A516 Grade 60 NACE HIC plate is a pressure vessel quality carbon steel supplied to ASTM A516 or ASME SA516 Grade 60 with additional qualification for resistance to hydrogen damage in wet hydrogen sulfide environments. In practical engineering terms, a516 grade 60 nace hic is not a separate standalone steel grade; the base material remains A516/SA516 Grade 60, while NACE and HIC define supplementary sour service performance requirements covering chemistry control, steel cleanliness, hardness, ultrasonic inspection, laboratory testing, and traceable documentation.
This material is widely specified for pressure-retaining equipment in refineries, gas processing plants, petrochemical units, offshore production systems, and upstream oil and gas facilities where aqueous H2S can promote hydrogen blistering, hydrogen induced cracking (HIC), or stepwise cracking (SWC). Typical equipment includes separators, knockout drums, absorber columns, amine contactors, inlet scrubbers, storage vessels, and heat exchanger shells.
What A516 Grade 60 NACE HIC Means
A516/SA516 Grade 60 is a carbon steel plate intended for welded pressure vessels for moderate and lower temperature service. It is commonly selected because it offers reliable weldability, good formability, and predictable fabrication behavior for shell courses, dished ends, nozzles, and structural attachments.
When ordered for NACE HIC service, the purchaser is addressing the risk that corrosion reactions in sour environments generate atomic hydrogen. That hydrogen can diffuse into the steel and accumulate at inclusions, segregation bands, laminations, or other internal discontinuities. If the steel is not produced and qualified correctly, the result can be blistering, HIC, or SWC. For this reason, HIC-resistant plate is normally produced with tighter control of sulfur, phosphorus, segregation, inclusion morphology, and plate manufacturing route, followed by mandatory laboratory verification.
In project specifications, environmental suitability is generally considered with reference to NACE MR0175 / ISO 15156, while HIC resistance is commonly demonstrated by testing to NACE TM0284. Depending on project requirements, additional provisions may address sulfide stress cracking, hardness limits, weld heat affected zone control, and post-weld heat treatment simulation.
Applicable Standards and Reference Documents
For technical clarity, the base plate standard should be separated from the sour service qualification standard. Buyers and fabricators should review the complete requirement package rather than relying only on the phrase a516 grade 60 nace hic.
- ASTM A516 / ASME SA516 Grade 60 – base pressure vessel plate specification
- ASTM A20 / ASME SA20 – general requirements for pressure vessel plates
- NACE MR0175 / ISO 15156 – materials guidance for H2S-containing environments in oil and gas production
- NACE TM0284 – evaluation of steels for resistance to hydrogen induced cracking
- NACE TM0177 – laboratory testing for sulfide stress cracking resistance where specified
- Project or end-user specifications – supplementary chemistry, UT, hardness, PWHT simulation, and reporting requirements
Typical Technical Requirements for Sour Service Plate
Actual acceptance criteria vary by end user, but most A516 Grade 60 HIC-tested plate orders include a combination of the following controls:
- Fully killed, fine-grain steel with controlled melting and plate rolling practice
- Low sulfur and phosphorus to improve cleanliness and reduce crack initiation sites
- Calcium treatment or inclusion shape control where required
- Normalized or controlled rolled condition, depending on thickness and project specification
- Ultrasonic testing to a defined acceptance level for internal soundness
- HIC testing to NACE TM0284 with stated solution, duration, and acceptance limits
- Maximum hardness requirement for base metal and sometimes weld procedure qualification
- Full traceability from heat number to test certificate and test coupon
Because HIC performance depends on steelmaking quality as much as nominal chemistry, two plates both marked SA516 Grade 60 may not offer the same sour service reliability unless the HIC qualification and inspection scope are equivalent.
Chemistry, Cleanliness, and Hardness Considerations
For wet H2S service, lower residuals and improved inclusion control are often more important than simply meeting the basic A516 chemistry range. Buyers frequently request restricted sulfur and phosphorus values below standard maximums, because these elements can contribute to segregation and internal crack susceptibility. Steel cleanliness, deoxidation practice, and through-thickness soundness also influence performance under hydrogen charging conditions.
