The preferred method is by oxy-acetylene flame.Heat tube first, beginning one inch from edge of valve.Sweep flame around tube in short strokes up and down at right angles to run of tube.

• 首先从离1英寸的地方开始对管道进行加热，然后围绕着管道短距离上下交替对管道进行火焰烘烤，并以适当的角度旋转管道，避免烧穿管道。