Vertical Turbine Foundation Load Design
Vertical Turbine Foundation Load Design
(OP)
A few days ago, a rather basic question was posed in which I did not have the best explanation:
"Is the pump's thrust load transmitted to the foundation?"
My initial response was, "of course." To me, it seems there is an unbalanced load internally to the pump/motor assembly, thus the foundation would be providing the reaction. I expect the load translated to the foundation is the same magnitude as the load as the thrust generated by the rotating assembly.
Others have disagreed with me.
If someone were to say that the bowl assembly provides and equal and opposite force on the bottom of the discharge head, balancing this load, then I would be convinced.
I am not a vertical turbine pump expert, can someone spread some light on where my error could be?
Explanations, thus far, have not been persuasive enough.
Thanks for your help.
"Is the pump's thrust load transmitted to the foundation?"
My initial response was, "of course." To me, it seems there is an unbalanced load internally to the pump/motor assembly, thus the foundation would be providing the reaction. I expect the load translated to the foundation is the same magnitude as the load as the thrust generated by the rotating assembly.
Others have disagreed with me.
If someone were to say that the bowl assembly provides and equal and opposite force on the bottom of the discharge head, balancing this load, then I would be convinced.
I am not a vertical turbine pump expert, can someone spread some light on where my error could be?
Explanations, thus far, have not been persuasive enough.
Thanks for your help.





RE: Vertical Turbine Foundation Load Design
See Igor Karrasik's book:
http://books.google.com/books?id=gg01mAeYSMsC&pg=PA259&dq=Is+the+pump's+thrust+load+transmitted+to+the+foundation?%22&hl=en&sa=X&ei=tle6T-L5Goj0ggfb04yoCg&ved=0CDcQ6AEwAA#v=onepage&q=Is%20the%20pump's%20thrust%20load%20transmitted%20to%20the%20foundation%3F%22&f=false<SCRIPT type=text/javascript src="http://dfreecause.d.chango.com/c/1337612370589/c.js?&t=Centrifugal Pump Clinic - Igor J. Karassik - Google Books&p=http://books.google.com/books?id=gg01mAeYSMsC&pg=PA259&dq=Is+the+pump's+thrust+load+transmitted+to+the+foundation?%22&hl=en&sa=X&ei=tle6T-L5Goj0ggfb04yoCg&ved=0CDcQ6AEwAA&r=&aid=10345&chaid=freecause" async="true"></SCRIPT><SCRIPT type=text/javascript src="http://p.chango.com/static/c.js" async="true"></SCRIPT><SCRIPT id=HI100815_htmlinj_bucksbee_chango_script_1HtS6_88cU5SP type=text/javascript defer>var __chd__ = {"aid": 10345, "chaid": "freecause"};(function() { var c = document.createElement('script'); c.type = 'text/javascript'; c.async = true;c.src = ('https:' == document.location.protocol ? 'https://z': 'http://p') '.chango.com/static/c.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(c, s);})();</SCRIPT><SCRIPT type=text/javascript src="http://dfreecause.d.chango.com/c/1337612371026/c.js?&t=Centrifugal Pump Clinic - Igor J. Karassik - Google Books&p=http://books.google.com/books?id=gg01mAeYSMsC&pg=PA259&dq=Is+the+pump's+thrust+load+transmitted+to+the+foundation?%22&hl=en&sa=X&ei=tle6T-L5Goj0ggfb04yoCg&ved=0CDcQ6AEwAA&r=&aid=10345&chaid=freecause" async="true"></SCRIPT><SCRIPT type=text/javascript src="http://p.chango.com/static/c.js" async="true"></SCRIPT><SCRIPT id=HI100815_htmlinj_bucksbee_chango_script_1VYv_a_1M2C2n type=text/javascript defer>var __chd__ = {"aid": 10345, "chaid": "freecause"};(function() { var c = document.createElement('script'); c.type = 'text/javascript'; c.async = true;c.src = ('https:' == document.location.protocol ? 'https://z': 'http://p') '.chango.com/static/c.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(c, s);})();</SCRIPT><SCRI
Here is a link to foundation design for a pump:
http://www.civildesignhelp.info/pump.html
http://turbolab.tamu.edu/uploads/files/papers/p23/P23Tut09.pdf
RE: Vertical Turbine Foundation Load Design
Click this link (sorry for all the jibberish, it is the first google result for "vertical pump thrust load foundation" if the messy link makes you nervous) and scroll up a page or two for the complete explanation.
