gate valve location

[archirodon]

hello everyone. we are in the process of adding new pipes for water distribution. being new in our company, i noticed that gate valves are being installed "only" where tees are located. May I ask then, what is the proper spacing of gate valves. How do we install them?

 

[pennpiper]

I think we would be able to help you more if you gave us some important details about you installation and your question.
What size is your main header?
What size are your branch lines?
Are your valves flanged or screwed?
What do you mean by 'proper spacing of gate valves?'
What do you mean by 'How do we install them?'

 

[Cockroach]

It depends on the particular fluid application. Are we talking Slab Gate?

Typically gates are used in liquid application where batching is not an application. These valves are not intended for throttling or fluid control, but are simply an "ON", "OFF" application. In other words, the fluid flows or it doesn't.

On petroleum pipeline services, slab gates are used a few bore diameters downstream of a tee. This is to let turbulence dampen out. I often see them beyond the transition zone, in the laminar region.

Hope this simple answer addresses a simple question.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[BRIS]

I guess as you are installing water pipes the process media will be water (sorry cockroach - couldn't resist it) and gate valves will operate in an on off.

Normally in a distribution system valves are installed at tees as you describe. the spacing is determined from a balance of economics and down time for any maintenance. But, as pennpiper notes you need to provide more details.

 

[BarryEng]

I usually locate valves in a reticulation system, to "protect the main source of supply".

If you have a DN 500 pipe with a DN 200 off the larger pipe, one of the main purposes of the valve, is to ensure the integrity (safety & reliability of supply) of the main pipe. In other words, don't have a DN 500 pipe with a DN 200 tee, & a length of DN 200 pipe before a valve is installed (such as going under a road reserve). This leaves the DN 500 vulnerable if there is a fault in the section under the road.

The extension of this, is, if you have a DN 1,500 pipe with a DN 150 scour, the valve should be as close to the main pipe as possible. You do not want the main pipe supply to be shut down if a long length of DN 150 is damaged in any way. A closely located (to the main pipe) valve will enable the damaged section of DN 150 to be isolated for repair without any impact on the supply from the main pipe.

Another 'empirical rule' that is often used, is that valves are located, such that no more than 5 valves in a reticulation system should be shut off in the event of a burst. More than 5 valves results in a long period (mainly thru' trying to find the valves) before complete isolation of flow into the area of the burst (more consumer complaints about the time to "shut off" & the "waste of water").

 

[gerhardl]

Nothing to add to already several sensible answers than that you obviously (almost not necessary to mention) must have an on /off near or at local distribution points to cut off single houses, plants etc if the branch stretch to the valve near the main is of any distance.

Check also for necessity for air valves and pipeline bursting valves in addition to on/off.