What is the difference between A213 and A335 ?

When sourcing alloy or stainless steel tubing and pipes for high-temperature or high-pressure applications, understanding the difference between ASTM A213 and ASTM A335 is essential. Though both are ASTM standards for high-temperature services, they apply to different product forms, materials, and mechanical expectations.

In this article, we'll explain the key differences between A213 and A335, their typical grades (like T91, P91, TP316, etc.), and which one you should choose based on your application needs.

 

What is the difference between A213 and A335 ?

Standard	ASTM A213	ASTM A335
Product Type	Seamless tubes (mainly for boilers, heat exchangers)	Seamless pipes (mainly for pressure piping systems)
Material	Ferritic & austenitic alloy steel and stainless steel	Ferritic alloy steel
Applications	Boilers, superheaters, heat exchangers	High-temperature and high-pressure pipelines
Size Range	Small OD tubes (typically ≤ 5")	Larger diameter pipes (often > 2")
Delivery	Tubes in cold-drawn or hot-finished condition	Pipes in hot-finished or cold-drawn condition

 

ASTM A213 vs ASTM A335：Chemical Composition 

ASTM A213 includes:

Austenitic stainless steels like TP304, TP316, TP321

Ferritic alloy steels like T11, T22, T91

ASTM A335 covers only ferritic alloy steels, such as:

P1, P5, P9, P11, P22, P91, P92

Mechanical Property Comparison (Example: Grade 91)

Property	ASTM A213 T91 Tube	ASTM A335 P91 Pipe
Tensile Strength (min)	585 MPa	585 MPa
Yield Strength (min)	415 MPa	415 MPa
Hardness (max)	250 HBW or 25 HRC	250 HBW or 25 HRC

 

Are A213 and A335 interchangeable?

Not directly. A213 is used for tubes, A335 for pipes. If your design requires specific pipe dimensions, wall thickness, or pressure ratings, you must choose accordingly.

What is the difference between A213 T91 and A335 P91?

Chemically, they are the same. T91 refers to tubes, while P91 refers to pipes. The mechanical and thermal performance is also similar, but each must meet the dimensional and NDT standards of their respective specification.

What is the main reason to use ASTM A335 over A213?

If your system requires large diameter pressure-bearing piping for transporting fluids, A335 is the appropriate standard.

Can ASTM A213 be used for high-pressure service?

Yes, but typically for smaller diameter components like boiler tubes, not full-length pipelines.