GOS,

Do you have a sketch?

--
JHG

Just look at or search asme b16.48

That will give you all you need.

Through bolted spacers and blinds can be made but that is simply a waste of metal as they do nothing for you but if you want it you can have it.

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

Gos
Regarding
Spacer and Blind:
Question #1
Engineering has advise me it is THROUGH BOLTED and explained it as they are expecting bolt holes drilled all round the circumference?
Answer #1:
"Engineering" has given you wrong information on this issue. The Spacer and the Blind DO NOT come with Bolt holes all around the edge.

Question #2
Would this be correct from the research I have found for the product to work it would have to fit within the Bolt circle, is that correct?
Answer #2:
You are correct!

Question #3
In brief how does this product configuration operate?
Answer #3
At the bottom of this posting I have included a Link (Images of Spacers and Blinds). When you look at the many examples you will see (a) they do not have Bolt Holes all around the outside edge. There is sometimes only one hole in the Connection Tab (of the Figure "8" model) or in the "removal Tab" (Handle) of the individual Spacer or Blind. To Remove or insert a Spacer or Blind you first depressurize the System, Then make it Safe. Then you remove all the Bolts on One (1) side of the Flange set. Then you "Jack" the Flanges apart using the built-In Jack Screws (in the Flanges) or with Flange Spreaders (Look it up). Now with the Flanges spread apart you lift the Blind (or Spacer) out and make the change. Note, The hole found in the handle of the typical Blind or Spacer in not in the location that makes useful for Flange Bolts. That hole is there to provide an attachment point for a hook and chain for lifting during removal and installation.

Question #4
Also my workshop have submitted drawings to me that show a bolt hole drilled into the TAB part of both products, is this how they connect together just with studs and nuts ? if so though surely the two pieces would be offset from each other once bolted ?
Answer #4
NO! That hole in the Tab is NOT for joining of a Blind and Spacer (See answer #3).

Look at this Link for many examples of Spacers and Blinds"
https://www.google.com/search?site=&source=hp&...

Sometimes its possible to do all the right things and still get bad results

Only thing to add to an excellent post by pennpiper is that you can buy spectacle blinds which are designed to have ONE bolt hole permanently engaged ( usually one of the top or side ones, so that once you remove all the other bolts and separate the flanges, you can swing the blind / spacer around with ease and it also give you a very easy way to visually see whether you have a spacer or a blind flange.

They look like this.

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

Would the answer be the same if the flanges were Class 125, full-face and made of cast iron? I would be uncomfortable with a standard paddle blind in that flange. Is there another alternative for this case?

Johnny Pellin

JJPellin,
You ask an interesting question. I do not remember ever having Spec Blinds, Spacers or Figure "8"s in a Class 125 System.
There could have been some there, I just don't remember any.

Lets wait and see if any show up and what was the solution.

Sometimes its possible to do all the right things and still get bad results

If you are going up against a pump or other piece of equipment with a flat faced flange you might need a full-face spacer, especially if it were cast vs forged. I'm reminded of a project where we did this for about 100 20 inch valves but I don't remember the details.