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shameemmuhammed
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Join Date: Mar 2013
Posts: 3

Use of Ball Valve for Low Pressure Steam Throttling Application

03/19/2013 4:42 AM

Hi All,

As part of one of our renovation project, we would like to replace one of our existing buttefly valve used in steam throtling service with a ball avlve. The design details are as follws

Design Pr. /temp : 5.5 bar /300 deg C

Delta Pr Sizing : 5.45 Bar

Size : 24 Inch

service : LP superheated Steam.

Seek your experte advice whethre ball valve is suitable option for the throttling service?
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Pathfinder Tags: Control valve for throttling suerheated LP steam
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PWSlack
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#1

Re: Use of Ball Valve for Low Pressure Steam throttling application

03/19/2013 4:45 AM

24-inch ball valve? What a whopper that one will be! Try justifying the investment!

Wouldn't it be easier to run the boiler at a lower pressure?

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#2

Re: Use of Ball Valve for Low Pressure Steam throttling application

03/19/2013 5:28 AM

Have you phoned your local valves distributor yet?
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PWSlack
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#3

Re: Use of Ball Valve for Low Pressure Steam throttling application

03/19/2013 5:36 AM

Why not distribute the steam at 5.5 barg and reduce the pressure in the branches off to the individual pieces of equipment where the pipeline becomes smaller in diameter instead?

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jesw55
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#4

Re: Use of Ball Valve for Low Pressure Steam throttling application

03/19/2013 5:49 AM

Hi shameem...

In my experience, a ball valve is not ideal as a throttling device, due to the rapid change in cross sectional area as it is turned and the turbulence caused by the shape of the orifice causing erosion of the valve seals.

Best regards,

John

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Drew K
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#5
In reply to #4

Re: Use of Ball Valve for Low Pressure Steam throttling application

03/19/2013 7:13 AM

Depending on the valve seat / sealing materials this might lead to flow accelerated corrosion.

What are you throtteling with this?

Drew K

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jesw55
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#6
In reply to #5

Re: Use of Ball Valve for Low Pressure Steam throttling application

03/19/2013 7:23 AM

Hi Drew K,

According to the O.P's post it is Super Heated Steam!!!!!

John

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Drew K
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#8
In reply to #6

Re: Use of Ball Valve for Low Pressure Steam throttling application

03/19/2013 12:03 PM

I meant, what is being controlled. I hope this isn't the control valve to a turbine...or even a steam driven pump.

If it is being used to control steam to the water treatment facility or plant heating, I could possibly understand it. Otherwise, only a throtteling valve should be used to throttle superheat steam.

I should have been more clear in my response (was early...before first cup of coffee).

Drew K

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jesw55
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#9
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Re: Use of Ball Valve for Low Pressure Steam throttling application

03/19/2013 12:41 PM

Hi again Drew K,

I think the general consensus is a ball valve is not the thing to use but it is outside my sphere of knowledge as to what you would use that is 24" diameter (some sort of Gate type valve?)

Best regards,

John

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Drew K
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#10
In reply to #9

Re: Use of Ball Valve for Low Pressure Steam throttling application

03/19/2013 1:23 PM

I have used many 24" ball valves in the fuel industry, and I am new to the power plant game. From what I have learned so far the throttle valves are designed to resist erosion / flow accelerated corrosion caused by superheat steam passing through them at tremendous velocities and high temperatures.

Steam at those temperatures is very hard on valve materials which is why everyone is suggesting the ball valve is a bad idea. There could be some very few applications where one could be used (for a short time till it wore out). The OP doesn't state what the purpose of this valve will be.

Most throttle valve companies use the toughest materials they can create to wear the longest, some designs use a tortureous path for the steam or superheated water to go through so the valve seat surface is not the critical device that is changing the flow.

Drew K

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#7

Re: Use of Ball Valve for Low Pressure Steam Throttling Application

03/19/2013 9:58 AM

'....whether ball valve is suitable option for the throttling service?....'

.

No. While ball valves are sometimes used for throttling, ball valves are not designed for throttling. Ball valves provide very poor throttling control, and experience excessive wear when used to throttle.

.

If you are going to spend the time and money to replace a valve, replace it with one designed to do the job.

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mog
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#11

Re: Use of Ball Valve for Low Pressure Steam Throttling Application

03/19/2013 11:21 PM

Shameem.... you may be in a tough position. Mueller Steam Specialties here in North Carolina has obsoleted the large 51,52 and 53 series butterfly steam valves and the ball valve as mentioned above would suffer severe 'wire draw' at the ball orifice face. Here is a line card from Kerotest that may be of help. Kerotest may make a custom but their largest is a 16". Just Google Kerotest Steam Valves and look at the line card (manufacturers) at the bottom of the page. Good luck
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srini
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#12

Re: Use of Ball Valve for Low Pressure Steam Throttling Application

03/20/2013 9:14 AM

First ,why are you replacing the Butterfly valve?

Are you throttling manually or is this a control valve throttled by pressure or temperature or flow controller.

Based on the pressure drop this is a very noisy application.

Assuming you are ready to cut the pipe to fit another kind of valve, a globe valve would be better.

There are people like Mogas and Metso who make control-ball valves, but these don't come cheap.

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vargaalex
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#13

Re: Use of Ball Valve for Low Pressure Steam Throttling Application

03/20/2013 9:15 AM

Yes you can change a butterfly valve to a ball valve, but the costs will be much higher.

Also you need to analyze what your true steam distribution requirements are and then check what type of valve to use.
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Lalit Shukla
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#14

Re: Use of Ball Valve for Low Pressure Steam Throttling Application

03/26/2013 5:33 AM

sir

Replace the valve with Gate valve of class 300
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