I've seen topics of 'move any machine'; movable (motor) or fixed (pump) whichever is easiest.

Generally a pump is set to elevation and level with having piping connected. So, if a pump is set to a specific elevation, level and piping afixed - any movement of the pump would require consideration for level and pipe stress.

Likewise, when we are bottom-bound and need to rasie a pump because we can't lower the motor we need to consider pipe stress, level and future subsidence.

Does anyone find this a problem in maintenance introducing vibration problems that weren't properly recorded during maintenane re-installation or refurbishments or asking for assistenance from engineering or techinical staff?

Do you find that records generally aren't kept properly?

Sam,

I find it is a rare plant that keeps any records of any kind, that can be found, on any modifications done in the field. Sometimes the electrical departments do now, but for mods done 10 or more years ago, there is hardly any hope of finding any records.

Dave

Well then; what about someone moving the fixed machine or what should be normally fixed? A pump let's say; it's set to elevation and level and piping afixed. It is no longer a 'fixed' machine for all practicle puropses. If subsidence were ever to present itself to enter a bottom-bound condition in the movable then movment of the fixed machine has a numbe of considerations, the least are not pipe strain and level. Without records - where are you? I like to see plotted graphical representations of machines in a folder somewhere. Am I alone? Surely not!

"I like to see plotted graphical representations of machines in a folder somewhere. Am I alone?"

Sam,

You are not alone in liking to see them, but in actually seeing them....maybe not alone, but you won't run out of turkey around that table.

Danny

Hello Sam. Yes, these days records are NOT kept properly! I'm affraid it's the old problem of not enough time and not enough people!
As a Maintenance Superintendent over thirty+ years, I have always given the lads time to complete records after a job, because I realised the importance for future reference. I had huge filing cabinets with a folder for every piece of running equipment in the refiney, 1400 pumps, 30 odd compressors, 200 steam turbines etc etc. As we did a job, all the field generated paperwork, alignment charts, comments etc came through me and were put into the appropriate folder. You can't do that with an "only computerised" system. Who's going to scan in all this in the field generated information? It's a duplication of work. You still need to have a full, hard copy system in place to facilitate future work and problem solving.

In 40 years in this business I can tell you that records rarely if ever are kept properly.

Another statement that I've worn out over the years is "inspection records usually have the correct numbers."

In short, don't trust anything unless you measured it yourself, did it yourself, or actually watched it being done.

John

Sam,
'Move any machine'; Generally we will move the driver, even in the case of a turbine driven pump.
'elevation'; We have sometimes put shim under a pump, however, we don't find that the piping is free from stress anyway. It depends on the original installation, which is not likely to be a very high standard.
'Bottom bound'; I aligned a bottom bound motor to a pump yesterday. It wasn't much, it was 12 thou high. I pitched the back of the motor upwards to assist the pump and motor centrelines to meet at the middle of the coupling. The alignment chart showed that the parallel versus angular misalignment was in the acceptable area of the graph.
'Vibration problems'; I haven't found that this solution introduces problems. It may reduce life of the bearings by a percentage, but, up to now, not significantly enough to register.
'records'; Snap! in general, our records are in a lamentable condition. Our best records were kept by an engineer who retired about five years ago. He refused to have a computer in his office.

As you say; 12 thousandths isn't much but still a consideration. In the case where you may have pipe stress, the 12 mils may work to your advantage or against it? Regardless, not a bad idea to check piping and correct as necessary. RE: not changing bearing life - if you're approaching L10 life then OK but swapping 2 yrs for 2 yrs isn't an improvement. Not being critical as you gave no numbers but extending MTBF is a goal of PdM.

Ever run into Malcomb Graham or John Raby in your neck of the woods?

I spent the first 14 years of my career in power plants (large steam) and had the good fortune of doing start-up work on 4 units. So I had a chance to see things "done properly" (usually). When I left and went out on my own, I was shocked to see that most plants don't do things that way.

Most of the plants I work in now have no concept of 'pipe strain' much less any records. I find it very hard to get any movement -- vertical or lateral -- out of pumps when I try to move them, usually only as a last resort when the motor is hopelessly bolt-bound. After I take my first set of readings (with a laser usually) I do actually hand plot the centerlines, showing the required moves for the 'moveable' machine. Often moving one foot of the 'fixed' machines a few thousandths has the same effect as moving the 'moveable' machine a large distance. If so, I will often attempt the small move of the fixed machine if it looks feasible.

Fan bearing moves are usually easier (than pumps) but you have to watch housing seal clearances and watch out for rubs of the wheel on the inlet or discharge cones. If you have plenty of clearance, it's usually pretty easy. And you have to watch that you don't misalign the bearings during the process.

You don't have to reorient the laser or anything... just make the move indicated by the graphical plot, and take the readings again. The laser (or any other alignment system) is a fine tool, but only one of many you should have in your alignment toolbag.

Generally if you're going to move the pump: it is for a specific reason - bolt bound etc...

I usually treat it as a new installation as I don't want the same problem next time the alignment task is performed. Set the pump high enough to avoid future bolt-bound problems and set it in the center of its bolt-holes. Remove all stresses; pipe and soft foot. Now align the motor to the pump and future subsidence problems should be as "new installation".

Fan bearings are a different can of worms so to speak. The fan rotor needs to be sitting properly in its housing and around the shroud or inlet nozzle with proper spacing so moving the rotor end bearing causes massive shifts and if you chose to move the fan's bearings then you have to contend with rotor alignment, bearing to shaft alignment and bearing to bearing alignment which on some bases is a nightmare as the soft foot correctons for base's warpage is now a new consideration on some rare base problems, never-the-less a consideration.

I was wondering if any of you guys have read the article in the November 2006 issue of UPTIME MAGAZINE on alignment?

"Alignment Modeling Basics" by John Piotrowski.
On page 34 there is something mentioned about moveable and unmoveable machines.

Not sure if I get that anymore... didn't see the article. But I'll bet that somewhere in the article he said something to the effect that "dial indicators are superior to lasers"...

You can subscribe to Uptime electronically at
http://www.uptimemagazine.com/

Once you subscribe and get emailed a link, you can access all the old articles. It's an electronic magazine, so you'd better have a fast connection. And you can't download the file, unlesss you work at it.

Attached is the article mentioned. See pages 5 and 6 regarding moveable machine discussion. I don't think there is any copyright problem here, but please let me know if there is.

UptimeMagNov06_AlignmentModelingBasicsPiatrowski.pdf (1,602 Kb, 28 downloads)

Great article.... my apologies to John, as he didn't even mention lasers (I don't think... the pdf is not "searchable"). His alignment handbook is must reading... chock full of good ideas and techniques, even if you use a laser. I have intuitively used his methods which are really just common sense, but he does a great job of explaining things. His illustrations are especially well done and easy to understand. Highly recommended.

I can't say I subscribe to "move any machine" as though it were normal and the same as the normal movable machine. It isn't. The pump is fixed and should be as it is connected to piping and set elevations and consideration for level. To do it correctly you would have to disconnect the piping and move within elevation parameters or specifications and consider level. Some machine trains (turbine and pump for example) may have piping considerations for both machines, uneven thermal growths and level considerations that require offsets for both to have them grow into level and alignment. But you don't just move a machine without taking some things into account.