NEW QUALITY INSPECTION METHOD FOR GAS PRESSURE WELDS

In Japan, a majority of steel bars are welded by the gas pressure welding because it is superior to other joining methods in workability. In the Hyogoken-Nanbu earthquake on January 17, 1995, a number of gas pressure welds in reinforced concrete members were fractured at the weld interface. Since then, a reliable quality inspection method has strongly been demanded. A method of "flash removal by hot shearing," which makes it possible to easily inspect the weld immediately after welding, has been recently developed. This method is effective in evaluating gas pressure welds in real time, and it possesses high workability and high reliability. The reliability of inspection method, such as penetrant test, ultrasonic test and flash removal by hot shearing method, was verified by tensile and bending tests of welded joints. After that, the relation between the inspection results and the destructive test results was investigated. As a result, it was clear that flash removal by hot shearing method has the highest reliability. Thus, flash removal by hot shearing method is superior to penetrant testing and ultrasonic testing as a quality inspection method for gas pressure welds.