In my project i have a 96" cooling water line. I want to know that how can i minimize the water hammer effect in this line and what are the supports need to be given

Read good books on the subject & kill the water hammer in the source. Determine the reason of water hammer - any fast closing valve or anything else; increase valve closing time, at least near the end of closing time. Check the thickness calculation due to surge pressure developed.

regards,

sam

I believe it has been well known for many decades that high pressures have occurred (per the "good books" for many reasons, and in some cases maybe some of these not necessarily very obvious) in pipelines of all materials. Devices and means of minimizing some effects of high pressure transients etc. have been around nearly as long, and in fact have been employed for many years on many pipelines. Nevertheless, problems still reportedly occur to the present day that are blamed on surge (I noticed the latest apparent example presented on the list thread http://eng-tips.com/viewthread.cfm?qid=209291&page=1, and related links, a couple days ago). "Good books" are helpful to learn about all these mechanisms. A selection of pipeline materials that are resistant to high pressures, or at least catastrophic failures in high pressure events, may also be helpful.

But, who will read "good books"! Why will people learn - they are born to bet in stock market & housing, earn & enjoy!

Taking cue from Susan Jacoby, author of “The Age of American Unreason", from quite a under-developed part of the World, I am witnessing the change of culture, here too!

regards,

sam

Thanks for your reply sir,
but i have a 38" ball valve in that line after reducers and pressure is 2kg/cm2. If i provide the thrust pads as the supports for this line near elbows is it reduces the water hammer effect and will the pipe line be safe.

Dear,

First investigate why there will be water hammer. Then, quantify the loads & locations. Then, find out the mitigation measures & implement the chosen mitigation measure.

This is the reason why you should read books on fluid transients. You will learn from others' mistakes & successes by this way. Convert your challenge to your opportunity to return to school - may be a continuing education program is available nearby!

regards,

sam

Among other things, the magnitude of hammer loads are directly related to how quickly you stop the fluid column. Is this ball valve what's stopping the flow? If so, how fast can it be closed? If not, what is?

Let the distance from the "stop flow" point to the "echo point" be L, the speed of sound in your fluid be c, and your effective valve closing time be t. If t > 2L/c there should be no hammer.

An ounce of prevention is worth a pound of cure.

Are you actually having water hammer?
and if so, why in a cooling water line?

Your asking a really big question in a very vague manner.

I would suggest you seek some experience to asses your actuall situation, and then formulate a list of possible causes. only then can you deal with the effects.

If it is a quick acting valve, then you need somebody to "hold your hand" through the identification and solution as a quick acting valve would be the first port of call for any seasoned engineer

When you make sure the closing time of the valves is set long enough, you'll not have WH problems caused by the valves. Remember that not only the closing of a valve can cause WH. Also a pump trip is a known reason for WH.
With the jouwkosky formulas you can calculate the maximum water hammer that CAN occur. As long as the pressure do to WH doesn't exceed the maximum system pressure it's OK. Check your supports (where appropriate) for F=p*A in axial direction.