A516 NACE HIC plate refers to ASTM A516 / ASME SA516 pressure vessel steel supplied with additional controls for sour service, typically including HIC resistance and, where specified, SSC-related qualification for wet H2S environments. These plates are commonly selected for separators, scrubbers, drums, columns, and other refinery, gas processing, and petrochemical equipment where standard carbon steel may be vulnerable to hydrogen damage.
For procurement and engineering teams, the key issue is that SA516 Grade 60, 65, or 70 alone does not automatically mean HIC-resistant material. The purchase order usually needs supplementary requirements covering steelmaking route, sulfur and inclusion control, heat treatment condition, ultrasonic examination, and acceptance criteria for HIC testing to recognized industry practice.
What A516 NACE HIC Means
In industry usage, “A516 NACE HIC” generally describes a pressure vessel plate produced to ASTM A516 / ASME SA516 with additional sour-service requirements aligned to project specifications, end-user standards, and NACE-related testing expectations. The term is widely used in purchasing, but it is important to separate three different elements:
- Base specification: ASTM A516 or ASME SA516 for pressure vessel quality carbon steel plate.
- Service condition: wet H2S or other sour environments that can promote hydrogen entry into steel.
- Additional qualification: HIC testing, low sulfur chemistry, inclusion shape control, and sometimes hardness or SSC-related requirements depending on the equipment design code and client specification.
Because sour service requirements vary by project, buyers should state the exact grade, plate thickness, testing method, acceptance criteria, and documentation package required at the enquiry stage.
Typical Grades and Use Cases
The most common material ordered in this category is SA516 Grade 70 HIC, although Grades 60 and 65 are also used where design stress, weldability, or project standardization favors them. Grade choice depends on vessel design calculations, minimum design metal temperature, and fabrication requirements.
| Material | Typical Application | Common Sour Service Requirement | Notes |
|---|---|---|---|
| SA516 Gr. 60 NACE HIC | Pressure vessels, low to moderate strength designs | HIC-tested plate for wet H2S service | Often selected where improved formability is preferred |
| SA516 Gr. 65 NACE HIC | Process vessels and storage equipment | Low sulfur, clean steel, HIC qualification | Intermediate strength option |
| SA516 Gr. 70 NACE HIC | Refinery drums, separators, columns, scrubbers | HIC-tested, project-specific sour service compliance | Most commonly requested grade |
Why HIC Resistance Matters in Sour Service
Hydrogen-induced cracking occurs when atomic hydrogen generated by corrosion reactions diffuses into the steel and accumulates at inclusions or internal discontinuities. In susceptible plate, this can lead to stepwise cracking and reduced service reliability. Wet H2S environments are especially critical because they promote hydrogen charging while also affecting corrosion behavior.
For that reason, HIC-resistant A516 plate is generally produced from clean steel with tighter control of sulfur, phosphorus, and non-metallic inclusions than commodity pressure vessel plate. Steelmaking practices such as secondary refining, vacuum degassing, calcium treatment, and controlled rolling may be used depending on the mill route and the final project requirement.
In many projects, the material is also supplied in a normalized condition or with a specified heat treatment route to achieve a balance of strength, notch toughness, and resistance to hydrogen damage.
Common Technical Requirements for SA516 HIC Plate
There is no single universal wording that covers every “A516 NACE HIC” order. However, project specifications often include a combination of the following requirements:
- ASTM A516 / ASME SA516 base grade, usually Grade 70
- Normalized or as-required heat treatment condition
- Low sulfur chemistry, often with project-defined maximum sulfur limits
- HIC testing to purchaser-approved methodology and acceptance criteria
- Ultrasonic testing to a specified standard and acceptance level
- Z-quality or through-thickness properties where required for highly restrained fabrication
- Charpy impact testing if required by code, MDMT, or client specification
- Hardness limits where sour service procedure demands additional control
- Full traceability and mill test certificates
Where the service is particularly severe, end users may also require demonstrated resistance to SSC at the weld procedure or fabrication level, although this is distinct from plate HIC qualification and should not be assumed from the phrase “HIC tested” alone.
