November 24, 2015
Proper Installation is Essential to Equipment Reliability
By Alan Lashley
Performing precision shaft alignment correctly the first time is crucial to the longevity of your equipment and your long term cost savings.
New installations suffer greatly from infant mortality rates if the proper installation procedures are not followed. Most common causes are lack of follow up on the essentials, such as proper foundation work, elevations, and grout work.
Most if not all currently installed pumps, blowers, and fans have been in service for many years and frequently are the source for your repeat failures due to the fact that “back in the day”, precision maintenance was not thought of as being necessary. Terminology was “get it close and let it run. “ As we all know this is not good business practice and proper repairs have to be made. The best constructed base is not good enough unless it is installed properly and grouted correctly. I have been to locations where bases have no grout left due to years of deterioration or erosion, and the best alignment you can have will not last because the vibration will take its toll and lead to other factors and then you have another failure at some point.
Advances in technology have come a long way to better serve the rotating equipment industry. Smart phone users have apps available to them to calculate thermal growth, determine Off Line 2 Running conditions, and torque wrench configurations to name just a few.
Many of the motor manufacturers do not leave enough room to get a socket in the space to torque the foot bolts, so you have to use a crows foot to accomplish this and we all know what happens when a large torque has to be applied, after a few torque reps, the corners of the bolt or nuts start rounding. My mechanics began having trouble with this and started to use box end wrenches to tighten foot bolts and the end result was inconsistent readings and nonrepeatability issues with the laser alignment tool. We use the Fixturlaser XA Pro and NXA Pro. I equipped them with a set of box end torque wrench extensions to help solve this problem. These extensions are 4” long, but only have a 3/8” drive end and ¾” is the max size.
There is a very good smart phone app that will let you figure the extension length added to your torque wrench and calculate your correct torque value for your cap screws. You can be creative with your larger size cap screws and how you fab tools using old end wrenches you cut off, flat hammer wrenches, etc. You can vary the length to accommodate for the torque multiplication.
We are currently expanding our facility and are applying these new techniques to our new rotating equipment installations. Paying attention to detail, making sure all elevations are correct, base plates are installed correctly, fabricating transfer punch tools for motor feet centerlines after the rough alignment has been done for the horizontal offset, and starting with a 0.125 shim under motor feet, and stationary feet. Verify your shims even though they say precision, mic them to be sure as I have seen variations that will cause headaches. We are doing a pre grout alignment, and a final alignment after grout and piping is connected, checking for pipe strain. I have had positive results following these guidelines and procedures and hopefully this will help others in the future.