Flange gasket inner bore intrusion 1

[A8yssUK]

Hi there, I work for a flange gasket manufacturer and I've been asked to look into a problem a little out of my normal area of expertise.

Some changes to a European gasket testing standard has now stated the intrusion of a flange gasket into the inner bore of the flange is not allowed i.e. the gasket cannot intrude into the media flow.

Obviously I can see why it isn't a good idea but I'd like to try and put some numbers to it.

I'd like to understand more how a small intrusion into the media would effect the flow and the energy required to maintain the flow, I understand the use of k values for minor losses in a pipeline system (valves,bends etc) but how would I go about trying to figure out how the k value changes with differing gasket intrusion amounts for example. Or would it be more reasonable to use equations for sudden pipe diameter changes ?

Anybody have any tips or perhaps something I could read up ?

Thanks

 

[LittleInch]

Orifice plate calculations are your best bet.

At the sort of beta ratio you might not be getting accurate numbers, but you won't be far off.

There are many programs / calculation websites out there to get you a good idea of the pressure drop at each of these flanges.

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

 

[XL83NL]

For e.g. spiral wounds used in slipon flanges, it may (i.e. will) result in disintegration of the spirals into the flow when there's no inner ring. This is what Ive been reading on the board over a few times. Not sure how this affects other gasket types though.

 

[A8yssUK]

Thank you both for your replys,

using the third section regarding water in the FAQ found on these boards here

http://www.eng-tips.com/faqs.cfm?fid=841

I selected Q as 10 litres/s (0.01 m^3/s) for a DN40/PN40 flange ID = 43.1mm (0.0431m) and used the recommended C value of 0.62 for turbulent flow

With a gasket intrusion of 1.0mm (orrifice id = 0.0411 m) I get a head loss of 7.85 mm (0.00785 m)

Sorry I have no reference/feel for the values, does this seem reasonable ?

This calculation is only an example of how the flow is effected by the intrusion, I shall also be writing about the effect of the flow on different gasket materials too. Mainly resulting from damage from fatigue and abrasion. The intrusion of the gasket also sets up a crevice in the flow stream, which could be a site of corrosion and/or build up of contamination.

Again thank you for your time.

Edit : After a little research on how the C value is worked out I think as my ratio is close to 1 for the orifice diameter to pipe diameter the C value is going to be much more like 1 also, so using 0.97 I get a head loss of just 3.2mm now