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Forged Pipe Fittings Duplex Stainless Steel Union ASTM A815 UNS S31803 ASME B16.11
| Surface Treatment | Solid Solution | Color | 3000 PSI |
|---|---|---|---|
| Chemical Composition | Ni MIn63%,Cu 28%-34%,Fe Max2.5% | Standardscompliance | ASME B16.11, ASTM A105, ASTM A182 |
| Wall Thickness | Sch5S-Sch160, XS,XXS | Class | 1500#, 2500# , 3000#, 6000#, 9000# |
| Cusomized Support | OEM | Pressure Rating | 3000LBS, 6000LBS, 9000LBS |
| Business Type | Manufacturer | Packaging Type | Wooden Case |
| Deliver Time | 15Days |
Forged Pipe Fittings Duplex Stainless Steel Union ASTM A815 UNS S31803 ASME B16.11
1. Product Description
This product is a forged pipe fitting union manufactured from UNS S31803 (Duplex 2205 / F51) stainless steel in accordance with ASME B16.11 standards. The union is a three-piece threaded fitting consisting of a female threaded end, a male threaded end, and a central nut that secures the two halves together. UNS S31803 is a dual-phase stainless steel with a microstructure of approximately 50% austenite and 50% ferrite, offering roughly double the yield strength of standard 300-series austenitic stainless steels while providing excellent corrosion resistance. As a forged fitting, it is produced by shaping solid steel billets under high pressure, resulting in a tighter grain structure and superior performance under pressure and thermal cycling.
2. Key Product Parameters
| Parameter | Details / Range |
|---|---|
| Material Standard | ASTM A815 / ASME SA815 |
| Dimensional Standard | ASME B16.11, MSS SP-83 |
| Material Grade | UNS S31803 (Duplex 2205 / F51) |
| Type | Threaded Union (Three-piece: female end, male end, center nut) |
| Size Range | 1/8" – 4" NB |
| Pressure Classes | 2000#, 3000#, 6000#, 9000# |
| Thread Type | NPT (ASME B1.20.1), BSPT, BSPP |
| Chemical Composition | Cr: 21.0-23.0%, Ni: 4.5-6.5%, Mo: 2.5-3.5%, N: 0.08-0.20%, Fe: Balance |
| Tensile Strength (min) | 620-800 MPa (90-116 ksi) |
| Yield Strength 0.2% (min) | 450-550 MPa (65-80 ksi) |
| Elongation (min) | 25% |
| Density | 7.8 g/cm³ |
| PREN Value | ~34-36 |
| Heat Treatment | Solution annealing at 1020-1100°C |
3. Application / Usage
This union is ideal for demanding corrosive and high-pressure environments:
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Oil & Gas: Offshore platforms, subsea piping, high-pressure process lines, wellhead connections
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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 standard 300-series austenitic stainless steels (316/316L)
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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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Easy Disassembly: Three-piece union design allows for quick connection and disconnection of piping systems without rotating pipes
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Cost-Effective: Lower nickel content compared to austenitic grades offers significant material cost savings
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Good Weldability: Compatible with standard welding procedures; solution annealing recommended post-weld
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Forged Integrity: Tighter grain structure than cast fittings; superior performance under pressure and vibration
5. Functions
The threaded union provides a reliable, leak-proof mechanical connection between two sections of pipe, enabling quick assembly and disassembly for maintenance, inspection, or component replacement. The three-piece design (two threaded ends and a center nut) allows the piping system to be separated without rotating the connected pipes, making it ideal for systems requiring frequent maintenance.
6. Installation Instructions
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Preparation: Clean pipe threads and fitting 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 union halves onto the respective pipe ends by hand, then tighten with a wrench to appropriate torque
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Assembly: Bring the two halves together and tighten the center nut to secure the connection
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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: Ensure the union nut is properly tightened to maintain leak-proof seal
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Stress Corrosion: Threaded fittings create stress concentrators; verify suitability for the specific service environment
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
- 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.

