Overview

ASTM A789 UNS S32750, commonly known as Super Duplex 2507, is a high-performance ferritic-austenitic stainless steel tube designed for highly corrosive industrial environments. It combines excellent chloride corrosion resistance with very high mechanical strength, making it ideal for offshore oil and gas, seawater desalination, chemical processing, heat exchangers, and marine engineering.

The alloy's balanced duplex microstructure provides approximately equal amounts of austenite and ferrite, delivering strength and corrosion resistance that conventional austenitic stainless steels such as 304 and 316 cannot match.

Key Advantages

High Strength: Minimum yield strength of 550 MPa and tensile strength of 800 MPa.
Excellent Chloride Resistance: PREN 41–43, with high resistance to pitting, crevice corrosion, and stress corrosion cracking.
Weight Savings: Higher strength allows thinner walls and reduced weight in high-pressure systems.
Wide Application Range: Suitable for offshore, desalination, chemical, marine, and power industries.
Reliable Quality: Manufactured to ASTM A789 / ASME SA789 with full testing and documentation.

Chemical Composition

Element	Range (%)
Carbon (C), max	0.030
Manganese (Mn), max	1.20
Phosphorus (P), max	0.035
Sulfur (S), max	0.020
Silicon (Si), max	0.80
Chromium (Cr)	24.0–26.0
Nickel (Ni)	6.0–8.0
Molybdenum (Mo)	3.0–5.0
Nitrogen (N)	0.24–0.32
Copper (Cu), max	0.50
Iron (Fe)	Balance

Mechanical Properties

Property	Requirement
Tensile Strength, min	800 MPa
Yield Strength (0.2% offset), min	550 MPa
Elongation, min	15%
Hardness, max	32 HRC / 310 HBW
PREN	41–43

Corrosion Resistance

UNS S32750 offers outstanding resistance in chloride-bearing environments:

Critical Pitting Temperature (CPT): Exceeds 50°C; in 6% FeCl₃ testing, 2507 resists pitting up to about 65°C.

Critical Crevice Temperature (CCT): ≥ 35°C.

Stress Corrosion Cracking: Excellent resistance to chloride-induced SCC.

General Corrosion: Very low corrosion rates in organic acids compared with 316L.

This makes 2507 a reliable choice for seawater, offshore, and chemical applications where standard duplex 2205 may not be sufficient.

Applications of ASTM A789 UNS S32750

The high strength and corrosion resistance of UNS S32750 tubing make it suitable for a wide range of harsh environments, including chloride and sulphide service:

Offshore Oil & Gas

Subsea umbilicals and flowlines
Offshore platform topside piping
Deepwater risers
Sour service applications
Oil and gas exploration and offshore rigs

Seawater Desalination

Reverse osmosis (RO) pressure vessels
High-pressure seawater feed piping
Brine pumps and transport systems
Heat exchanger tubing
Concentrated seawater side components

Chemical & Petrochemical

Reactors handling acidic chloride solutions
Heat exchangers in pulp and paper mills
Transport lines for corrosive chemicals
Pollution control equipment
Flue gas desulfurization scrubber systems

Marine & Shipbuilding

Seawater piping systems
Marine engineering structures
Shipboard heat exchangers

ASTM A789 Duplex 2507 Stainless Steel Pipe

Comparison: 2205 vs 2507

Property	2205 (S32205)	2507 (S32750)
Classification	Standard Duplex	Super Duplex
Chromium	22.0–23.0%	24.0–26.0%
Nickel	4.5–6.5%	6.0–8.0%
Molybdenum	3.0–3.5%	3.0–5.0%
Nitrogen	0.14–0.20%	0.24–0.32%
PREN (typical)	34–36	41–43
Yield Strength, min	450 MPa	550 MPa
Tensile Strength, min	620 MPa	800 MPa
CPT in 6% FeCl₃	~35°C	~65°C
Relative Cost	Baseline	30–50% premium

Why Choose TOM?

Quality control is integrated into every stage of our manufacturing process.

We exclusively use raw materials from renowned steel mills with full traceability; every batch of steel strip and billet comes with complete production certification and chemical composition analysis reports, ensuring consistent and reliable product quality right from the source.

Our facility is equipped with a full suite of professional testing instruments. Every steel pipe undergoes multiple precision inspections-including hydrostatic testing, eddy current testing, and ultrasonic testing-to ensure no defective products leave the factory.

We provide comprehensive official technical documentation for every order, including MTC 3.1/3.2 material certificates, dimensional inspection reports, and heat treatment records. We also fully support third-party inspections, ensuring complete transparency and verifiability of quality.

We offer flexible ordering options starting from a single piece to meet diverse customer needs-whether for sporadic equipment replacements, small-batch top-up orders, or bulk procurement for large-scale engineering projects, we provide a one-stop solution.

We ensure stable production and delivery with ample supply capacity. For urgent projects, we offer rapid dispatch to efficiently meet tight delivery schedules.