Line pipe blinds feedback please

[ER_Azza]

Hi All

I am considering putting in line blind in place of spec blind on our venting (DN600) pipe.
However, I could not find the review on the performance and reliability of these line blind, other than from the OEM, which is obviously biased.

We would need to swing the current spec blind once in probably every 5 years.
I am weighing the cost of purchasing these blind and to modify the pipework to facilitate its installation, as oppose to just using the current spec blind.
The blind is about 50K to 60K in cost as oppose to the spec blind, which cost almost nothing.

Apart from the convenient to easily swing the blind, and require less personnel, I don't see the tangible benefit unless the equipment would last a very long time.

Any feedback in terms of their reliability, leakages and maintenance issue would be appreciated.

Thank

 

[LittleInch]

What exactly do you mean by "Line blind"??

It seems to be something a lot more complex than this

Officially called paddle blanks (ASME B 16.48), these also go under the name of line blinds, spades, line blanks.

If you've got details then please post them or provide a link.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[georgeverghese]

The problem with a line blind is that it can easily missed out when operators are doing a final plant piping inspection prior to startup. Find a way to flag the line blind is in place and can be seen from far away so operators dont miss it during the final prestart line survey.

 

[ER_Azza]

Hi

Attached is the line blind I was referring to. I know few manufacturer. One of them is Strahman.

However, for my particular application, the size is of the pipe is DN600 and will have valves upstream and downstream of the blind to isolate the system, and release the pressure before operating the blind .... Not sure if seized or passing valves would affect the blind insertion greatly.

Regards

 

[LittleInch]

Well the vendor reckons it save about 8-12 man hours.

At $60K that's a lot of operations.

The non spreading ones appear to have an internal piston which is screwed back and forth by the wheel to allow the blind to be pulled in and out. There are some animations out there apparently.

I've not seem many in operation and for once every 5 years I would guess your issue is that when you come to use it the thing seizes solid or doesn't seal on closure due to debris, failed O ring etc.

whatever it is, if you haven't isolated the system then gas or liquid will seep / pour out as you need to generate a gap in which to move the slide/blind. now this system would do it much faster, but even so...



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[XL83NL]

Not sure if this is of any use, but regarding your Strahman option; we have used similar valves in the past from Schuf. Sizes we had were much smaller though, the largest was NPS 6"-Cl.300 and costed around 6000USD.

 

[ER_Azza]

Thanks all.

At this stage, I am not really keen.....
1) Cost against the frequency of use (therefore man-hours)
2) As per LittleInch, when the actual operation take place, once every 2 years shortest, or 4 years likely, the associated equipment might failed due to the factors discussed.

 

[KevinNZ]

If the problem is indication that the blind is in place then you could add an external indicator to the blind. Like the tag on the spades the photo above, the tag can be a large filled circle for the blind and a smaller circle with a hole for the donut spade.