can flat face flange be installed with a raised face flange 1

[hassmx0f]

Dear Experts

I have a situation where piping flage is Raised face and the valve to which it is connecting to has a flat face. Is this acceptable?
The gasket is spiralwound gasket

 

[LittleInch]

No.

See multiple posts on this site to explain why.

either get a flat face flange for your pipe or get a valve with a RF.

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

 

[gerhardl]

You have actually compressed several questions into one.

1.Is there any rule or regulation forbidding the connection? Answer: Unsure. For simple, unqualified connections, lower pressures and diameters probably none. If dangerous fluids, flammable, toxic or large consequences if anything goes wrong: common sense and rules will apply.

2.Any flange has two purposes: being of correct size and form to bear weight and allow correct thightening without deformation (according to norms), and secondly ensure correct compression of sealings.(Sealings correctly adapted to the flange and fluid, temperature etc).

3. If all above is OK, and valve and pipeline properly mounted, aligned and supported correctly you could try. If matching flaanges are too costly or difficult to obtain, I would personally have contacted a company specialised in producing adapted sealings for advice. Under circumstanses it would be wise to even the raised face flange with an extra outer ring of suitable sealing material to obtain even pressure over the whole flat-flange area of the flat-faced sealing.

 

[gerhardl]

Hello LittleInch! / (hassmx0f)

Your answer got in while I was composing mine. I do actually agree with you: the best technical solution should always be used if practical possible, and even if it will cost more.

The but is that there might be in some rare cases necessary to do engineering adaptions.

Example: I was some years ago asked to solve a flange sealing problem, caused by miscommunication: a grooved flange to be connected to a flat-faced flange, relatively large diameter (800mm) and for a fairly high pressure, I believe 25 bars or higher. Application: fresh water for a hydroelectric power plant. A new delivery or re-machining would have had large economic and delay consequences. All parties (and authorities) agreeing in the adaption of the sealing if no-leaking could be obtained.

Solved by engineered plastic ring and extra elastic sealing ring and o-ring for the groove (correct free rom allowing compression) against the flat-faced sealing.

Conclusion: Adapting sealings and sealing surfaces is an engineering task, not a 'slap on' solution type of job, and should generally be avoided.

 

[MickMc]

Normally I only see FF Flanged Valves when body is ductile or cast iron then connecting flange is specified FF to avoid damage/failure when overtorqued at gap between RF & FF and typically all flanges in piping spec will be FF. If allowed by client you could simply provide FF flange or if already fabricated machine RF off in field or alternatively machine valve flanges to RF if steel body and no integrity issues.

 

[LittleInch]

Specify materials of the valve.

I agree with all above as well.

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

 

[donf]

The answer to the question as posted is: Yes, it is acceptable. I've done it many times with no problems (usually involving pumps, not valves). I know of no industry code or standard that prohibits doing so.

However - If the valve is cast iron - then NO. It is not acceptable. ASME B16.5 sect 5.3.5 specifically addresses mating class 150 steel flanges to class 125 cast iron flanges. It requires the steel flange to be flat face. Further, it requires using full face gaskets. So, you also need to reconsider the spiral wound gasket.

The reason is that cast iron is a brittle material, and if there is a gap between the two flanges, at the bolt circle, there's the possibility of excessive bolt tension cracking the CI flange.

Regards,

donf

 

[rconner]

See some history and background at

http://www.eng-tips.com/viewthread.cfm?qid=341363.