Threaded Coupling ASTM A815 UNS S31803 Duplex Stainless Steel 1/2"-4" SCH40 ASME B16.11
Threaded Coupling ASTM A815 UNS S31803 Duplex Stainless Steel 1/2"-4" SCH40 ASME B16.11
1. Product Description
This product is a threaded pipe coupling manufactured from UNS S31803 (Duplex 2205) stainless steel in accordance with ASTM A815 and ASME B16.11 standards . A coupling is a fundamental pipe fitting used to connect two sections of pipe in a straight line. UNS S31803 is a dual-phase stainless steel with a microstructure of approximately 50% ferrite and 50% austenite, offering roughly double the yield strength of standard 300-series austenitic stainless steels while providing exceptional corrosion resistance . This coupling features male or female threaded (NPT) connections and is designed for small-bore piping systems (1/8″ to 4″) .
2. Key Product Parameters
| Parameter | Details / Range |
|---|---|
| Material Standard | ASTM A815 / ASME SA815 |
| Dimensional Standard | ASME B16.11, MSS SP-79, BS 3799 |
| Material Grade | UNS S31803 (Duplex 2205 / F51 / WNR 1.4462) |
| Type | Threaded Full Coupling |
| Size Range | 1/2" – 4" NB (DN15 – DN100) |
| Wall Thickness | Schedule 40 (SCH40) |
| Pressure Class | 3000# (Class 3000 LBS) |
| Thread Type | NPT (ASME B1.20.1), BSPT, BSPP |
| Chemical Composition (Cr/Ni/Mo/N) | 21.0-23.0% / 4.5-6.5% / 2.5-3.5% / 0.08-0.20% |
| Tensile Strength (min) | 620–800 MPa (90–116 ksi) |
| Yield Strength 0.2% (min) | 450–550 MPa (65–80 ksi) |
| Elongation (min) | 25% |
| Hardness (max) | 293 HBW / 31 HRC |
| Density | ~7.8 g/cm³ |
| PREN Value | ~34–36 |
| Heat Treatment | Solution annealing at 1020-1100°C, water quench |
3. Application / Usage
This threaded coupling is ideal for high-pressure and corrosive fluid systems:
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Oil & Gas: Offshore platforms, subsea piping, high-pressure process lines
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Chemical Processing: Chloride-containing acids, brine services, heat exchangers
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Marine Engineering: Seawater piping systems, desalination plants
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Power Generation: Cooling water systems, high-temperature service
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Pulp and Paper: Bleaching lines, digester systems
4. Advantages
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Superior Strength: Yield strength is approximately double that of 316L austenitic steel, enabling thinner wall designs
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Excellent Corrosion Resistance: PREN ~34-36 provides outstanding resistance to pitting, crevice corrosion, and chloride stress corrosion cracking
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Threaded Convenience: No welding required; fast installation and easiest disassembly for maintenance
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Cost-Effective: Lower nickel content compared to austenitic grades offers significant material cost savings
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Versatile Installation: Suitable for both indoor and outdoor piping systems
5. Functions
The threaded coupling provides a reliable, leak-proof mechanical connection between two sections of pipe of the same diameter. It connects two pieces of pipe together using threaded connections, enabling pipe extension, repair, or system modification without welding operations .
6. Installation Instructions
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Preparation: Clean pipe threads and coupling threads thoroughly; remove all dirt, oil, and debris
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Thread Sealant: Apply PTFE tape or pipe dope to male threads to ensure a reliable seal
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Thread Engagement: Screw the coupling onto one pipe end by hand, then tighten with a wrench. Screw the second pipe into the opposite end
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Avoid Over-tightening: Do not exceed recommended torque to prevent cracking the fitting body
7. Precautions
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Thread Compatibility: NPT, BSPT, and BSPP threads are not interchangeable. Verify thread type per system specification
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Temperature Limitation: Not recommended for use above 300°C or below -50°C due to reduced toughness
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Ferrite Balance: Ensure proper material specification to maintain the 50/50 austenite-ferrite microstructure
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Vibration Sensitivity: Threaded fittings are not recommended on lines subject to significant vibration, thermal shock, or hazardous fluid service
8. Shipping & Delivery
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Standard delivery time is typically 15–30 days, subject to order quantity and specification availability.
9. Payment Terms
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Common international payment methods include T/T (Telegraphic Transfer) and L/C at sight (Letter of Credit) .
10. Packaging
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Products are securely packed in plywood cases or wooden crates with internal cushioning to ensure safe transportation and prevent damage during transit .
11. After-Sales / Return & Warranty Policy
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All products undergo strict quality inspection before shipment, with Mill Test Certificates (EN 10204 3.1/3.2) available .
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In case of quality issues, retain original packaging and provide relevant photos or third-party inspection reports.
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Specific return, exchange, and warranty terms are subject to the final sales contract agreement.
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FAQ
1. Are you trading company or manufacturer ?
We are manufacturer ,You can see the certification.
2. How long is your delivery time?
Generally it is 5-10 days if the goods are in stock. or it is 15-20 days if the goods are not in stock, it is according to quantity.
3. Do you provide samples ? is it free or extra ?
Yes, we could offer the sample for free charge but need pay the cost of freight.
4. What is your terms of payment ?
Payment<=1000USD, 100% in advance. Payment>=1000USD, 50% T/T in advance ,balance before shippment.
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