SA516 GR60N HIC (ASTM/ASME standard) and Q345R HIC (GB/T standard) are both widely used hydrogen-induced cracking resistant pressure vessel steels.
- SA516 GR60N HIC offers stricter HIC acceptance criteria and global ASME code compliance, making it the go-to choice for international sour service projects.
- Q345R HIC provides higher yield strength and cost advantages, dominating domestic Chinese refinery and petrochemical applications.
SA516 GR60N HIC: The ASTM/ASME Standard
ASTM/ASME SA516 GR60N HIC
- Standard: ASTM A516 / ASME SA-516
- Grade: 60 (Grade 60)
- Delivery Condition: Normalized (N), vacuum degassed
- HIC Test: NACE TM0284 Solution A
- Key Markets: Global oil & gas, ASME-code vessels, export projects
Chemical Composition
SA516 GR60N HIC is a carbon-manganese steel with tightly controlled impurity levels. The HIC variant imposes significantly stricter limits on sulfur and phosphorus compared to the standard grade:
| Element | SA516 Gr 60 (Standard) | SA516 Gr 60 HIC (Typical) |
|---|---|---|
| Carbon (C) | ≤ 0.21% | ≤ 0.20% |
| Manganese (Mn) | 0.85 – 1.20% | 0.85 – 1.20% |
| Silicon (Si) | 0.15 – 0.40% | 0.15 – 0.40% |
| Phosphorus (P) | ≤ 0.035% | ≤ 0.010% (typical) |
| Sulfur (S) | ≤ 0.035% | ≤ 0.002% (typical ≤0.001%) |
| Nickel (Ni) | ≤ 0.40% | ≤ 0.40% |
| Chromium (Cr) | ≤ 0.30% | ≤ 0.30% |
| Molybdenum (Mo) | ≤ 0.12% | ≤ 0.12% |
| Carbon Equivalent (CEV) | ≤ 0.43 – 0.45% | ≤ 0.43 – 0.45% |
Mechanical Properties
SA516 Grade 60 is the lowest-strength grade in the A516 family, offering excellent notch toughness and ductility - particularly important for low-temperature service and HIC resistance:
| Property | Value (Imperial) | Value (Metric) | Test Direction |
|---|---|---|---|
| Yield Strength (min) | 32 ksi | 220 MPa | Transverse |
| Tensile Strength | 60 – 80 ksi | 415 – 550 MPa | Transverse |
| Elongation in 2" (min) | 25% | 25% | Transverse |
| Elongation in 8" (min) | 21% | 21% | Transverse |
HIC Resistance Performance
SA516 GR60N HIC plates are tested per NACE TM0284 Solution A (standard H₂S-saturated NaCl/acetic acid solution). The typical acceptance criteria for HIC-tested grades are among the most stringent in the industry:
| HIC Parameter | Acceptance Criterion (Sample Average) | Significance |
|---|---|---|
| CLR (Crack Length Ratio) | ≤ 5% | Total crack length / specimen width |
| CTR (Crack Thickness Ratio) | ≤ 1.5% | Total crack area / specimen thickness × 100 |
| CSR (Crack Sensitivity Ratio) | ≤ 0.5% | Total crack area / total section area |
Important: HIC performance is guaranteed in the normalized + stress-relieved/PWHT condition. The minimum stress relief cycle is typically 1 hour per inch of thickness at 1125°F (607°C), with a 1-hour minimum. This means your fabricated vessel must receive equivalent post-weld heat treatment to realize the full HIC resistance of the material.
Key Advantages of SA516 GR60N HIC
- Global code acceptance: ASME BPVC Section VIII compliance recognized worldwide
- Stringent HIC criteria: CLR ≤5%, CTR ≤1.5%, CSR ≤0.5% - tighter than many competing grades
- Proven track record: Decades of successful service in refineries, gas plants, and offshore facilities
- Excellent low-temperature toughness: Designed for moderate-to-low temperature service
- Superior weldability: Lower carbon content and CEV enable straightforward welding procedures
- Wide supplier base: Available from major mills globally (SSAB, ArcelorMittal, Nippon Steel, etc.)
