Provision of Extended Stem to a ball valve in operating condition_Retrofit

[ET1983]

Dear All,

I had been through a case where, the 6" ball valve, trunnion mounted was erected with gear operator. But, after the commissioning, the operation team of the plant is asking for valve access from the platform located 1.5 meters above. Even the provision of platform is very difficult to accomodate there due to congested piping around the valve. hence i would like to know, whether the RETRO-fit of Extended stem is possible in this case, and the possibility to carry out this without plant shutdown.

Pls advise.

 

[donf]

ET1983,

Try also searching for "remote valve operator". Here's one company (of many):

http://www.elliott-stow.com/index.html

Whatever you use, be sure to securely support the extension so as not to side-load the valve stem and cause packing wear. As far as retro-fitting, while in service - you need to work that out with valve OEM, extension supplier, and plant operations and safety folks. I've performed retro-fit for gear operators without incident.

Good luck, and let us know how you solve the issue.

donf

 

[zdas04]

It is pretty common on non-gear-operated valves in valve cans (for example) to have a handle to operate them from the surface.

Occasionally you see a gear operator mounted sideways (i.e., the stem leaving the valve body 3 o'clock or 9 o'clock instead of 12 o'clock) and then you can simply connect a remote actuator to handwheel using a plate and U-bolts without any major issues.

When the stem comes out the top of the valve body, the issues are bigger. You can still put a stem extension on the valve and move the gear operator up to your platform, but you have to take extraordinary steps to make certain that the gear box is ridgedly mounted and the stem extension is supported against lateral movement like donf said.

There are extended-body ball valves on the market (marketed for direct burial), but all of them have an extended body (i.e. the stem packing would be on your platform and the extended bonnet is under pressure) and are expensive to retrofit.

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[gerhardl]

(Also) in my opinion the answer is yes, most problems already covered by the two other replies.

Let me in addition add that operation with extended stem at 1,5 m plus (for example) 0,9 m for handling height) is a moderate length, although good guiding for the extended stem and solid stem (pipe rather than bar?) is necessary. Note that changing or adding to the gearbox could give a better solution. If hand-operated an altered ratio (for instance 1:2 ) could give easier operation and reduced forces also for the extended stem.

 

[ET1983]

Dear donf & zdas04,gerhardl,

Thanks for your excellent suggestions and answers. First time i am hearing about this Remote valve Operator, and it seems to be an apt answer to my case. Will get into touch with these experts and will share with you the informations. Thanks