Different BCD for Valve flange and Pipe

[nabeel3]

Dear All

I have a situation as below in my work now.

Replace an existing MOV (Gate Valve) size 4 inch with a new Super duplex MOV in a seawater line of 4 inch GRE piping.
Bolt circle Dia of Pipe flange is 190.5 mm ,Rating Class 150
BCD of new Valve is 180 mm, Class 150.

How to connect the valve flange with pipe flange. BCD of pipe flange and valve flange is not matching. This is a running pump station.

Any solution is most welcome

 

[LittleInch]

You have a mismatch of flange codes.

There is no way both are ASME B 16.5 flanges. The pipe flange dimensions matches a 4" ASME B16.5 class 150.

Looks to me like someone has sent you a valve with flanges to EN 1092 PN16 or PN10 which for a 4 inch has a BCD of 180mm.

What EXACTLY did you order?

What does it say on the valve itself?

You can manufacture a conversion plate where you offset the bolts and drill in two sets of studs, but far easier to get a valve with matching flanges....





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[nabeel3]

Dear Little inch

Yes mistake happened. You are correct the valve flange is of EN 1092. They offered us as in below, but we did not notice it.

The valve lead time is about 4 or 5 months.

can u please give more info about the conversion plate . That will be most helpful .

 

[LittleInch]

Basically you need to get someone to make up a plate a bit like this

https://www.avkuk.co.uk/en-gb/product-finder/couplings-adaptors/flange-adaptors/209-30-001

You will need bolts spaced alternatively so the valve will not be centred or the flange will not be centred as normal (bolt holes flat.

You could start with a blind flange and machine the back side, drill and tap holes for the bolts or just start with a circular piece of steel at least as thick as a nut so that you can tap the holes to insert stud bolts and then machine the raised face into both sides.

It will look truly terrible so get another one on order as soon as you can.

Or you could drill new holes in the flange at a lower BCD? Actually No - the flange is a GRE flange? Is it flat face?

Would look equally terrible and may not be the best plan.

I had a quick look but can't find anyone making these as standard. Most people would assume you can get the right flange.... BUT that is the strangest spec I've ever seen - why give you ASME dimensions for everything except the BCD? Cut and paste error?



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[nabeel3]

Yes, its a GRE flat face flange for pipe. Our Engg team overlooked this. Today when we tried to change the valve after shut down of the plant we were shattered to see this.

 

[LittleInch]

If it's replacement of an existing valve then the extra plates at either end won't fit unless you can adjust the piping??

You can't mess with a GRE flange.

Can you put the old valve back in??



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Also: If you get a response it's polite to respond to it.

 

[GDHTX]

Another product similar to what Littleinch suggested is the double studded adapter.

https://www.whitliejospecialty.com/product/double-studded-adapters/

Its a relatively easy part to manufacture, so it shouldnt have a long leadtime.

 

[LittleInch]

Can the pipework accommodate the extra length. That's now the key question.

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Also: If you get a response it's polite to respond to it.

 

[nabeel3]

Below is the Existing pipe fitting upstream of the valve which has to be replaced. A strainer ,then this reducer after that 4 inch MOV that has to be replaced. That is the arrangement

,

 

[LittleInch]

Yes, but do you have room in the piping overall to add in another probably 50mm in total.

Plus those connectors need the flanges to be slid onto them. You can't just drop the valve in.

The only other way perhaps is to drill the valve flange to a BCD of 190mm? in between the existing holes. Would look terrible and may not be fully compliant, but would get you out of a hole...

what are you going to do?

Please respect those who have given you advice and finish the story. Please.

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

 

[Joe591]

on the spoolpiece that goes from 6" to 4", did they really weld the 4" asme flange directly onto the reducer? often they will put a short piece of pipe on to make it easier to put the bolts in. see below.

if that was the case you can cut that short piece of pipe off and weld a replacement en1092 flange on to replace the 4" asme flange. then do the same on the other side. might be your best best. ive done it plenty. if a valve pcd doesnt match the piping we cut the piping flanges and weld on new ones that match the valve. of course it does depend on the exact configuration...

and of course if they did weld the 4" asme flange directly onto the reducer then that gets interesting...

 

[nabeel3]

Dear Joe591

It was directly attached to the Reducer. This is a GRE Piping work.

 

[Joe591]

Yeah, I missed the GRE part. Was reading a bit too fast. Yeah, you got yourself an interesting situation...If there is no give in the pipe then you might have to send the valve back or get a new spoolpiece made on either side of the EN1092 flanged valve...

 

[nabeel3]

Dear Joe591
Now i am planning to elarge the hole of GRE flange as a temporary solution. This is a running sea water pumping station.

 

[LittleInch]

I would do this on the valve not GRE.

You can replace the valve. Difficult to repair the GRE flange.

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

 

[Joe591]

its usually better to slot the holes intead of just drilling them bigger and that's only when its permissible to do so.