Shims under pump?

[billbusy]

I am working on some Large ANSI pumps (slurry pumps) recently.
One question is about shimming the pump.

I suppose during the shipping, some baseplates are deflected. Thus when we check the soft foot for these pumps, many of them are beyond 2 mils.
Normally we use API 686 as a practice standard for all pumps installtion.

As per API 686, there is no prohibition for shimming the pump although API 610 7.3.6 mentions that shimming pump is not allowed.

1. As these are ANSI pumps, any one have experinces with shiming the pump?
2. Why shimming pump is not allowed in API 610?
3. Besides machining the baseplate in the field OR shimming the pump, any other good ideas on how to solve the soft foot issue?

Thanks for any input.

MSc. Mechanical Engineering;
8 years EPC experience;
Oil & Gas industry in Canada.

 

[Artisi]

Good engineering practice is the firstly mount the baseplate so that the mounting points are all in their appropriate location to each other. That means the baseplate isn't twisted, hogged or bowed.
This requires the baseplate to be carefully installed into its location with some care, not just dropped onto the floor/ plinth and then bolted down, it could require shims / packers under the baseplate to achieve a correct installation.
Spending some time with the baseplate installation will pay dividends later then it comes time to align the pump and driven.

Shims under the pump is or should be discouraged as not necessary. If you look at pump base to centre dimensions the tolerance is or should be minus zero plus xxx whereas the driver should be reversed, plus zero minus xxx. This ensures the driver height is always lower than the pump, this should also be a consideration in the pump / driver baseplate relative heights for manufacture.
If you have a soft foot issue, either the baseplate isn't installed correctly or you have a poorly manufactured baseplate.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[MJCronin]

What does the pump vendor recommend ??? Is this a used pump ? Where is that local pump rep who sold you the pump ???

Have you found an installation/operating manual on the internet ??? Who makes the pump ????

Large, expensive pump installation is NOT a matter where the client relies on the memories-recollections of the installer.

Goulds Pumps allows and recommends shims in certain installations...... There are no general industry rules recommending or banning shims.

MJCronin
Sr. Process Engineer

 

[pennpiper]

How to install a pump:

https://www.google.com/#q=how+to+install+a+large+pump

http://www.mcnallyinstitute.com/14-html/14-08.htm

Sometimes its possible to do all the right things and still get bad results

 

[electricpete]

I can't imagine that shimming would be worse than leaving a soft foot (as long as shims are properly selected and installed). But I guess the issue is how it reflects on the quality of a skid assembly received from the manufacturer (and why should you have to fix it after it arrives)? Can you provide more info on the specific requirement in API 610?

=====================================
(2B)+(2B)' ?

 

[Artisi]

My experience with pump/driver installation/alignment caused by "soft-foot" problems,bowed or twisted baseplates can usually be traced to a poorly installed baseplates - as pointed out in an earlier post, time spent on careful and correct installation of the base prior to even considering aligning the pump/driver will usually pay dividends in the long run.
Irrespective of how "rigid" you might consider the base to be, poor installation can/will create problems.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[1gibson]

It is not unusual for baseplates to "move" during shipment or installation. API 610 11th allows purchaser to specify a flatness check in the shop, but then immediately mentions that it can be affected by transport, handling, and installation that is beyond pump vendor's scope. It is unlikely that this would be considered warranty work for the pump vendor.

Shims are definitely better than soft foot, but the correct fix is to skim the pump pads, and then compensate for the reduced height by using thinner shims on the driver.

 

[TenPenny]

Are these pumps large ANSI pumps, or slurry pumps?

Not that it matters, but just as a point of interest, at one time, Goulds would supply ANSI pumps with 1/8" shims under the pump. I'm pretty sure that practice has ended, but it's still relatively common.

You're talking slurry pumps, and then using API specs to evaluate them? Good luck with that. Remember that slurry pumps are designed to allow for wet end wear, so the wet end is designed to be taken apart/removed for maintenance.

 

[billbusy]

yes, like 600HP slurry pumps

MSc. Mechanical Engineering;
6 years EPC experience;
Oil & Gas industry in Canada.