A516 Grade 60 NACE HIC plate is a pressure vessel quality carbon steel plate supplied to ASTM A516 or ASME SA516 Grade 60 with additional requirements for sour service. In procurement and engineering practice, the term a516 grade 60 nace hic does not identify a separate ASTM grade; it indicates that the base plate must also satisfy laboratory verification and manufacturing controls intended to reduce susceptibility to hydrogen induced cracking (HIC), blistering, and stepwise cracking (SWC) in wet H2S environments.
This material is commonly selected for pressure-retaining equipment in refineries, gas processing plants, petrochemical units, offshore facilities, and upstream oil and gas installations. Typical service includes separators, amine absorbers, inlet scrubbers, knockout drums, storage vessels, heat exchanger shells, and other welded components exposed to aqueous hydrogen sulfide where ordinary pressure vessel plate may not provide adequate resistance to hydrogen damage.
What A516 Grade 60 NACE HIC Means
A516 / SA516 Grade 60 is a carbon steel plate for welded pressure vessels in moderate and lower temperature service. It is widely used because it offers good weldability, formability, and predictable fabrication performance for shell courses, heads, nozzles, and attachments.
When a purchase order specifies A516 Grade 60 NACE HIC, the buyer is usually requiring the plate to be suitable for sour environments where corrosion reactions generate atomic hydrogen that can diffuse into steel. If the plate contains unfavorable segregation, elongated sulfide inclusions, laminations, or poor through-thickness quality, hydrogen can accumulate internally and initiate cracking. For this reason, HIC-resistant plate is generally produced with tighter chemistry control, steel cleanliness measures, inclusion shape control, and mandatory test certification.
Applicable Standards and Reference Documents
For technical clarity, the base material specification should be separated from the sour service qualification method. The wording on the order should identify the applicable standard editions, acceptance criteria, and any supplementary requirements.
| Standard | Scope | Relevance to A516 Grade 60 NACE HIC |
|---|---|---|
| ASTM A516 / ASME SA516 Grade 60 | Pressure vessel quality carbon steel plate | Base plate specification for mechanical properties and delivery condition |
| ASTM A20 / ASME SA20 | General requirements for pressure vessel plates | Defines testing, retests, tolerances, marking, and certification framework |
| NACE TM0284 | Laboratory evaluation of HIC resistance | Primary test method used to qualify plate for hydrogen induced cracking resistance |
| NACE TM0177 | Sulfide stress cracking test methods | May be specified separately where SSC testing is required by project documents |
| NACE MR0175 / ISO 15156 | Material selection for H2S-containing oil and gas production environments | Provides service environment guidance; not a plate manufacturing specification by itself |
| NACE MR0103 | SSC-resistant metallic materials for refining environments | Often referenced for refinery sour service material selection and hardness limits |
Typical Manufacturing and Quality Controls
HIC-resistant A516 Grade 60 plate is normally produced with additional process discipline beyond standard pressure vessel plate practice. Exact limits vary by mill, project specification, and end-user approval list, but the following controls are commonly requested:
- Low sulfur and low phosphorus chemistry to reduce segregation and inclusion-related crack paths
- Vacuum degassing or equivalent secondary metallurgy for improved steel cleanliness
- Calcium treatment or equivalent inclusion modification to reduce elongated manganese sulfides
- Controlled rolling and, where specified, normalized delivery condition for uniform microstructure
- Hardness control to project or NACE-related limits, especially in heat affected zones after fabrication qualification
- Ultrasonic examination for internal soundness and lamination control
- Traceable mill test certificates with heat number linkage to test coupons and plate dimensions
In practical terms, the performance of a516 grade 60 nace hic depends not only on tensile strength or yield strength, but also on segregation control, through-thickness integrity, and the reproducibility of the steelmaking route. Buyers therefore often specify supplementary requirements for UT testing, impact testing if applicable, and witness or third-party inspection.
NACE TM0284 HIC Testing and Acceptance
The most important verification for this material is usually NACE TM0284. This laboratory method evaluates the tendency of steel plate to develop internal hydrogen damage after exposure to a sour test solution. Test specimens are typically taken from the supplied plate and examined for cracking using metallographic methods.
