ASTM A790 UNS S31803 Seamless Pipe Specification

ASTM A790 UNS S31803 Seamless Pipe Specification

Duplex Stainless Steel S31803 Seamless Pipes | Technical Specification PDF Download

The ASTM A790 UNS S31803 Seamless Pipe Specification PDF provides a comprehensive technical reference for duplex stainless steel seamless pipes used in corrosive, high-pressure, and high-temperature service. This specification covers chemical composition, mechanical properties, heat treatment, manufacturing process, dimensions and tolerances, testing and inspection, and typical applications in oil & gas, petrochemical, offshore, and industrial piping systems.

ASTM A790 Standard

ASTM A790 is the standard specification for seamless and welded ferritic/austenitic (duplex) stainless steel pipes intended for general corrosive service, with particular emphasis on resistance to stress corrosion cracking. Pipes manufactured to ASTM A790 offer higher strength and improved corrosion resistance compared with conventional austenitic stainless steels.

UNS S31803 is one of the most widely used duplex stainless steel grades covered under ASTM A790.

Material Grade: UNS S31803 (Duplex Stainless Steel)

  • Standard: ASTM A790 / ASME SA790

  • Grade: UNS S31803

  • Material Type: Duplex Stainless Steel (Ferritic-Austenitic)

  • Manufacturing Method: Seamless

  • Product Form: Stainless Steel Pipes

UNS S31803 provides an excellent combination of high mechanical strength and resistance to pitting, crevice corrosion, and chloride stress corrosion cracking.

Chemical Composition (Typical, %)

  • Carbon (C): ≤ 0.03

  • Chromium (Cr): 21.0 – 23.0

  • Nickel (Ni): 4.5 – 6.5

  • Molybdenum (Mo): 2.5 – 3.5

  • Nitrogen (N): 0.08 – 0.20

  • Manganese (Mn): ≤ 2.00

  • Silicon (Si): ≤ 1.00

  • Phosphorus (P): ≤ 0.035

  • Sulfur (S): ≤ 0.020

Chemical composition limits are defined by ASTM A790 for UNS S31803.

Mechanical Properties (Minimum Requirements)

  • Tensile Strength: ≥ 620 MPa

  • Yield Strength (0.2% Offset): ≥ 450 MPa

  • Elongation: ≥ 25%

Duplex stainless steel S31803 offers approximately twice the yield strength of austenitic stainless steels such as 304 and 316.

Heat Treatment

ASTM A790 UNS S31803 seamless pipes are supplied in the solution-annealed condition followed by rapid quenching. Proper heat treatment ensures balanced ferritic-austenitic microstructure and optimal corrosion resistance.

Manufacturing Process

ASTM A790 UNS S31803 seamless pipes are manufactured by:

  • Hot rolling or hot extrusion

  • Cold finishing (if required)

  • Solution annealing

  • Pickling and passivation

  • Straightening and final inspection

The seamless construction provides uniform wall thickness and excellent pressure resistance.

Dimensions & Tolerances

ASTM A790 UNS S31803 pipes are typically ordered by NPS (Nominal Pipe Size) and Schedule (wall thickness).

Key dimensional controls include:

  • Outside Diameter (OD) tolerance

  • Minimum wall thickness requirement (commonly based on the 87.5% rule)

  • Ovality and straightness

  • Length: random length, double random length, or fixed cut length

General dimensional requirements are usually governed by ASTM A999 / A999M unless otherwise specified.

Testing & Inspection

Each ASTM A790 UNS S31803 seamless pipe may be subjected to:

  • Chemical analysis

  • Tensile testing

  • Flattening or flaring test

  • Hydrostatic testing or non-destructive testing (UT / ET)

  • Dimensional and visual inspection

Mill Test Certificates (EN 10204 3.1) are typically supplied.

Applications

  • Oil & Gas Pipelines

  • Offshore and Marine Systems

  • Petrochemical Processing

  • Chemical Plants

  • Desalination Facilities

  • Pressure Piping Systems

ASTM A790 UNS S31803 seamless pipes are widely used where high strength and corrosion resistance are required.

Download ASTM A790 UNS S31803 Seamless Pipe Specification PDF

Download the complete ASTM A790 UNS S31803 Seamless Pipe Specification PDF, including chemical composition limits, mechanical requirements, heat treatment conditions, and testing procedures.

👉 Download astm_a790_uns_s31803_seamless_pipe_specification

For the complete standard covering all austenitic stainless steel pipe grades,
you may also download the ASTM A790 Specification PDF.

👉 Download astm_a790 standard specification

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