Testing, Certification, and Documentation
For pressure vessel projects, documentation quality is as important as nominal compliance. Buyers typically request EN 10204 3.1 or project-equivalent mill certification showing heat number traceability, chemical analysis, mechanical properties, heat treatment condition, and supplementary test results.
HIC test reporting generally includes specimen orientation, exposure conditions, and acceptance values such as crack length ratio, crack thickness ratio, and crack sensitivity ratio where specified by the purchaser. The exact acceptance limits are often defined by the end user, EPC contractor, or refinery standard rather than by the base A516 specification itself.
When comparing offers, procurement teams should verify not only that the plate is described as “NACE HIC,” but also that the supplier can provide:
- Mill-origin plate with traceable heat numbers
- Documented HIC test results for the supplied heat or lot
- Declared heat treatment condition
- UT results to the requested standard
- Mechanical and chemical compliance to the ordered grade
Procurement Considerations for A516 NACE HIC
Ordering sour-service plate without a complete technical description can create avoidable risk. The phrase “A516 NACE HIC” is widely searched, but in practice it should be translated into a precise purchase specification. This is particularly important for thick plates, critical pressure parts, and projects with owner-specific approval requirements.
A practical enquiry should identify:
- ASME SA516 or ASTM A516 designation and grade
- Plate thickness, width, length, and quantity
- Required heat treatment condition
- HIC test standard and acceptance criteria
- Any SSC, hardness, impact, or PWHT-related conditions
- UT standard and acceptance level
- Documentation level and third-party inspection requirements
- Destination country and code stamping needs, if applicable
For global projects, it is also useful to confirm whether the order is intended for code vessel fabrication, replacement plate, or stockholding for future shutdown work, since these scenarios often require different document packages and release procedures.
Applications in Oil, Gas, and Process Industries
SA516 HIC-resistant plate is routinely specified in sectors where wet H2S exposure is expected or where owner standards call for sour-service materials as a conservative design measure. Typical applications include:
- Amine service vessels
- Inlet separators and scrubbers
- Fractionation and process columns
- Knock-out drums and flash drums
- Refinery and gas plant pressure vessels
- Storage and process equipment handling sour hydrocarbons
Material selection should still be reviewed against the actual process chemistry, operating pressure, temperature, corrosion allowance, and fabrication sequence. HIC-resistant carbon steel can be appropriate in many sour environments, but it is not a substitute for project-specific corrosion engineering.
A516 NACE HIC Supply Scope
At Stancor Group, enquiries for A516 NACE HIC plate can be aligned to project requirements for pressure vessel fabrication and sour-service applications. Typical supply scope may include SA516 Grades 60, 65, and 70 in mill-certified plate form with requested supplementary testing, subject to mill availability and ordered specification.
To support technical review, enquiry packages should include the full material description, applicable code or client specification, required dimensions, and any mandatory HIC or UT criteria. This helps ensure that quotations are compared on an equivalent technical basis rather than on grade designation alone.
FAQ
Is SA516 Grade 70 automatically NACE HIC compliant?
No. SA516 Grade 70 is a pressure vessel steel grade, but HIC resistance requires additional steel cleanliness, testing, and acceptance criteria. The purchase order must define the sour-service requirements rather than assuming they are included in the base grade.
What is the difference between NACE and HIC in plate procurement?
HIC refers to hydrogen-induced cracking resistance, typically demonstrated by testing. “NACE” in market terminology usually indicates suitability for sour service, but the exact requirement may involve HIC testing, hardness control, SSC-related conditions, or project-specific compliance. The term should always be clarified in the specification.
Which grade is most common for A516 HIC service?
SA516 Grade 70 is the most commonly requested option because it provides a practical balance of strength, fabricability, and broad acceptance in pressure vessel construction. Grades 60 and 65 are also used where design calculations or fabrication preferences make them more suitable.