Valve orientation 1

[ER_Azza]

In a processing unit, 2 x 20” gate valves serve as the battery limit isolation to the venting flare.
These valves don’t operate regularly. Possibly, once every 18 months.
But when we do operate them, the deposit on the seat will result in the valve unable to close fully -passing.

I wonder if installing the valve sideway would alleviate this?

 

[Danlap]

Hi,

What type of gate valves are you using? wedge or through conduit or slab or double expanding?
Gate valve in horizontal pipes shall be positioned with their stem horizontal or even upside down where fouling substances could collect in the bottom cavity and in a systems where a component failure could cause closure of the valve (read: stem broken and wedge left in close position) and lead to unsafe situations e.g. flare systems.
In general, yes positioning stem horizontal might help to reduce fouling collection in the bottom cavity. I am not a fouling expert, but sometimes it is better to alter the design of the valve.

Some ideas that we have personally implemented in our Plant
- Change the design into trough conduit gate valve...even in open position the cavity is 'protected' from fouling collection due to energized seats. This is good for heavy fouling.
- Some wedge gate valve re-oriented to stem horizontal
- Some Plant still want to use gate valve with stem on vertical position. Due to economical and also ergonomic reason. What we did was hot tapping the bottom cavity and install a steam or nitrogen purge connection to blow fouling from cavity back into main line. Sometimes it work, sometimes not. This is also an alternative until newer through conduit valve / other valves about to be installed.

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

 

[LittleInch]

Danlap is spot on here.

The key is to protect your seals when in the open condition if you've got sticky stuff in your flare line.

I can't see how moving the valve sideways is going to help other than get debris in the channels on the side.

Many gate valves really don't like being installed horizontally even if the vendor says it's OK.

So give us a bit more info on the type and section of the valves you have and we can review a bit better - "gate valve" doesn't give anyone enough information to help further.

also what is the residue being deposited on the seals?

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

 

[ER_Azza]

Hi Gents

Thanks for the quick response.

Our current setup has spec blind between the two (regular) gate valves.
Everytime when we need to isolate the system, it is always a drama trying to shut the gate valves.
It passes, coz it can't seat properly.

Danlap idea of putting in steam injection point is interesting.

There are many other options, like those valves with the wedge plate insertion.
I reckon those valves would still be exposed to fouling deposit. But just sufficient to allow the wedge plate insertion for isolation.

Or, another option is the welded steel plate valves.

What's your thought?