ASTM A516 NACE HIC plate refers to pressure vessel quality carbon steel plate, typically supplied to ASTM A516 or ASME SA516 grades, with additional qualification for sour service through hydrogen-induced cracking (HIC) and, where required, sulfide stress cracking (SSC) testing. In practice, buyers use the term a516 nace hic to identify plate intended for fabrication of separators, scrubbers, drums, columns, heat exchangers, and other equipment exposed to wet H2S-containing environments.
For these applications, base specification compliance alone is not usually sufficient. Material is commonly ordered with supplementary requirements covering steelmaking route, low sulfur and phosphorus levels, inclusion control, ultrasonic examination, impact properties where applicable, and HIC test acceptance criteria to recognized NACE methods.
What A516 NACE HIC Means
A516 is a carbon steel plate specification for moderate and lower temperature pressure vessel service. The grades most commonly requested for sour service are Grade 60, Grade 65, and Grade 70, with Grade 70 being widely used because of its strength-to-fabricability balance.
When the plate is described as NACE HIC, it generally means the material has been produced and tested for use in sour environments in accordance with project or end-user requirements referencing standards such as:
- NACE TM0284 for evaluation of hydrogen-induced cracking resistance
- NACE TM0177 where sulfide stress cracking testing is specified
- NACE MR0175 / ISO 15156 for material selection guidance in H2S-containing environments in oil and gas production
- ASTM A20 / ASME SA20 general requirements for pressure vessel plate supply
- Project-specific refinery, petrochemical, LNG, or offshore sour-service material requisitions
It is important to note that NACE MR0175 does not by itself create a standalone plate grade. Instead, it provides a framework for selecting and qualifying materials for sour service. Actual procurement should therefore state the base plate specification, grade, thickness, heat treatment condition if required, and exact HIC/SSC acceptance criteria.
Typical Applications for Sour-Service A516 Plate
A516 HIC-tested plate is commonly specified for equipment handling wet H2S, acidic condensate, or process streams where atomic hydrogen can enter the steel and create internal cracking. Typical sectors include upstream oil and gas, gas processing, refineries, petrochemical plants, fertilizer units, and sulfur recovery systems.
Common fabricated equipment includes:
- Pressure vessels and separators
- Amine absorbers and regenerators
- Knockout drums and flash drums
- Heat exchanger shells
- Filter vessels and scrubbers
- Storage and process tanks under sour conditions
- Columns and reactor shells where project specifications permit carbon steel
Key Material Requirements Buyers Commonly Specify
Because HIC resistance depends not only on chemistry but also on cleanliness, segregation control, and steelmaking practice, sour-service purchase orders often include tighter requirements than standard A516 plate. The exact values vary by end user, but the following are commonly reviewed during technical evaluation:
- Fully killed steel with controlled deoxidation and inclusion shape control.
- Low sulfur content, often significantly below standard maximum limits.
- Restricted phosphorus to reduce segregation and improve through-thickness integrity.
- Calcium treatment or equivalent inclusion control where specified.
- Normalized or controlled rolled condition depending on thickness and project requirements.
- HIC testing by heat or plate to NACE TM0284 using the required solution and exposure duration.
- Optional SSC testing to NACE TM0177 when mandated by the client specification.
- Ultrasonic testing, often to ASTM A578 or equivalent acceptance level.
- Traceability and mill test certification showing heat number, chemistry, mechanicals, and test results.
A516 NACE HIC Grades and Reference Data
The table below summarizes the most commonly requested grades and procurement considerations. Actual acceptance values must always follow the purchase order and approved material requisition.
