Line Blanks

Find a huge selection of line blanks from China at SN Valve. 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.