How to check SSAW steel pipe quality from appearance?

SSAW (Spiral Submerged Arc Welded) steel pipe is a type of welded steel pipe produced from strip steel coil. It is extruded at normal temperature and welded using an automatic double-wire, double-sided submerged arc welding process. SSAW pipes are commonly used for fluid transportation, metal structures, and steel pipe piles. A key inspection method for SSAW pipes is appearance quality inspection, which focuses on identifying surface defects on the weld and checking for dimensional deviations.

The appearance quality inspection is typically performed in the following ways:

Visual Inspection of the Spiral Steel Pipe Surface
By examining the surface of the spiral steel pipe, one can assess the quality of the production process. High-quality manufacturers take care to avoid surface defects, such as friction marks. In contrast, counterfeit or substandard spiral steel pipes may have an oval cross-section, indicating that the manufacturer cut corners to save raw materials by applying a larger reduction during the initial production stages. Such pipes often have reduced tensile strength and fail to meet rebar specifications.

In well-made pipes, the steel composition is uniform, and the cold shearing machine exerts high tonnage, resulting in clean, smooth internal threads at the cutting head. Conversely, inferior pipes, made from poor-quality materials, often have slag or uneven surfaces on the cutting head, lacking the metallic luster seen in higher-grade products. Additionally, burrs at the head and tail may appear due to improper cutting.

Auditory Inspection
Tapping the steel pipe can also provide clues about its quality. A brittle sound with a clean echo usually indicates that the pipe is new and produced in a proper factory, whereas recycled or substandard pipes often produce duller, less distinct sounds.

Tool-Assisted Inspection
Using standard templates, gauges, and magnifying glasses, inspectors can closely examine the weld surface. If any defects are present on the surface, it could signal internal defects within the weld.

However, the appearance alone does not determine the overall quality of the spiral steel pipe. The physical and mechanical properties, such as strength, are equally important. Therefore, when purchasing SSAW pipes, it is essential to request inspection certificates and other relevant documentation from the supplier to ensure the pipe meets required standards.