In one of my pump turbine drawings, I found a note stating “Final hot alignment of the turbine and driven equipment must be based on actual shaft rise at steady state conditions”.

What is hot alignment? If I presume hot alignment is nozzle alignment after system warm up- is hot alignment required for all rotating equipments?

Forum members kindly throw some light on this….

My experience in the field with pump installations are:
- poor pump to motor alignment can cause leakage of the seal and performance can decrease
- poor alignment can be due to pump casing growth in relation to motor shaft position, therefore misalignment can occur after a cold installation
- poor alignment can also occur due to substantial nozzle loads, so if the pipe inlet experiences substantial thermal growth, it can put loads on the pump casing which will cause shaft misalignment

So therefore aligning the pump to motor once the system is warmed up can improve the installation, however there are plenty of other installation issues that could adversely affect performance.

Having said that, I never had to do any hot installations, but the hottest system was about 70-80 deg C. Most of the installation issues I experienced were misaligned flanges (up to an inch sometimes) due to old piping having moved over the years.

In answer to your question, I don't think hot alignment is required for all rotation equipment. I am sure some clients and consultants would have procedures for systems at particular temperatures.

Good luck.

EDIT: and forgot to say that I know you're query is in relatino to compressors, but I think some of the issues are common.

HI DUDE,

good answer