ASTM A480 vs ASTM A240: What’s the Difference?

When selecting stainless steel materials for your project, you might come across both ASTM A480 and ASTM A240 specifications. Although they are closely related, understanding their differences is essential for proper material selection, quality assurance, and compliance.

In this article, we explain what ASTM A480 and ASTM A240 are, highlight their key differences, and help you determine which standard applies best to your needs.

 

What is ASTM A240?

ASTM A240 is a standard specification by ASTM International for chromium and chromium-nickel stainless steel plate, sheet, and strip used in pressure vessels and general applications. It covers various grades, including 304, 304L, 316, and 316L, focusing on corrosion resistance, formability, and weldability.

 

ASTM A240 Technical Form Download
 

What is ASTM A480?

ASTM A480/A480M is the standard specification covering general requirements for flat-rolled stainless and heat-resisting steel plate, sheet, and strip, including technical delivery conditions, tolerances for dimensions (thickness, width, length), flatness, and surface finishes. It applies to various products such as Types 304, 316, and others, dictating testing, marking, and packaging requirements.

 

ASTM A480 Technical Form Download

 

Key Differences Between ASTM A240 and ASTM A480

Aspect	ASTM A240	ASTM A480
Scope	Chemical and mechanical requirements for stainless steel grades	General requirements for flat-rolled stainless steel products
Focus	Specific grades like 304, 316, 321	Overall product requirements (tolerances, finishes, testing)
Applies To	Plates, sheets, strips for corrosion resistance and pressure applications	Plates, sheets, strips under various ASTM grade standards
Testing Requirements	Detailed chemical and mechanical tests	Additional dimensional, surface finish, and workmanship tests
Usage	Material specification for production and acceptance	Quality assurance and general production standards

 

Why Both Standards Are Often Used Together?

Most stainless steel plate or sheet orders will reference both ASTM A240 and ASTM A480 to ensure the product:

Meets the chemical and mechanical properties per ASTM A240.

Complies with dimensional tolerances, surface finish, and testing requirements of ASTM A480.

This combination ensures that the material is both technically suitable and manufactured to consistent quality standards.

 

In the industry, you will almost never see one without the other. When a mill produces a sheet of 304L stainless steel, the "Mill Test Report" (MTR) will typically state that the material "Conforms to ASTM A240/A480."

Example: You are building a pressurized chemical tank.

You look at ASTM A240 to make sure the steel you bought is actually 316L and won't explode under pressure.

You look at ASTM A480 to make sure the 1/4" plate you ordered isn't actually 0.230" thick (which would be out of tolerance).

 

Can ASTM A480 be used alone without ASTM A240?

No. ASTM A480 provides general requirements but does not specify chemical or mechanical properties. It is typically used alongside ASTM A240 or other product specifications.

 

Does ASTM A480 cover surface finish requirements?

Yes, ASTM A480 defines surface finishes such as mill finish, No. 2B (cold rolled and pickled), No. 4 (brushed), and No. 8 (mirror polish) to meet application needs.

 

Are there dimensional tolerances in ASTM A240?

ASTM A240 focuses more on chemistry and mechanical properties; dimensional tolerances and workmanship are primarily covered by ASTM A480.