(S)A516Gr70

(S)A516Gr70, with its correct spelling as (S)A516 Gr. 70, is the most commonly used high-strength grade in the series, with a minimum tensile strength of 70 ksi (485 MPa) and a yield strength of at least 38 ksi (260 MPa). Its high strength allows for thinner vessel walls and reduced equipment weight, making it ideal for high-pressure or large-diameter pressure vessels. Although stricter control of preheat and interpass temperatures is required during welding, it exhibits excellent low-temperature toughness (impact test qualified at -29 °C) and structural reliability. It is extensively used in critical equipment in the petrochemical and energy sectors and is the mainstream material for moderate- and low-temperature pressure vessels.

A general description of the (S)A516 group is shown below:

(S)A516 is a widely used series of carbon steel plates for pressure vessels operating at moderate and low temperatures. The designation "A516" refers to ASTM A516/A516M, the standard specification titled "Standard Specification for Carbon Steel Plates for Moderate- and Lower-Temperature Service," issued by the American Society for Testing and Materials (ASTM). The prefix "S" indicates compliance with the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, making it SA516, which is required for ASME-certified pressure equipment. The notation "(S)" is a common informal format, indicating applicability under both ASTM and ASME codes, and is frequently seen in engineering drawings and technical documents. The standard includes several strength grades, most commonly Gr.55, Gr.60, Gr.65, and Gr.70, with Gr.70 being the most widely used due to its excellent balance of properties.

(S)A516 steel plates are primarily used in the fabrication of pressure vessels operating at moderate and low temperatures, such as liquefied petroleum gas (LPG) storage tanks, liquid ammonia vessels, refrigeration systems, chemical reactors, heat exchangers, and various industrial storage tanks. Its typical service temperature range is from -29 °C to 425 °C, making it especially suitable for equipment requiring good low-temperature toughness. It effectively resists brittle fracture, ensuring safe operation in cold climates or low-temperature processes. Due to its high reliability, excellent weldability, and mature manufacturing processes, the (S)A516 series is extensively adopted worldwide, particularly in the petrochemical, energy, refrigeration, and offshore industries.

Key features include superior low-temperature impact toughness, typically verified by Charpy V-notch testing at -29 °C (with optional testing at lower temperatures upon request), ensuring resistance to brittle fracture; excellent weldability without requiring special welding procedures or post-weld heat treatment (under proper design conditions); moderate strength levels (e.g., minimum tensile strength of 70 ksi / 485 MPa for Gr.70), combined with good ductility and formability for rolling, stamping, and welding. Plates are typically supplied in the normalized condition to refine grain structure and enhance mechanical uniformity and performance.

The current applicable standard is ASTM A516/A516M-23 or the corresponding ASME SA-516/SA-516M-23, titled "Standard Specification for Carbon Steel Plates for Moderate- and Lower-Temperature Service." Published in 2023, this version specifies requirements for chemical composition, mechanical properties, through-thickness (Z-direction) properties, and non-destructive testing, serving as a key technical reference for international pressure vessel design and construction.