ASTM A312 vs ASTM A358 – What’s the Differences

DIFFERENCE BETWEEN ASTM A358 AND ASTM A312

Both A312 and A358 are ASTM stainless steel materials with excellent corrosion resistance. They are widely used in the piping and pipeline industries. In this article, we’ll look at the fundamental differences between ASTM A312 and ASTM A358.

What is ASTM A312?

ASTM A312 or SA 312 is an American Standard material specification for austenitic stainless steel pipe that is seamless, welded, or heavily cold-worked. A312 pipes are generally designed for high-temperature and corrosive service. The most common grades of A312 specification are 304/304L stainless steel and 316/316L stainless steel.

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What is ASTM A358?

ASTM A358 or SA 358 is a material specification for austenitic chromium-nickel stainless steel pipe that has been electric-fusion welded. A358 stainless steel is commonly used in high-temperature and corrosive service industrial applications.

 

A312 and A358 Uses

Because stainless steel pipes of Specification A312 and A358 are corrosion resistant, they are widely used in harsh environments. Both A358 and A312 proved their durability in corrosive environments. Furthermore, they have good low-temperature resistance. As a result, the following industries commonly use A312 and/or A358 materials: chemical, petrochemical, and pharmaceutical.

  • Mining
  • Food and drink
  • Petroleum and natural gas
  • Marine
  • Pharmaceutical
  • Generation of electricity
  • Energy from renewable sources

Differences Between A312 and A358

ASTM A312 is a specification for seamless, welded, and cold worked austenitic stainless steel pipe while ASTM A358 is for electric-fusion-welded austenitic chromium-nickel alloy steel pipe. Both specifications are used in many industrial applications such as high temperature services or pressure vessels. However, the key differences between these two standards include manufacturing process type (seamless/welded), material grades (304L grade inASTM A312 vs 316L grade in ASTM A358), wall thickness range (minimum 0.188″ vs minimum 0.235″), maximum operating temperatures (1150°F/600°C vs 1500°F/815°C) and other dimensional & mechanical properties variations due to different materials used commercially.

Despite the fact that A312 and A358 are both Stainless Steel materials for the piping and pipeline industries with similar compositions and applications, the two alloys have some differences. The following table compares and contrasts 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 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

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