1. Core Definition & Standard Compliance

1.1 Fundamental Overview

• Standard Nomenclature (EN 10028 Part 2):
  • “P”: Denotes pressure vessel application;
  • Numeric prefix (e.g., 235, 265): Minimum yield strength in MPa (at room temperature);
  • “GH”: Indicates normalized heat treatment (G = normalized, H = high-temperature service capability);
  • Alloy grades (e.g., 16Mo3): “16” = approximate carbon content (0.16%), “Mo” = molybdenum alloy, “3” = molybdenum content (≈0.3%).
• Key Grades & Service Temperature Ranges:
  • P235GH: ≤400°C, low-carbon grade for general high-temperature pressure vessels;
  • P265GH: ≤425°C, medium-strength grade for boilers and heat exchangers;
  • P295GH: ≤435°C, high-strength grade for heavy-duty pressure vessels;
  • P355GH: ≤450°C, high-strength grade for critical high-pressure applications;
  • 16Mo3: ≤530°C, molybdenum-alloyed grade for high-temperature boilers and petrochemical reactors.
• Key Aliases: EN 10028 Pressure Vessel Steel Plates, EN 10028-2 GH Grades, 16Mo3 Alloy Steel for Boilers.
• Equivalent Grades:
  • ASTM: P235GH ≈ ASTM A516 Gr. 60, P355GH ≈ ASTM A516 Gr. 70, 16Mo3 ≈ ASTM A387 Gr. 11;
  • Chinese: P235GH ≈ GB/T 713 Q245R, P355GH ≈ GB/T 713 Q345R, 16Mo3 ≈ GB/T 713 15CrMoR;
  • API: 16Mo3 ≈ API 6A F22 (for oilfield pressure equipment).

1.2 Core Standards

• Primary Standard: EN 10028 (Series) – Part 2 (Non-alloy and alloy steels for pressure vessels), Part 3 (Austenitic stainless steels), Part 4 (Nickel alloy steels) (focus on Part 2 in this guide);
• Complementary Standards: EN 10029 (dimension tolerances for steel plates), EN 10204 (material test reports), EN ISO 15614 (welding procedure qualification), ASME Section VIII Div. 1 (pressure vessel design compatibility);
• Quality Certifications: ISO 9001, CE PED (Pressure Equipment Directive) Certification (for European market), third-party certifications (SGS, BV, TÜV) for material composition and mechanical performance;
• Critical Requirements: Mandatory high-temperature tensile and creep tests (for 16Mo3), impact testing (≥27 J at -20°C for P355GH), strict impurity control (P ≤0.035%, S ≤0.035%), and weldability validation.

2. Chemical Composition

2.1 Key Alloy Advantage

3. Mechanical & Physical Properties

3.1 Physical Properties

• Density: 7.85 g/cm³ (standard carbon/alloy steel density);
• Melting Point: 1450–1510°C (P235GH/P355GH), 1470–1530°C (16Mo3);
• Thermal Conductivity: 45–50 W/m·K (room temperature); 30–35 W/m·K (400°C);
• Thermal Expansion Coefficient: 11.5×10⁻⁶/℃ (20–100°C); 13.0×10⁻⁶/℃ (400–500°C);
• Corrosion Resistance: Moderate—resists high-temperature oxidation and neutral aqueous corrosion; requires protective coatings (e.g., FBE, high-temperature paint) for acidic or marine environments;
• Weldability: Excellent—compatible with SMAW, GMAW, GTAW, and SAW welding processes; pre-heat required only for thick plates (>25mm) or high-restraint joints (16Mo3 requires post-weld heat treatment at 600–650°C).

4. Product Forms & Dimensional Range

4.1 Core Product Forms

• Hot-Rolled Plates: Primary form for pressure vessel shells, boiler drums, and flanges;
• Normalized Plates: Standard heat treatment form for all GH grades (ensures uniform grain structure and high-temperature performance);
• Cut Blanks: Custom-cut shapes for vessel heads, nozzles, and specialized components;
• Welded Plates: Large-diameter vessel shells (via submerged arc welding of plates).

4.2 Dimensional Range

• Thickness: 6mm–200mm (common: 10mm, 16mm, 20mm, 30mm, 50mm); 16Mo3 available up to 300mm for heavy-duty boilers;
• Width: 1000mm–4000mm (standard: 1500mm, 2000mm, 2500mm);
• Length: 2000mm–12000mm (standard: 6000mm, 8000mm, 10000mm);
• Dimensional Tolerance: Thickness ±0.5mm (≤50mm) to ±1.0mm (>50mm); width ±1mm; length ±50mm (per EN 10029).

4.3 Surface & Heat Treatments

• Surface Finishes:
  • Hot-Rolled Mill Finish: As-rolled surface (for immediate fabrication);
  • Shot Blasted Finish: Cleaned to Sa 2.5 standard (preparation for welding or coating);
  • Pickled Finish: Acid-washed to remove oxide scale (for critical weld joints).
• Heat Treatments:
  • Normalizing: 880–920°C (air cooling) – Standard for GH grades; refines grain structure and improves high-temperature toughness;
  • Stress Relieving: 580–620°C – Mandatory after welding to reduce residual stress;
  • Quenching & Tempering (Q&T): Optional for thick P355GH plates (>50mm) to enhance strength uniformity.

