UNS S31500|1.4417|3RE60 Seamless Duplex Steel Pipe
Our S31500 duplex pipes are specifically designed to provide a strategic combination of high mechanical strength and exceptional resistance to chloride-induced stress corrosion cracking (SCC). With a yield strength nearly double that of conventional 300-series stainless steels, these pipes allow for thinner wall designs and increased pressure ratings in heat exchangers and chemical processing systems. Through advanced cold-drawing and precise solution annealing, XinZhe ensures every pipe maintains optimal phase balance and a high-integrity surface finish for the most demanding industrial environments.
"Our S31500 pipes offer a PREN value that ensures durability in brackish water and mildly corrosive chemical media."
What Is UNS S31500 Duplex Stainless Steel Pipe?
UNS S31500 (also known as 3RE60) is a lean duplex stainless steel engineered to bridge the performance and cost gap between conventional austenitic grades (such as 304/316) and standard duplex grades like S31803.
A seamless UNS S31500 pipe is produced from a solid billet without any weld seam, ensuring superior structural integrity and reliability under high-pressure conditions. Its duplex microstructure (≈50% ferrite + 50% austenite) provides high mechanical strength,excellent resistance to chloride-induced stress corrosion cracking (SCC) andimproved fatigue performance compared with austenitic stainless steels.
Manufacturing is in compliance with ASTM A790 / ASME SA790 as specified in the order, with composition per the heat analysis on the material test certificate.
Key Advantages of Seamless UNS S31500 Pipe
High Strength Performance
approximately 2× the yield strength of 300-series stainless steels, enabling reduced wall thickness, lower material weight and cost-efficient system design.
Enhanced Corrosion Resistance
strong resistance to pitting, crevice corrosion and chloride stress corrosion cracking in aggressive environments.
Cost-Effective Alloy Design
as a lean duplex grade, S31500 contains reduced nickel and molybdenum — lower alloy cost, reduced sensitivity to raw material price fluctuations and stable long-term supply economics.
Seamless Structural Integrity
the absence of weld seams eliminates potential weak points, ideal for high-pressure piping systems, heat exchanger tubing and critical process applications.
Technical Specifications and Material Data
Chemical Composition
Composition of UNS S31500 (3RE60) and related duplex grades, mass %. Confirm the ordered standard edition and heat analysis on the material test certificate.
| Grade | C | Mn | P | S | Si | Ni | Cr | Mo | N | Cu | Others |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 31803 | ≤0.03 | ≤2.00 | ≤0.03 | ≤0.02 | ≤1.00 | 4.50-6.50 | 21.00-23.00 | 2.50-3.50 | 0.08-0.20 | … | … |
| 32205 | ≤0.03 | ≤2.00 | ≤0.03 | ≤0.02 | ≤1.00 | 4.50-6.50 | 22.00-23.00 | 3.00-3.50 | 0.14-0.20 | … | … |
| 31500 | ≤0.03 | 1.20-2.00 | ≤0.03 | ≤0.03 | 1.40-2.00 | 4.3-5.2 | 18.00-19.00 | 2.50-3.00 | 0.05-0.10 | … | … |
| 32550 | ≤0.04 | ≤1.50 | ≤0.04 | ≤0.03 | ≤1.00 | 4.50-6.50 | 24.00-27.00 | 2.90-3.90 | 0.10-0.25 | 1.50-2.50 | … |
| 32750 | ≤0.03 | ≤1.20 | ≤0.035 | ≤0.02 | ≤0.80 | 6.00-8.00 | 24.00-26.00 | 3.00-5.00 | 0.24-0.32 | ≤0.50 | … |
| 32760 | ≤0.03 | ≤1.00 | ≤0.030 | ≤0.01 | ≤1.00 | 6.00-8.00 | 24.00-26.00 | 3.00-4.00 | 0.20-0.30 | 0.50-1.00 | W 0.50-1.00 |
| 32950 | ≤0.03 | ≤2.00 | ≤0.035 | ≤0.01 | ≤0.60 | 3.50-5.20 | 26.00-29.00 | 1.00-2.50 | 0.15-0.35 | … | … |
| 32906 | ≤0.03 | 0.80-1.50 | ≤0.030 | ≤0.03 | ≤0.50 | 5.80-7.50 | 28.00-30.00 | 1.50-2.60 | 0.30-0.40 | ≤0.80 | … |
Typical Mechanical Properties
UNS S31500 is specifically designed to maintain its strength and shape in high-stress, corrosive environments.
| Tensile Strength | Yield Strength | Elongation | Hardness |
|---|---|---|---|
| ≥ 630 MPa | ≥ 440 MPa | ≥ 30% | ≤ 290 HBW |
Typical Physical Properties
These physical properties highlight the material’s ability to perform reliably under a wide range of conditions.
