ASME SA240 316H Hot-Rolled Stainless Steel Plate

ASME SA240 316H is the hot-rolled stainless steel plate grade used for pressure vessels and other equipment operating at elevated temperature. The H suffix denotes the controlled carbon range of 0.04-0.10%, which is higher than the 0.08% maximum of standard 316. This carbon control is the reason 316H is selected when design temperatures exceed about 500 degree C: the higher carbon content sustains creep and rupture strength in the range where the low-carbon grades would soften.

Chemical composition (ASME SA240 316H, wt%)

The composition below is the certified requirement for UNS S31609 plate per ASME SA240. Note that it differs from standard 316 in the carbon range; the carbon content is specified as a range, not a maximum.

Element	Requirement
Carbon	0.04 - 0.10
Manganese	2.00 max
Phosphorus	0.045 max
Sulfur	0.030 max
Silicon	0.75 max
Chromium	16.00 - 18.00
Nickel	10.00 - 14.00
Molybdenum	2.00 - 3.00

Mechanical properties

For plate in the solution-annealed condition, ASME SA240 316H requires a minimum tensile strength of 515 MPa, a minimum yield strength of 205 MPa and a minimum elongation of 40% in 2 in. The plate is supplied in the hot-rolled and annealed condition with the surface pickled or blast-cleaned.

Property	Minimum value
Tensile strength	515 MPa
Yield strength (0.2% offset)	205 MPa
Elongation in 2 in	40%

Physical properties

Property	Typical value
Density	8.00 g/cm3
Melting point	1400 degree C approx
Thermal expansion (20-100 degree C)	15.9 x 10-6 / K
Modulus of elasticity	193 GPa
Thermal conductivity (100 degree C)	16.3 W/m.K

Thickness range, testing and certification

Hot-rolled SA240 316H plate is commonly supplied in thicknesses from 3 mm to 80 mm. Thickness, width, length and flatness tolerances follow ASME SA240 and the ordering specification, and each plate is marked with the heat number, grade and standard for traceability. Mill test certificates report the heat analysis and the mechanical test results.

Typical acceptance testing for pressure-vessel plate includes chemical analysis per heat, room-temperature tensile testing, and for specific orders, elevated-temperature tensile testing, impact testing, ultrasonic examination and hardness verification. Material certificates are issued in accordance with the purchaser requirement and the applicable code.

Typical applications

SA240 316H plate is used for pressure vessel shells, heat exchanger shells and channel covers, hot-section process piping supports, furnace components, superheater headers and other parts in petrochemical plants, refineries and power stations where the design temperature requires the elevated-temperature strength of the H-grade chemistry.

Frequently asked questions

Q1: What does the H in 316H mean? A1: The H suffix designates the high-carbon range 0.04-0.10%, which is required for elevated-temperature creep and rupture strength in pressure vessel service.

Q2: Is ASME SA240 the same as ASTM A240? A2: The two documents are technically identical; ASME SA240 is the version adopted into the ASME Boiler and Pressure Vessel Code for pressure vessel construction.

Q3: What is the difference between 316H and 316L plate? A3: 316L limits carbon to 0.030% max for welded aqueous service; 316H specifies 0.04-0.10% carbon for elevated-temperature strength. They serve different design regimes.

Q4: What is the maximum service temperature of 316H plate? A4: Continuous service up to about 870 degree C is commonly cited for oxidation resistance, while the allowable stress at temperature is defined by ASME Section II Part D data.

Q5: Does 316H plate require special welding consumables? A5: For matching strength, low-carbon or stabilized consumables such as ER316L or ER316H are used with qualified procedures; the high carbon base material does not require preheat.