Burying a 12" gate valve underground

[frizzmizz]

Hello everyone,
I am working on an underground Recycled Cooling Water Line and we are adding a 12" drain to this line which requires the addition of an underground 12" gate valve.

Design conditions are 24C and 100psi.

I am just wondering what the best way to go about this would be. I am looking at a few options right now and I am not sure what to do:
1) Get a post indicator valve - this seems like a good option however I feel like this will be overkill for this application as all the vendors I have seen so far for this also include UL/FM approvals which I don't really need. Additionally, most of these valves seem to come with only ASME B16.42 flanges while my piping system is only using B16.5 flanges...

2) Use 12" standard gate valve that meets the client specs and get it epoxy coated. However, I don't have any designs for a valve box or sleeve that would prevent the dirt from reaching inside close to the stem.

Any recommendations?

 

[MickMc]

frizzmizz,

Have you considered valve pit?

Also if his is not option the post indicator concept would still work as basically this is just the sleeve design you refer to. Also if you are looking at off shelf type consider using Ductile Iron Valve (B16.42)with your corresponding flanges Flat Face instead of Raised Face, it is quite common to use DI valves in what I am assuming is Carbon Steel Piping in water service.

 

[LittleInch]

Just buy a valve with an extended stem.

Very common in the pipeline world and fire hydrant systems.

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

 

[gerhardl]

'Underground' is not vey specific. In some parts of the world underground can mean frostfree depth of 2- 3 meters. Depending on ground conditions cover could be anything from sand or stone, or asphalt or concrete top layer.

Point is: the more costly and difficult to get access later, the more reasonable to use a prefabricated 'valve pit'. The same goes for valve quality and outer and inner surface. There is a number of adaptive loose flanges, extension pieces, stem extensions etc. available on the market, both for direct burial or operation through or in a pit.

It all boils down to cost/lifetime to decide which is best for the total operational cost f the plant.

 

[LittleInch]

Valve pits are a complete pain nearly all the time. They leak, fill up with dirt, snakes, never big enough to actually do anything and the valve and its flanges then rusts and leaks as it is isolated form the CP system.

just bury it and if you've got flanges fill the gap with grease and tape them off.

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

 

[frizzmizz]

Thanks for the suggestions everyone. I did consider valve pit but this is a very low risk water service and client would like to avoid getting a valve pit to reduce project costs as much as possible.

LittleInch, do you know of any vendors that provide valves with extended stem as shown in the picture?

 

[gerhardl]

Hello, LittleInch! I agree that under the circumstances given, burial is cheapest and OK.

Your experience with valve pits may well be correct in your part of the world, but does not describe the common pit in my part: Western Europe including Scandinavia .(Some few snakes excist bit would hit the paper fronts found in a valve-pit)

 

[LittleInch]

Most valve vendors will provide extended stems if you just ask them and state length of extension required from centerline of the valve.

Just call a few of them up to make sure before you send the data sheet, but this is a very common requirement so most should be able to supply.

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

 

[frizzmizz]

Thanks, I will post an updated on what path we go with.

 

[fel3]

How often will this valve be used? If it will be used a lot, I like the idea of having a handwheel above ground or a post indicator. If the valve will be used infrequently, you may be better off doing something similar to a buried gate valve in a municipal water system.

You can try your local jurisdiction for a detail for a buried water valve. Most details will show a 2-inch square AWWA operating nut on top of the bonnet and a vertical can extending from the bonnet to the ground surface. Unfortunately, it is possible to get debris in the can that will cover the nut. One solution is to use a stem extension.

For an example, go to this link:

http://www.lvmwd.com/other-services/facilities-and-operations/design-standards.

LVMWD is a water district one of my former employers consulted for back in the day (I did a lot of work with LVMWD in the early 1980s). Under "Plans and Specifications for the Construction of Water Mains and Facilities" near the bottom of the page, click on "Potable Water". When the document comes up, scroll down to details PW-117, PW-118, and PW-119.

PW-119 shows something very similar to a device I have used from American Flow Control called a Trench Adapter. You can find it here:

http://www.american-usa.com/products/valves-and-hydrants/trench-adapters/trench-adapter

==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[Running82]

I think littleinch's reply is very good.

The extended stem is so common. This will be a cheap and good way.

 

[Running82]

Littleinch's reply is very good. It is very easy to do an extended stem gate valve. His option is correct and easy to carry out.

By the way, since the valve is underground, I'm afraid only epoxy coated is not enough. There are a few specific painting for underground valves. So, please put some attension on painting.