Evaluation of Improved Gas Pressure Welding for In-Track HAL Service

This article describes an old welding technique, newly improved in Asia, that complements contemporary field welding methods. The technique, gas pressure welding (GPW), was used for decades by North American railroads until increasing axle loads began to cause weld failures. GPW was abandoned in favor of electric flash butt welding. Changes in the technique, which is used exclusively in certain Japanese high-speed lines and in China, involve grinding, filing and cleaning operations in rail end preparation to ensure tightly fitting surfaces at the weld interface. Removal of oxides or surface contamination is crucial. Improvements in rail quality and modern GPW equipment also make the technique viable.