短语词组短语pipe rolling welder 卷管焊接工automatic heat pipe joint welder 热管接头自动焊机elbow pipe welder 弯头焊接机all position pipe welder 全位置管焊机pipe girth joint welder 管道环缝焊工orbital pipe welder 管子环缝自动焊机galvanized welder steel pipe 镀锌钢管 返回 pipe welder