The acetylene gas is changed to the other fuel gas from the middle the gas pressure welding manner

摘要

PROBLEM TO BE SOLVED: To provide a gas welding method which is more economical and more stable in joining strength as a joining material becomes thicker, and capable of implementing a safe work, and changing the acetylene gas to other fuel gas halfway. ;SOLUTION: In this gas welding method, butted surfaces are initially heated using the acetylene gas until they are closely attached to each other, and then, post-heated by changing the acetylene gas to one of propane gas, LNG, ethylene gas, butane gas, methane gas, ethane gas, propylene gas, hydrogen gas or the like, or the mixture thereof. The gas changing timing is set to a point when the pressure is dropped by 10-30% from the upper limit value, or the point when the gas is shrunk by 5-20% of the estimated shrink margin, and preferably, the acetylene gas and other gas are supplied in an overlapping manner for 3 to 5 seconds.;COPYRIGHT: (C)2001,JPO