Repurposing Water & Steam Valve for Gas Application 1

[Victarion]

Can we repurpose a water & steam valve for fuel gas application? This fuel gas consists of common gases such as CO2, N2, and hydrocarbons with molecular weight of 40.

The valve is a DBQ Fisher class 900 valve

https://www.spartancontrols.com/~/media/resources/fisher/d/dbq info.pdf

What are the most critical requirements for gas valves and liquid valves? That way I can know if this DBQ valve can be acceptable repurpose for gas applications.

Thank you!

 

[LittleInch]

This is a vendor question as the specifics need to be known.

In theory Yes, but there are a lot of practical issues to deal with depending on the particular application.

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

 

[Victarion]

To LittleInch

Thanks! I've submitted a query to the vendor. However I'm still curious about the practical issues you mentioned. Can you give me some examples?

From what I know, leakage is an important factor. But since the control valve is also applicable for steam, logically it should do fine with other gases right?

I also read somewhere that some valves use their working fluid as lubrication.. which I guess is not the case here since it's steam or water.

What about flow characteristics of the working fluid? Shouldn't fuel gas have similar flow characteristics with steam? (not big enough to create the need of changing the internal trims of the valve?)

 

[LittleInch]

Water, steam and gas are three quite different fluids.

As said above, the valve will be able to handle it, but it's the "repurpose" bit I don't fully get.

It sounds like you have an existing valve which you want to use for another purpose, but don't provide any data about size, mass flow, fluid type, pressure in / out temperature etc.

It might work, but I doubt it unless you get lucky without some major trim changes.

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

 

[Victarion]

Ah, what I mean by repurpose is using the DBQ valve (which is supposed to handle water and steam) to handle fuel gas.

I have conducted control valve sizing for my process of interest. The results show that the DBQ valve can handle the process. However I have to make sure that the valve will not have problems such as significant leak, lack of lubrication, etc. Or at least I need to know them all to provide suggestions to my superiors.


That's what I fear. If we have to modify lots of the internal trim, might just buy a new valve after all.

 

[Danlap]

Your "sizing" have to be re-confirmed by manufacturer, otherwise Fisher will not be responsible for any damage due to altering the process condition.
Agree with LittleInch, different fluids will have different characteristic. Will it flashing or changing phase while through vena contracta, what is critical pressure of this fluid (you mention high pressure, so that is an alarm that medium potentially will experience critical pressure), etc. etc.

All control valve datasheet should address Cv, DeltaP, P, Flow, temperature at given maximum, normal and minimum condition. Have you address this?
Is this a control valve of which you want to throttle flow, or will you treat this as fully open and fully close valve?

Leak can be two things: external leak (through gland, gasket, etc) and internal passing. Unless the medium drastically corrosive and/or abrasive, there should be no concern over this.
With the exception of lubricated Plug valve, all valves are intended to work regardless the medium (or in your terms 'work fluid as lubrication'). Lubrication usually only applied on gland packing, bolts and first time around sealing area (ball/plug/seat) during installation of the valve. After some period of time, some OEM would recommend to re-apply lubricant, but again this is independent from the process medium.

I personally would be more concern over the output towards process and some potential effect around the 'choking' area inside valve.

Regards,
MR

https://nosuchvalve.com

All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected

http://www.eng-tips.com/faqs.cfm?&rat1=2&fid=376

 

[btrueblood]

I'd be leery of using steam valve in hydrocarbon service. Typical steam valve will have EPDM seals, which don't like hydrocarbons. You may be able to retrofit said seals for a type fit for the hydrocarbon service.

 

[Victarion]

To Danlap

Thanks! So I'll check the flow characteristics especially around vena contracta. It shouldn't reach critical pressure though, the pressure is only around 270 psia max. while all the gas components have Pcr above 400 psia.

I have addressed Cv, maximum working P at given T (according to ANSI class 900). But I havent found anything related to delta P. There are some information about flow characteristics, direction, and coefficients.

The control valve will be used for throttling flow.

Thank you for the insight regarding leak! Should I just do a leak test to find out if the valve is good enough to use?

Lastly, do you have any references/books that contain sufficient information about control valves, CV service, or flow characteristics in CV? I only have the "Control Valve Handbook" by Emerson, but seems to lack some in depth information.

Thank you!


To btrueblood,

Thank you very much! I will check if it has EPDM seals!

 

[Danlap]

to complement btrueblood as well,
Indeed you (Victarion) should check material compatibility of valves with the medium. And thoroughly, not just the seals.
For example: spindle, is it 17-4PH? there is a grown hesitance of not using this material for medium with H2S content due to potential sulfide stress cracking,
What is the base material of the plug, hard facing, etc.? Check its compatibility with the medium. Suggest to involve metallurgist for this assessment.

Leak? Yes, standard pressure testing should be ok.
Is it good enough? its for you and hopefully your line manager and other inspector to judge. I assume you will only do with water, static pressure and ambient temperature. Only a handful of facilities in the world which can perform simulated flow pressure testing.

In my opinion, Emerson 'Control valve Handbook' is by far the most accessible and clear book which address general yet in depth information for control and sizing information (mostly for Emerson related product). Is it sufficient for non-Emerson (sizing) engineer to judge the compatibility of x valve against y medium characteristic? No. Emerson have more in depth flow and sizing software.

First hand experience, I've seen so many incidents where flow characteristic were altered (assessed by simple calculation should be ok), or its location shifted to other places. And this 'management of change' triggering either premature worn on material and/or flow induce vibration on piping. Then either gland leakage or valve become stuck.

I never see even experienced engineers do this kind of assessment solo. It is always have to be re-checked by several counter part, due too potential overlooking something.

regards,
MR

https://nosuchvalve.com

All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected

http://www.eng-tips.com/faqs.cfm?&rat1=2&fid=376