Blind Flange Buying Guide: How to Pick the Right One for Your Project

What is a Blind Flange?

A blind flange is a solid plate used to block off the end of a piping system or valve, commonly used when sections of the pipeline need to be isolated. Blind flanges can be temporary or permanent and are often used in conjunction with gaskets to ensure a leak-proof seal. 

Blind flanges are essential in many industries, including oil and gas, power generation, and chemical processing, due to their ability to withstand high pressures and temperatures.

When selecting a blind flange, you need to consider key factors such as the system’s pressure, temperature, and material requirements. 

To ensure a leak-proof fit in your piping system, it is advisable to start by determining the appropriate blind flange dimensions, pressure class, and compatible facing type. 

Choosing the right flange also involves selecting the proper material and gasket to match your application, whether dealing with corrosive fluids, high temperatures, or specific industry standards.

More details on these factors are provided in this blog to help you make the best decision for your needs.

Key Factors for Choosing Blind Flanges

Selecting the right blind flange is a multi-step process. It requires attention to system specifications and operational conditions. Below is a list of essential factors you should include in your checklist when choosing blind flanges.

Understand the Purpose of the Blind Flange

Before selecting a blind flange, it’s essential to understand its purpose within your system. A blind flange is a solid disk used to block the end of a piping system or valve. It may also serve as an access point for future maintenance or expansion. Blind flanges from a reputable manufacturer offer reliable sealing for temporary or permanent shutdowns in a system.

Determine the Pressure and Temperature Requirements

Blind flanges come in various pressure ratings or “classes.” These help determine how much pressure can a blind flange withstand. The most common classes are 150, 300, 600, 900, 1500, and 2500.

Higher class numbers indicate a greater ability to withstand higher pressures. This is especially critical in industries like oil and gas. In such environments, blind flanges become reliable to handle immense pressure.

Temperature is important, too. Remember that materials may weaken at elevated temperatures. For example, carbon steel blind flanges can handle higher temperatures. On the other hand, if the environment involves corrosive substances, stainless steel might be a better option.

Choose the Right Material

The material of the blind flange must be compatible with the fluid being transported and the overall system. Common materials include:

• Carbon Steel: Known for its strength and suitability for high-pressure environments.
• Stainless Steel (304, 316L): Offers corrosion resistance, making it ideal for chemical processing, food, and pharmaceutical applications.
• Alloy Steel: Used in extreme temperature or pressure conditions due to its high strength and durability.

Consider the Size and Thickness of the Blind Flange

Selecting the correct blind flange dimensions is crucial to ensure a proper fit with your piping system. The dimensions should match the nominal pipe size (NPS) and flange thickness. 

The flange must be thick enough to handle the system’s pressure; otherwise, it may fail under load. Larger, high-pressure systems typically require thicker blind flanges to ensure safety and integrity.

Identify the Facing Type

Flange facings impact the gasket type required and ensure a proper seal between the flange and piping components. Common facing types include:

• Raised Face (RF): Most widely used, offering a raised sealing surface for better gasket compression.
• Flat Face (FF): Typically used in low-pressure environments where metal-to-metal contact is required.

Ensure Compatibility with Industry Standards

Blind flanges must adhere to established standards to ensure safety and compatibility within your system. Common standards include:

• ASME B16.5: Covers piping dimensions and pressure classes.
• DIN, BS, JIS: International standards for flange manufacturing.
• GB/T9119-2010, HG/T20592-2009: Chinese manufacturing standards.

Keep in Mind Long-Term Maintenance

For systems requiring frequent access for maintenance, it is essential to choose a blind flange that can be easily unbolted and reinstalled. A well-chosen flange allows for quick maintenance, inspection, or repairs, reducing downtime and maintaining system integrity. Longan’s blind flange is a perfect example of such a flange.

Why Choose Longan Blind Flanges?

Longan blind flanges stand out for their superior quality, durability, and design. Here are a few reasons why Longan flanges are a preferred choice:

• Reliable Sealing: Longan blind flanges provide an effective seal. Several of our clients testify how effective they are in blocking fluid flow while maintaining the integrity of the pipeline, valve, or pressure vessel.
• High Mechanical Strength: Designed to handle significant mechanical stress, Longan blind flanges can withstand both system pressure and bolting forces. Such quality explains why our bling flanges are used by complex piping systems from different industries. They are suitable for even the most demanding applications.
• Easy Access: These flanges can be easily unbolted, providing quick access to the pipeline for maintenance or inspections, and can even serve as manholes.
• Versatile Use: Longan blind flanges are suitable for various applications, including permanent or temporary seals in pipelines and pressure vessels.
• Quality and Compliance: Manufactured to meet rigorous standards like GB/T9119-2010, ASME, and DIN, Longan blind flanges are available in high-quality materials such as 304, 316L, and high-strength alloys, ensuring long-lasting performance.

References:

Blind Flange – an overview (1)

How to Calculate Blind Flange Thickness for Hydrostatic Testing? (2)