Installation of SSAW steel pipe

1. Preparing the Joint

To ensure the quality of welding, a thorough inspection and correction are carried out before welding. This includes making sure that the pipe ends, bevel angles, blunt edges, and roundness meet the required interface size specifications. Occasionally, on-site groove processing is necessary, which involves gas welding cutting and subsequent slag removal followed by grinding with a grinding wheel.

The procedure for joint preparation includes:

Checking the interface connector size

Clearing the chamber

Determining and adjusting the longitudinal seam of the steel pipe to ensure it is properly aligned

Straightening the pipeline

Adjusting the gap size of the joints

Leveling the mouth

Ensuring alignment

Spot welding

2. Welding

Interface welding is done using arc welding, with a base pass followed by a second pass. Each weld is completed in one pass, with each layer's lead-off arc staggered.

Welding Steps:

A. Preparation: Ensure the pipe joints are clean, and that the slag, groove angle, blunt edge, and clearance at the pipe ends meet specifications. Avoid narrowing the gap by welding in the gap. B. Alignment: Align the pipe ends flush with the wall. Use a 300mm long ruler along the inner wall of the interface to check alignment. The allowable misalignment should be 0.2 times the wall thickness and no more than 2mm.

B. Weld Positioning: Ensure longitudinal welds are about 45° from the vertical line's semicircle on the pipe. The weld seam of the reinforced steel pipe and the reinforcement ring should be staggered by at least 100mm. The circumferential weld of the reinforcement ring section should not be less than 50mm, and cross-shaped welds should be avoided.

C. Positioning Welds: The positioning welds should be of the same quality as the final welds, though a finer electrode diameter can be used. The welding current for positioning welds should be 10%-15% higher than for final welds to ensure proper penetration.

D. Pipe Welding: Ensure the weld quality meets GB50268-97 4.2 standards. Welds should be smooth, of uniform width, root penetration, without visible defects, and free from undercutting. The weld reinforcement should be about 2mm above the tube face, with the groove edge extending 2-3mm.

E. Flange Welding: Insert the pipeline two-thirds into the flange. Ensure the flange and the pipeline are perpendicular and their axes coincide.

By following these steps, the installation of SSAW steel pipes can be completed with high quality, ensuring a durable and reliable pipeline system.

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