When you see “ASTM A270 S2″ on a tubing certification, it is a precise “fingerprint” that defines the material’s standard, grade, and condition. Here’s a detailed breakdown:
1. ASTM
● What it stands for: ASTM International, originally the American Society for Testing and Materials.
● What it means: This is the organization that develops and publishes technical standards for materials, products, systems, and services. An ASTM standard ensures consistency, safety, and reliability.
2. A270
● The Specific Standard: This is the standard title: “Standard Specification for Seamless and Welded Austenitic and Ferritic/Austenitic Stainless Steel Sanitary Tubing.”
● Key Implications:
● Application Focus: It is specifically designed for sanitary (hygienic) service. This means the tubing is intended for industries where cleanliness, sterility, and corrosion resistance are critical.
● Primary Industries:
● Food and Beverage Processing
● Dairy Processing
● Pharmaceutical and Biotech
● Breweries and Distilleries
● Cosmetics
● Surface Finish: Tubing made to this standard typically has a smooth, polished internal finish (often measured in Ra or microinches) to prevent bacterial adhesion and allow for easy cleaning (CIP – Clean-in-Place).
● Manufacturing: It covers both seamless and welded tubing, but the welded tubing must have the weld bead removed and polished to match the interior surface.
3. S2
● The Grade Designation: This specifies the exact type of stainless steel alloy.
● Composition: S2 corresponds to UNS S31603, which is the common 316L stainless steel.
● Key Alloying Elements:
● Chromium (~16-18%): For corrosion resistance and the “stainless” property.
● Nickel (~10-14%): For austenitic structure (non-magnetic, ductile).
● Molybdenum (~2-3%): The critical addition. It dramatically increases resistance to pitting and crevice corrosion, especially from chlorides (like salt). This makes it superior to 304/304L stainless for many applications.
● Low Carbon (L grade): The “L” in 316L stands for low carbon (<0.03%). This prevents harmful carbide precipitation during welding, which can lead to corrosion in the weld zone.
What the Certification Itself Verifies:
A proper Mill Test Report (MTR) or Certificate of Compliance referencing ASTM A270 S2 will provide verified evidence that the tubing lot meets all aspects of the standard, including:
● Chemical Composition: Confirmation that the alloy chemistry meets S2 (316L) limits.
● Mechanical Properties: Such as tensile strength and yield strength.
● Dimensional Tolerances: Outer diameter, wall thickness, and straightness.
● Hydrostatic (or Nondestructive) Testing: Proof the tubing can hold pressure without leaking.
● Surface Finish Verification: Often a critical data point for sanitary applications.
● Heat Number/Batch Traceability: Links the material back to its original melt at the steel mill.
In Simple Terms:
“ASTM A270 S2″ on your certification means you have received sanitary-grade tubing made from premium 316L stainless steel, specifically certified for use in hygienic processing systems where corrosion resistance, cleanability, and material traceability are paramount.
Post time: Feb-03-2026