Project specifications commonly define acceptance through ratios such as:
- CLR - Crack Length Ratio
- CTR - Crack Thickness Ratio
- CSR - Crack Sensitivity Ratio
The required maximum values are not universal. End users, EPC contractors, and licensors may impose their own limits, specimen orientation, number of samples, and retest rules. Because of this, a compliant order should state the exact edition of TM0284, the solution type, exposure duration, acceptance criteria, and whether SWC evaluation is required in addition to HIC assessment.
It is also important to distinguish HIC resistance from sulfide stress cracking resistance. HIC testing under TM0284 focuses on internal hydrogen damage in plate steel, while SSC concerns cracking under tensile stress and may require separate qualification under TM0177 or project-specific weld procedure controls.
Mechanical Properties and Plate Supply Considerations
The base mechanical properties remain those of ASTM A516 / ASME SA516 Grade 60 unless supplementary requirements modify the order. Grade 60 is chosen where a balance of strength, weldability, and fabrication economy is needed for pressure vessel construction.
When evaluating supply, purchasers typically review:
- Plate thickness range and available width/length
- As-rolled versus normalized condition
- Heat treatment records where applicable
- Charpy impact requirements if specified by design code or project
- Ultrasonic test level and reporting format
- HIC test lot definition and coupon traceability
- Third-party inspection, stamping, and documentation package
For fabricated vessels, weld procedure qualification remains critical. A plate that passes HIC testing can still be compromised by poor welding practice, excessive hardness in the heat affected zone, or uncontrolled repair procedures. Material selection should therefore be aligned with fabrication controls, post weld heat treatment requirements, and the actual sour service severity.
Common Applications in Sour Service Equipment
A516 Grade 60 NACE HIC plate is used where process streams contain water and hydrogen sulfide, creating conditions for hydrogen entry into steel. The material is frequently specified for:
- Inlet separators and production separators
- Amine absorbers and regenerators
- Knockout drums and scrubbers
- Storage and surge vessels in sour hydrocarbon service
- Heat exchanger shells and channel components
- Refinery pressure vessels handling sour condensate or wet gas streams
Selection depends on process chemistry, partial pressure of H2S, chloride content, pH, operating temperature, and whether the equipment falls under upstream production, gas processing, or refinery service. The phrase alone is therefore not enough; the complete datasheet should define the environment and the acceptance basis.
How to Specify A516 Grade 60 NACE HIC Correctly
To avoid ambiguity, purchase orders should state the full technical requirement rather than only the shorthand keyword. A robust specification usually includes the following elements:
- ASTM A516 or ASME SA516 Grade 60 as the base material standard
- Required delivery condition, such as normalized
- Plate dimensions and quantity by heat or lot
- NACE TM0284 edition, test solution, and acceptance criteria for CLR, CTR, and CSR
- Any SWC examination requirement
- Maximum hardness requirement where applicable
- Ultrasonic examination standard and acceptance level
- Documentation, traceability, and third-party inspection requirements
This approach reduces the risk of receiving standard A516 Grade 60 plate without the sour service verification that the application actually requires.
FAQ
Is A516 Grade 60 NACE HIC a separate ASTM grade?
No. The base material remains ASTM A516 or ASME SA516 Grade 60. The phrase indicates that the plate must also meet additional sour service controls and HIC test requirements, typically under NACE TM0284 and related project specifications.
Does NACE HIC plate automatically satisfy SSC requirements?
No. HIC resistance and sulfide stress cracking resistance are related but different issues. HIC qualification is commonly verified by NACE TM0284, while SSC may require separate evaluation under NACE TM0177, hardness limits, and fabrication controls for welds and heat affected zones.
What documents should be requested with A516 Grade 60 NACE HIC plate?
Typical documentation includes the mill test certificate, heat analysis, mechanical test results, delivery condition, ultrasonic examination report, HIC test report with acceptance values, traceability records, and any third-party inspection release required by the project.