📄 PSL1 L245/B Pipeline Steel Plate (GB/T 21237-2018) – Technical Data Sheet
This standard specifies technical requirements for wide and heavy plates of 6mm~50mm thickness for petroleum and natural gas pipelines. L245/B (PSL1) is a versatile carbon steel grade offering good strength, weldability and formability for low-to-medium pressure pipeline systems.
PSL1 L245/B pipeline steel plate conforms to GB/T 21237-2018, equivalent to API 5L Grade B. It is widely used in oil and gas transmission, water pipelines, and structural applications where reliable mechanical performance and cost efficiency are essential. With moderate carbon content and controlled manganese, L245/B delivers excellent weldability and bending properties, making it ideal for field fabrication and high-volume pipeline projects.
📌 Designation Rules (3.2.1 / 3.2.2)
🔹 Standard Naming (3.2.1)
Example: L415M
L — First letter of "Line" for pipeline
415 — Specified minimum yield strength (MPa)
M — Thermomechanical rolled condition
L245/B: L245 = yield ≥245MPa, /B indicates Grade B (PSL1, hot-rolled/normalized/normalized-rolled)
🔸 API 5L Common Naming (3.2.2)
Example: X60M
X — Line pipe identifier
60 — Minimum yield strength (ksi)
M — Delivery condition
L245/B corresponds to API 5L Grade B, yield ≥245MPa.
📘 Per Table 1, PSL1 hot-rolled/normalized state = L245/B.
🧪 Chemical Composition (PSL1, ladle & product analysis)
| Grade | Cb (≤%) | Mnb (≤%) | P (≤%) | S (≤%) | V | Nb | Ti | Other restrictions |
|---|---|---|---|---|---|---|---|---|
| L245/B | 0.26 | 1.20 | 0.030 | 0.030 | c,d | c,d | c,d | Cu≤0.50, Ni≤0.50, Cr≤0.50, Mo≤0.15 |
📋 Table 2 Notes:
a Copper max 0.50%; Nickel max 0.50%; Chromium max 0.50%; Molybdenum max 0.15%.
b For each 0.01% reduction in carbon below 0.26%, manganese may be increased by 0.05% above 1.20%, but max Mn ≤1.65% for L245/B.
c Unless otherwise agreed, total Nb+V ≤0.06%.
d Total Nb+V+Ti ≤0.15%.
e Unless otherwise specified, boron not intentionally added, residual B ≤0.001%.
⚙️ Mechanical & Technological Properties (PSL1 Table 4)
| Steel grade | Rt0.5 (MPa) ≥ | Rm (MPa) ≥ | A50mmc (%) ≥ | 180° bend test | Specimen direction |
|---|---|---|---|---|---|
| L245/B | 245 | 415 | 21 | D=2a, no cracks | Transverse |
📋 Table 4 Notes:
a Tensile property range to be agreed between purchaser and supplier to ensure finished pipe compliance.
b Specimen direction transverse, to be stated in contract.
c Standard gauge length 50mm. Arbitration specimen: 50mm gauge length, 38mm width.
📐 Min elongation formula: A50mm=1940×S00.2/Rm0.9. Bend former diameter D=2a.
🔄 L245/B vs API 5L Grade B – What's the Difference?
🇨🇳 GB/T 21237 L245/B
- Standard: Chinese national standard GB/T 21237-2018 (PSL1)
- Yield strength: ≥245 MPa
- Tensile strength: ≥415 MPa
- Carbon (max): 0.26%
- Manganese (max): 1.20% (adjustable up to 1.65%)
- Delivery condition: Hot-rolled, normalized, normalized-rolled
- Typical use: Oil & gas pipelines, water transmission, low-pressure services
🇺🇸 API 5L Grade B
- Standard: API Spec 5L (PSL1 / PSL2)
- Yield strength: ≥245 MPa (35,500 psi)
- Tensile strength: ≥415 MPa (60,200 psi)
- Carbon (max): 0.26% (Grade B)
- Manganese (max): 1.20%
- Delivery condition: As-rolled, normalized, TMCP
- Typical use: Low/medium pressure pipelines, structural pipe
💡 Bottom line: L245/B (GB/T 21237) is fully equivalent to API 5L Grade B in mechanical properties and chemical composition. The naming differs — "L" stands for "Line" in the Chinese standard, while API uses "B" — but material performance is identical. For projects requiring API 5L Grade B steel plates, L245/B from Chinese mills is a direct, cost-effective substitute. It delivers the same yield strength (245MPa minimum), tensile strength (415MPa minimum), and excellent weldability.
📜 Supplementary Chemical Requirements (6.1.3 ~ 6.1.6)
✅ 6.1.3 Thickness > 25.0mm — Chemical composition may be agreed between supplier and purchaser for heavy plates up to 50mm.
✅ 6.1.4 Ladle analysis & CE — Supplier provides ladle analysis and carbon equivalent (CE); product analysis upon negotiation.
✅ 6.1.5 Intermediate grades — Intermediate grades between consecutive Table 2 grades may be supplied by agreement.
✅ 6.1.6 Other alloying elements — For L290/X42 and above other elements may be added; L245/B conventional microalloy limits apply.
🏭 Smelting Method · Delivery Condition (6.3 & 6.4)
🔥 6.3 Smelting process
Oxygen converter or electric furnace. For PSL1 L245/B conventional smelting with controlled residuals.
📦 6.4 Delivery condition
Hot-rolled (R), normalized (N), normalized-rolled. L245/B typically delivered as hot-rolled or normalized.
📏 Dimensions & Other Technical Specifications
Dimensions (Clause 5): Per GB/T 709. Thickness 6mm~50mm. Trimmed/untrimmed edges. Tolerances per GB/T 709.
Grain size (6.6): Not mandatory for PSL1, reference No.7 or finer.
Non-metallic inclusions (6.7): PSL1 no mandatory limits, but clean steel practice required.
Banding (6.8): Not specified for PSL1; for reference only.
📋 Summary: Steel plate surfaces must be free from cracks, blisters, folds, inclusions, and visually detectable laminations. Defect removal permitted within tolerance limits, welding repair prohibited.
✅ 6.9.1 The steel plate surface shall be free from cracks, blisters, folds, bubbles, inclusions, and visually detectable laminations harmful to use. Removal allowed up to half thickness tolerance, maintaining min thickness.
✅ 6.9.2 Other local imperfections that do not affect use are permitted, provided minimum thickness is maintained.
✅ 6.9.3 For untrimmed edges, edge crack depth shall not exceed half width tolerance, min width maintained.
✅ 6.9.4 Upon agreement, defect depth and area may be measured per GB/T 14977.
✅ 6.9.5 Welding repair on steel plate surface is not permitted.
📋 Ordering content & Inspection rules
📑 Ordering content (Clause 4)
- Standard: GB/T 21237—2018
- Quality level: PSL1
- Grade: L245/B
- Dimensions & thickness precision
- Delivery condition & edge condition
- Specimen direction (transverse)
- Application: gas/oil/fluid
🔬 Inspection rules
Batch: same grade, heat, thickness, rolling schedule. ≤60 tons per batch. Test methods: GB/T 228.1 (tensile), GB/T 232 (bend), GB/T 4336 (chemistry). Rounding per GB/T 8170.