Flash-Butt Welding of Large-Diameter Oil and Gas Pipelines

Interest in developing a high-production automatic joining method for quality offshore pipelines led to full-scale evaluation of the flash-butt welding process. During the past five years, two separate flash-butt welding machines have been used to provide over 1100 welds in 914-mm (36-in.) o.d. pipe for test and evaluation. Increased speed and the quality inherent in a fully automatic welding process were the two major incentives for the development project. It is estimated that flash-butt welding can produce up to 377 joints per day in 914-mm (36-in.) o.d. × 25-mm wall thickness pipe—twice what can be produced by conventional manual (shielded metal arc) welding techniques. This paper describes the flash-butt welding process and plans to install production equipment aboard a semi-submersible laybarge in the near future.