How to Inspect the Weld Quality of Spiral Steel Pipes?

Spiral steel pipe welds are critical for pressure resistance,structural safety and service life.Common inspection methods include non-destructive testing(NDT)and visual inspection,which are used in factory production and on-site construction.

1.Visual Inspection(VT)

Check weld appearance for uniform forming,smooth surface,no undercut,cracks,porosity,slag inclusion or spatter.

Inspect weld size,leg length and transition to base metal.

Check pipe end misalignment,weld straightness and surface defects.

2.Ultrasonic Testing(UT)

Use ultrasonic waves to detect internal defects:incomplete fusion,cracks,voids,slag inclusions.

Suitable for thick-wall spiral steel pipes and factory full-length weld inspection.

High sensitivity,can locate and quantify defects accurately.

3.Radiographic Testing(RT)

Use X-ray orγ-ray to take films of welds.

Clearly show internal defects such as pores,inclusions,cracks and lack of penetration.

Commonly used for key pressure pipelines,oil and gas pipelines and important engineering welds.

4.Magnetic Particle Testing(MT)

Apply magnetic field and magnetic powder to detect surface and near-surface cracks.

Only applicable to ferromagnetic carbon steel spiral pipes.

Fast and intuitive,widely used for surface crack inspection.

5.Liquid Penetrant Testing(PT)

Apply penetrant and developer to display tiny surface openings.

Suitable for austenitic stainless steel or non-magnetic pipe welds.

Mainly used to detect surface pores,cracks and leaks.

6.Hydrostatic/Pressure Test

Test under specified water pressure to check overall sealing and pressure bearing capacity.

Observe whether there is leakage,permanent deformation or pressure drop.

Final comprehensive inspection before delivery and installation.

7.General Requirements

Inspection shall be carried out by qualified personnel in accordance with standards such as GB/T 9711,API 5L,AWS or project specifications.

Defective welds must be repaired and re-inspected until qualified.

Factory-manufactured spiral pipes usually undergo full-length ultrasonic testing and random radiographic testing.