Ball Valve Inside Groove 1

[McDermott1711]

Hi there,
Somebody sent me this picture and asked about the inside grooves. Does anyone know about it?

Any answer will be highly appreciated.

Nothing is more fairly distributed than common sense: no one thinks he needs more of it than he already has. Rene Descartes

 

[LittleInch]

That seems to be part of an insert into the body of the valve. I can only guess that they are there to allow the insert to be a force fit into the body.

What type of construction is this? = Looks like a two part end entry to me.

Any special internal material?

Do you have a sectional view / diagram?

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

 

[McDermott1711]

Thanks LittleInch for y,our reply. Actually, I've only this photo and there isn't any other information.

Nothing is more fairly distributed than common sense: no one thinks he needs more of it than he already has. Rene Descartes

 

[passist]

This is a ball valve seat. The grooves have at least two purposes;

1. The seat acts as a spring, when the 2- piece valve body is tightened, both ( there should be another seat on the other body half ) seats are somewhat compressed, the other end against the valve body, the other end at the ball surface. This helps sealing, even at alternating temperatures.

A little like this one (notice, there are also grooves on the outer peripheral!) :

http://www.wermac.org/images/bellow_ss.jpg

2. When the pressure inside the valve grows, it fills the grooves, which will simultaneously try to stretch the seat, therefore increases the pressure at the sealing contacts.

 

[men8th]

I'm not sure the fluid filling the grooves will stretch the seat passist. Each groove has a front and back face of equal areas. When the valve is pressurised, the force exerted on the front face of a groove will equal the force on the back face and the net result will be no movement.

 

[passist]

Men8th, here is the link to a technical bulleting covering the seat;

http://valveproducts.metso.com/documents/neles/TechnicalBulletins/en/1D21EN.pdf

( page 5, seat C )

" The bellows acts as a spring and seal, and also
increases the seat pressure at higher pressure differentials. "

A normal seat in a trunnion mounted ball valve acts in a different manner. Without proper pictures it is kind of hard to explain it, but if you take a look at the seat in the technical bulletin, you might get this;

When a normally seated trunnion mounted ball valve is in the closed position, and pressure is being applied, the pressure reaches to the outer peripheral of the seat, which is usually blocked by an o-ring, or a graphite for example. the inside peripheral is also under pressure, but the outer peripheral area wins, therefore sealing happens.

Now with this bellows seat this does not ocurr. When under pressure, the pressure fills the internal grooves, while simultaneously trying to push its way to the outer peripheral as well, but it is blocked by a graphite seal, therefore not getting there. The result is that the outer grooves are not pressurized, but the internal ones are, this does cause the seat to try to stretch itself, the other end pushing itself towards the graphite seal, the other end towards the ball.

Hope that I could make it a bit clearer!

 

[men8th]

You have made it clearer. I've learnt something new today...