Duplex

UNS S31803 / S32205 (F51/F60)

A strong and reliable solution for corrosive and high-stress environments.

Duplex UNS S31803 / S32205 is widely used in demanding service conditions where high mechanical loads and aggressive corrosive environments are present. The material performs particularly well in chloride-containing environments and offers strong resistance to localized corrosion mechanisms such as pitting, crevice corrosion and stress corrosion cracking. These properties make it a reliable choice for critical applications in industries where durability and operational safety are essential.

From a metallurgical perspective, Duplex UNS S31803 / S32205 is a 22Cr duplex stainless steel with a mixed austenitic–ferritic microstructure. In the solution-annealed condition, the material typically consists of approximately equal proportions of ferrite and austenite. This balanced microstructure results in a combination of high mechanical strength and excellent corrosion resistance.

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Key Characteristics

Duplex UNS S31803 / S32205 is characterized by:

High resistance to stress corrosion cracking in halide-containing environments
Resistance to pitting and crevice corrosion
Resistance to general corrosion
High mechanical strength
Resistance to erosion corrosion and corrosion fatigue

The higher yield strength compared to conventional austenitic stainless steels such as 304L and 316L allows for higher design pressures or reduced wall thickness in demanding applications.

Fast, Flexible, Global Delivery

Whether you need immediate delivery from stock or scheduled shipments for long-term projects, we deliver where and when you need it.

From urgent single shipments to complete packages, we tailor our delivery to your planning.

Prefer to handle logistics yourself? No problem. We offer flexible delivery terms, including Ex Works. Want us to take care of everything? We’ll arrange full-service transport, tracking, and documentation.

Get in touch to discuss the best delivery setup for your project.

Product Details

Application by Service and Function

Duplex UNS S31803 / S32205 is suitable for services involving high chloride content, elevated mechanical stress and corrosive process conditions.

Typical applications include:

Upstream production of high-chloride oil and gas liquids
Seawater systems
Seawater pumps and valves
Chemical process vessels
Pipes and heat exchangers
Oilfield piping
Feed process equipment

The material is generally not recommended for prolonged service above approximately 300 °C or below –50 °C due to the risk of embrittlement.

Application by Industry

Duplex UNS S31803 / S32205 is widely used across several industries, including:

Upstream oil and gas production
Chemical processing industry
Water and seawater handling systems
Pulp and paper industry, including digesters and bleach scrubbers
Flue gas desulfurization (FGD) systems

These industries benefit from the material’s combination of corrosion resistance, strength and durability in aggressive operating environments.

Standards & Specifications

Stainalloy supplies Duplex stainless steel in full accordance with ASTM specifications:

Product Type	Standard	Grade
Seamless pipe	ASTM A790	UNS S31803 / S32205
Welded pipe	ASTM A928	UNS S31803 / S32205
Fittings (seamless & welded)	ASTM A815	UNS S31803 / S32205
Flanges & forgings	ASTM A182	F51 (S31803) / F60 (S32205)

All materials are supplied from qualified mills and can be delivered with enhanced testing to meet client-specific requirements, including oil & gas majors.

Stainalloy Capabilities

Stainalloy has more than 40 years of experience in supplying Duplex UNS S31803 / S32205 piping materials. This long-standing expertise has resulted in strong technical know-how and established relationships with leading manufacturers.

Key capabilities include:

Worldwide supply of large piping packages for oil and gas production and processing industries
Availability of mid-sized piping packages from stock during advanced construction stages
Short lead times due to extensive stock availability
Comprehensive stock programme covering sizes from ½” up to and including 48”
Supply of seamless and welded pipes, fittings, forgings and flanges

Stainalloy’s Duplex UNS S31803 / S32205 stock programme is particularly suitable for construction projects in the upstream oil and gas and water treatment industries, where reliability, material performance and delivery certainty are critical.

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