0前言在制造具有长径比较大且口径较小的筒体的有机热载体设备和缩聚设备时,对其内部直焊缝进行焊接是比较困难的。由于口径的限制,使用市场提供的专用自动焊机一般无法完成此类筒体的焊接。为了生产的需要,可以将普通小型埋弧自动焊机改制成专用焊机,完全能够满足了小口径圆筒 0 Introduction In the manufacture of organic heat carrier devices and polycondensation devices having a cylinder with a large diameter and a small caliber, it is difficult to weld the internal straight weld seam. Owing to the limitation of caliber, it is generally unable to complete the welding of such cylinders by using the special automatic welding machine provided by the market. In order to production needs, can be ordinary small submerged arc welding machine adapted into a special welder, fully able to meet the small-caliber cylinder