What is the Steel Material of SA612 welded pressure vessels Steel Plates

SA612 / SA612M steel plate is an American standard carbon–manganese–silicon (C–Mn–Si) killed steel designed for spherical tanks, storage tanks, and welded pressure vessels.

It is primarily used for the storage of gases and liquefied gases, and is widely applied in industries such as oil & gas, petrochemical, city gas, power generation, and metallurgy.

The steel is produced and supplied in accordance with:

ASME SA612 / SA612M

ASTM A612 / A612M

SA612 / SA612M steel plates are supplied in:

Hot rolled condition, or

Normalized condition, depending on project requirements

Normalization improves mechanical property uniformity, impact toughness, and structural reliability, especially for low-temperature pressure service.

Composition adjustment rule:
For each 0.01% reduction in carbon below the specified maximum, manganese may be increased by 0.06%, with a maximum heat analysis limit of 1.65% Mn (product analysis up to 1.70%).

When the measured content of an element is 0.02% or lower, it may be reported as ≤ 0.02%.

Hardness reflects a material's resistance to indentation and surface deformation, and is an important auxiliary indicator of mechanical performance.

For SA612 / SA612M, hardness is not the controlling acceptance criterion, but may be used for reference and quality evaluation.

Brinell Hardness (HB)

Uses a hardened steel ball (typically Ø10 mm)

Applied load: usually 3000 kg

Hardness value is calculated based on the indentation area

HB is suitable for medium-strength structural steels.

Rockwell Hardness (HR)

Used when:

HB > 450, or

Specimen size is limited

Three common Rockwell scales:

HRA: 60 kg load, diamond cone (very hard materials)

HRB: 100 kg load, Ø1.58 mm steel ball (low hardness steels)

HRC: 150 kg load, diamond cone (high hardness steels)

Vickers Hardness (HV)

Load ≤ 120 kg

Diamond pyramid indenter with a 136° angle

Suitable for thin plates and microstructure evaluation

SA612 / SA612M steel plates are mainly used for pressure-retaining and load-bearing structural components, including:

Spherical tanks for liquefied gas storage

Oil and gas storage tanks

Welded pressure vessels and reactors

Heat exchangers and separators

Boilers and auxiliary pressure components

Petrochemical and city gas equipment

Power plant pressure systems

Due to its high tensile strength, stable yield performance, good weldability, and reliable low-temperature toughness, SA612 is well suited for medium-pressure and moderate-to-low temperature service environments.

SA612 steel is not a wear-resistant steel and is not typically used for high-wear components such as gears or shafts. It is primarily selected for pressure containment, structural safety, and long-term service reliability.

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1. What is SA612 steel plate?

SA612 steel plate is a killed carbon–manganese–silicon (C–Mn–Si) pressure vessel steel produced in accordance with ASME SA612/SA612M and ASTM A612/A612M standards.
It is designed for welded pressure vessels operating at moderate and lower temperatures, requiring high strength and reliable toughness.

2. What is the typical application temperature range of SA612?

SA612 steel plate is suitable for moderate and low-temperature service, and impact testing is commonly performed at –40°C.
This makes SA612 appropriate for pressure vessels exposed to:

Seasonal low temperatures

Start-up and shutdown thermal cycling

Medium-pressure, non-cryogenic environments

3. What is the thickness range of SA612 steel plate?

According to ASTM A612/A612M and ASME SA612/SA612M:

Standard maximum thickness: ≤ 25 mm (1 inch)

In industrial production, SA612 plates may be supplied in:

Thickness range: 8 – 120 mm (subject to technical agreement)