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Join Date: Apr 2018
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Gate Valve with Wedge Disc

01/07/2019 7:35 AM

I have been asked to supply a DN1100 gate valve(non rising) with solid wedge disc.

Main problem is that they want one face of wedge perpendicular to flow direction and the other face tapered to 2.5 degrees.

Not finding any reference anywhere.

Afraid that this small wedge angle will lead to galling.

The valve will also be buried after installation with concrete

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#1

Re: Gate Valve With Wedge Disc

01/07/2019 10:03 AM

Then declining the invitation to supply is the natural consequence of the too-tight specification that the <..they...> has provided.

Move on. Life is short enough as it is.

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#2

Re: Gate Valve with Wedge Disc

01/07/2019 12:01 PM
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#3
In reply to #2

Re: Gate Valve with Wedge Disc

01/07/2019 2:05 PM

Butterfly ≠ Gate

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#4
In reply to #2

Re: Gate Valve with Wedge Disc

01/07/2019 2:29 PM
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#5

Re: Gate Valve with Wedge Disc

01/07/2019 11:48 PM

Are you planning to design and fabricate this valve, with a novel design feature, or are you expected to source this from some reputable supplier?

Metal seated or resilient seats, though with this odd specification, it would apply to hard seated valves, metal on metal.

It appears your specifier plans to leverage the advantages of each type of gate for either side of the flow path. This may be a one-off design that one supplier has come up with, with perhaps unknown or very narrow operating history.

Or maybe this is a novice designer's language inserted into the bid document...

Parallel gate valves are usually designed with two piece gates spring loaded, wedge type gates can be flexible or not. So maybe a two piece gate with asymmetrical faces?

it is interesting to note that gate valves do wear out, and at ~42" non-standard size, you will probably have to chip away the concrete and remove the valve body before you can reface the seats. Depends upon liquid and leak specifications...

The spring loading and machining/shaping methods used on 5 degree wedges should take care of galling concerns.

This design that Babcock Valves has come up with, https://babcockvalves.com/double-disc-gate-valves/, up to 36" size, is something I would trust to bury in concrete, and last a typical lifetime of isolation service.

I think your best bet would be to take Mr. PWSlack's advice, and give this opportunity a pass.

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#6
In reply to #5

Re: Gate Valve with Wedge Disc

01/08/2019 12:35 AM

Williams:Thanks for this beautiful answer. Mr. Slack has given his opinion without wasting time.

You have wasted your time to give me some insight. Thanks

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#7

Re: Gate Valve with Wedge Disc

01/08/2019 1:09 PM

In my 30 years in mechanical engineering I had so many gate valves fail that I stopped using them, I use ball fix valves which are self cleaning, the trouble with gate valves is that if they're not operated for long periods they get stiff or the slotted seat at the bottom gets muck stuck in it so when the blade is brought down it doesn't always seal & most people will try to wind it down harder & then they try to open it but they sometimes strip the thread, then it won't open or shut. Be warned!

Bazzer

.!

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Users who posted comments:

Bazzer Englander (1); PWSlack (1); rwilliams (1); SolarEagle (2); Sumit Basu (1); truth is not a compromise (1)

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