Dear All,

In one of our project, we are facing flashing problem in choke valve and restriction orifice plate. We have done the EIG screening and the outcome is specialist predictive techniques have to be adopted to resolve this issue. 1. Structural finite element analysis 2.CFD 3.Valve sizing calculations.

Refer to EIG, process condition has to be altered to avoid this flashing issue and the same is communicated to our process team and still the issue on...

If anyone comes across this issue and advise me the procedure to be followed as a stress engineer to resolve this.

thanks in advance
Regards,
Murugan

Your vena contracta pressure is always going to be well below your target recovered pressure, i.e. outlet pressure.

Try relocate the valve as far upstream as you possible can. This way, you drop from say 1000 to 900 and let your piping to the rest, rather than at the end of the line trying to drop from 300-200 where your vapour pressure is say 180 [numbers are just examples and mean nothing].

Introduce as many downstream flow restrictions as you possibly can - is effectively the same as the point above, just not using your piping to do the pressure drop.

Alternatively, start spending some money on a specific designed valve with multiple stage pressure drop and anti-cavitation trim.

Thanks dspags for your valuable reply.

Can we do time history analysis in caesar to mitigate the vibration induced (wear and erosion cannot be mitigated in stress) by flashing? Please advise.

Regards,
Murugan

Hi Murugan,

I've never needed to look into it specifically. The cavitation we've managed to design out, or alternatively where there was no other option, hard faced a section of spooling downstream of the valve. Then again, that was a slurry line, to wear was expected at some stage.

Sorry I cannot be of any more assistance in your problem.