When an electric heating method is used for heating, thermal couple and heating coil should be installed closest to the bevel while should not hinder the access of welder to the joint.
采用电加热法加热时，需注意热电偶及加热圈的安装要尽可能靠近坡口，但不得妨碍焊工接近接头。
2
Pipeline inner loop welder is applicable for big-caliber pipeline welding in construction procedure to joint the ends of pipes and fulfill roots welding.
管道全位置自动内焊机适用于大口径管道焊接施工过程中组对管口、完成根焊。
3
The paper introduces the welder training, joint design, bevel preparation and welding procedure as well.