少 10％以上的變化；

3 添加焊(han)絲(si)或不添加焊(han)絲(si)的變換(huan)；冷態送絲(si)和熱態送絲(si)的變換(huan)；焊(han)絲(si)類型、強度級別型

號變化；

4 焊炬手動(dong)與(yu)機械行走的變換(huan)；

5 按(an)電(dian)極直徑規定的(de)電(dian)流值(zhi)、電(dian)壓(ya)值(zhi)和焊接速度的(de)變化分(fen)別超過評定合格值(zhi)的(de) 25％、7

％和 10％；

6 電流極性變化。

二、埋弧焊：

1 焊絲直徑的變化(hua)超過 1mm；焊絲與焊劑(ji)型號(hao)變化(hua)；

2 多絲焊(han)與單絲焊(han)的變化(hua)；

3 添加與不添加冷絲的變(bian)化；

4 電(dian)流(liu)種類和極性(xing)的變換；

5 按焊絲直(zhi)徑(jing)規定的電(dian)流值(zhi)(zhi)、電(dian)壓值(zhi)(zhi)和焊接速度(du)變(bian)化分別超(chao)過評定合格值(zhi)(zhi)的 10％、

7％和 15％；

6 清焊根(gen)改(gai)為不清焊根(gen)。