Abstract: Assembling and welding of steel pipes are the major activities in the construction of long distance oil and gas pipelines, so it is of great importance to properly select a welding procedure and welding plan. A well selected welding procedure can not only result in high welding speed, high welding quality, but also good economic benefit. Taking the Tunisian Gas Transimission Pipeline as an example, the paper discusses how to define a proper welding plan, and points out some problems to be duely solved in actual projects.