Quality control of SSAW steel pipe

Welded pipes are cylindrical pipes manufactured by welding steel plates. They are categorized into three types:

High-Frequency ERW Steel Pipes

LSAW Steel Pipes

SSAW Steel Pipes

Inspection Equipment and Procedures

To ensure the quality of welded pipes, various inspection methods are employed:

Industrial TV Internal Inspection Equipment: Inspects the appearance quality of internal welding seams.

Magnetic Particle Flaw Detector: Detects near-surface defects in large-diameter steel pipes.

Ultrasonic Automatic Continuous Flaw Detector: Inspects transverse and longitudinal defects along the full-length weld of spiral steel pipes.

Ultrasonic Manual Flaw Detector: Re-inspects large-diameter steel pipe defects, repaired welds, and weld quality after hydraulic pressure testing.

X-ray Automatic Flaw Detector and Industrial TV Imaging Equipment: Inspects the internal quality of the full-length weld of spiral steel pipes with a sensitivity of at least 4%.

X-ray Filming Equipment: Inspects original and repaired weld seams with a sensitivity of at least 2%.

2,200-ton Hydraulic Press and Computer Automatic Recording System: Tests the pressure-bearing quality of each large-diameter steel pipe.

Quality Assurance Plan

To ensure product quality, a comprehensive quality plan, on-site work procedures, and inspection and test plans are implemented:

Raw Material Inspection

Leveling Inspection

Butt Welding Inspection

Forming Inspection

Inner Welding Inspection

Outer Welding Inspection

Pipe Cutting Inspection

Ultrasonic Inspection

Groove Inspection

Dimension Inspection

X-ray Inspection

Hydrostatic Test

Final Inspection

Anti-Corrosion Measures

This project’s anti-corrosion requirements differ significantly from typical domestic projects:

- Internal Anti-Corrosion: Uses non-toxic epoxy paint (0.4mm thickness) instead of the commonly used cement mortar in China.

- External Anti-Corrosion: The electric spark test voltage is set at 10 kV, much higher than the domestic standard of 3,000-5,000 volts.

To meet these stringent requirements, the following procedures are followed:

- Sandblasting: Ensures quality rust removal, with internal and external primers sprayed within 1 hour to maintain anti-corrosion quality.

- Anti-Corrosion Process: Glass cloth is soaked with epoxy coal tar pitch paint, semi-mechanically rolled, and manually flattened with a roller to ensure uniform and fine outer coating. The pipes are inspected in open storage for 4 months to ensure the inner coating remains intact and the outer anti-corrosion layer passes the 10 kV electric spark test.

Applications of Spiral Welded Pipe

Spiral welded pipes are extensively used in various industries:

Water Supply Projects

Petrochemical Industry

Chemical Industry

Electric Power Industry

Agricultural Irrigation

Urban Construction

Specific uses include:

Liquid Transportation: Water supply and drainage.

Gas Transportation: Gas, steam, and liquefied petroleum gas.

Structural Purposes: Piling pipes, bridges, wharves, roads, and building structures.