Forged Pipe Fittings Duplex Stainless Steel Union ASTM A815 UNS S31803 ASME B16

Product Specification

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

3. Application / Usage

This union is ideal for demanding corrosive and high-pressure environments:

• Oil & Gas: Offshore platforms, subsea piping, high-pressure process lines, wellhead connections

• Chemical Processing: Chloride-containing acids, brine services, heat exchangers

• Marine Engineering: Seawater piping systems, desalination plants

• Power Generation: Cooling water systems, high-temperature service

• Pulp and Paper: Bleaching lines, digester systems

4. Advantages

• Superior Strength: Yield strength is approximately double that of standard 300-series austenitic stainless steels (316/316L)

• Excellent Corrosion Resistance: PREN ~34-36 provides outstanding resistance to pitting, crevice corrosion, and chloride stress corrosion cracking

• Easy Disassembly: Three-piece union design allows for quick connection and disconnection of piping systems without rotating pipes

• Cost-Effective: Lower nickel content compared to austenitic grades offers significant material cost savings

• Good Weldability: Compatible with standard welding procedures; solution annealing recommended post-weld

• 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

1. Preparation: Clean pipe threads and fitting threads thoroughly; remove all dirt, oil, and debris

2. Thread Sealant: Apply PTFE tape or pipe dope to male threads to ensure a reliable seal

3. Thread Engagement: Screw the union halves onto the respective pipe ends by hand, then tighten with a wrench to appropriate torque

4. Assembly: Bring the two halves together and tighten the center nut to secure the connection

5. Avoid Over-tightening: Do not exceed recommended torque to prevent cracking the fitting body

7. Precautions

• Thread Compatibility: NPT, BSPT, and BSPP threads are not interchangeable. Verify thread type per system specification

• Temperature Limitation: Not recommended for use above 300°C or below -50°C due to reduced toughness

• Ferrite Balance: Ensure proper material specification to maintain the 50/50 austenite-ferrite microstructure

• Vibration Sensitivity: Ensure the union nut is properly tightened to maintain leak-proof seal

• Stress Corrosion: Threaded fittings create stress concentrators; verify suitability for the specific service environment

8. Shipping & Delivery

• Standard delivery time is typically 15–30 days, subject to order quantity and specification availability

9. Payment Terms

• Common international payment methods include T/T (Telegraphic Transfer) and L/C at sight (Letter of Credit)

10. Packaging

• 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

• 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

• 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.