Isolating valves for liquid HCL / service with coke

[1771978]

Hi,

We have been facing serious problems in two areas of our plant. One is in liquid HCL isolating valves, we have more than 50 valves on dry HCL service at very low temperature but every now and then, we face gland leakage issue. Second, in valves afetr furnace where at pressure around 25 bar and temp of 100 deg C, HCL, VCL, EDC is there where we would need class 6 isolating valve. Currently we have butterfly valves but afetr some time, valve doesnot islate the system mainly due to carbon deposition on seats. Need urgent help

 

[itascot]

1771978,
For gland leakage, you could try "live loaded packing configuration" that can compansate (within reason) on wear & thermal expansion/contraction issues). Important that you are using the correct packing materials...
What type of valves are you using ?
Ciao,

 

[1771978]

Dear Ciao,
FOA, thanks for ur prompt response. We mostly have plug valves installed in the system. Could you please xplain live loaded packing configuration as I am not familiar with it
thanks

 

[ione]

Live loaded packing configuration is an arrangement which adjusts the gland position to provide optimal sealing pressure on the packing. Disc springs are usually adopted to achieve this goal.

 

[ione]

Ball valves are probably a better choice for chlorine applications.

http://www.engvalves.com/itemfiles/valveselectionessentials.pdf

 

[1771978]

Thanks, If you can provide details of any system being used with live loaded mechanism and which vendors can provide it. Also, could you please help me out about the coking issue in valves. We would need to know the best vendor who can help us out in this area also

 

[ione]

All the leakage seat classes as per FCI 70-2 (included class VI) refer more properly to control valves than to isolating valves. For isolating valve you should focus your attention on API 598 and API specification 6D.

 

[itascot]

1771978,

Check this link out regarding liveloaded packing on globe valves, its not "new" to valve stems, I think you will find just about everyone can supply (at extra price).

http://en.wikipedia.org/wiki/Globe_valve

For your sealing problems, metal seated butterfly valves are best for your application, triple offset again probably best, they tend to swipe clean sealing areas during final (last 3-5°) closure, solving your root problem of deposits in this area.
Ciao,
Itascot

 

[itascot]

Forgot to mention butterfly valve manufacturers...Try: Tyco flow control(Vanessa valves), Cameron group (formerly CCV) (Orton), Tomoe valves. These are but three of them, the first two practically every working condition experience, as they have been around the longest.
Ciao,
Ian

 

[1771978]

Thanks to all. This was my first experience in Engieering Tip. Great experience

 

[camvalves]

Hi

I've used Zwick Triple Offset valves on Coke Oven Gas service with relatively good results. These had live loaded gland packing too.