Forces on Valve chambers 1

[Maher K]

I have a valve inside a concrete valve chamber. Upstream the valve there is a dismantling joint that connects the valve to a flanged pipe which have a puddle flange at the place where it intersects with the wall of the chamber. The same is on the downstream side of the valve without having a dismantling joint.
When the valve is closed, a force is generated along the direction of the pipe which depends can be calculated by multiplying the column of water (water pressure) by the cross sectional area of the valve.
As far as I know, the use of a puddle flange at the locations where the pipe intersects with the walls of the chamber is to ensure a watertight and pressure-tight seal.
Now the question is this, is the generated force/thrust transferred to the walls of the chamber? If yes, is it on the upstream wall only or distributed equally between the upstream and downstream walls? I am concerned whether I have to take into design any force when designing the walls of the chamber

 

[LittleInch]

Well some of the force might be, but depends on a number of issues.

Do you mean both upstream and downstream have a puddle flange?
Is the pipe welded / flanged or what?
How big is the pipe?
What's the pressure?
Drawings / sketches help hugely to understand your issue / design.

Some of the force will be transmitted to the pipes outside the chamber, but If you take the worst case, which is the downstream disconnected and the valve closed then there is an end reaction force on the valve which will be resisted by the puddle flange.

If your chamber is quite big you need to be careful about pipe expansion if the contents get warm as you have now anchored both ends. Those forces are huge.



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

 

[HTURKAK]

I want to tell the worst case scenario ;

i ) The pipeline joints are bell and spigot, double bell reka etc (which are not pull-out resistant )..,
ii) The pl is connected to chamber piping at both sides with flexible coupling, collar piece, socket -spigot etc ..again not pull-out resistant,
iii) while the upstream side dismantling joint is not fixable type , downstream side the double flanged pipe piece one of the flange is puddle flanged cast in the wall, or dismantling joint is fixable (i.e. pull out resistant ) and down stream side puddle pipe is connected to valve with flanged socket , VJ coupling piece etc.

If this is the case, the hydraulic force developing when the valve closed will be resisted by one wall !!! , you are expected to design that wall for this load ...check punching also!! , and the whole chamber will resist as a thrust block...

P.S. The valve is used for service ..should not be used as end-cap during hydro testing..

 

[Maher K]

Thank you LittkleInch and Hturkak,

Please find attached a drawing that might be helpful. It seems I had a mistake in my first message. The dismantling joint is on the downstream side of the valve.
All connections inside the chamber between the valve, dismantling joint and the pipes are by using bolts.
I'm proposing puddle flanges at both walls to have a watertight connection.
Joints outside the chamber are flexible (double spigot, etc...)
Will the load be transferred to the walls when closing the valve? to one wall or more? how to calculate the force distribution?
Thanks again

 

[1503-44]

We are going to need to see a detail. Flexible coupling is where?

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[1503-44]

There it is.

I suggest you do need to design for highest pressure differential when closed and for surge forces if such is applicable.

If the valve is closed under pressure and dismantled at bolts, you would have full force on one wall only, assuming valve is not held to foundation by other means not shown in plan view. Otherwise you could assume half load is applied to each wall, one through the bolted connection.

The pull out connections will not transmit axial loads very well, so significant thermal loads should not reach the vault.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[HTURKAK]

I'm proposing puddle flanges at both walls to have a watertight connection.
Joints outside the chamber are flexible (double spigot, etc...)
Will the load be transferred to the walls when closing the valve? to one wall or more? how to calculate the force distribution?

I totally agree with ax1e (Petroleum) .

You did not mention the diameter and service pressure . I think the picture is typical for butter fly valve chamber ..but the wall thickness will not be typical for large size valves !!.

Your concern could be strength of walls rather than watertight connection .

If you post the dimensions, pressure etc. you may get better answers..

 

[Maher K]

The pipe diameter 1400mm, valve dimensions 3m*2.5m, working pressure 15 bar.

 

[1503-44]

I think that you're also going to need a proper, thick solid floor (acting as a footing) with a concrete pedestal and some kind of a chair or other type of support for that large of a valve. It may be quite heavy.

I hope that drawing is not to scale as I would also allow more working room around the pipe, valve and actuator. Will it have a bent reinforcing rods ladder embedded into the wall for personnel access? One? or two ladders, on each side of the pipe.

