What Do You Know About Blind Flange Boards?

In industrial piping systems, blind flange boards—commonly referred to as blind flanges—play a critical role in sealing pipe ends and ensuring the safety and integrity of fluid and gas transmission. These components are often overlooked but are indispensable in systems that require pressure testing, isolation, or future expansion capability.

This article explores everything you need to know about blind flange boards, including their structure, functions, materials, industry standards, and applications. Whether you are a mechanical engineer, maintenance technician, or procurement manager, this guide will help you understand the value and proper use of blind flanges in modern infrastructure.

What Is a Blind Flange Board?

A blind flange board is a solid, disk-shaped component that has no central bore (hole). It resembles a standard flange but is completely sealed off in the center. It is bolted to the end of a pipe or fitting to block fluid or gas flow.

Key Features:

Round metal disk with bolt holes
No internal opening or passage
Often manufactured with raised face, flat face, or RTJ (Ring Type Joint)
Available in a wide range of sizes and pressure classes

A blind flange is commonly used where a piping system needs to terminate temporarily or permanently.

What Are Blind Flange Boards Used For?

Blind flanges serve several crucial functions in various industries:

1. Pipe End Sealing

They close off the end of a piping system, preventing the escape of media or pressure.

2. Pressure Testing

Blind flanges allow pressure tests to be conducted on newly installed pipelines or vessels.

3. Future Expansion Planning

They seal off open ends where future piping or equipment will be connected later.

4. Maintenance and Isolation

Used to isolate a section of the pipeline during shutdowns or repairs without disturbing the rest of the system.

sasaflange provides blind flange boards in multiple pressure ratings (150 to 2500 class, PN10 to PN160) to suit a variety of operational conditions.

Blind Flange vs Other Flange Types

It’s essential to distinguish blind flanges from other common flange types:

Flange Type	Central Hole	Purpose
Weld Neck	Yes	Permanent pipe connection
Slip-On	Yes	Easy to slide over pipe ends
Socket Weld	Yes	For small diameter high-pressure pipes
Threaded	Yes	Connects to threaded pipes
Lap Joint	Yes	Works with stub ends
Blind Flange	No	Blocks the end of a pipe

Blind flanges are the only type designed specifically to seal off a piping system rather than allow flow through it.

Materials Used for Blind Flange Boards

The material selection depends on pressure, temperature, and the nature of the fluid in the system:

Carbon steel (A105, A350 LF2) – For general service
Stainless steel (304, 316, 321) – For corrosion resistance
Alloy steel (F11, F22, F91) – For high temperature and pressure
Duplex/Super Duplex – For offshore and chemical applications
Nickel alloys (Hastelloy, Inconel, Monel) – For highly corrosive environments

sasaflange offers custom manufacturing services to supply blind flange boards that meet both standard and special material requirements, ensuring suitability for your application.

Industry Standards for Blind Flange Boards

Blind flanges are manufactured according to international standards such as:

ASME B16.5 – Pipe flanges and flanged fittings (½” to 24″)
ASME B16.47 Series A/B – For larger diameter flanges (26″ to 60″)
EN 1092-1 – European standard
DIN 2527 – German blind flange standard
JIS B2220 – Japanese standard

Each standard specifies dimensions, pressure classes, facing types, and tolerance limits.

Pressure Ratings and Thickness

Blind flanges are subject to full internal pressure since there is no flow-through. Therefore, they are typically thicker than regular flanges of the same size and pressure class.

Pressure Classes (ASME):

Class 150
Class 300
Class 600
Class 900
Class 1500
Class 2500

Blind flanges must be selected based on design pressure and temperature to ensure safety and long-term performance.

Sealing Face Types

Blind flange boards come in several face types for compatibility with gaskets and pipe connections:

Raised Face (RF) – Standard for most process piping
Flat Face (FF) – Used where flanges are cast iron or non-metallic
Ring Type Joint (RTJ) – For high-pressure applications with metal-to-metal seals

Choosing the correct face type ensures proper gasket compression and leak-proof sealing.

Advantages of Using Blind Flange Boards

Complete system isolation
Easy to install or remove
Low maintenance
Adaptable to different piping systems
Ideal for future system modification

With proper handling and installation, blind flanges offer a cost-effective and secure method to terminate or isolate pipelines.

Installation Guidelines

To install a blind flange board correctly:

Inspect sealing surfaces for damage or rust
Select appropriate gasket material for media and temperature
Use proper bolt torque sequence (star pattern)
Tighten in stages to ensure even compression
Recheck bolt torque after system pressurization

Improper installation can lead to gasket failure or flange warping, resulting in leaks or blowouts.

sasaflange recommends following ASME PCC-1 bolting standards for safe flange assembly practices.

Maintenance Tips

Inspect sealing face regularly for corrosion or dents
Replace gaskets during each reinstallation
Retorque bolts periodically in high-pressure or vibrating systems
Use protective covers when flanges are stored or idle

Routine maintenance prolongs flange life and enhances system reliability.

Why Choose sasaflange Blind Flange Boards?

At sasaflange, we specialize in the manufacture and global supply of high-quality blind flange boards:

Compliance with ASME, DIN, JIS, EN standards
Wide material selection, including stainless steel, alloy, and carbon steel
Custom machining for size, thickness, or special surface finishes
Corrosion-resistant coatings upon request
Fast delivery and export-ready packaging

Whether you’re building a pipeline, pressure vessel, or process system, sasaflange ensures your blind flanges are precision-engineered for safety, strength, and performance.

Conclusion

Blind flange boards are more than just solid disks—they are crucial safety components in pressurized systems. They block flow, isolate systems, and enable testing and maintenance operations. With wide material options, high pressure ratings, and compatibility with global standards, blind flanges are indispensable in modern industrial systems.

When selecting or specifying blind flanges, consider material compatibility, pressure class, face type, and standard compliance. For high-performance blind flange boards backed by expert support, trust sasaflange—your reliable partner in industrial piping components.