API 5L Grade B seamless steel pipe specifications are primarily applicable to sizes ranging from 1/8" to 48" (DN6 to DN1200). The wall thickness of these pipes must conform to ASME B36.10 standards, with wall thickness grades including SCH 10, SCH 20, SCH 40, STD, XS, SCH 100, SCH 120, SCH 160, and XXS.
api 5l grade b pipe wall thickness table
Tolerance for Diameter at API 5L GRB Pipe Ends
|
Size |
Tolerance (with respect to specified outside diameter) |
|
<2 3/8 |
+ 0.016 in., - 0.031 in. (+ 0.41 mm, - 0.79 mm) |
|
> 2 3/8 and ≤4 1/2, continuous welded |
±1.00% |
|
> 2 3/8 and < 20 |
±0.75% |
|
> 20. seamless |
± 1.00% |
|
>20 and <36, welded |
+ 0.75%.-0.25% |
|
> 36,welded |
+ 1/4 in.. - 1/8 in. (+ 6.35 mm, -3.20 mm) |
manufacturing process of API 5L GRB Pipe line
| Process Stage | Key Control Points | Process Parameters |
|---|---|---|
| 1. Billet Heating | - Continuous-cast round billet purity (S/P≤0.025%) - Uniform heating in rotary hearth furnace to prevent decarburization |
Temp: 1200±50℃ Duration: ≥90 min |
| 2. Hot Rolling | - Piercer point life management (replace every 300 pipes) - Tension control in continuous rolling to prevent wall thickness variation |
Speed: 0.8-1.2m/s Reduction ratio: ≤15% |
| 3. Cold Drawing | - Pickling concentration control (HCl 15%±2%) - Multi-pass die wear monitoring (≤1.2mm reduction per pass) |
Drawing force: 80-120MPa Surface roughness: Ra≤0.8μm |
| 4. Heat Treatment | - Mandatory normalizing for PSL2 (Ac3+30℃) - Grain size control (Grade 5-8) |
Normalizing temp: 890±10℃ Cooling: Air |
| 5. NDT | - 100% automatic UT + eddy current for PSL2 - Rejection criterion: ≥φ2mm equivalent defects |
UT standard: API 5L App.E EMI frequency: 20-100kHz |
