Sludge steel pipes mainly refer to welded steel pipes. Welded steel pipes include spiral steel pipes and straight seam steel pipes. The adopted technology is basically double-sided submerged arc welding technology. Submerged arc welding (including submerged arc welding and electroslag surfacing, etc.) is a method in which an arc is burned under a layer of solder to perform welding. Its inherent stability in welding quality, high welding productivity, no arc, and little smoke and other advantages, making it the main welding method for the production of pressure vessels, pipe section manufacturing, box beam and other important steel structures. The production technology of the mud-separated steel pipe straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is rapid. Large diameter steel pipes are mostly spiral welded.