ASTM A312 Seamless and Welded Steel Pipes Specification
A312/A 312M-09 is one of the most widely used specifications for seamless and welded stainless steel pipes in industries such as chemical processing, oil & gas, food, marine, and construction. In this article, we'll cover key topics buyers care about, including its material definition, wall thickness range, HS code, price factors, and how it compares to ASTM A358.
What is ASTM A312 Material?
ASTM A312 is a standard issued by ASTM International for seamless, welded, and heavily cold-worked austenitic stainless steel pipes intended for high-temperature and general corrosive service.
Common Grades under ASTM A312:
TP304 / TP304L – General-purpose stainless steel
TP316 / TP316L – Chloride-resistant, ideal for marine/chemical use
TP321 / TP347 – Stabilized for high-temperature cycling
TP310S, TP317L, TP904L – For more aggressive or high-temperature environments
These materials are known for their excellent corrosion resistance, strength, and pressure performance.
What is the Wall Thickness of ASTM A312 Pipe?
ASTM A312 pipes are produced in:
Nominal Pipe Sizes (NPS): from 1/8" to 48"
Wall Thickness Schedules: SCH 5S, 10S, 40S, 80S, 160, XXS
🔹 Typical examples:
NPS 2", SCH 10S = 2.77 mm wall
NPS 4", SCH 40S = 6.02 mm wall
NPS 6", SCH 80S = 10.97 mm wall
👉 Customized wall thicknesses (e.g., for heat exchangers or pressure vessels) are available upon request.
What is the HS Code for ASTM A312 Stainless Steel Pipe?
The HS (Harmonized System) Code for ASTM A312 stainless steel pipes typically falls under:
730441 – For seamless stainless steel pipes
730449 – For welded stainless steel pipes
⚠️ Exact HS code may vary slightly by country depending on pipe use and dimensions. Always confirm with your local customs broker.
What is the Price of ASTM A312 Pipe?
As of Q2 2025, the price range for 2" SCH 40S pipe is approx. USD 3.5–5.5/kg FOB China, depending on quantity and grade. Contact us for exact quote.
What's the Difference Between ASTM A312 and ASTM A358?
The main difference between ASTM A312 and ASTM A358 lies in the manufacturing method and application scope. ASTM A312 covers seamless and welded austenitic stainless steel pipes for general corrosive and high-temperature service, using conventional welding or extrusion processes. In contrast, ASTM A358 applies specifically to electric-fusion-welded (EFW) stainless steel pipes, typically used in high-pressure, large-diameter, or heavy-wall applications. While both standards cover similar grades like 304 and 316, ASTM A358 is more suited for industrial pressure piping systems, especially when strength and diameter are critical.
✅ ASTM A358 is often used when high-pressure and large-diameter pipes are required, while ASTM A312 is suitable for most general-purpose piping.
