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Shimming the pumps 1

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extremechanical

Mechanical
Sep 8, 2009
65
Hi Experts,

API 676 para 7.4.16 does not allow shims beneath the pumps ( for Positive displacement) and similarly API 610 6.3.4 for centrifugal.

* May I know if API 686 also does not allow shimming beneath pumps?

* Other than pipe strain is there a reason why shims are not allowed?

* I am also told shimming should be avoided more so for API 676 pumps ( PD pumps ) than centrifugal, is this correct?

* We have a vertical VS6 Pump and I am planning to shim the gap between sole plate on the foundation and the mounting plate which is part of the can. Is this also not allowed? Someone said it decreases natural frequency. May I know why?

* Could anyone also confirm the reason for limiting the thickness to only 3 mm



Thanks a lot in advance !


 
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Err, section 7.3.6 of API 610 11th edition specifically allows shims beneath pump baseplates. I couldn't find any reference in 6.3.4.

True it doesn't allow them under the pump, probably because something needs to be fixed before you move the other component around and the pump could suffer more from strain if you get it wrong than the motor.

It says at least 3mm and a max of 15mm.

don't know much about 676, but double check your references and what it says.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way
 
LittleInch, My mistake , it is para No. 7.4. 16 of API 676 which says, no shims allowed, unless specified. As far API 610, it is para 7.3.6 . Sorry again

Thanks for your reply, but any more information please?

 
Re-grout the sole plate at the correct height and levelness.

7.3.6 (all of 7.3 actually) is in reference to baseplates for horizontal pumps only. A VS6 pump does not have a "baseplate" it has a "mounting plate." See fig.38 in 610 11th for mounting arrangement and 9.3.8.3 "Mounting plates" for the vertical pump equivalent of 7.3.

A sole plate is a type of mounting plate that is a separate component from the pump can, it allows the can to be removed/reinstalled without messing with grout, or having to worry about re-leveling every time.
 
1Gibson, Thank you.

You are right here the mounting plate is integral part of the can which rests on the sole plate. Hence it is a part of the static can. so we are basically shimming two static components ( grouted sole plate ) with can's mounting plate.

 
Horizontal API pumps are centerline mounted machines; meaning the bottom of the pump "feet" are on a horizontal plane with the pump's shaft centerline. They are mounted on a very sturdy pedestal welded to the baseplate. This is done to keep any thermal growth centered on shaft plane to keep from distorting alignment. You wouldn't want to upset that with shims; also, motors can be changed out to different sizes on the unit, so keeping shims only on motors makes more sense.

Terminologies have meandered all over the place on sole plates, foundations plates, and leveling plates for vertical pumps. No matter what you call them, there should never be shims on vertical pump installations if properly installed. The main issue in mounting a vertical pump is to make certain the pump lineshaft is hanging ABSOLUTELY vertical.

For a can pump, there should be a foundation plate which is bolted firmly into the foundation, whether concrete or structural steel, and should be set ABSOLUTELY level. The bottom edge of the can's flange will be bolted to the foundation plate; it is assumed the can flange is ABSOLUTELY perpendicular to the can's axis. Next, the Pump's discharge head will be bolted to the top flange of the can's falnge; both of these surfaces should be machined flat also (usually to an RMS spec).

Sole plates (in old time terminology) were for use on cast iron discharge heads (not can pumps) to provide a machined surface to bolt to, and one that could be leveled no matter what the underlying surface's flatness was.

Why you would ever shim a PD pump, I don't know.
 
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