We enforce strict quality control throughout every production stage-from raw material sourcing to final dispatch. At each step, our experienced inspectors conduct thorough inspections, record findings with photos, and archive them to ensure traceability. This rigorous process guarantees that every batch meets our high standards in both quality and consistency.
Our on-site quality laboratory spans over 1,000 m² and houses more than 100 advanced testing instruments. Core tests include:
- High- and low-temperature tensile testing
- Bending and impact resistance analysis
- Flattening resistance evaluation
- Salt spray corrosion test
- Chemical composition verification
These capabilities enable real-time verification of product mechanical properties and durability under diverse conditions.
Our commitment to excellence is backed by internationally recognized certifications. We have obtained ISO 9001 for quality management and other relevant industry certifications, reinforcing our authority and reliability in the steel pipe market.
Straight seam welded steel pipe inspection and main technical indicators
| No. | Project | Standard | Standard Value (mm) |
|---|---|---|---|
| 1 | Pipe except the end diameter tolerance | API 5L, GB/T9711-2017, GB/T3091-2015 | D ≤ 60.3: -0.8, +0.4; 60.3 < D ≤ 168.3: ±0.0075D; 168.3 < D ≤ 610: ±0.0075D but not more than ±3.2; 610 < D ≤ 1422: ±0.005D but not more than ±4.0 |
| 2 | Pipe end diameter tolerance | API 5L, GB/T9711-2017, GB/T3091-2015 | 60.3 < D ≤ 168.3: ±1.6; 168.3 < D ≤ 610: ±0.005D but not more than ±1.6; 610 < D ≤ 1422: ±1.6 |
| 3 | Thickness tolerance | API 5L, GB/T9711-2017, GB/T3091-2015 | t ≤ 5: ±0.5t; 5 < t ≤ 10: ±1.0t; t > 15: ±1.5 |
| 4 | Length | API 5L, GB/T9711-2017, GB/T3091-2015 | ±500; +20, 0 |
| 5 | Straightness | API 5L, GB/T9711-2017, GB/T3091-2015 | <0.2%L |
| 6 | Out-of-roundness | API 5L, GB/T9711-2017, GB/T3091-2015 | D ≤ 219: ≤ 1%; D > 219: <0.8% |
| 7 | Pipe end shape | API 5L, GB/T9711-2017, GB/T3091-2015 | Bevel angle: 30° ± 5°; Width of root face: 1.6 ± 0.8mm; Out-of-squareness: ≤ 1.6mm |
| 8 | Outer burrs | API 5L, GB/T9711-2017, GB/T3091-2015 | Flush with the arc; ≤0.5 |
| 9 | Radial offset | API 5L, GB/T9711-2017, GB/T3091-2015 | The radial offset of the strip/plate edges shall not cause the remaining wall thickness at the weld to be less than the minimum permissible thickness |
| 10 | Surface defects | API 5L, GB/T9711-2017, GB/T3091-2015 | Convex parts or scratches/indentations not exceeding 0.25t; Internal/external surfaces smooth, free of cracks, folds, delamination, scarring |
| 11 | Repair | API 5L, GB/T9711-2017, GB/T3091-2015 | Minimum welding seam interval ≥ 50 mm; Maximum repair length ≤ 150 mm; No more than 3 repairs per weld |
| 12 | Nondestructive test | API 5L, GB/T9711-2017, GB/T3091-2015 | According to ISO 9711, ISO 9001, ASTM E213, ASTM E273 |
| 13 | Hydrostatic test | API 5L, GB/T9711-2017, GB/T3091-2015 | P ≥ 60% of specified minimum yield strength, holding time ≥ 5 seconds |
| 14 | Flattening | API 5L, GB/T9711-2017, GB/T3091-2015 | D < 168.3: distance between two plates h = (1/3)D; No cracks or breaks after flattening |