HEAT EFFECT REDUCING METHOD OF INSIDE SURFACE OF BUTT WELDED JOINT PART OF REACTION PIPE FOR CHEMICAL MACHINERY

摘要

PURPOSE:To suppress the deposition of carbide which becomes the point for initiation of crazing by taking the root face of the root pass portion larger thereby reducing heat effect extending to the inside surface side of the pipe of the second and subsequent passes. CONSTITUTION:In the case of butt welding reaction pipes for chemical machinery, the root pass 2 fusion bonds the base pipes 1 by a keyhole method of plasma welding. Here, the root face 5 is taken about 5mm or over. Then, the distance up to the inside surface of the pipe becomes larger and the heat effect at the forming of the deposited metal 3 of the second and subsequent passes by using wire cores becomes relatively smaller. Hence, the deposition of the carbide 4 deposited owing to this heat effect is suppressed and the fortification of the joint is achieved.