Q345R HIC: The Chinese GB Standard
GB/T 713 Q345R HIC
Standard: GB/T 713.2-2023 (latest revision)
Grade: Q345R (yield strength 345 MPa)
Delivery Condition: Normalized
HIC Test: NACE TM0284 / GB/T 8650
Key Markets: Chinese domestic refineries, petrochemical plants, SINOPEC/CNPC projects
Chemical Composition
Q345R is a low-alloy pressure vessel steel with a higher manganese content than SA516 Gr 60, contributing to its higher strength. The HIC variant imposes strict controls on sulfur and phosphorus:
| Element | Q345R (Standard) | Q345R HIC (Typical) |
|---|---|---|
| Carbon (C) | ≤ 0.20% | ≤ 0.20% |
| Manganese (Mn) | 1.20 – 1.70% | 1.20 – 1.60% |
| Silicon (Si) | ≤ 0.55% | ≤ 0.50% |
| Phosphorus (P) | ≤ 0.025% | ≤ 0.012% |
| Sulfur (S) | ≤ 0.010% | ≤ 0.003% |
| Aluminum (Al) | ≥ 0.020% | ≥ 0.020% |
| Carbon Equivalent (CE) | ≤ 0.45% | ≤ 0.45% |
Mechanical Properties
Q345R offers significantly higher yield strength than SA516 Gr 60, though properties decrease with increasing plate thickness. Below are typical values for normalized delivery:
| Property | Thickness ≤ 16 mm | Thickness 16 – 36 mm | Thickness 36 – 60 mm |
|---|---|---|---|
| Yield Strength (min) | 345 MPa | 325 MPa | 305 MPa |
| Tensile Strength | 510 – 640 MPa | 500 – 630 MPa | 490 – 620 MPa |
| Elongation A (min) | 21% | 20% | 20% |
| Impact Energy KV₂ @ -30°C (min) | 34 J (longitudinal) | 34 J (longitudinal) | 24 – 34 J |
| Bend Test | 180°, d=3a, no cracking | ||
HIC Resistance Performance
Q345R HIC plates are tested according to GB/T 8650-2006 (equivalent to NACE TM0284). The standard acceptance criteria for Q345R HIC are:
| HIC Parameter | Acceptance Criterion | Test Solution |
|---|---|---|
| CLR (Crack Length Ratio) | ≤ 10% | Solution A (H₂S-saturated NaCl solution) |
| CTR (Crack Thickness Ratio) | ≤ 3% | |
| CSR (Crack Sensitivity Ratio) | ≤ 1% |
For more severe sour service requiring both HIC and SSCC (Sulfide Stress Corrosion Cracking) resistance, the upgraded grade Q345R(R-HIC) is available, with additional SSCC testing per NACE TM0177 (720-hour test without fracture).
Key Advantages of Q345R HIC
- Higher strength: 345 MPa yield (vs 220 MPa for SA516 Gr 60) enables thinner-wall designs and material savings
- Cost competitiveness: Chinese mill production offers favorable pricing, especially for bulk orders
- Domestic supply chain: Widely available from major Chinese steel mills (Wuyang, Baosteel, Angang, etc.)
- GB code compliance: Standard material for all domestic Chinese pressure vessel projects per GB 150
- Good impact toughness: -30°C Charpy V-notch requirements provide adequate low-temperature performance
- SSCC upgrade option: Q345R(R-HIC) variant for combined HIC + SSCC service
Key Insight
For NACE Level 1 (mild sour) and many Level 2 (moderate sour) services, both materials are technically viable. For severe sour service (NACE Level 3) or critical safety equipment, SA516 GR60N HIC's stricter HIC criteria provide an additional safety margin. Always verify with your process engineer and applicable code requirements.
How to Choose: A Practical Decision Framework
Selecting between SA516 GR60N HIC and Q345R HIC depends on a combination of technical, commercial, and regulatory factors. Use this framework to guide your decision:
- Project Code Requirements: If your vessel must be built to ASME Section VIII, SA516 GR60N is the natural choice. If it's a Chinese domestic project under GB 150, Q345R is the standard grade.
