What is the real reason behind establishing a perfectly level (2 mils/ft) pump baseplate? I totally understand the reasoning for the tight tolerances on alignmnet but, functionally, if you achieve proper shaft alginment, soft foot, and pipe strain, why does it matter if the baseplate isn't perfectly level?
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Baseplate Leveling
- Thread starter jdogg05
- Start date
Thermal expansion and growth of the frame begins at the base plate and goes on upward. Base plates will bend where they are not well an uniformly supported and the resulting growth of the frame as it warms up from base plate to the rotating axis will not be uniform, so the shaft will be forced out of alignment every time the pump runs.
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It establishes an easily measured reference that can be used for for all other measurements and minimizes shimming required alignment. Think of all the extra work if the baseplate were 5 degrees out of level.
Unless the point of measuring the +- level of the baseplate has been machined at the same setting as the mounting points for the pump / motor - cannot see any major advantage.
An installation spec. should be specific and say, the mounting pads should be level with +- tolerance, however this should be used with some discretion as the most important aspect is the pump / driven alignment.
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.)
An installation spec. should be specific and say, the mounting pads should be level with +- tolerance, however this should be used with some discretion as the most important aspect is the pump / driven alignment.
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.)
I get what you're saying. These tolerances are really installation specifications; guidelines for construction contractor to owner/user agreements. Not mandatory, but beneficial in establishing proper soft leg and alignment.
To achieve this on a poorly leveled base plate would be tedious, but if you say you can do it, with minimal effort, then why bother with having a level baseplate, if the one you have now causes no issues.
- Thread starter
- #7
I guess another important point to make would be that you only get one chance to level the baseplate. After it is grouted, that's it. It would help elminating all future shimming, alignmnet, thermal growth distortion issues later on. Also, in the case that the pump and/or driver need to be replaced, you will have a solid, repeatable surface to work off of (an unlevel baseplate that worked for one particular pump/driver combo, might be horrible for a different set of equipment).
In my opinion, the spec relates to having all of the equipment mounting surfaces parallel and less to do with absolute levelness. Having said that, I would accept a baseplate the was .005/foot (or more on smaller utility pumps) out of absolute level as long as the equipment mounting surfaces were parallel and the slope was towards the baseplate drain. The immediate problem with mounting pads that are not coplanar is point contact of the equipment mounting feet.
Bingopin raises a very valid point, as well as being level within an acceptable tolerance, more importantly is the relative position of the pump / driver pads as machined (assuming the location pads have been machined) and the baseplate is not hogged, bowed or twisted.it is possible to have the pump pads level but not at the correct height realtive to the motor pads or vice versa, this can negate the designed centre heights of the components in relation to each other. An important consideration as some specs. are very specific as to the amount of shim under the driver.
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.)
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.)
- Thread starter
- #10
In regards to bingopin's point, I see what you are saying (btw, my reference was to API 686 in regards to this leveling business). I guess it wouldn't necessarily be that bad for the operation of a particular pump/driver (as long as the alignment, soft foot, pipe strain, etc. were adequate) if the baseplate were not level, or more specifically horizontal, as long as the surfaces were complanar with respect to each other. I think the reason these specifications make these requirements for horizontality (if that's a word lol) is becauce it's simply the easiest reference point. When measuring the coplanar relationship between pads, a precision machinist level will read "0" at exactly horizontal.
I thank everyone for their input. Problem solved!
I thank everyone for their input. Problem solved!
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- #12
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