ERW pipe welding code - common defects and prevention strategies

ERW (Electric Resistance Welding) pipes are manufactured by welding steel plates, with the weld seam formed by melting the base material of the steel strip. This results in superior mechanical strength compared to conventional welded pipes. The most distinguishing feature of ERW pipes, in contrast to seamless steel pipes, is their weld seam, which directly influences their quality. However, welding defects pose a major challenge in ERW pipe production, affecting safety, structural integrity, and increasing manufacturing and maintenance costs. Understanding common welding defects and their preventive measures is essential for enhancing the quality and reliability of ERW pipes.

Union Steel Industry Co., Ltd is professional ERW pipes manufacturer, for more details, please contact:sales@union-steels.com

Common Welding Defects in ERW Pipes

- Lack of Fusion
This defect occurs when the edges of the steel strip fail to fully fuse during welding. It can be categorized into:

Complete lack of fusion

Partial lack of fusion

Incomplete fusion (cold welding)

Causes of lack of fusion include insufficient welding heat input, improper edge deformation, the presence of crescent bends, and rust on the strip edges.

- Undercut
Undercut appears as a groove or depression along the weld toe, reducing structural integrity. It is primarily caused by:

Excessive arc heat due to high welding current

Slow wire feeding speed

Insufficient replenishment of deposited metal after base material melting

- Weld Nodules
Weld nodules are excess metal formations on the weld surface, typically resulting from liquid metal overflowing during welding. Contributing factors include:

Excessive welding parameters

Rapid melting of welding rods

Poor-quality welding rods (e.g., eccentricity)

Instabilities in the welding power supply

Improper welding posture, especially in horizontal, vertical, or overhead positions

Prevention Strategies

- Optimizing Welding Process Parameters

Adjusting welding current, voltage, and speed to maintain proper heat input.

Avoiding excessive welding current to prevent undercut and weld bead defects.

Ensuring adequate heat input to avoid incomplete fusion.

- Controlling Raw Material Quality

Ensuring strip edges are flat, free from cracks and rust to promote seamless fusion.

Monitoring chemical composition and mechanical properties to meet industry standards.

- Enhancing Operator Skills

Providing regular training to improve welding precision and awareness.

Conducting periodic skill assessments to encourage continuous improvement.

Emphasizing responsibility and quality control in welding operations.

Conclusion

Welding defects are a critical factor affecting the performance and longevity of ERW pipes. By optimizing welding parameters, maintaining raw material quality, and enhancing operator skills, manufacturers can significantly reduce defects, improve production efficiency, and enhance the overall reliability of ERW pipes in various industrial applications.