7 replies to this topic

[krishnamurthy]

what is the difference between specatcle blind and isolation valve? where can we use speatcle blind ? pls explain me.

[breizh]

http://www.astsaudig...m/?page_id=2357

 

Consider reading this document .

 

If you intend to use valve , you need to provide a car seal lock to ensure the valve is locked in position (open or close) to prevent wrong manipulation .

 

 

 

hope this helps

Breizh

[fallah]

what is the difference between specatcle blind and isolation valve? where can we use speatcle blind ? pls explain me.

 

Hi,

 

The key point would distinguish an isolation valve from a spectacle blind is: A spectacle blind, contrary to an isolation valve, will provide positive isolation...

 

Then, you would use a spectacle blind in the cases you need zero leakage...

Edited by fallah, 10 December 2013 - 02:47 AM.

[Rush123]

A Spectacle blind looks like two flat circles of metal in a "figure 8" type of set up. One side is flat and the other side, is only the outline of a circle. Thus, depending on which side is inserted into the pipe, the spectacle blind can allow flow or not.

 

Spectacle blinds are seen as being used for "positive isolation" because it can be seen from a distance as to whether the pipe has been isolated or not. It also provides a more intrinsically safe method of isolating one system from another. 

 

Valves are used for isolation, and are meant to be manipulated depending on the service u need. 

 

Please keep in mind the following:

You may need suitable valved isolation in place before turning a spec blind in the closed postion.

If your spec blind is on a pressure spec change, make sure you rate it / specify it for the higher side pressure.

[fallah]

 

Spectacle blinds are seen as being used for "positive isolation" because it can be seen from a distance as to whether the pipe has been isolated or not.

 

 

Rush,

 

Not always...because:

 

In applications with large pipe sizes or in the systems where maintenace is often not necessary, to prevent unnecessary weight to a flange connection, spectacle blind will be divided to two separate parts: Spacer and spade; which not to be distinguished from a distance...

Edited by fallah, 11 December 2013 - 12:21 PM.

[curious_cat]

 

In applications with large pipe sizes or in the systems where maintenace is often not necessary, to prevent unnecessary weight to a flange connection, spectacle blind will be divided to two separate parts: Spacer and spade; which not to be distinguished from a distance...

 

 

If you divide them are they still commonly referred to as "spectacle" blinds? Or just a spade / spacer separately? 

[fallah]

 

If you divide them are they still commonly referred to as "spectacle" blinds? Or just a spade / spacer separately? 

 

 

Hi,

 

The spade/spacer are basically same as spectacle blind, except that aren't attached to each other due to weght load limitation to flange connection and easy handling in the case of position change...

[Sharma Varun]

 

 

In applications with large pipe sizes or in the systems where maintenace is often not necessary, to prevent unnecessary weight to a flange connection, spectacle blind will be divided to two separate parts: Spacer and spade; which not to be distinguished from a distance...

 

 

If you divide them are they still commonly referred to as "spectacle" blinds? Or just a spade / spacer separately? 

 

Well as the name goes, spectacle blind is a blind where both spade (usually referred as blind) & a spacer (the hollow ring) are attached together. Separated these are know as blind (or spade) & spacer.

 

As fallah pointed out spectacle blinds are used for smaller sizes generally upto 6-8". For small sizes these become more preferable as you dont need to store the spare or blind in the warehouse, as usually blinds are used during maintenance or shutdown, however with large size you have the issue of weight.