Hardness control is another common requirement. Excessive hardness in the base metal, heat affected zone, or weld deposit can increase susceptibility to sour service cracking mechanisms. For that reason, project specifications may define a maximum hardness value, require normalized plate, or include procedure qualification records demonstrating compliance after welding and any post-weld heat treatment.
Where severe service is expected, purchasers may also request simulated PWHT testing, through-thickness tensile properties, or additional metallographic examination. These are not universal requirements, but they are common on critical refinery and gas processing projects.
Typical Data Points Buyers Should Confirm
| Parameter | Typical Requirement to Confirm | Why It Matters |
|---|---|---|
| Base specification | ASTM A516 or ASME SA516 Grade 60 | Defines mechanical properties and pressure vessel plate compliance |
| Delivery condition | Normalized or as required by project | Affects toughness, hardness, and fabrication behavior |
| HIC test standard | NACE TM0284 | Verifies resistance to hydrogen induced cracking |
| Environmental reference | NACE MR0175 / ISO 15156 | Aligns material selection with sour service conditions |
| UT requirement | Specified ultrasonic examination level | Controls laminations and internal discontinuities |
| Hardness limit | Project-specific maximum value | Reduces cracking risk in sour environments |
| Chemistry restrictions | Reduced S and P, controlled residuals | Improves cleanliness and HIC resistance |
| Documentation | EN 10204 / MTC, test reports, traceability | Provides auditable proof of compliance |
Common Applications of A516 Grade 60 NACE HIC Plate
A516 Grade 60 NACE HIC plate is commonly used where pressure-containing equipment handles sour water, wet gas, amine systems, or hydrocarbon streams contaminated with H2S. The material is regularly considered for:
- Oil and gas separators
- Knockout drums and scrubbers
- Amine absorbers and contactors
- Sour water strippers
- Heat exchanger shells
- Storage and surge vessels
- Refinery process columns and associated pressure parts
Final material selection should always be based on the actual process environment, design code, operating temperature, H2S partial pressure, pH, chlorides, fabrication route, and inspection philosophy. The phrase a516 grade 60 nace hic alone does not define all of these variables.
How to Specify A516 Grade 60 NACE HIC Correctly
Many procurement issues arise because purchase orders use only a short product description without the supporting technical detail. A more complete specification should identify the base grade, plate thickness, dimensions, delivery condition, HIC test method, acceptance criteria, ultrasonic testing level, hardness limit, and required documents. If weldability, PWHT, low temperature impact properties, or SSC performance are relevant, these should be stated explicitly.
A practical purchase description may include the following elements: SA516 Grade 60 plate, normalized, HIC tested to NACE TM0284, suitable for sour service per project specification, with restricted sulfur and phosphorus, specified UT level, maximum hardness, and full mill test certification. This approach reduces ambiguity and makes offers from different suppliers technically comparable.
For buyers evaluating stock versus mill production, it is also important to confirm whether the HIC qualification is heat-specific and plate-specific, whether coupons represent the actual supplied material, and whether all supplementary requirements appear on the material test certificate. These details are often decisive in end-user approval.
FAQ
Is A516 Grade 60 NACE HIC a separate steel grade?
No. The base grade remains ASTM A516 or ASME SA516 Grade 60. The terms NACE and HIC indicate additional sour service qualification requirements such as HIC testing, chemistry restrictions, hardness control, and inspection scope.
Which test standard is normally used for HIC resistance?
The most commonly referenced laboratory method is NACE TM0284. Project specifications may also define the test solution, exposure duration, specimen orientation, and acceptance criteria for crack length ratio, crack thickness ratio, or crack sensitivity ratio.
What should be included in a purchase order for a516 grade 60 nace hic plate?
The order should state the base specification, grade, thickness, dimensions, delivery condition, HIC test standard, acceptance criteria, ultrasonic testing requirement, hardness limit, chemistry restrictions, and required certification. If impact testing, PWHT simulation, or SSC-related testing is needed, those items should also be listed.