About Us

Concept & products

应用

客户服务

媒体中心

Contact

常见问题

Line Blanks and Applications in Piping Systems

Michael Mann

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”.

Figure 1: ASME B16.48 Line Blank. This type of line is known as a Figure-8 or “Spectacle Blind”

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.

Furthermore, the operation of blinding can be cumbersome, requiring personnel to break apart flanged piping such that the blanks can be inserted. The connection must then be remade to the proper torque specification so that the connection is made pressure containing.  

A Spectacle Blind installed in a flange connection and in the “isolated” position preventing upstream fluids from going downstream.
Figure 2: A Spectacle Blind installed in a flange connection and in the “isolated” position preventing upstream fluids from going downstream.

Onis provides an advanced type of spectacle blind that is mechanized and doesn’t require the breaking and re-making up of flanges to perform blinding.

This type of blind is ideal if there is a higher frequency of blinding where reducing the blinding operation time by 95% could provide efficiency gains or increased capacity to a unit.

The Onis blinds provide an integrated cam system that can be used to separate and remake piping with ease by an operator moving a lever or turning a handwheel. The cam system multiplies the input force from the operator and provides adequate preload to make-up the pressure containing seals.

You can see a video animation of how an Onis line blind works:

You can learn more about Onis blinds and types ranging from 150# to 2500# pressure classes here.

If you would like to find out more or discuss a specific application, CONTACT US.

Follow us

Last articles

Onis Hi-Safe Explains

Onis Hi-Safe is unique safety system designed to keep personnel safe by eliminating the risk of “human error” that exists with other systems.

Onis Custom design

At Onis we create custom products that best fit your requirements, find out about the custom design options available.

Fire Safe design by ONIS

In many critical applications fire incidents can cause major disaster. How the Onis Fire safe design help to reducing risks due to fire.

What is positive isolation ?

In pipe industry, there are different methods of isolation including positive isolation. Focus on the best solution: the pipe blinding operation.

联系我们

Discover how ONIS can help you to increase your business.

0条评论

递交一条评论

您的电子邮箱地址不会被公开。 必填项已用*标注

Shares
Share This