Temporary Natural Gas Pressure Regulator Design

[markus_naslund]

Hi, I've been asked to design temporary natural gas regulator stations to reduce pressure in 3 separate lines (12in, 18in. 20in) from 4000kPa to approximately 3200kPa. I'm hoping to reuse a few 6in and 8in Becker globe regulator valves and Grove ball monitor valves that we already have. I have my min/max flows, temperature, and max velocity of ~30m/s. I have 0 experience in this and was hoping I can get some guidance on how to start and go about doing this design. Thanks!

Kevin

 

[mk3223]

The simplest way is to contact the vendors and ask them to verify your new operation conditions for possibly reusing these valves. Also, you may need to inspect and test the existing valves if suitable for the operation.

 

[LittleInch]

Well you need to obtain the Cv versus opening data for the valves in question.

You would normally try to operate within the 30-70% open position of a control valve so that will give you your mac and minimum valve CV.

Then there are many on line calculators to calculate flow for a CV given the different gas inlet conditions. e.g.

https://www.engineeringtoolbox.com/flow-coefficients-d_277.html

and scroll down for air and other gases

Then you can find max / min gas flow for your pressure drop.

I would then check with the valve vendor once you've found this or simply ask them to do the calculation.

40 bar to 32 bar pressure drop seems a bit strange to do and if these valves are manual any change in pressure up stream won't be accounted for.

It's also a little strange, if not potentially dangerous to ask someone who's never done this to do a design. I sincerely hope you have someone to check and authorise this work. If not don't do it.

The Grove valve you note appears to be a standard ball valve. They do not work well in pressure regulation service. Don't use one for this purpose unless it is designed for it ( I might be mistaken).





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

 

[markus_naslund]

Thanks for both of your responses.

Littleinch, in the past we ran inline inspection tools. However, the tool run data showed that there are a few speed excursion locations and the tool vendor claim the data in these spots could be unreliable. So we are looking to drop the pressure from roughly 40 to 32 bar until the speed excursion can be rectified.

 

[LittleInch]

Ok. That makes some sense.



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