Line Blanks

Line blanks, also known as “line blinds,” covered under ASME B16.48 standards are used to isolate a portion of pipe, usually for maintenance purposes. There are different types of line blanks used to isolate piping by generally inserting a solid disc with seals to eliminate the ability of upstream process liquids and gases to migrate downstream. Even if the seals failed, it is not possible for process fluids to migrate downstream. The different types of line blanks are the following:

Figure-8 Blank: These types of blinds have a circular, solid disc with seals for isolating. There is also a tie-bar that connects the solid disc to another similar disc, but one that has an inner-diameter so you can have unrestricted flow. The Figure-8 is secured by a bolt on the flange and can rotate between “blinded” (isolated) or “full-bore” position. These blinds are also known as “spectacle blinds” or “figure-8 blank”.

Paddle Blank: These blinds are solid circular discs with seals. There is a handle on the outer diameter of the disc so an operator can insert it between the flanges and isolate the piping.

Paddle Spacers: These spacers are like paddle blanks but have an inner-diameter hole to allow unrestricted flow. Paddle spacers are used to create a pressure containing gap between the flanges such that a paddle blank can be inserted when it is removed.

Definition and Function

A pipeline blind, also known as a blind flange or pipe plug, is a flange without a hole in the center that is used to seal a pipeline opening. It serves a variety of purposes in piping systems, including:

Leakage prevention

The pipe is installed in the closed end of the pipe system to prevent leakage of the medium and guarantee the safety of production.

Check and repair

In the course of maintenance and inspection of pipe system, when it is necessary to remove a section of pipe or to replace parts, the pipe can be blocked by pipe blind, so that the following maintenance and inspection work can be done.

Cleaning and changing the line

The pipe transfers various kinds of media, in the case that the transfer medium needs to be changed, the pipe can be blocked by the pipe, and the medium can be cleaned and replaced.

Avoid oxidation corrosion

In the course of maintenance and repair of pipe system, if the parts are exposed to air and media for a long time, it will cause oxidation corrosion, which will influence the operation of the pipeline system. Pipe blind can effectively prevent oxidation corrosion.

Classification and Material

Pipeline blinds can be divided into many types according to different structures and functions, such as bolted blinds, clamped blinds, firm blinds and special purpose blinds. At the same time, according to the different materials, pipeline blind can also be divided into various types, the common ones are:

Stainless steel blind plate

Usually made of 304, 316, 316L, etc. It has the advantages of high temperature resistance, corrosion resistance, etc., and is mainly used in the fields of chemical industry, medicine and food.

Carbon steel blind plate

Usually made of Q235, Q345, 20# and other materials, with high strength, good pressure resistance and other characteristics, mainly used in petrochemical, natural gas, heat and other fields.

Polyurethane blind plate

Mainly made of polyurethane material, with waterproof, heat preservation, wear-resistant and other characteristics, mainly used in water supply and drainage, plumbing system and other fields.

PVC blind plate

Mainly made of PVC material, with acid and alkali resistance, corrosion prevention and other characteristics, mainly used in acid, alkali, salt media transmission piping system.

Selection and Installation

The following factors need to be considered when selecting and installing pipeline blinds:

● Working pressure and temperature: according to the working pressure and temperature and other conditions of the pipeline system, select the appropriate blind specifications and models.

● Sealing: Ensure that the blind is well sealed after installation to avoid leakage.

● Safety: In the process of installation and use, you need to ensure that the blind is safe and reliable to avoid accidents.

Spectacle Blind Flange read more

Your Professional Line Blanks Supplier

Our goal is to become your true partner in the field of line blanks in China. Zhejiang Gangda Flange Pipe Fittings Co., Ltd. is specializes in the production of flanges and pipe fittings. The company has been committed to the manufacturing and research and development of flange pipe fittings for petroleum, petrochemical, power, natural gas and other projects. Our company is committed to applying advanced manufacturing technology and strict quality control standards to every product. The price is competitive and the product is quality-assured, which is a good choice for your long-term cooperation.

Why Choose Us

Quality control

In terms of quality assurance, the company strictly follows the standards and norms of the industry quality system. Adopt industry-leading testing equipment to ensure product quality and good reputation.