| Density | Melting Point | Thermal Expansion | Thermal Conductivity | Modulus of Elasticity | Electrical Resistivity |
|---|---|---|---|---|---|
| 7.7 g/cm³ | 1450–1510 °C approx. | 13.0 µm/m·°C (20-100°C) | 18.0 W/m·K (20°C) | 200 GPa | 0.85 × 10⁻⁶ Ω·m (20°C) |
Size Tolerance Chart
The standard of stainless steel seamless pipe size tolerance (ASTM A790 / ASME SA790, per ASTM A999 references):
| NPS Designator (Inches) | Over | Under |
|---|---|---|
| 1/8 to 1 1/2, incl. | +1/64 in. (0.015 in.) | −1/32 in. (0.031 in.) |
| Over 1 1/2 to 4, incl. | +1/32 in. (0.031 in.) | −1/32 in. (0.031 in.) |
| Over 4 to 8, incl. | +1/16 in. (0.062 in.) | −1/32 in. (0.031 in.) |
| Over 8 to 18, incl. | +3/32 in. (0.093 in.) | −1/32 in. (0.031 in.) |
| Over 18 to 26, incl. | +1/8 in. (0.125 in.) | −1/32 in. (0.031 in.) |
| Over 26 to 34, incl. | +5/32 in. (0.156 in.) | −1/32 in. (0.031 in.) |
| Over 34 to 48, incl. | +3/16 in. (0.187 in.) | −1/32 in. (0.031 in.) |
Wall Thickness (WT) Tolerance — minimum wall at any point shall not be more than 12.5% under the nominal wall; maximum over-nominal variation depends on size and the t/D ratio:
| NPS Designator (Inches) | t/D Ratio | Permissible Variation (Over Nominal WT) |
|---|---|---|
| 1/8 to 2, incl. | All ratios | +20.0% |
| 3 to 18, incl. | t/D ≤ 5% | +22.5% |
| t/D >5% | +15.0% | |
| 20 and larger (Seamless) | t/D ≤ 5% | +22.5% |
| t/D >5% | +15.0% | |
| 20 and larger (Welded) | All ratios | +17.5% |
Length Tolerance: for pipe ordered to a specific cut length, the standard tolerance is +1/8 in. (3.2 mm), −0. Pipe is typically supplied in Single Random Lengths (17 to 24 ft) or Double Random Lengths (38 to 40 ft), unless otherwise specified.
Disclaimer: these tolerances reflect common ASTM A790 requirements (primarily via its reference to ASTM A999). The current edition of the applicable specification governs acceptance.
Typical Applications of UNS S31500 Seamless Pipes
Seamless UNS S31500 duplex pipes are widely used in demanding industrial environments:
Petrochemical and Refining
- Process piping
- Heat exchanger tubes
Pulp and Paper Industry
- Digesters
- Bleaching systems
- Chemical liquor tanks
Marine and Offshore Engineering
- Subsea pipelines
- Seawater handling systems
- Shipboard piping
Chemical Processing
- Organic acid transport
- Chloride-containing media
Quality Assurance and Inspection
To ensure full compliance and traceability, the following quality controls are typically applied:
Certification
EN 10204 3.1 / 3.2 material test certificates.
Non-Destructive Testing
100% PMI (Positive Material Identification), Ultrasonic Testing (UT) and Eddy Current Testing (ET).
Mechanical Testing
flattening test, flaring test, bend test and intergranular corrosion (IGC) test.
Third-Party Inspection (optional)
TÜV, BV, SGS or Lloyd’s Register can be arranged on request.
Frequently Asked Questions About UNS S31500 Pipe
What is 3RE60 steel?
3RE60 is the trade name for UNS S31500, a lean duplex stainless steel (about 18.5% Cr, 5% Ni, 2.5% Mo plus silicon) developed for chloride stress-corrosion-cracking resistance and high strength.
What standards apply to UNS S31500 seamless pipe?
Seamless pipe is supplied to ASTM A790 / ASME SA790 with dimensional tolerances per ASTM A999 references; confirm the exact edition on the purchase order.
How does S31500 compare with S31803?
S31500 is a leaner alloy (lower Cr, Ni and cost) with good SCC resistance, while S31803 offers higher alloying and broader corrosion allowance. Selection depends on medium, chloride level and design temperature.
What mechanical properties does S31500 pipe provide?
Typical annealed values: minimum tensile strength 630 MPa, minimum yield strength 440 MPa, minimum elongation 30% and maximum hardness 290 HBW, per the ordered specification.
Where is UNS S31500 seamless pipe commonly used?
Petrochemical and refining process piping, pulp and paper digesters and bleach systems, marine and offshore seawater handling, and chemical processing with chlorides and organic acids.
Ready to Request a Quotation?
Send your S31500 (3RE60) pipe enquiry with grade, ASTM A790 or ASME SA790 and edition, OD × wall thickness or NPS/schedule, length, quantity, end finish, delivery destination and inspection documents — you will get a written quotation stating the specification and edition, delivery condition, documents included and lead time.
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