ASTM A240

USED FOR:

Governs chromium and chromium-nickel stainless steel plate, sheet, and strip for pressure vessels and general applications.

A240 material may be used as flat-rolled stainless steel stock for fabrication of various components, including some welded products, but ASTM A312 defines the requirements for seamless and welded austenitic stainless steel pipe.

RELATED STANDARDS:

• Sibling specs: ASTM A480 covers general requirements common to flat-rolled stainless steel products and is applied in conjunction with A240 (A480 supplies the shared dimensional tolerances, surface finish, and general provisions; A240 supplies the grade-specific chemistry/mechanical requirements); ASTM A167 was the historical predecessor now largely superseded/consolidated into A240; A276 covers stainless steel bars and shapes rather than flat-rolled product, for components like machined parts rather than plate.
• Design code that invokes it: ASME Section VIII references SA-240 materials for pressure vessel construction, while allowable stresses are provided in ASME Section II Part D for the applicable SA material specifications and grades.; ASME B31.3 also references A240 material where plate is used for fabricated fittings or vessel components in piping systems.
• Dimensional standard that pairs with it: ASTM A480 provides general dimensional tolerances (thickness, flatness, width) for the plate/sheet/strip forms; there is no schedule-based dimensional standard analogous to pipe, since plate thickness is specified directly by the purchaser/design rather than a standardized schedule system.

GRADE / TYPE RANGE:
A240 covers a wide range of chromium and chromium-nickel stainless steel grades, including austenitic grades such as 304, 304L, 316, 316L, 321, and 347, ferritic grades such as 409 and 430, and selected duplex stainless steel grades. The specific grades included depend on the applicable ASTM A240 edition, mirroring much of the same grade family seen in A182’s wrought stainless forgings.

The austenitic “L” grades trade a modest reduction in high-temperature strength for low carbon content that resists sensitization and intergranular corrosion after welding, which matters significantly for vessel/piping fabrication involving field or shop welding without post-weld solution annealing.

The stabilized grades (321, 347) use titanium or niobium respectively to tie up carbon and protect against sensitization at higher service temperatures than the L-grades can reliably cover.

Duplex and super-duplex grades offer notably higher strength and superior chloride stress corrosion cracking resistance compared to standard austenitics, at the cost of tighter heat treatment and welding control requirements. Grade selection tracks the same logic as A182 — process fluid chlorides/sour species, welding exposure, and design temperature — since A240 plate and A182 forgings are frequently specified together on the same corrosion-resistant vessel or piping system.

DESCRIPTION:
A240 covers hot-rolled and cold-rolled stainless steel plate, sheet, and strip intended primarily for pressure vessel applications but broadly used across piping, tankage, and structural stainless work.

The standard specifies chemical composition ranges per grade, mechanical property requirements (tensile, yield, elongation), and heat treatment requirements, Heat treatment requirements depend on the applicable grade. Austenitic grades are generally solution annealed, while duplex grades require controlled solution annealing and cooling to achieve the required phase balance

It addresses surface finish designations (referenced from A480), flatness and dimensional tolerance provisions (via A480), and quality/testing requirements including tension testing and, for certain grades or applications, intergranular corrosion testing to confirm resistance to sensitization.

Marking requirements identify grade, heat number, and thickness, which becomes especially important on fabrication jobs cutting plate into multiple smaller pieces where heat traceability can otherwise be lost if not carefully managed.

TYPICAL INDUSTRY USE:
Extremely widely specified across chemical processing, oil & gas, pharmaceutical, food/beverage, and power generation industries for pressure vessel shells and heads, tank construction, and as base material for fabricated stainless fittings and welded pipe.

IMPORTANT NOTES:

• We found 316 specified where 316L was actually needed (or vice versa) on vessel fabrication jobs. since post-weld solution annealing isn’t always practical on large field-erected vessels, the low-carbon grade is often the safer default.

• Supplementary requirements under A240 (and cross-referenced A480) can add intergranular corrosion testing, additional NDE, or more stringent surface finish/flatness requirements.

• NACE MR0175/ISO 15156 compliance is a major consideration for A240 duplex grades in sour service hardness limits and ferrite content control are essential, and we always request the ferrite scope data and hardness survey directly rather than accepting a general mill certificate statement.

• Pay close attention to heat traceability when plate is cut into multiple smaller pieces for fabrication (blanks, heads, patches), losing the link between a cut piece and its original heat/MTR is a common, and entirely avoidable, documentation mistake that causes real headaches during later QA audits.

• Plate flatness and surface finish (per A480) matter more than engineers sometimes appreciate during fabrication planning, certain forming or welding processes are sensitive to as-received flatness and finish, and we recommend confirming the finish designation (e.g., 2B, No. 1, No. 4) matches both the process requirement and any aesthetic/cleanliness requirement for the intended service.