Seam treatment of spiral welded pipe

Impact of Gap Size on Welding Quality

- Large Gap:

A large gap reduces the proximity effect, leading to insufficient eddy current heating. This results in poor joint formation between the welds, causing issues like incomplete fusion or cracks.

- Small Gap:

A small gap increases the proximity effect, causing excessive welding heat. This can lead to weld burns or deep pits forming after extrusion and rolling, negatively impacting the surface quality of the weld.

Effect of Squeeze Force in Spiral Steel Pipe Production

After heating the two edges of the tube blank to the welding temperature, the squeeze roller compresses the edges. This causes the formed metal grains to penetrate and crystallize with each other, creating a strong weld. However, the squeeze force must be correctly calibrated:

- Insufficient Squeeze Force:

If the squeeze force is too small, fewer common crystals are formed, reducing the strength of the weld metal and making it prone to cracking under stress.

- Excessive Squeeze Force:

If the squeeze force is too large, the molten metal is pushed out of the weld. This not only reduces the weld's strength but also creates excessive internal and external burrs, potentially leading to defects such as weld overlap.