How to make steel pipe?
The methodology and steps are as follows:
Steel plate delineation is based on construction drawings and takes into account factors such as cutting loss and welding shrinkage. After delineation, the steel pipe sections, section numbers, water flow direction, horizontal and vertical center line, bevel angle, cutting lines and other symbols are marked with stencil and paint respectively.
Steel pipe rolling
Steel pipe rolling uses the cold coil method. The bending direction is the same as the rolling direction of the steel plate, and it is not allowed to bend and correct the curvature of the steel pipe by hammering at the steel plate port. The rolled and shaped pipe is held upright on the platform in a free state, and the curvature of the pipe is checked with a template.
Steel pipe is X-bevel and double-sided welding of longitudinal seam. Longitudinal seams of the same section of steel pipe use automatic submerged arc welding, generally welding the inner seam first. After passing the appearance inspection of the inner seam, use carbon arc gouging to clear the back side and weld the outer seam after passing the treatment.
Pipe joint assembly and welding
Pipe rounding is performed on a rounding platform, and the rounded individual pipe sections are assembled in one piece in numbered order. Checking the manufacturing tolerances of steel pipe so that they conform to the relevant provisions of the specification.
To ensure uniform shrinkage during pipe group welding, four welders are assigned to each annular seam at the same time, and take symmetric, segmented, multi-layer, multi-channel, regressive welding with hammering method to eliminate welding residual stresses. Welded joints are staggered by 50mm for each layer, and cover seam is formed in one go. After all welds have been welded, they are inspected cosmetically first. And after they are qualified, they are inspected nondestructively inside the weld.