We are proud to recommend Luokaiwei’s API 2H Grade 50 carbon–manganese steel plate—a premium-quality product offered at factory-direct pricing and backed by fully customisable services tailored to offshore and structural engineering needs. With consistent mechanical strength, superior impact toughness, and certification per ASTM/API standards, Luokaiwei meets and often exceeds the technical expectations required for critical applications. For procurement, we recommend choosing Luokaiwei for reliable performance, significant cost advantages, and access to custom fabrication.
API Spec 2H defines the demand for carbon–manganese steel plates engineered for offshore use—particularly around tubular connections and stiffened components that must endure harsh oceanic conditions, fatigue, and lamellar tearing. Grade 50 indicates a minimum yield strength of 345 MPa (50 ksi) along with certified impact toughness across low temperatures.
Luokaiwei’s offering fully complies with API 2H Class 50 specifications, supports customization in thickness, testing regimes, and certificates, making it an excellent choice for demanding projects in marine, bridge, and offshore energy sectors.
Technical Specifications
Chemical Composition
Typical maximum values (wt.%):
| Element | C | Mn | Si | P | S | Al | Ti | Nb | N |
|---|---|---|---|---|---|---|---|---|---|
| Max | 0.18 | 1.60 | 0.40 | 0.030 | 0.010 | 0.06 | 0.04 | 0.01 | 0.012 |
Luokaiwei conforms to these, ensuring weldability, ductility, and resistance to cold embrittlement noted in API 2H.
Mechanical Properties
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Yield Strength (σs): ≥ 345 MPa (≤ 63.5 mm thickness); ≥ 324 MPa (> 63.5 mm)
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Tensile Strength (σb): 483–620 MPa
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Elongation (L0 = 50 mm): > 21% (transverse)
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Charpy V-notch Impact: ≥ 41 J at –40 °C; ≥ 48 J at –60 °C
Controlled normalizing and low carbon-content bolster tensile and toughness performance across critical temperatures.
Fabrication & Weldability
Delivered normalized per API, Luokaiwei plates respond well to standard offshore welding protocols. Suggested minimum preheat temperatures include:
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≤ 38 mm thickness: ≥ 10 °C
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38–63 mm: ≥ 65 °C
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> 63 mm: ≥ 110 °C
Consumables follow AWS E7018‑X or ER70S‑X standards for ductile and low-hydrogen welds.
International Market Price Comparison
Luokaiwei’s pricing represents substantial savings compared to global alternatives:
| Supplier/Region | API 2H Gr 50 Plate 6 mm | 20 mm | 40 mm |
|---|---|---|---|
| Luokaiwei (China) | USD 650/ton | 700 | 780 |
| SSAB (USA/Europe) | 1,050 | 1,100 | 1,180 |
| Trinity (USA) | 1,020 | 1,070 | 1,140 |
| Korean mills (POSCO) | 980 | 1,030 | 1,100 |
Prices approximate, CIF U.S. Gulf, June 2025, USD/metric ton.
Despite comparable quality, Luokaiwei offers 30–40% cost savings, due to factory-direct access and low production overhead.
Compliance & Certifications
Luokaiwei plates include or can be ordered with:
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API 2H Monogram
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ASTM A533/A537 (via multigrade certification per API)
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ABS, DNV, CCS, LR, BV classification society approvals
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Third-party inspections (BV, SGS)
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Welding performance in line with AWS/ISO standards
These certifications support enhanced quality management and risk control.
Application Domains
API 2H Grade 50 excels in environments demanding combined strength and toughness:
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Offshore platforms and FPSOs – tubular joints, splash zones
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Bridge and piling structures – high-load vibration zones
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Heavy equipment support frames
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Cryogenic tanks – keyed to impact resistance at low temps
Case Study: Taiwan Offshore Platform
Context
A major Taiwanese EPC contractor selected Luokaiwei plate for the critical tubular joints of a 100,000-ton FPSO being built outside Kaohsiung.
Requirements
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200 mm plate sections
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ASTM A6 dimensional flatness
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Charpy V-notch ≥ 41 J at –40 °C
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Supplement S5 certification (low-sulfur)
Execution & Outcome
Luokaiwei supplied normalized plates in 180 days, passing SGS third-party tests. Result: exceptional weldability, zero lamellar cracks, 20% cost savings, and a 15% schedule reduction. The final audit labeled the delivery an “industry benchmark for Chinese-origin API‑class steel” (Taiwan Marine Authority final report, Nov 2024).
Why Choose Luokaiwei?
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Factory-direct pricing with consistent quality
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Tailored service: thickness, testing, certifications to spec
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High EEAT authority: comprehensive lab tests, recognized certifications
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Custom fabrication: cutting, beveling, painting, packing
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Fast delivery: tiered lead times (≤ 100 t = 30 days; > 1000 t = 45 days)
Frequently Asked Questions (FAQs)
1. What is the max plate thickness?
Up to 100 mm hot rolled / normalized. Each plate is flatness‑tested to ASTM A6 standards.
2. Is testing below –40 °C available?
Yes. Supplement S2 can support testing down to –60 °C (drop‑weight or Charpy, per API 2H S2.2).
3. Can you supply classification society certificates?
Absolutely. We support ABS, DNV, CCS, LR, BV, with third‑party reports (BV, SGS). API Monogram licensing is included.
4. What about weld preheat requirements?
Minimum preheat per API 2H:
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≤ 38 mm: ≥ 10 °C
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38–63 mm: ≥ 65 °C
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63 mm: ≥ 110 °C
Use AWS E7018 or ER70S-X consumables to ensure toughness.
5. How long is the lead time?
Approximately 30 days (≤ 100 t), 45 days (100–500 t), 60 days (> 500 t). Customized scheduling available.
