What is STS316 stainless steel pipe?

1. Definition and Standards

STS316 stainless steel  Standard Origin:
STS316 is a grade of austenitic stainless steel pipe specified under the Korean KS standard (KS D3551). It is equivalent to:

Japanese JIS standard SUS316

American ASTM standard 316 (ASTM A240/A240M)

Internationally recognized as the 316-type stainless steel, a classic molybdenum-containing austenitic alloy.

Material Type:
Austenitic stainless steel (face-centered cubic crystal structure), non-magnetic, with excellent ductility, toughness, and weldability after solution annealing.

 

2.STS316 stainless steel  Chemical Composition

Element	Content Range
Carbon (C)	≤0.08%
Chromium (Cr)	16.0–18.0%
Nickel (Ni)	10.0–14.0%
Molybdenum (Mo)	2.0–3.0%
Others	Trace Si, Mn

 

3.STS316 stainless steel  Corrosion Resistance

Chloride Resistance:
The molybdenum addition makes it superior to 304 stainless steel (non-Mo) in chloride-containing environments (e.g., seawater, salt solutions, neutral salt spray). It performs well in moderate chloride conditions (≤3000 ppm Cl⁻, temperature ≤60°C).

STS316 stainless steel  High-Temperature Oxidation Resistance:
Suitable for long-term use at ≤870°C and short-term exposure up to 1150°C, ideal for high-temperature applications (e.g., boilers, heat exchangers).

Intergranular Corrosion Resistance:
Low carbon content (≤0.08%) and solution treatment reduce carbide precipitation at grain boundaries, eliminating the need for post-weld heat treatment (provided heat input is controlled).

 

4.STS316 stainless steel  Mechanical Properties

Strength and Ductility:
At room temperature, tensile strength ≥515 MPa, yield strength ≥205 MPa, elongation ≥40%. Balances high strength with good formability for cold working (e.g., bending, shaping).

Processability:
Excellent weldability (TIG welding or low-hydrogen electrodes recommended) and moderate machinability (requires HSS or carbide tools with cooling lubrication).

 

5.STS316 stainless steel  Typical Applications

Marine Engineering:
Seawater pipelines, valves, ship components, offshore platform structures (resistant to salt spray and seawater erosion).

Chemical and Petrochemical:
Pipelines for organic acids (e.g., formic, acetic acid), chemical reactors, heat exchangers (resistant to chloride-containing acidic media).

Food and Pharmaceutical:
Food processing equipment, pharmaceutical pipelines (hygienic requirements, resistant to chloride and organic corrosion).

Energy Sector:
Nuclear condenser tubes, thermal power boiler pipes (high-temperature oxidation and moderate corrosion resistance).

 

6.STS316 stainless steel Differences from Related Grades

STS316L:
Extra-low carbon version (C≤0.03%), eliminating intergranular corrosion risk entirely, suitable for critical welded structures (e.g., thick plates, non-solution-treatable components).

1.4401 (EN Standard):
Chemically almost identical to STS316 (Mo up to 2.5%), differing only in certification (EN vs. KS). Performance is equivalent and interchangeable.

304 Stainless Steel:
Lacks molybdenum, offering ~3x lower resistance to pitting corrosion in chloride environments compared to STS316.