Valve isolation tank 1

[Vladimir99]

I have to purchase a valve to isolate a 30'' outlet line located at the bottom of a storage tank of Bunker 150 000 Barels.

I will connect a future line to this valve in few months. However, the tank will already be in operation.

Should I installed a standard gate valve, a parallel slide gate valve or a knife gate valve ?

I think a gate valve could do the jobs but will be more expensive.

I don't know ''parallel slide gate valve" but I have seen that type of valve installed on similar application.

Knife gate valve : my feeling is that it's leaks.


Thanks for your help,

Vlaidmir99

 

[JimCasey]

No, No, and No.

Maybe a gate valve but they do leak. Parallel slide: expensive and the packing will rpobably leak. Knife-gates are for slurries like paper stock, but not for tight isolation.

I would look first at a butterfly valve. You may need a fire-safe valve. THese are available with a zero-leak resilient primary seat and a metal secondary seat for post-fire shutoff.

 

[11echo]

I second JimCasey's choice of a butterfly valve! I work in the oil fields and we use this type of valve alot for the application you are describing here (not in such a large size, but the application is the same). My experience, knife gates leak and they are more expensive then butterfly valves. Just rememeber to get the threaded lug type of butterfly valve!!! ...Good Luck!

 

[tsmith62]

Given the size of the line being 30" and I am assumeing an ANSI 150# or 300# tank rating or less I would suggest you look at a Triple Offset Butterfly Valve. These are typically firesafe to API 607 4th edition and are zero leakage. I would first contact Adams Valve in Houston TX or if you are in Europe they are located in Germany.

If the line were 12" or less in size then I would suggest using a sleeved plug valve. This valve can be reseated in line without disassembly. Xomox is a good manufacturer of plug valves.

Gate Valves, Knife Gate Valves leak.

 

[NGiLuzzu]

If you go with triple offset metal seated valves, I dare to say that the two leading Manufacturers are located in Italy (see, for example, trixvalve's post in thread408-135872 within this Forum).

You may also find the links to the relevant websites in thread408-64692 and thread408-126483 within this Forum).


If you go with knife gate valves intead, try visiting

http://www.knifegate.com/

for instance...


Hope this helps, 'NGL

 

[bcd]

Hello,

Considering that this is normally low temperature, is a large valve, and does not cycle very often, your lowest cost option would be a double-offset butterfly. A triple-offset will be more expensive and takes a lot more torque to operate so not necessary unless you need to benefits of this type of valve. As JimCasey suggests, use a polymer seated version which has a metal back-up for fire safe. This is common in double-offset type.

bcd

 

[Vladimir99]

Thanks,

We finally purchased a std gate valve for my application. I was looking for a parallel slide gate valve as provided by hattersley heaton (wafer type, slimline catalogue) but the delivery was too long.

I know it will leak as it is not a class 6 valve but our criteria was to meet API 598 low and high closure test.

Vladimir99