| Item | Typical Requirement | Notes |
|---|---|---|
| Base specification | ASTM A516 / ASME SA516 | Pressure vessel quality carbon steel plate |
| Common grades | Gr 60, Gr 65, Gr 70 | Grade 70 is frequently requested for vessels |
| Sour-service qualification | HIC tested | Usually to NACE TM0284 with project-specific acceptance criteria |
| Optional SSC qualification | When specified | Often referenced to NACE TM0177 |
| Service environment | Wet H2S / sour service | Used in oil, gas, refining, and petrochemical process equipment |
| Steel cleanliness | Low S, low P, inclusion control | Important for crack resistance and reduced segregation |
| Supply forms | Plate, cut blanks | Cut-to-size supply may be available depending on thickness and width |
| Inspection documents | EN 10204 3.1 / MTC | Should include chemistry, mechanicals, and HIC results where ordered |
How HIC Testing Is Evaluated
Hydrogen-induced cracking occurs when hydrogen generated in sour environments diffuses into the steel and accumulates at internal trap sites such as inclusions, laminations, or segregated regions. Under unfavorable metallurgical conditions, this can form stepwise internal cracks even without external stress.
In plate procurement, HIC resistance is commonly evaluated using NACE TM0284. Test specimens are exposed to a defined sour solution for a specified duration, after which sections are examined metallographically. Results are often reported using ratios such as:
- CLR — Crack Length Ratio
- CTR — Crack Thickness Ratio
- CSR — Crack Sensitivity Ratio
Acceptance limits are not universal; they are usually set by the end user, EPC contractor, or project specification. For that reason, a plate described simply as HIC tested should not be assumed acceptable for every sour-service project without reviewing the actual test method, sample location, solution type, and pass criteria.
Procurement Checklist for A516 HIC Plate
When sourcing A516 NACE HIC material, technical clarity at the enquiry stage reduces the risk of nonconforming supply. Buyers typically confirm the following before order placement:
- Required standard: ASTM A516 or ASME SA516
- Grade: 60, 65, or 70
- Plate thickness, width, length, and quantity
- Normalized, as-rolled, or controlled rolled condition as permitted
- Exact HIC test standard and acceptance criteria
- Whether SSC testing is also required
- Maximum sulfur and phosphorus limits
- Ultrasonic testing standard and acceptance level
- Charpy impact testing requirements, if any
- Documentation format and third-party inspection needs
For fabricated pressure equipment, compatibility with welding procedures is also important. Heat input control, consumable selection, hardness limits where specified, and post-weld heat treatment requirements should be aligned with the vessel design code and sour-service specification.
Documentation and Traceability Expectations
Industrial buyers generally expect complete traceability from plate to heat number and test certificate. A compliant documentation package may include mill test certificates, HIC test reports, ultrasonic examination records, marking details, and any third-party inspection release notes. Where material is supplied as cut pieces, transfer of identification from parent plate to each item should be maintained throughout processing.
For projects in refining and oil and gas, this documentation is often reviewed alongside approved vendor lists and project datasheets. Therefore, consistency between the purchase order, test certificate wording, and actual test standard references is essential.
Supply Scope for ASTM A516 NACE HIC Plate
Stancor Group supplies industrial steel products for pressure vessel and process industry applications. For enquiries related to a516 nace hic, buyers typically request plate by grade, thickness range, dimensions, HIC testing requirement, and destination. If the project specification includes additional sour-service clauses, those should be shared at the quotation stage so the offered material can be matched to the required qualification route.
Where applicable, enquiries should also identify whether the requirement is for ASTM A516 or ASME SA516 designation, whether normalized material is mandatory, and whether end users require specific refinery or offshore approval conditions beyond standard mill practice.
FAQ
Is A516 NACE HIC the same as standard ASTM A516 plate?
No. Standard ASTM A516 defines the base pressure vessel plate requirements, but sour-service HIC material includes additional controls and testing. The order usually adds low-impurity chemistry limits, steel cleanliness requirements, and HIC test qualification to NACE methods.
Which grade is most common for A516 HIC applications?
ASTM A516 Grade 70 is commonly specified because it offers a practical combination of strength, weldability, and availability. However, Grade 60 and Grade 65 are also used depending on design pressure, thickness, and project specification.
What should be stated on an enquiry for A516 NACE HIC plate?
At minimum, specify the base standard, grade, dimensions, quantity, delivery condition, HIC test standard, acceptance criteria, and any additional requirements such as SSC testing, ultrasonic examination, impact testing, or third-party inspection. This prevents ambiguity and helps ensure the supplied plate is suitable for the intended sour-service duty.