spectacle blind flange

spectacle blind flange

Spectacle Blind Flange (also called a “spectacle blind” or “figure-8 blind”) is a special type of flange that is used in piping systems to either isolate or block a section of the pipeline, allowing the system to remain operational in the event of maintenance.

Brand Name : Locus
Product Name : Spectacle Blind Flange
Product Type : Flange (Spectacle Blind)
Material : Carbon Steel, Stainless Steel, Alloy Steel
Standard : ANSI, ASME, DIN, JIS, or customer-specific standards
Size Range : 1” to 36” (custom sizes available upon request)
Thickness : 5mm to 50mm (depending on size)
Pressure Rating : Class 150, 300, 600, 900, 1500, 2500
Finish : Smooth or Raised Face (RF), Flat Face (FF), Ring Joint (RJ)
Certification : ISO 9001:2015, CE, PED (Pressure Equipment Directive)
Weight : Varies with size and material (available upon request)
End Connections : Flanged Ends
Color : Black, Stainless Steel Finish, or customized
Application : Piping Systems, Pipeline Isolation, Valve Applications, Pressure Systems

Description

1. Description

A Spectacle Blind Flange (also called a “spectacle blind” or “figure-8 blind”) is a special type of flange that is used in piping systems to either isolate or block a section of the pipeline, allowing the system to remain operational in the event of maintenance. It consists of a circular disc that is connected to the piping system through a flanged connection, allowing easy removal and replacement.

- Locus Brand Spectacle Blind Flanges are used in industries where regular maintenance is needed but full pipeline isolation is necessary, such as in chemical, petrochemical, pharmaceutical, and water treatment plants.

2. Specifications

Specification	Details
Material	Carbon Steel, Stainless Steel, Alloy Steel
Flange Size	1” to 36”
Pressure Rating	150, 300, 600, 900, 1500, 2500
Face Type	Raised Face (RF), Flat Face (FF), Ring Joint (RJ)
Thickness	5mm to 50mm (depends on application)
Connection Type	Flanged Ends
Temperature Rating	-20°C to 425°C (depending on material used)
Finish	Smooth or Matte Finish
Standards	ANSI B16.5, ASME B16.47, JIS B2220, DIN 2573

3. Working

The Spectacle Blind Flange works as a piping isolation device by blocking or diverting the flow of fluid within a pipeline. It is installed between two flanges, with one side of the flange sealed and the other side open to allow flow. The flange is typically mounted in such a way that it can be rotated to either block or allow the flow of materials through the system.

4. Principle

The Spectacle Blind Flange operates on a simple mechanical principle: it provides a physical barrier to the flow of material in pipelines when required, and it can easily be rotated to allow the flow through the pipeline when necessary.
The two metal discs connected by a small arm resemble a spectacle lens, with one disc being a blind plate that blocks the flow and the other being an open disc that permits the flow. This unique design allows easy switching between isolation and flow.

5. Assembly

Place the spectacle blind flange between two flanges.
Align the holes on the spectacle blind flange with the holes on the mating flanges.
Insert bolts through the holes of the flanges and tighten to the specified torque.
Ensure that the flange is installed with the blind side (solid disc) facing towards the pipe that needs to be isolated, and the open side facing the pipe that will continue to carry the flow.
Check for leaks once installed and tighten bolts if necessary.

6. Installation Process

Preparation:
- Ensure the pipeline is shut off and pressure is released before installation.
- Clean all sealing surfaces of the flanges and the spectacle blind flange.
Positioning:
- Place the spectacle blind flange in the correct position between the two flanges.
Bolting:
- Insert and tighten bolts in a cross-pattern to ensure uniform pressure.
Inspection:
- Inspect the installation for any visible leaks.
- Check that the flange is properly aligned and secure.
Testing:
- Once installed, perform a pressure test to ensure there are no leaks and the system operates as intended.

7. Technical Specifications

Parameter	Details
Material	Carbon Steel, Stainless Steel, Alloy Steel
Pressure Rating	Class 150, 300, 600, 900, 1500, 2500
Thickness Range	5mm to 50mm
Face Type	Raised Face (RF), Flat Face (FF), Ring Joint (RJ)
End Type	Flanged Ends
Temperature Rating	-20°C to 425°C
Certification	ISO 9001:2015, CE, PED (Pressure Equipment Directive)

8. Troubleshooting

Problem	Possible Cause	Solution
Leaking	Flange bolts not tight enough or sealing surface damaged	Tighten bolts to correct torque; inspect and replace sealing material
Difficulty in Rotation	Contamination of flange or lack of lubrication	Clean the flange; apply lubrication for easy operation
Misalignment	Incorrect installation or wear of the flange mounting surface	Realign the flanges or replace the worn-out parts
Pressure Loss	Flange not sealed properly	Reinstall flange and check for proper sealing

9. HS Codes

- HS Code: 730721 – Flanges of Iron or Steel (for Standard Spectacle Blind Flanges)
- HS Code: 73072190 – Other Flanges (for Specialty Spectacle Blind Flanges)
- HS Code: 73072120 – Flanges, welded, for use in pressure vessels or systems

10. FAQs

Q1: What materials can Spectacle Blind Flanges be made from?

- Spectacle Blind Flanges can be made from carbon steel, stainless steel, and alloy steel based on the application and the environment they will be used in.

Q2: How do I determine the correct size for my application?

- The correct size depends on the piping system specifications, including the diameter of the pipe and pressure rating. Consult with an engineer to ensure proper fitment.

Q3: Can I use a Spectacle Blind Flange in a high-temperature system?

- Yes, but you should choose a material that is rated for high temperatures, such as stainless steel or alloy steel.

Q4: Are these flanges suitable for use in hazardous environments?

- Yes, depending on the material choice, spectacle blind flanges can be used in hazardous and high-pressure environments.

11. Applications

Pipeline Isolation: Spectacle Blind Flanges are commonly used to isolate sections of pipelines for maintenance or repairs.
Petrochemical and Chemical Industries: Used to isolate reactors, valves, and other pressure systems.
Water Treatment Plants: Often used in water supply systems where flow needs to be diverted or stopped.
Oil and Gas: For offshore platforms, processing plants, and refineries.
HVAC Systems: Used in heating and cooling systems for isolation.

Locus Brand Details

- Locus is a trusted name in industrial equipment manufacturing, offering high-quality products including spectacle blind flanges made with precision and adherence to international standards.
- Our manufacturing unit is ISO 9001:2015 certified, and we ensure all our products are tested for durability and performance.