Slip On Flange ASTM A815 UNS S31803 Duplex Stainless Steel 2" High Pressure Pipeline Connecting Flange

Slip On Flange ASTM A815 UNS S31803 Duplex Stainless Steel 2" High Pressure Pipeline Connecting Flange

1. Product Description

This product is a Slip-On (SO) flange manufactured from UNS S31803 (Duplex 2205 / F51) stainless steel in accordance with ASTM A815 and ASME B16.5 standards. 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 such as 304L or 316L while maintaining excellent corrosion resistance. A slip-on flange is designed to slide over the pipe end and is then secured by two fillet welds—one internal and one external—providing a strong, leak-proof connection. This 2" flange is suitable for moderate-to-high pressure applications and is widely used in demanding industrial piping systems.

2. Key Product Parameters

3. Application / Usage

This slip-on flange is ideal for high-pressure and corrosive fluid systems:

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

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

• Desalination Plants: High-pressure seawater intake and RO feed piping

• Marine Engineering: Seawater piping systems, shipbuilding

• 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 316L austenitic steel, enabling thinner wall designs and weight reduction

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

• Slip-On Simplicity: Easy to install; flange can be rotated for bolt-hole alignment before welding

• Cost-Effective: Lower initial cost compared to weld neck flanges; more economical installation

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

5. Functions

The slip-on flange provides a bolted connection point for joining pipes, valves, or equipment in a piping system. The flange slides over the pipe end and is secured by fillet welds on both the inside and outside, forming a strong, leak-proof joint. The flange face accommodates a gasket to ensure a reliable seal when bolted to a mating flange.

6. Installation Instructions

1. Unpacking Inspection: Check for transit damage; verify markings and dimensions per ASME B16.5

2. Surface Preparation: Clean the pipe end and flange bore using dedicated tools; remove all oil, grease, and contaminants

3. Positioning: Slide the slip-on flange over the pipe to the required position. The pipe end should be set back from the flange face by approximately the pipe wall thickness + 1/8" (3mm) to allow space for the internal weld

4. Alignment: Rotate the flange to align bolt holes with the mating component

5. Tack Welding: Apply tack welds at several points around the flange to hold it in place

6. Final Welding: Perform fillet welds on both the inside and outside of the flange. For duplex materials, strict heat input control is essential. Solution annealing at 1020-1100°C followed by water quenching is required to maintain the duplex structure and corrosion resistance

7. Post-Weld: Clean weld areas; visual and PT/MT examination recommended

8. Bolting: Install gasket, bolts, and tighten in a cross-torque sequence to the recommended torque value

7. Precautions

• Ferrite Balance: Ensure ferrite content remains between 40-60% by volume. Improper heat treatment is the most common cause of out-of-spec ferrite ratios

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

• Cleanliness: Requires a higher degree of cleanliness than carbon steel fabrication; use dedicated tools to prevent contamination

• Welding Gap: The 1/8" (3mm) setback gap is mandatory to prevent weld metal from damaging the flange face

• Bolting Torque: Do not exceed recommended torque to prevent gasket damage or flange distortion

• Gasket Selection: Choose gasket material compatible with the service medium and pressure/temperature conditions

• Quality Testing: PMI per ASTM E1476, UT per ASTM A388, PT/MT per ASTM E165/E709 recommended

8. Shipping & Delivery

• Standard delivery time is typically 15–30 days for standard sizes; larger sizes and custom specifications may require extended lead time

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

• Third-party inspection (ABS, DNV, CCS, LR, BV, etc.) available upon request

• 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.

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.