What is the predicted surge force when the valve closes quickly? It could be huge.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[Maher K]

All what you mentioned regarding the ladders, support under the valve, sump pit, etc.. are proposed but I removed them from the dwg I sent us for clarity.
The working pressure is 15 bar and the surge is 19 bar.
Appreciating your thoughts

 

[HTURKAK]

If the chamber dwg is scaled ,apparently the wall thk for 3.0 (L) is greater than 2.5 m (W). while the force due to closing the valve will be resisted primarily by 2.5 m Walls !!..

Below find preliminary calc. to determine the wall thk =

If the design pressure including the surge is 19 bars, the thrust developing when BV closed will be P=2800 kN.

The wall thk. (assuming the puddle flange w =150 mm ) ; punching will control the design.. assuminG C35 ,vc=1.8 MPa.

Vc= ( 1400+300)*3.14 *d*1.8)≥ 2800000 N d≥ 300 mm

If the design pressure including the surge is (15+19=) 34 bars ,the thrust developing when BV closed will be P=5250 kN.

Vc= ( 1400+300)*3.14 *d*1.8)≥ 5250000 N d ≥ 550 mm.

It is reasonable to assume , half the load will be applied each wall, if the dismantling joint removed, the surge pressure will dissipate and The working pressure 15 bar load will be applied to upstream wall.

The puddle flange should be located not to the center but near to the outer face of upstream wall . The wall thk. from the interior surface =300+200 =500 mm . (for the upstream wall, and 200+300=500 mm for downstream wall.

 

[1503-44]

It's a very large pipe diameter, so 19 bar total max pressure during surge I think, so that would be a max total axial load of around 3,000 KN (650 Kips). You're going to need some pretty thick walls.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[saikee119]

I haven't designed a valve pit before but I did a lot of water hammer studies, designed thrust blocks and seen a big failure of a 1400mm diameter line.

My thought is the puddle flanges at both upstream and downstream are for watertightness first and then load transfer second.

Hydraulically one does get a shut off head and that will be huge. For a 1400mm pipe the valve could have automatic closure built in and equipped with spring loaded drop weight and damper. However as the pipework is fully connection the force will deflect the entire pit and not just the puddle flange at the upstream wall. In fact the real stress point would be the foundation supporting the valve because the pressure, infront and after the puddle flange would be just the same.

Thus I would use the dead weight of the pit plus the weight of the equipment inside as a thrust block. Also when the pit is pushed the backwall against the soil should offer passive resistance in concert with the dead weight to resisting shut off pressure.

 

[r13]

You can't escape from design the full thrust if the pipe movement is restricted. Maybe try other type of sealing ware, Link, at higher cost.

 

[1503-44]

The puddle flanges are not suitable for high load transfer.
You will need two "pipeline anchor flanges" to hold that into the wall, if you want to transfer load there.

http://www.buffaloflange.com/anchorflange.html

I believe you must design for shutoff load on one wall. However I don't think the surge load occurs while under maintenance, so you could distribute surge load to both anchor flanges at each wall and at an appropriately designed support at the valve as well, if you can make one there.

The flanges should be placed at the wall centerline, because surge pressures passing through the valve when it is closing may be reflected back shortly thereafter. Possibly by a valve farther downstream that had enough time to close and reflect waves back to this station arriving at a now closed valve. Surge pressure reflections from closed valves are typically seen in decreasing amplitudes up to 4 or 5 times before dissipating entirely, so it may not be safe to assume they only come from one direction. I wouldn't anyway.

That is a very high surge load in relation to normal pressure. I presume this is a welded steel pipeline.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[cristiano.ronaldo]

Walls must design as plate elements, see EN1993-1-5

 

[1503-44]

cristiano.ronaldo I don't see how
EN 1993-1-5 : 2006 AMD 1 2017 EUROCODE 3 - DESIGN OF STEEL STRUCTURES - PART 1-5: PLATED STRUCTURAL ELEMENTS
applies in this case. I see concrete and I see pipeline fittings.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[HTURKAK]

Dear Maher K (Civil/Environmental)(OP) ,

In order to get useful, better answer, you should provide the pipeline material, soil conditions , service,surge and static pressures..

If the pipe material D.I. , i will suggest as an option the use of straining glands at upstream side .

 

[1503-44]

With good soil it is possible to dump some load there, but it is not possible with push in pipe joints.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[LittleInch]

Are you sure this is 15bar? The diagram looks like a push fit type joint which isn't normally good for 15 bar.

Also at each change of direction you're going to need a BIG anchor block.

As your design is at the moment and ignoring any reactive force from the pipe buried int he soil upstream, this is basically an anchor block.

Puddle flanges won't be good enough, nor does a valve chamber like being an anchor block.

Check the numbers first please.

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