OEM/ODM

When you put forward your needs, our engineers will provide you with faster and more perfect customized solutions. We have a wide range of products, and we will provide technical support according to your actual needs to choose the right product for you.

Our service

The company has a professional sales team to provide you with high-quality pre-sales consulting services. During the order production process, customers can communicate with us at any time to understand the production progress. At the same time, we provide high-quality after-sales service to meet the different needs of customers.

Advantages of Line Blanks

Versatility

Line blanks are suitable for various industrial applications, including oi and gas, chemical processing, an power generation, where pipeline isolation is frequently necessary.

Safety

By providing a physical barrier in the pipeline, line blanks significantly enhance safety during maintenance or in case of system failure.

Cost-effectiveness

Since they can be easily rotated without being fully removed from the pipeline, line blanks reduce downtime and labor costs associated with system isolation.

Specification Parameter of Line Blanks

Spec	Class	Available Size Range
B16.5	150	0.5” – 24”
B16.5	300	0.5” – 24”
B16.47	150	26” – 60”
B16.47	300	26” – 60”

Customizable options of Line Blanks

We offer both standard and non-standard sizes, ranging from dn 10 to dn 2000, as well as 1/2"- 48" sizes, to cater to diverse user requirements, including user input on specific size needs. Our product adheres to various international standards, ensuring seamless integration with different piping systems. Designed for industrial use, our Blind Flange withstands harsh environments and heavy-duty operations, providing a secure connection for pipes and fittings.

Production Process of Line Blanks

The production process of line blanks can be divided into three types: forging, casting and cutting. Cast flange and forged flange have a shape with accurate size, and advantages such as small workload, and low cost, but they may also have defects like pores, cracks, inclusions. The internal streamline of cast flanges is relatively poor, of which, those cut by lathe are even worse. Compared with cast flanges, forged flanges have better streamline, mechanical performance, compact structure, as well as lower carbon content, and are not easy to rust. But if the forging process is improper, there will still be large or uneven grains, hardening or crack. Besides, the cost of forging is higher than that of casting.

Packaging and Shipping of Line Blanks

Packing	Wooden box or pallet or carton
Shipping	Container transport, by sea.

FAQ

Q: How many types of blind flanges are there?

A: Blind flanges are available in various types, including slip-on flanges, threaded flanges, weld neck flanges, and socket weld flanges. These types allow for flexibility in choosing the best blind flange depending on the specific requirements of the pipeline system, such as pipe size, pressure, or installation method.

Q: What is the difference between RF blind flange and FF blind flange?

A: Flat face (FF) flanges are similar to the RF flanges, but they do not have the raised area like the RF flange. Instead, the whole surface is flat. That means that the gasket used with the FF flange has full contact with the whole surface where two flanges are mated.

Q: Do blind flanges need gaskets?

A: Installing a blind flange is relatively straightforward. It is bolted onto the pipe's open end using the holes around its circumference. A gasket is often placed between the flange and the pipe to ensure a tight and leak-free seal. Tightening the bolts evenly provides a secure connection.

Q: Can a blind flange be threaded?

A: Depending upon the application, a blind flange may be drilled and used as a slip-on flange, or tapped and used as a threaded flange.

Q: Can you tap a blind flange?

A: You can draw a sockolet on to a blind flange or tapped blind flange in the normal way. If you want to use a nipple, see below. The following can also be used for connections to Orifice Flanges and Bleed Rings.

Q: What is the ASME Code for blind flanges?

A: Blind flanges manufactured in accordance with ASME B16. 5 can be provided in Class 150 through Class 2500. It is basically a circular disc that does not have a hub or bored center. Bolts holes are drilled and aligned symmetrically along the circumferential edge of the solid disc.

Q: What is a ported blind flange?

A: Blind flanges are used to seal flanged connection in piping or process equipement. Blind flanges are often tapped for instrumentation ports and used to access / maintain equipment.

Q: What is a spider blind flange?

A: Using a spider blind flange assists in disconnecting the flange downstream and preventing a leak or a spill. In most of the case, RF Blind Flange is used when there is a repair needed at a further point in the pipeline.

As one of the most professional line blanks manufacturers and suppliers in China, we're featured by quality products and good service. Please rest assured to buy customized line blanks from our factory.

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