Hydrazine & Ammonia Compatible Valves

[curvyrace]

Hello All!

I am working on quoting a system to inject ammonia and/or hydrazine into a boiler makeup water line. The customer has specified that one of the pumps be dual use standby with a diverter valve before the pump relief valve. I'm having trouble finding anyone that is willing to quote a high pressure diverter valve for ammonia/hydrazine dual use. Fluid pressure is 1800 psi with 104 deg F max temperature. Anyone have any suggestions for a source for this valve? The information I have says 316 SS construction with PEEK or PTFE seals are good material choices. Thanks!

 

[chengg29]

curvyrace,

I am not sure a diverter valve is a good idea since one of the lines from the out let of this valve leads to a relief valve. Though I have not done much of these boiler / steam generation systems what I know is as per any local regulations / API etc. the inlet pipe work leading upto the relief valve should be as simple as possible in terms of hydraulics / pressure drops etc with no obstructions in between the relief flow / overpressurised fluid to the relief valve. Therefore I hope your client is aware of all these things.

As regards the seals I have heard from my colleagues in this company that they would use Carbon filled TFE seals as they seem to last long for steam applications especially if the operating temperatures are below 260 Deg C

 

[curvyrace]

Thanks chengg29 for the reply. Actually ASME B31.1 is the spec quoted by the customer for this valve and it lays out the requirements for diverter valves located upstream of a relief valve.

 

[chengg29]

Curvyrace,

ASME B31.1, as you may be aware, is a Code which needs to be followed / adhered to to meet permit / regulations / certification requirements. API is a Standard which would be used as an aid to applying good engineering practices in the design. Hence as you may notice, the language of the Code is such that it may encompass all that is said in a related standard although broadly. Hence the practice followed by my company folks was to use these standards (API etc.) in the design on the proejects as applicable and finally check with the Code to see whether we are in compliance with local international regulations.

Irrespective of whatever I said above, I think at all times a free path to the releif valve must be maintained......until and unless....someone can vouch for the diverter valve not to malfunction at the right time when a demand is imposed on the relief valve by the process system at the time of any process upset. What is desired is that your system is safe at all times in its entire operational life.