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TOPIC: Specticle Blind rotation procedures

7 years 8 months ago #8155

  • hc
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Anybody have an idea what the procedure would be to change a Spec Blind from open to closed or vise versa. How would the guys in the field proceed to do it step by step. I've never seen it done. I have an idea but, I'd like to know. For example say its at a valve at a piece of equipment. Hit me with some answers.

Re: Specticle Blind rotation procedures 7 years 8 months ago #6494

  • Anton
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I'll start by saying I've never actually seen it done either.

But this is how I see it ....

The Spectacle Blind is held in place by a hole drilled in the bridge piece between the open end and the closed end. This hole is the point about which the blind will pivot / rotate.

When the blind is installed, one of the flange bolts goes throught this hole.

The diameter of the spec blind ends is smaller than the PCD of the flanges between which it sits.

When changing the Blind from open to closed or vice versa, the bolts on the flange need to be loosened, and some of the bolts need to be removed to allow the blind to rotate.

Eg. on an 8 bolt flange, working clockwise:

Loosen all bolts
The blind is held in place by bolt #1.

Leave bolt #1 in place
Remove bolt #2
Remove bolt #3
Leave bolt #4 in place
Leave bolt #5 in place
Leave bolt #6 in place
Remove bolt #7
Remove bolt #8

Rotate the blind about bolt #1, reinsert bolts 2,3,7,8

At this point you may want to consider replacing the gaskets.

Tighten all bolts.

I hope that makes sense!
- If you're the smartest person in the room ... you're in the wrong room.

Re: Specticle Blind rotation procedures 7 years 8 months ago #6495

  • WNRF Piper
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Depending on line size, pipe run. Jacking bolts & plates may be requied to spread the flanges. Theseaa re usually lugs which have been welded to the flanges. So if you take Antons bolt numbering then the Lugs would be welded on at bolt No.1 & 5. One lug one be drilled and tapped to take a suitably sized bolt. A spanner is then used to tighten the bolt up against the lug on the opposite flange. There can be several variations of these, but the principal is the same.

Re: Specticle Blind rotation procedures 7 years 8 months ago #6497

  • shrivallabha
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This youtube clip may be of some use:
http://www.youtube.com/watch?v=C-MP07KkC8k

Re: Specticle Blind rotation procedures 7 years 8 months ago #6498

  • hc
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So are they basically prying apart the flanges with a bar to create enough give to allow the blind to freely rotate say for 2" to 8" where a jacking bolt wouldn't be used.
Thanks guys

Re: Specticle Blind rotation procedures 7 years 8 months ago #6499

  • Jop
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There is another alternative for spreading flanges and it is portable so it can be used anywhere.
Look here:
http://www.cleanvalve.com/products12.html
Do it once and Do it Right
Moderators: Jop
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