Natural Frequency of Vertical Pipe

7 comments

Rate

IRSHAD Power-User Join Date: Nov 2008 Posts: 121 Good Answers: 4	Natural Frequency of Vertical Pipe 09/28/2019 5:45 AM
	I am facing high vibration problem in the *vertical* discharge pipe of the pump Pipe supports location, flow rate, pressure and pipe material properties are known. I want to calculate the natural frequency theoretically of the pipe before shutting down the pump and conduct bump test. Anyone play help.
	Register to Reply
	Pathfinder Tags: Pipe line

Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!

JE in Chicago Guru Join Date: Apr 2008 Location: Chicago Posts: 3990 Good Answers: 144	#1 Re: Natural frequency of vertical pipe 09/28/2019 6:08 AM
	Calculation? What about dampenization? __________________ High Tolerance is Beautiful
	Register to Reply

MJCronin Power-User Join Date: Oct 2009 Location: Central Midwest Posts: 455 Good Answers: 38	#2 Re: Natural Frequency of Vertical Pipe 09/28/2019 12:01 PM
	Develop a piping isometric of the discharge piping including all flanges, pipe supports dimensions etc... Perform a modal based vibration analysis of the piping in a computer based program such as CAESAR-II or AUTOPIPE. Look at the first vibration modes of your piping model. I suspect that they will not be in the vertical section of the system Having significant vertical piping vibration of your discharge piping is unusual. I am willing to bet that you have a broken pipe support or loose bolted connection. You may find that the supporting steel for the pipe supports is far too flexible or that anchor bolts are broken somewhere in the system. __________________ We have met the enemy....and he is us. POGO
	Register to Reply Score 1 for Good Answer

SolarEagle Guru Join Date: Mar 2007 Location: by the beach in Florida Posts: 33392 Good Answers: 1817	#3 Re: Natural Frequency of Vertical Pipe 09/28/2019 12:52 PM
	This might give some insight.... https://pdfs.semanticscholar.org/808a/af2a7ef1751c006aee3ef9272276d063ef61.pdf ..."Increased stiffness will therefore raise the natural frequency, and increased mass will lower it. That’s logical since stiffness creates a force that is always directed against motion, while mass has inertia, which is a force always directed with motion. Resonance is what happens when these two opposing forces are equal; they cancel each other out, allowing vibration to increase."... https://www.plantengineering.com/articles/understanding-of-resonance-essential-for-solving-vibration-problems/ __________________ All living things seek to control their own destiny....this is the purpose of life
	Register to Reply

rwilliams Guru Join Date: Jul 2016 Posts: 1367 Good Answers: 105	#4 Re: Natural Frequency of Vertical Pipe 09/29/2019 2:17 PM
	Here is the formula for the pipe resonance calculation https://www.petroskills.com/blog/entry/piping-vibration-calculate-natural-frequency#.XZD0IiUpCEc
	Register to Reply Score 1 for Good Answer

IRSHAD Power-User Join Date: Nov 2008 Posts: 121 Good Answers: 4	#6 In reply to #4 Re: Natural Frequency of Vertical Pipe 10/01/2019 12:30 AM
	Is it applicable for vertical pipe also.
	Register to Reply

rwilliams Guru Join Date: Jul 2016 Posts: 1367 Good Answers: 105	#7 In reply to #6 Re: Natural Frequency of Vertical Pipe 10/01/2019 1:06 AM
	I expect that the acceleration of gravity is not a significant factor in the calculation, so it should work at any position. The critical factor would be the mass, and the modulus of elasticity. For a poorly supported horizontal system, gravity could be modeled as an asymmetrical force, which then would tend to require an additional force to start flexing, but then a lower force to restore the position. I doubt that in any practical application you would be able to determine the difference.
	Register to Reply

PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#5 Re: Natural Frequency of Vertical Pipe 09/30/2019 10:07 AM
	B-flat is quite popular... __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
	Register to Reply

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!

Copy to Clipboard

	Got Something to Say?
	Ask a Question Start a Discussion

	Aerospace
	BioMech & BioMed
	Chemical & Material Science
	Civil Engineering
	Communications & Electronics
	Education and Engineering Careers
	Electrical Engineering
	General Discussion
	Instrumentation
	Manufacturing
	Mechanical Engineering
	New Technologies & Research
	Software & Programming
	Sustainable Engineering
	Transportation

	Site Directories
	Forum Directory Blog Directory User Group Directory RSS Feeds CR4 Rules of Conduct CR4 FAQ Site Glossary Who's Online (63 right now) Show Members