What is a blind pipe flange?

What is a blind pipe flange?

A Blind pipe flange is round plate which has all of the relevant boltholes but no center hole, and because of this feature this flange is used to close off the ends of a piping systems and pressure vessel openings. It also permits easy access to the interior of a line or vessel once it has been sealed and must be reopened.

The blind pipe flange is used to close ends of piping systems. It is a kind of round plate with no center hold but with all the proper bolt holes. This blind flange is available in various sizes and materials and is used to provide positive closer on the ends of pipes, valves or equipment nozzles. This flange helps in easy access to a line once it has been sealed. The blind flange is sometimes custom made or machined to accept a nominal sized pipe to which reduction is being made.

A blind pipe flange is a solid disk used to block off a pipeline or to create a stop.

Similar to a regular flange, a blind flange has mounting holes around the perimeter and the gasket sealing rings are machined into the mating surface. The difference is that a blind flange has no opening for fluids to pass through. Instead, it is placed in between two open flanges, which stops the flow through a pipe. Many times this type of blockade is used when adding another line onto an existing pipeline or when a new valve is being added.

Often a blind flange is inserted into a pipeline when a repair is required further up the line. This allows the flanges down stream to be disconnected without fear of losing liquid. Many times this type of blockade is used when adding another line onto an existing pipeline or when a new valve is being added. This blockade is also used to shut down a line when it is no longer needed.

Without the blind flange it would be difficult to perform maintenance or repairs on a pipeline. The flow would need to be shut off at the nearest valve, which could be miles away from the repair area. Valves are also very expensive and are prone to sticking. The blind flange is a much more cost efficient way of sealing a pipe.

When a pipeline is being constructed, a blind flange is often incorporated into the final length of pipe. This design allows for expansion or continuation of the pipeline by simply adding onto the final flange. This holds true for the addition of tees in the pipeline as well. A tee can be installed and then blocked in order to leave the option of running a pipe at a later date.

The use of flanged pipe has allowed pipelines to be built in a much faster manner than traditional welded seam pipelines. Moreover, it has made the task of repair and sectional replacement a simpler job. Sections of pipe can now be assembled anywhere in the world and shipped to the job site. Once there, they can simply be bolted into place and the pipeline can resume transportation of its liquid cargo.

Details of Blind flanges

flg bl det - What is a blind pipe flange?

1. Blind flange 2. Stud Bolt 3. Gasket 4. Other flange

Size: 1/2” to 60”, DN 12mm to DN 1500mm
Pressure class: Class 150 to Class 2,500, PN 2.5 to PN 250
Facing: RF / RTJ

Material:

  • Cabon steel: A105, A350 LF2
  • Stainless steel: A182 F304/F304L/F316/F316L/F321
  • Alloy steel: F11, F12
Specifications:

Blind flange is put at the end of pipe or at the junction that would possibly be a future expansion into that direction.

What is the use of a blind flange?
blind flange usage close the end of pipe - What is a blind pipe flange?

Piping is easier to drill or weld at the construction stage. Once it was in use, drilling or welding will need prolong cleaning especially when the fluid transferred is combustible. For the mean of future extension, either the blind or valve would be used to seal the end.

Where are Blind Flanges Most Commonly Used?

Blind flanges are commonly used in petrochemical, pipe engineering, public services and water works.

A blind flange is useful for making repairs to a pipeline further up the line. In fact, during construction of a pipeline, a blind flange may be built into the final length of pipe. This allows for expansion or continuation of the pipeline simply by adding onto the final flange.

What Do Blind Flanges Do?
blind flange usage - What is a blind pipe flange?

Without a blind flange, it would be next to impossible to repair or perform ongoing maintenance to a pipeline unless the flow was shut off at a earlier valve, which could affect miles of pipeline.

The use of flanged pipe has significantly sped up the process for constructing pipelines. It has also made the task of repair and sectional replacement easier. Sections of pipe can now be assembled anywhere in the world and shipped to the job site. Once there, they can simply be bolted in place and the repair is done.

A blind flange is useful for making repairs to a pipeline further up the line. In fact, during construction of a pipeline, a blind flange may be built into the final length of pipe. This allows for expansion or continuation of the pipeline simply by adding onto the final flange.

BLIND FLANGE IN CREATE A STOP

blind flange usage close the end of pipe - What is a blind pipe flange?

BLIND FLANGE IN BLOCK OFF A PIPELINE

blind flange usage block off a pipeline - What is a blind pipe flange?

Without a blind flange, it would be next to impossible to repair or perform ongoing maintenance to a pipeline unless the flow was shut off at a earlier valve, which could affect miles of pipeline.

Types of Blind Flanges

In terms of blind flanges, there are four main types available in the market.

The first type is called welding neck flanges. They usually feature with a long tapered hub. Such hub is able to provide excellent reinforcement in many situations. Generally speaking, they are able to be tolerant with high pressure and low to rather high temperature. As we all aware that these flanges are generally placed in the inside of the mating pipe because the flanges can expand with the increasing or decreasing temperature and pressure. Such placement would effectively prevent turbulence and reducing erosion.

The second main type is called socket weld flanges. They can be applied into small or high-pressure piping. With the excellent strength, they are usually used in heavy duty situations. It is obvious that these flanges are welded to the required pipes. As a result, a space between the flange and the pipe should be left. And previous cleaning job before welding should be done carefully. Otherwise, corrosion or leaks would result in.

The last two main types are called lap joint flanges and slip-on flanges. The former type features with no raised faces. These two types are similar in many aspects. For example, they are both not able to hold very mush strain. But the lag joint flanges have more sturdiness than the slip of flanges. And for slip of flanges, it is asked that the attaching pipe must have a thickness greater than 3 mm. Otherwise, the flange face will break during the welding process.

In words, all these types of blind flanges can provide excellent and effective performance to close the end of the pipes. But they have their own individuality and have respectively installing features. Do use them according to their features properly. All these blind flanges take effects in many relative fields.

Source: China Pipe Flange Manufacturer – Yaang Pipe Industry Co., Limited (www.pipelinedubai.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@pipelinedubai.com

Please notice that you might be interested in the other technical articles we’ve published:

References:

  • https://www.yaang.com

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