ASTM A516 Grade 60/70 dual certified plate is a carbon steel pressure vessel plate supplied to meet the requirements of both ASTM A516 Grade 60 and ASTM A516 Grade 70 on a single mill test certificate. In practice, this means the plate chemistry, tensile properties, and manufacturing route are controlled so the material satisfies the higher strength requirement of Grade 70 while remaining fully compliant with the Grade 60 specification. For fabricators, EPC contractors, and inspection teams, dual certification can simplify procurement where project documents reference either grade across different vessel components.
ASTM A516 is one of the most common specifications for moderate- and lower-temperature pressure vessel service. It is used in boilers, separators, storage vessels, heat exchangers, columns, and process equipment in oil and gas, petrochemical, fertilizer, power, and general process industries. The keyword ASTM A516 Grade 60/70 dual usually refers to plate ordered with dual certification rather than a separate ASTM grade.
What ASTM A516 Grade 60/70 Dual Means
Dual certification indicates that one plate lot has been tested and documented to comply with both Grade 60 and Grade 70 requirements. Because Grade 70 has higher minimum tensile and yield strength than Grade 60, a dual certified plate is typically produced to Grade 70 mechanical values. This gives the purchaser flexibility if drawings, legacy documents, or client standards mention Grade 60 in one location and Grade 70 in another.
From a quality and compliance perspective, buyers should confirm that the mill test certificate clearly states:
- ASTM A516 / ASME SA516 specification edition
- Dual certification to Grade 60 and Grade 70
- Heat number and plate traceability
- Chemical analysis results
- Mechanical test results including yield, tensile, and elongation
- Heat treatment condition, if normalized or stress relieved
- Supplementary requirements such as impact testing, ultrasonic testing, or HIC testing where applicable
ASTM A516 Grade 60 vs Grade 70
The main distinction between Grade 60 and Grade 70 is strength level. Grade 70 offers higher minimum tensile and yield strength, which can support thinner wall design in some pressure vessel calculations, subject to code rules and corrosion allowance. Grade 60 may still appear in older specifications or applications where the higher strength of Grade 70 is not required.
| Property | ASTM A516 Grade 60 | ASTM A516 Grade 70 | Typical Dual Certified Plate |
|---|---|---|---|
| Product form | Pressure vessel plate | Pressure vessel plate | Pressure vessel plate |
| Minimum tensile strength | 60 ksi (415 MPa) | 70 ksi (485 MPa) | Meets Grade 70 minimum |
| Minimum yield strength | 32 ksi (220 MPa) | 38 ksi (260 MPa) | Meets Grade 70 minimum |
| Primary use | Moderate and lower temperature vessel service | Moderate and lower temperature vessel service | Flexible use across both grade references |
| Procurement advantage | Standard grade purchase | Standard grade purchase | Reduces mismatch between project specifications |
Actual chemistry limits vary by thickness and applicable specification edition, so design and purchasing teams should always verify the current ASTM or ASME code text and the mill certificate rather than relying only on summary charts.
Chemical Composition and Metallurgical Characteristics
ASTM A516 is a carbon-silicon steel developed for good weldability and dependable notch toughness compared with ordinary structural carbon plate. The chemistry is controlled to provide a balance of strength, ductility, and fabrication performance. Carbon, manganese, phosphorus, sulfur, silicon, and sometimes residual alloying elements are reported on the test certificate. For pressure vessel service, low sulfur and phosphorus are particularly important for through-thickness quality and weld integrity.
Many buyers also request supplementary testing where service conditions are more severe. Examples include Charpy V-notch impact testing for low-temperature service, ultrasonic examination to detect internal discontinuities, and hydrogen induced cracking resistance for wet H2S environments when project specifications require it. These are not automatically included in every ASTM A516 Grade 60/70 dual order and should be stated at the purchase stage.
Heat Treatment, Normalizing, and Forming Considerations
ASTM A516 plate may be supplied as rolled or normalized, depending on thickness, code requirements, and end use. Normalizing refines grain structure and can improve toughness consistency, especially in thicker plates. In pressure vessel fabrication, normalized material is often preferred where impact properties or more uniform mechanical performance are important.
Fabricators should also consider the effect of forming and welding on final properties. Cold forming, dishing, flanging, and post weld heat treatment can influence strength and toughness. Where the vessel design is governed by ASME Section VIII or similar codes, the material condition after fabrication should remain consistent with code assumptions and approved welding procedures.
- Confirm whether the plate is supplied as rolled or normalized.
- Check if impact testing is required at the minimum design metal temperature.
- Review plate thickness because toughness and heat treatment requirements may change with section size.
- Match welding consumables and WPS/PQR to the specified service and code.
- Verify whether PWHT is mandatory under the design code or client specification.
Typical Applications of ASTM A516 Grade 60/70 Dual Plate
Dual certified A516 plate is commonly used where pressure vessel fabricators want a single inventory item that can satisfy multiple project requirements. It appears in shell courses, heads, transition sections, support components, and other pressure-retaining parts, subject to design approval.
Common industries and equipment include:
- Boilers and steam drums
- Oil and gas separators and scrubbers
- Refinery and petrochemical vessels
- Heat exchangers and deaerators
- Ammonia, urea, and fertilizer plant equipment
- Power generation pressure parts
- Storage and process tanks designed to pressure vessel codes
Ordering Checklist for Buyers and EPC Teams
When specifying ASTM A516 Grade 60/70 dual, the purchase order should be precise. A generic request for A516 plate may not capture all project requirements. The following details reduce the risk of nonconforming supply or documentation gaps:
- Specification reference: ASTM A516 or ASME SA516, including grade and edition
- Dual certification requirement to Grade 60 and Grade 70
- Plate dimensions, thickness tolerance, and quantity
- Supply condition: as rolled, normalized, or other approved condition
- Impact test temperature and acceptance criteria, if required
- NDT requirements such as UT to a defined standard
- Additional sour service or HIC testing requirements
- Documentation package including MTC, stamping, and traceability
- Any code-specific requirements under ASME Section II or Section VIII
How ASTM A516 Grade 60/70 Dual Differs from Structural Plate
A516 pressure vessel plate should not be treated as interchangeable with general structural steel plate. The specification intent, testing regime, and end-use expectations are different. Pressure vessel materials are selected for controlled chemistry, weldability, and service reliability under internal pressure and temperature conditions. While some mechanical values may appear comparable on paper, design codes and inspection requirements usually make the distinction critical.
For this reason, engineering teams should review not only minimum strength values but also code acceptance, toughness requirements, and fabrication history. Dual certification is useful, but it does not override project-specific technical conditions.
FAQ
Is ASTM A516 Grade 60/70 dual an official separate grade?
No. It is not a separate ASTM grade. The term usually means the plate has been manufactured and tested so it complies with both ASTM A516 Grade 60 and Grade 70, with documentation showing dual certification.
Does dual certified A516 plate always meet Grade 70 strength?
Yes, in normal practice dual certified plate must meet the higher mechanical requirement of Grade 70 in order to satisfy both grades. Buyers should still verify the actual yield and tensile values on the mill test certificate.
Should normalized condition be specified for ASTM A516 Grade 60/70 dual?
Not in every case. Normalizing is often specified for thicker plate, improved toughness consistency, or code and client requirements. The correct condition depends on thickness, design temperature, fabrication route, and the governing pressure vessel code.