Both A312 and A358 are stainless steel materials with ASTM designation having very good corrosion resistance. They are widely used materials for the piping and pipeline industry. In this article, we will find out the basic differences between ASTM A312 and ASTM A358.
What is ASTM A312?
ASTM A312 or SA 312 is an American Standard material specification that covers seamless, welded, and heavily cold-worked austenitic stainless steel pipe. In general A312 pipes are intended for high-temperature and general corrosive service. 304/304L Stainless Steel and 316/316L Stainless Steel are the most widely used grade of A312 specification.
What is ASTM A358?
ASTM A358 or SA 358 is a material specification for electric-fusion-welded austenitic chromium-nickel stainless steel pipe. A358 stainless steel materials are widely used in high-temperature and or corrosive service industrial applications.
Applications of A312 and A358
As stainless steel pipes of Specification A312 and A358 are corrosion resistant, they find wide applications in harsh conditions. In corrosive environments, both A358 and A312 proved their durability. Additionally, They have good low-temperature resistance capability. Because of all these, the popular industries that use A312 and/or A358 materials are:
Even though both A312 and A358 represent Stainless Steel materials for piping and pipeline industries having similar compositions and applications, there are some differences between the two alloys. The following table lists the major differences between ASTM A358 and ASTM A312.
ASTM A312
ASTM A358
ASTM A312 materials are manufactured by Seamless without welding, Automatic Welding without filler material, or heavy cold working.
ASTM A358 materials are manufactured by fusion welding using single-welded or double-welded butt joints.
A312 materials have different grades and no sub-classes.
Depending on the type of welding, filler material requirement, and radiographic requirements they have 5 sub-classes within A358. They are designated as class 1 to class 5 and must be mentioned while ordering.
A312 material conforms to the requirements furnished in Specification A999
While A358 SS pipes conform to the requirements provided in A240.
Seamless A312 SS pipes are usually costly.
A358 pipes are usually cheaper.
In general A312 pipes are manufactured for a size up to 30 inches
A358 pipes are usually manufactured up to a size of 48 inches
I am a Mechanical Engineer turned into a Piping Engineer. Currently, I work in a reputed MNC as a Senior Piping Stress Engineer. I am very much passionate about blogging and always tried to do unique things. This website is my first venture into the world of blogging with the aim of connecting with other piping engineers around the world.
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Very good info and nicely explained.
Thank you. Very nice explanation and right to the core.
Muito obrigado pela explicação, sou engenheiro de Petróleo e pós graduado em materiais e corrosão.
Thanks for the useful information.
Exactly what I was looking for!
Keep up the good work