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

Product Specification

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.