Welding method:
When welding thick-walled steel pipes, first clean the oil, paint, water, rust, etc. of the welding joint, and then open the groove according to the wall thickness. The gap is generally 1-1.5 times the diameter of the electrode or wire. If the groove is accidentally opened, it can be appropriately left smaller. Spot welding at least three points, generally four points are better to work. When welding, it should be welded in half and half, and the starting point is about one centimeter above the bottom point so that the joint is good from the opposite side. If the wall of the steel pipe is thick, it should be layered, with at least two layers and the second layer can be welded after the whole circle is welded.
Process flow:
Round tube blank→heating→piercing→three-roll skew rolling, continuous rolling or extrusion→tube removal→sizing (or diameter reduction)→cooling→straightening→hydrostatic test (or flaw detection)→marking
Weld height:
When the wall thickness of the steel pipe is not greater than 12.5mm, the excess height of the weld shall not be greater than 3.0mm; when the wall thickness of the steel pipe is greater than 12.5mm, the excess height of the weld shall not be greater than 3.5mm.
Curvature:
The steel pipe with a nominal outer diameter of not more than 168.3mm shall be straight or according to the bending index specified in the agreement between the supplier and the buyer; for the steel pipe with a nominal outer diameter of more than 168.3mm, the bending degree shall not be greater than 0.2% of the full length of the steel pipe. For steel pipes with a wall thickness of more than 4mm at the pipe end, the pipe end can be beveled at 30°+5°0°, with a root of 1.6mm±0.8mm, and the pipe end slope is less than or equal to 5mm.
Post time: Nov-22-2022