ASTM Tubing Standards: Which standard should I use?

ASTM International specifies standard requirements for tubes to ensure their quality and reliability across industries. The standards that apply to tubing products define and identify the chemical, material and mechanical properties of stainless steel. ASTM is one of several standard organizations—for more details on common standards organizations read our blog article here https://www.vitaneedle.com/blog/2024/03/19/staying-in-line-the-world-of-manufacturing-standards-organizations/. 

Some common standards used for stainless and nickel alloy tubing include ASTM A269, A908, F138, and F139. How do you know which one (or another entirely different standard) might be most applicable for your product? It depends on the type of product being manufactured and characteristics such as material, tolerances, corrosion-resistance and temper (hardness). What is the ultimate application for your product? What does your end customer expect? For example if your customer is currently using a product that meets one standard, would they be willing to switch to a different standard or is there significant testing and requalification required to do so? These are just a few questions that should be considered before determining what standards you should specify for a tubing product.

ASTM A269 vs. A908

A269 is used for general purposes; the tubing can be welded or seamless and is suitable for use in low and high temperatures. It applies to stainless steel tubing alloys including but not limited to 304, 316 and 321. Importantly, this standard defines the temper of the tubing as annealed, which is the softest temper that can be achieved. Annealed tubes are easier to bend and form without cracking. However, ASTM 269 can be specified as “ASTM A269 Chemistry only”---which means that the product will meet the chemistry requirements of the standard but will be produced in hard temper for applications where rigid tubing is appropriate. In fact, any standard can be listed on product specifications with exceptions if they are not relevant to, or conflict with, the requirements for the product.

In comparison to ASTM A279, ASTM A908 is a short and simple standard for welded and drawn hard temper 304 stainless tubing. Cold drawn / hard temper tubing forms (bend, flare, flange etc.) less readily than annealed tubing, but it has superior mechanical strength, and ASTM A908 specifies an ultimate tensile strength of 150-200 KSI. It also defines product chemistry plus standard gauge sizes and tolerances. It is well suited for applications requiring small diameters and thin walls, such as needle and medical device applications.

ASTM F138 vs. F139

Is your product intended for a demanding medical application? F138 and F139 standards both apply to surgical implants using 316 L stainless steel (the “L” stands for low carbon) which has enhanced corrosion resistance. F138 has a slightly higher purity level compared to F139. For non-permanent applications, or ones where cost savings is a factor, F139 is typically sufficient.

Both standards define that the metal must be either vacuum re-melted or electro slag re-melted—both of these melting processes reduce impurities and thus enhance the performance of the end product with respect to corrosion resistance.

ASTM F138 covers material in bar or wire form, and ASTM F139 covers material in strip or sheet form—although either of these specifications can be used as a tubing standard because welded tube is formed from strip and seamless tube from forged hollow bars. Both standards allow materials to be supplied in cold worked (hard temper) condition or annealed.

Can I use multiple standards?

How many standards can be specified? It depends on your application; you can specify multiple standards, as long as they don’t contradict each other. There are other ASTM standards that cover different aspects of manufacturing processes. For example, you may have a stainless steel tube that is specified as ASTM A908 and then passivated per ASTM A967, which is a typical medical device passivation standard.

In this blog article, we’ve only discussed 4 common standards—proper selection of the best standard requires consideration of many engineering and product requirement variables and it is ultimately up to the customer to select the optimal standard. If you have any questions about which standard best applies to your product, we’re happy to discuss it with you!