When flux appears liquid and transparent on both tube and valve, start sweeping flame back and forth along axis of joint to maintain heat on parts to be joined, especially toward base of valve socket.

• 当焊剂变成液态并且在管道和阀门上呈现半透明状态时，开始将火焰沿着连接部件的轴线进行进退烘烤，以保持连接部件、特别是阀门套筒底座部位的热度。