Paddle Blank ASTM A815 UNS S31803 Duplex Stainless Steel 4" ASME B16.48

Paddle Blank ASTM A815 UNS S31803 Duplex Stainless Steel 4" ASME B16.48  

1. Product Description

This product is a paddle blank (also known as a spade flange) manufactured from UNS S31803 (Duplex 2205) stainless steel in accordance with ASTM A815 and ASME B16.48 standards . A paddle blank is a solid, flat steel disc with a protruding handle, designed to be inserted between two flanges to provide positive isolation of a piping section . Unlike a spectacle blind, the paddle blank is a single-use isolation device that is fully removed when flow needs to be restored . 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 4" Class 300# fitting is designed for bolted installation between ASME B16.5 flanges in high-pressure and corrosive service pipeline systems.

2. Key Product Parameters

3. Application / Usage

This paddle blank is ideal for high-pressure and corrosive fluid systems requiring positive isolation:

• Oil & Gas: Offshore platforms, subsea piping, wellhead connections, chemical injection lines 

• Chemical Processing: Chloride-containing process streams, acid services 

• Marine & Desalination: Seawater piping systems, high-pressure RO membrane feed lines 

• Power Generation: Cooling water systems, steam pipelines

• Pulp and Paper: Bleaching lines, digester systems 

4. Advantages

• Positive Isolation: Provides absolute, zero-leakage isolation—more reliable than valves which can leak or be accidentally opened 

• Superior Strength: Yield strength (450 MPa) is approximately double that of 316L, enabling higher pressure ratings with reduced thickness 

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

• Visual Indication: The protruding handle visibly confirms the line is blinded 

• Cost-Effective: Lower initial cost compared to spectacle blinds; ideal for infrequent isolation requirements 

5. Functions

The paddle blank provides a permanent, leak-proof isolation device for piping systems. The solid disc is inserted between two flanges with gaskets on both sides, completely blocking fluid flow . The protruding handle serves as a visual indicator that the line is blinded . To restore flow, the paddle blank is removed and replaced with a paddle spacer (bored disc) . Unlike spectacle blinds, paddle blanks are fully removed during normal operation, making them suitable for systems where isolation is required less frequently .

6. Installation Instructions

1. Unpacking Inspection: Check for transit damage; verify markings, dimensions, and pressure class per ASME B16.48

2. Surface Preparation: Clean the paddle blank and flange faces; remove all oil, grease, and contaminants

3. Flange Preparation: Depressurize and drain the line section; unbolt the flange pair and spread the flanges apart

4. Gasket Installation: Place new gaskets on both sides of the paddle blank (one on each face) 

5. Positioning: Insert the paddle blank between the flanges with the handle extending outward

6. Bolting: Install stud bolts and nuts (ensure sufficient length to accommodate the additional thickness). Tighten in a cross-torque sequence to the recommended torque value

7. Verification: Confirm the handle visibly indicates the line is blinded 

7. Precautions

• Ferrite Balance: Ensure ferrite content remains between 40-60%. 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 

• Gasket Requirement: Two gaskets are mandatory—one on each side of the paddle blank 

• Bolting: Longer stud bolts are required due to the additional thickness of the paddle blank and two gaskets

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

• Quality Testing: Ferrite content testing per ASTM E562 and corrosion testing per ASTM A923 recommended

8. Shipping & Delivery

• Standard delivery time is typically 15–30 days, subject to order quantity, pressure class, 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, including chemistry, mechanical properties, ferrite content, and corrosion test results

• 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.

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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.