The size of large-diameter welded pipes usually refers to steel welded pipes with larger diameters, usually made of steel. Its size can include diameters ranging from 6 inches to 60 inches, wall thickness is usually between 5 mm and 30 mm, and the length can be customized according to customer needs, usually 6 meters, 9 meters or 12 meters, etc.
The following are the main steps in the production process of large-diameter carbon steel, alloy or stainless steel welded pipes:
1. Raw material inspection
Purpose: To ensure that the quality of raw materials used to produce large-diameter welded steel pipes meets the standards.
Content: Physical and chemical inspection of raw materials such as strip steel coils, welding wires, and fluxes, including full-plate ultrasonic inspection, etc., to detect whether their quality meets production requirements.
2. Pretreatment
Milling and pre-bending: Use the milling machine to cut the edges on both sides of the steel plate to achieve the shape, length, width, parallelism and other standards required for the straight seam steel pipe. The edges of the steel plate are pre-bent by the pre-bending machine to achieve the specified curvature.
Leveling, trimming, and planing: The strip steel needs to be leveled, trimmed, and planed before forming to ensure that its surface is flat and the edges are neat.
3. Forming
Press forming: Use JCO forming machine or similar equipment to stamp the pre-bent steel plate to form an open O shape, which is the initial shape of the steel pipe.
Roller forming: Use external or internal control roller forming technology to gradually roll the strip into the shape of a steel pipe through a series of roller extrusion and bending.
4. Welding
Pre-welding: The formed straight seam steel pipe is welded, and then continuously welded using a gas shielded welding device to form a preliminary weld.
Internal and external welding: Internal and external welding usually use methods such as submerged arc, automatic welding or manual arc welding.
spiral welded pipe