- Sour Service Severity: For severe sour service (high H₂S partial pressure, low pH, elevated temperature), SA516 GR60N HIC's stricter CLR/CTR/CSR limits provide a greater safety margin.
- Design Pressure & Wall Thickness: Q345R's higher yield strength (345 MPa vs 220 MPa) can significantly reduce required wall thickness, lowering material cost and weld volume - especially for large-diameter vessels.
- Geographic Location: Projects in Asia benefit from Q345R's local supply chain and competitive pricing. Projects in the Americas, Europe, or the Middle East typically specify SA516.
- Inspection & Certification: SA516 has broader third-party inspection acceptance (TÜV, DNV, etc.). Q345R may require additional testing or certification for international projects.
- Total Cost of Ownership: Consider not just plate cost but also welding consumables, fabrication time, PWHT requirements, and long-term maintenance implications.
- Material Availability & Lead Time: Check current stock availability and mill lead times. Q345R is generally more readily available from Chinese stockists for immediate delivery.
Not Sure Which Grade Fits Your Project?
Our material engineers can analyze your specific operating conditions (H₂S partial pressure, temperature, pH, chloride content) and recommend the optimal HIC-resistant steel grade. Get a technical recommendation within 24 hours.
Applications and Industry Use Cases
SA516 GR60N HIC Typical Applications
- Refinery vessels: Hydrotreaters, hydrocrackers, desulfurization units
- Natural gas processing: Amine treaters, sour gas separators, dehydration units
- Offshore platforms: Topside process equipment in sour fields
- Oil sands processing: Heavy oil upgrading facilities
- Storage tanks: Sour crude oil and produced water storage
- Heat exchangers: Shell-side components in sour service
Q345R HIC Typical Applications
- Chinese refineries: FCC units, hydrofining reactors, separation towers
- Petrochemical plants: Ethylene cracker components, synthesis gas equipment
- LPG storage: Spherical tanks and horizontal vessels for liquefied petroleum gas
- Coal chemical industry: Coal-to-chemicals gasification equipment
- Power generation: Auxiliary boiler systems and pressure parts
- Nuclear power: Conventional island pressure equipment
Need Help Selecting the Right HIC Steel?
Our team of pressure vessel steel specialists can help you compare grades, verify specifications, and source the right material at competitive prices. Send us your project details - operating conditions, design parameters, required standards - and we'll provide a detailed material recommendation and quotation within 24 hours.
FAQ
Q1: Is Q345R equivalent to SA516 Gr 60 or Gr 70?
Q345R is generally considered equivalent to SA516 Gr 70, not Gr 60. Both Q345R and SA516 Gr 70 have similar yield strength levels (345 MPa vs 260 MPa / 38 ksi - though exact comparison depends on thickness). For a more direct strength comparison, SA516 Gr 70 HIC would be the closer counterpart to Q345R HIC. However, this article compares Gr 60 HIC because it is the most commonly specified HIC grade in the A516 family for moderate sour service, and many engineers compare it directly with Q345R HIC for procurement decisions.
Q2: Can Q345R HIC be used for ASME code vessels?
Standard Q345R per GB 713 is not an ASME-approved material. However, many Chinese mills produce dual-certified plates that meet both GB 713 Q345R and ASME SA-516 Gr 70 requirements. For ASME code vessels, you must purchase material with an ASME Material Test Report (MTR) and ensure the mill is ASME-certified. GB 150-2011 also lists SA-516 Gr 70 as an acceptable material, enabling cross-standard usage.
Q3: What's the difference between HIC and SSCC?
HIC (Hydrogen-Induced Cracking) is stepwise internal cracking caused by hydrogen accumulation at inclusions, occurring without external stress. SSCC (Sulfide Stress Corrosion Cracking) is cracking that occurs under the combined action of tensile stress and corrosion in H₂S environments. For severe sour service, both resistances may be required. Q345R(R-HIC) includes both HIC and SSCC testing (NACE TM0177). SA516 HIC grades can also be specified with SSCC testing by supplementary agreement.