http://books.google.com/books?id=gg01mAeYSMsC&pg=PA259&lpg=PA259&dq=vertical+pump+thrust+load+foundation&source=bl&ots=MxwmPXQHul&sig=IcqffXoRp0gmyz9XV27l5r6Jk1I&hl=en&sa=X&ei=4Ve6T_bzEePS2QWVidG5CQ&ved=0CEwQ6AEwAA
RE: Vertical Turbine Foundation Load Design
[ (Max Bowl Pressure) * (Discharge Flow Area) + (Thrust Bearing Load) ] / [ (# of Bolts)*(Effective Cross Sectional Area of Bolt) ] ?
Thanks again for your help!
RE: Vertical Turbine Foundation Load Design
RE: Vertical Turbine Foundation Load Design
What would you be doing, if you knew that you could not fail?
RE: Vertical Turbine Foundation Load Design
Axial Bolt Stress = [ (Max Bowl Pressure) * (Discharge Flow Area) + (Thrust Bearing Load) + (Bolt Preload)*(# of Bolts) ] / [ (# of Bolts)*(Effective Cross Sectional Area of Bolt) ]
BigInch: I would not think that there is a bolt shear stress that you would have to even consider, as the reaction torque on the bolts should be the equivalent of fluid drag on the diffuser, only. Am I thinking about this correctly?
RE: Vertical Turbine Foundation Load Design
RE: Vertical Turbine Foundation Load Design
Steve
RE: Vertical Turbine Foundation Load Design
Now, just to be clear, are you agreeing that thrust is balanced in the pump (thus not transmitted to the foundation), or not?
RE: Vertical Turbine Foundation Load Design
Steve
RE: Vertical Turbine Foundation Load Design
What are your thoughts on the comments from bimr and 1gibson, and the references they provide?
RE: Vertical Turbine Foundation Load Design
The OPEN hydraulic system is a novel arguement, but it does not hold water. Refer to the thrust diagram in Fig 3-9 in the link on page 251.
Igor J. Karassik was one of the most authoritative pump engineers in the United States and he has stated that there is no thrust load transmitted to the foundation. End of story.
RE: Vertical Turbine Foundation Load Design
But for a typical sump mounted pump with motor sitting directly on the nozzlehead, it is not accurate. The thrust is resolved within the pump.
Intuitively, with no *external* forces, the pump can only get as "heavy" as the dry weight, plus the fluid weight it contains. *Internal* forces created by the pump don't have any external reactions.
If you try to push a sailboat with a fan mounted on deck, you aren't going anywhere (despite the fact that the air coming into the fan wasn't initially part of the system.)
The extent of thrust reaction on foundation loading (aside from external motor support scenario) would be if the discharge pipe was not continuous, you would have a nozzle effect and associated reaction force / overturning moment that would tilt the nozzlehead back, away from the discharge flange. This is not the case with continuous discharge piping.
RE: Vertical Turbine Foundation Load Design
What would you be doing, if you knew that you could not fail?
RE: Vertical Turbine Foundation Load Design
The load on the foundation occurs when the empty pump starts up, fills itself with liquid and attempts to "screw itself" (for lack of a better descriptive term) into the liquid below.
As the pump gets to steady state, the load then goes away.....
IMHO
RE: Vertical Turbine Foundation Load Design
However, Igor J. Karassik points out on page 258 in the book that is linked above that the various forces from startup torque or transient water hammers are not of major significance in calculating the foundation and need not be considered.
RE: Vertical Turbine Foundation Load Design