Forged Pipe Fittings Duplex Stainless Steel Union ASTM A815 UNS S31803 ASME B16.11

Price Negotiable
Price: Negotiable
MOQ: 1PC
Delivery Time: 15-30 Workdays
Brand: TOBO
Product Description

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:

  • 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.

Get in Touch

Have questions about our products or want to discuss a custom order? Our team is ready to help you.

Company TOBO STEEL GROUP CHINA
Location 2F,Building7,Baolong Center,No.689,Xiwang Road,Jiading District,Shanghai,201800,China
Contact Person Joy Wang

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