Grade Identity and Standard Basis
SA516 Gr 60 is a carbon steel plate for pressure vessels defined by ASTM A516/A516M, the standard specification for pressure vessel plates, carbon steel, for moderate and lower temperature service. The number 60 refers to the minimum tensile strength in kilopounds per square inch, which corresponds to 415 MPa. Within the same specification, grades 55, 65 and 70 cover lower and higher strength levels, and grade 70 is the most common alternative where a higher tensile strength is needed.
The specification covers plate for welded pressure vessels, and it is widely adopted in ASME construction as SA516. In ASME Section VIII Division 1 the material is assigned to the carbon steel group, with allowable stresses derived from its tensile strength and with impact requirements determined by the minimum design metal temperature of the vessel through the applicable toughness rules.
Chemical Composition
The analysis is deliberately simple: this is a carbon manganese steel with controlled residuals, intended to combine adequate strength with good welding behaviour and notch toughness. The standard sets maximum carbon values that become tighter as plate thickness increases, because heavier plate is more prone to brittle behaviour in the heat affected zone of a weld.
| Element | Specification limit | Function |
|---|---|---|
| Carbon | 0.21 max for plate up to 25 mm, lower for heavier plate | Strength, limited for weldability and toughness |
| Manganese | 0.60 to 0.90 for thin plate, higher ranges permitted for heavier plate | Strength and notch toughness |
| Silicon | 0.15 to 0.40 | Deoxidation |
| Phosphorus | 0.035 max | Impurity restriction for toughness |
| Sulphur | 0.035 max | Impurity restriction for weld soundness |
Mechanical Properties and Toughness
Grade 60 plate is specified with a tensile strength of 415 to 550 MPa, a minimum yield strength of 220 MPa and a minimum elongation that varies with thickness, generally 21 percent for the common thickness range. These values give a moderate strength, highly ductile material that can undergo the forming, welding and post weld heat treatment operations used in vessel fabrication without a loss of integrity.
Tensile strength: 415 to 550 MPa.
Minimum yield strength: 220 MPa.
Minimum elongation: 21 percent for the ordinary thickness range.
Delivery condition: as rolled, or normalised where improved toughness or a specific fabrication requirement applies.
Impact testing: specified when the design temperature or the applicable code requires a guaranteed absorbed energy at a defined test temperature.
Thickness coverage under the specification extends to heavy plate, and for thick sections the carbon maximum is reduced and the manganese range is widened so that the required strength can be reached with better toughness. Plate that will be cold formed into a shell or head is usually ordered in the normalised condition, which gives more uniform properties and greater tolerance to forming strain.
Pressure Vessel and Industrial Applications
SA516 Gr 60 is used for the shells, heads, nozzles and internal components of pressure vessels, heat exchangers, reactors, separators, storage spheres and columns in the petroleum, petrochemical, chemical, fertiliser and power industries. It is also used for boiler drums and for pressure retaining components in pulp and paper plants, water treatment and desalination equipment, and in the cryogenic and low temperature equipment field where impact tested plate is required.
The grade is suitable for service across a wide temperature range, from low temperature applications when impact tested, up to the upper limit set by the design code for carbon steel. Where the environment is corrosive, the vessel is normally protected by a corrosion allowance, an internal lining or an overlay weld, since the base plate itself offers no alloy resistance.
Fabrication, Welding and Quality Control
Cutting is carried out by flame, plasma or waterjet process. Cold forming of shells and heads is routine, and hot forming, where used, is controlled so that subsequent heat treatment restores the required properties. Welding uses carbon steel consumables matched to the plate strength, with low hydrogen practice for heavier sections, and post weld heat treatment is applied where the code or the thickness requires stress relief.
Because the plate is intended for pressure retaining service, quality control is comprehensive. The mill test certificate reports chemical analysis per heat, tensile results, elongation, and impact energy where ordered, together with the delivery condition and heat number traceability. Plate is marked with the specification, grade, heat number and the manufacturer's identification. Additional requirements that can be ordered include ultrasonic examination for laminated plate quality, restricted analysis for a specific welding procedure, and third party inspection with a defined inspection and test plan.
Frequently Asked Questions
Q: What does grade 60 mean?
A: It refers to a minimum tensile strength of 60 kilopounds per square inch, equivalent to 415 MPa, which the plate must meet or exceed.
Q: What is the yield strength of SA516 Gr 60?
A: The minimum specified yield strength is 220 MPa, with a tensile range of 415 to 550 MPa.
Q: When is normalised plate required?
A: Normalising is specified where improved and more uniform toughness is needed, including plate that will be cold formed into shells or heads, and where the design temperature requires impact testing.
Q: Is impact testing part of the specification?
A: Impact testing is ordered when the design or the applicable construction code requires a guaranteed absorbed energy at a specified test temperature, and the results are then reported on the certificate.
Q: Why does the carbon limit change with thickness?
A: Heavier plate cools more slowly after rolling and welding, so carbon is reduced to protect toughness in the base metal and the heat affected zone.
Q: What documentation accompanies a vessel plate order?
A: A mill test certificate with chemical analysis, tensile and, where applicable, impact results, plate marking with heat traceability and the declared delivery condition, plus ultrasonic or third party inspection when ordered.