5. Production Process & Quality Control

1. Raw Material Preparation: High-purity low-carbon steel scrap + alloy additions (molybdenum for 16Mo3) with certified composition;
2. Smelting: Melting in basic oxygen furnaces (BOF) or electric arc furnaces (EAF); vacuum degassing to remove impurities (O₂, H₂) and ensure chemical uniformity;
3. Continuous Casting: Molten steel cast into slabs; homogenization annealing (850–900°C) to eliminate segregation;
4. Hot Rolling: Slabs heated to 1150–1200°C; hot-rolled to target thickness; controlled cooling to prevent grain coarsening;
5. Heat Treatment: Normalizing (standard for all grades) or Q&T (for thick plates) to optimize mechanical properties;
6. Surface Preparation: Shot blasting or pickling to remove oxide scale;
7. Quality Inspection (EN 10028-2 Mandatory):
   1. Chemical Testing: High-precision spectrometric analysis (EN ISO 10703) to verify composition;
   2. Mechanical Testing: Tensile, bend, and hardness tests for each batch; high-temperature tensile/creep tests for 16Mo3; impact testing at -20°C;
   3. Non-Destructive Testing (NDT):
      • Ultrasonic Testing (UT): 100% thickness inspection and internal flaw detection (EN 10160);
      • Magnetic Particle Testing (MT)/Liquid Penetrant Testing (PT): Surface flaw detection on edges and weld joints;
      • Radiographic Testing (RT): Weld inspection for critical components;
   4. Dimensional Inspection: Laser measurement for thickness, width, flatness, and straightness;
   5. Material Test Report: EN 10204 3.1 or 3.2 certification (mandatory for pressure equipment).

6. Core Applications

6.1 Power Generation Industry

• Boiler drums, superheaters, and economizers for thermal power plants;
• Pressure vessels for nuclear power plant auxiliary systems;
• Rationale: P355GH and 16Mo3 withstand high-temperature steam (up to 530°C) and high pressure; excellent creep resistance for long-term operation.

6.2 Petrochemical & Chemical Industry

• High-temperature reactors, distillation columns, and heat exchangers;
• Storage tanks for high-temperature chemicals (e.g., ethylene, propylene);
• Rationale: 16Mo3 resists chemical corrosion and thermal cycling; P265GH/P295GH offer cost-effective solutions for medium-temperature applications.

6.3 Boiler & Pressure Vessel Manufacturing

• Industrial boilers (steam boilers, hot water boilers);
• Pressure vessels for food processing, pharmaceutical, and textile industries;
• Rationale: P235GH/P265GH balance cost and performance; comply with PED certification for safe operation.

6.4 Oil & Gas Industry

• Offshore and onshore oilfield pressure vessels;
• Natural gas processing plants (high-temperature separation units);
• Rationale: Resists harsh oilfield environments (high temperature, pressure, and chemicals); weldability enables on-site fabrication.

7. Comparison with Similar Grades

8. Cost & Pricing Considerations (2025 Q4 Data)

8.1 Key Pricing Drivers

• Alloy Content: 16Mo3 costs 60–80% more than P235GH due to molybdenum addition (linked to LME molybdenum prices: 2025 Q4 ~$30,000/ton);
• Thickness: Plates >50mm cost 20–30% more than thin plates (<20mm) due to rolling complexity;
• Certification: PED 3.2 certification adds 10–15% to base cost vs. 3.1 certification;
• Order Volume: Bulk orders (≥100 tons) unlock 10–15% discounts vs. small orders (<20 tons);
• Market Region: European-manufactured grades cost 25–35% more than Chinese-manufactured grades with equivalent certification.

8.2 Cost Optimization Strategies

• Grade Right-Sizing: Select the lowest grade that meets service temperature (e.g., P235GH for ≤400°C vs. P355GH for ≤450°C);
• Bulk Purchasing: Partner with manufacturers for project-wide orders to reduce unit costs;
• Domestic Sourcing: Chinese-manufactured EN 10028 grades offer 25–35% cost savings vs. European/American suppliers with PED certification;
• Standard Thickness: Opt for common thicknesses (10–30mm) to avoid custom rolling premiums (15–20%).

9. Supply Chain & Value-Added Services

• Minimum Order Quantity (MOQ): 10 tons (standard grades/thicknesses); 50 tons (16Mo3 or custom thicknesses);
• Delivery Lead Time: 15–30 days (stock P235GH/P265GH); 30–45 days (P355GH); 45–60 days (16Mo3 or custom orders);
• Packaging: Seaworthy export packaging (steel bundles + wooden skids + moisture-proof film) to prevent corrosion and damage during transportation;
• Value-Added Services:
  • Precision cutting (plasma, laser, waterjet) to custom dimensions;
  • Heat treatment (normalizing, stress relieving);
  • Welding and fabrication of vessel components;
  • PED 3.1/3.2 certification and third-party testing (SGS/BV/TÜV);
  • Technical support (high-temperature design, welding guidelines, material selection).
• Global Supply Hubs: Core production bases in China (Hebei, Jiangsu), Europe (Germany, Italy), and USA (Pennsylvania, Ohio); loading ports: Shanghai, Tianjin, Hamburg, Rotterdam.

10. Conclusion