Common surface defects of welded steel pipe

Welded steel pipes can exhibit a range of surface defects that affect their quality and performance. Understanding these defects is crucial for quality control and ensuring the integrity of the pipes in various applications. Here are some common surface defects found in welded steel pipes.

Layered Steel

Description: Layered steel in a pipe wall means that the cross-section is divided into two distinct layers, often visible as vertical cracks on the steel surface. This defect may cause the steel's inner and outer surfaces to appear locally recessed or raised. The layered defect often results in sudden protrusions, dents, or warping along and around the weld seam.

Sticky Scar

Description: A sticky scar defect refers to large patches of steel adhesion on the internal or external surfaces of the pipe. These scars appear as focal adhesion plaques, disrupting the smoothness of the pipe surface.

Holes

Description: This defect involves the presence of local holes through the wall of the steel pipe. Such holes compromise the integrity and strength of the pipe, making it unsuitable for applications requiring pressure resistance.

Open Welding

Description: Open welding defects manifest as long, continuous cracks along the weld seam or partially along it. These cracks can severely weaken the structural integrity of the pipe.

Local Lap Welding

Description: This defect occurs when a portion of the outer surface of the steel pipe shows an arc-shaped overlap of the weld material. This overlapping creates inconsistencies in the pipe wall thickness and can lead to weak points.

Welding Groove

Description: A welding groove defect appears as a long groove along the weld seam on the outer surface of the pipe. This groove can act as a stress concentrator and potential failure point under load.

Collapse of Welding

Description: The collapse of welding defect refers to a situation where the outer surface of the weld shows a long trench-like depression, with corresponding convex edges. This collapse can weaken the pipe's ability to withstand external pressures.

Pipe Joint Dislocation

Description: Pipe joint dislocation occurs when there is a misalignment or stagger between the welded joints, causing an uneven surface. This misalignment can result in structural weaknesses and difficulties in pipe fitting.

Conclusion

Surface defects in welded steel pipes, such as layered steel, sticky scars, holes, open welding, local lap welding, welding grooves, collapse of welding, and pipe joint dislocation, can significantly impact the performance and safety of the pipes. Identifying and addressing these defects through rigorous quality control processes is essential to ensure the reliability and longevity of welded steel pipes in various applications.