The machinery mounts are adjustable for a reason and it never hurts to check

Agreed but when you are maintaining a plant with 2000 pumps. Its not practical.

machinery practice is that machinery alignment is done at first installation and threafter whenever pump or motor is out for maintenance, a realignment is done.

So far I've not encountered a practice of calendar base alignment checks; thats the reason of posting this query to see what other organisation are practising.

Thanks

I've included alignment checks in our PM, but not a full blow re-alignment, I've taken say a tooling bar and attached to a machine spindle and checked for runout and/or taper against two of the three axes, if something showed wrong, then it was a complete re-alignment

If nothing showed wrong, then I had to assume the machine was still in alignment.

I suggest you give each piece of equipment a good hard look, then find one, or two checks that you think you can do quickly, (less then one hour down time.) and if that check showed good, they your good to go.

I wouldn't wait for a breakdown to find out you have a problem that defeats the idea of PREVENTIVE .....

If you are doing a monthly vibration check there is no need to do a monthly alignment check. The vibration will let you know if you have a problem.

Even without vibration, I would only check alignment on reinstallation.

Dear Steve S.

You are right, where in most cases, the vibration is a good pointer to the presence of misalignment. May be there are another reasons for vibration depending on the type of events happening to the flow such as water hammer, slug flow, and two-phase flow and other events related to the type of equipment such as cavitation in case of pumps.

So, I agree with your recommendation "If you are doing a monthly vibration check there is no need to do a monthly alignment check".

Annual was the calender period I thought we were discussing for alignment checks oops. Some plants though having footed mounts are on shifting sands at best and alignment checks if assigned proactively are the best preventative...

Your replies are interesting.

You are right bwire, our guest was not specific as to how often.. he also was not specific as to what kind of plant. I assumed a process plant with a lot of pumps and what not, and in that case, even an annual alignment check is probably not practical. But it certainly makes sense to check it if the vibration changes drastically, or if the machine has been worked on.

Correct you are Steve S.,

A plant with a lot of pumps and or coupling driven equipment in and area of frequent seismic adjustments, machinery alignment may be time and labor intensive. There exist however alignment testing devices which may also be employed as indicators. The devices when used as indicators can be integrated with control features which could stop, slow down or restrict operation of the specific equipment if misalignment occurs.

I would think that it would depend on the type of equipment.

Here we weld plastics together. Alignment of the weld is critical for appearance. It all so insures a good weld. So in this application yes checks are necessary.

That suggestion is very general, lacks experience, and can result in unnecessary repairs.

As mentioned in other posts, It depends on the equipment.

It also depends on a number of other factors:

• how critical is the equipment?
• what is the life expectancy of the equipment?
• what is the work cycle of the equipment?
• what is the environment the equipment is operating in?
• what is the failure rate of the equipment?
• will PM significantly increase the life expectancy?
• what is the cost of the PM as compared to replacement of the equipment?
• What does the warranty require?
• what was recommended by the manufacturer?
• Will PM cause more problems then it solves?

And many more. Since all these factors will affect the maintenance procedures and will be different for all equipment, only a in-depth study of your equipment will give you the right answer.

I have spent my whole 30 year career maintaining multiple systems of all levels of complexity. The old standard was to indeed have periodic maintenance checks or alignments on critical equipment, and planned maintenance made significant improvements in the longevity of some systems. Other equipment, it caused unnecessary repairs or misalignments, shortening its longevity.

The latest standard is monitor the performance to tell you when alignment is required.

"The latest standard is monitor the performance to tell you when alignment is required." Well said...

If one opt for this condition monitoring strategy, the frequency of PM check for vibration monitoring is very important.

Worst consequences of misalignment is vibration, the victims are mechanical seal, bearing and equipment at large.

Once vibration starts (due to misalignment in this discussion), how fast it will get worse to the extent of loosening the fasteners including holding-down bolts, is subjective. The time between the 'Potential failure' to 'Functional failure' (PF interval) could be only couple of weeks or even days.

In such case, if the PM inspection is once in 3 months, we might probably miss catching up this failure at an earlier stage.

So the key is: PM frequency should be comfortably shorter than the PF interval.

Regular V.A. checks can pick up misalignment. We have hundreds of pumps here and one of our biggest assets is Laser Alignment gear. Done right it gives more life and reliability to seals,pumps and motors.

Rex Dev.

When an alignment is complete, I like to have the mounts dowel pinned to the base. This should guarantee your alignment until the unit is replaced.

We do not have a regular program to check alignment on most of our many pumps in the paper mill. If pm program has a need such as over amping in the motor or excessive heat or vibration or if we are swapping out a motor or pump, fan etc. we will always check the alignment. On some of our bigger (1000hp-2500 hp) we do check the alignment every time we get a chance and the motor is down. We use digital equipment for most of our alignments and require this by any contractors that do work in our mill and their work is checked and signed off by one of our PM engineers before it is put back into service.

pipewelder