high pressure restraints
high pressure restraints
(OP)
I am moving approximately 5000 gpm of water (inside the plant) at 130 psi. Do we need additional restrain on piping (rather than regular flanges. We have surge relief system that activates on appearance of transient pressure.
Thanks for your input
Thanks for your input





RE: high pressure restraints
What is the line size?
What is the material?
What is the operating Temperature?
What is the source of the water?
What kind of pump are you using?
What is the destination of the water?
What is the configuration of the suction and discharge lines?
RE: high pressure restraints
RE: high pressure restraints
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: high pressure restraints
RE: high pressure restraints
Someone has obviously considered water hammer (also known as surge or transient flow) there since you refer to a "surge relief system".
As eadwine states, such conditions occur whenever there are flow rate changes. Normally these are slow enough not to give much problem with pipe anchors, but it is possible to operate valves quickly, have pressure relief valves operate, have pump startups and trips, or flow in partially full lines that can give severe flow rate changes that can generate forces high enough to break supports and even collapse pipe bridges.
The forces produced can be frighteningly high - tens or hundreds of tons on large pipes! Fortunately most transients are brief, and the forces only apply for brief periods such that the pipe hardly moves despite the "bang".
Analysis of pressure surge to ensure your system is protected against overpressure is a specialised topic using modern software. Software like Flowmaster, AFT Hammer, HiTrans and others is good, but complex to use.
If you go to my web site page on this -http://www.cedcs.com/pages/waterHammer.php
you can read about it, and if you go to the downloads page http://www.cedcs.com/pages/downloads.php you can get a Powerpoint presentation and Excel workbook that hopefully will enlighten you!
Regards,
Stuart
RE: high pressure restraints
Stuart
RE: high pressure restraints
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"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
http://virtualpipeline.spaces.live.com/
RE: high pressure restraints
RE: high pressure restraints
Designing for dynamic loads often requires an impact factor, so I wouldn't call that a "harmonic" factor, as harmonic implies a load due to cyclic or vibration loads. Surge pressures might hopefully be estimated by taking the normal load X 2, if you didn't know the surge pressures themselves.
Short times or not, the acceleration and fluid masses can be high and its those that make the dynamic force, F = m*a
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"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
http://virtualpipeline.spaces.live.com/
RE: high pressure restraints
RE: high pressure restraints
Transient surge loads seldom exceed 50% normal operating pressure, if they are that high. Most of the time they generally fall into 20% to 30% of OP or so, as a rule of thumb, so 2X usually gives a very conservative answer. If you're happy with that, you could use it. If its a short pipeline, maybe you can afford to do that. Most of the time my clients can't afford it because the pipelines are very long with no room for such extras, so I use Stoner Pipeline Simulator for steady and transient surge and steady and transient thermal analysis whenever I need more detailed knowledge.
**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
http://virtualpipeline.spaces.live.com/
RE: high pressure restraints
**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
http://virtualpipeline.spaces.live.com/