Misalignment on running machines can be identified by a series of symptoms such as high vibration levels, coupling wear, oil leakage and abnormal machine temperatures. When you recognize any of this you can suspect misalignment being the root cause. As a rule of thumb shaft alignment should be carried out every time a coupled machine’s hold-down bolts has been loosened.
- New installations
- When a machine has been on service/repair
- When auxiliary equipment has been attached (such as piping to a pump)
- After coupling replacement
- …and of course if you recognize any of the above symptoms
OF COURSE IT’S ALIGNED….IT’S NEW
During training classes, it sometimes happens, that the class wants to check alignment of recently installed pumps. Their response always is, “It’s brand new, so it must be aligned, right?”. To which we respond, “Bet it isn’t”. See an example of results on Fig.1
For an 1800 RPM machine the maximum allowable angular misalignment is +/- 0.7 mils per inch and a maximum allowable offset of +/- 4.0 mils in both the vertical and horizontal planes.
The vertical angle is almost 3 times tolerance with the horizontal angle almost 13 times tolerance! The vertical offset is 13 times tolerance and the horizontal offset is 20 times tolerance!
Never trust that a newly delivered machine is aligned. Even if it has a tag saying it is. The company you purchased it from may say it is, but that is based on the conditions, when it left their facility.
Even if it was aligned correctly when it was installed, lots of things can happen between the factory floor and your plant floor.
- Machines can be moved to connect piping, ductwork, etc.
- Bases and piping can cause the alignment to be moved.
- Several hundred miles of hauling the machine down a highway can change the alignment.
- And their degree of alignment may not match yours.
We recommend aligning machines as soon as they are unloaded from the truck, whenever possible. Not only can you verify if the alignment is now “good”, you can correct any bolt bound or base bound problems before any additional components, such as piping and conduit are installed. After all the accessory components are installed, check it again!