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pump baseplate levelness

pump baseplate levelness

pump baseplate levelness

Hello everybody,

In pumps with at least one vertical nozzle (like OH2), can I use, for example, discharge nozzle to level the pump baseplate (pump + motor skid) ? I don't have room on pump foot mounting pad to use precision machinist level and also don't want to remove pump or motor from base?


RE: pump baseplate levelness

IMO, you may need to use both Suction and Discharge nozzles as references for leveling pump.
Should verify with the Pump vendor and Installation Guide for details.

RE: pump baseplate levelness

Thank you mk3223. Do you think this is acceptable in API 686 to use flange for skid levelling?

RE: pump baseplate levelness

Usually what is most important on a new installation is the suction flange face being vertical and the discharge flange horizontal, irrespective of the baseplate, on an existing installation the inlet and discharge flanges need to be positioned to suit any existing pipework so as not to introduce any strain into the pump case.
In the real world, the baseplate position is really a secondary consideration irrespective of what standards / procedures may say - they are a guide to ensure some comformity.

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.)

RE: pump baseplate levelness

Thank you Artisi. My problem is the baseplate does not have any machined surface that can be used for leveling the skid. Pump and Motor mounting pads are not extended enough that we can put machinist level on the edges. So the only way to make sure the skid is level is to remove pump or motor and use the machined surface under their feet. So I basically want to avoid removing pump from the skid and use the discharge flange facing(in OH2 pump)to level the skid and then do the necessary checking and adjustment for inlet/outlet piping spool with pump nozzles. Is this acceptable by API 686?

RE: pump baseplate levelness

Just fyi, per Annex. E , page 5-27 of API 686 , there is a Note : "Use only equipment mounting pads for determining level. Never use nozzles or baseplate rails.". So I'm a kind of puzzled here that in my situation, am I allowed or is this acceptable to use flange facing for leveling the skid?

RE: pump baseplate levelness

I have no idea what API 686 says, can only assume that by checking the baseplate is to ensure its not hogged or bowed, why are you using this standard?

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.)

RE: pump baseplate levelness

I don't know the answer.

Here's some reasons why level is important: If there are oil lubricated bearings, lack of level could affect relative heights of oil in the bearings vs oiler vs (if present) sightglass. Also perhaps oil ring operation may be affected slightly by out of level condition. Whatever role levelness plays in establishing initial vertical angular alignment with driver pads (which will also be checked level) is not that critical since misalignment will be corrected with shims under motor during alignment.

I doubt there is likely any significant lack of trueness (perpendicularity or parallelism) between pump mounting feet and pump flange surface. So what is the reason for the API requirement? The one thing I can imagine is that you can check level more accurately when you have a long horizontal span (like between mounting foot pads) vs a shorter horizontal surface (such as a flange). Maybe the API standard you mentioned prefers the longer measurement location since it's more accurate... in pursuit of perfection. Personally I don't think it makes a huge difference.

(2B)+(2B)' ?

RE: pump baseplate levelness

The pump may be mounted on shims which would make the nozzle not parallel with the base.

RE: pump baseplate levelness

- We are using AI 686 as dictated by Project. But since the baseplates do not follow API requirement that each mounting surface shall be extended at least 25 mm (1 inch) beyond the pump and driver feet to facilitate the leveling of the baseplate without removing the pump, drive, or auxiliaries, I might be able get away from 686.

- The pump is not big, in fact is relatively small and the skid is not that long.

- There are no shims under pump feet.

RE: pump baseplate levelness

Standards need to be a catch all. Some pumps may have shims, some may not. It's easiest to say don't use the pump as the leveling dimension.

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