HamzaNossair
Mechanical
- Feb 26, 2012
- 25
Hello Everyone,
I hope someone can give me some inputs on my following question.
25 MW motor, which has common lube oil system with a compressor and a gear unit.
Supplier is saying that we will have as good properties with cylindrical bearings as with 2-lobe bearings.The cylindrical bearing is robust, requires lower flow and pressure?
However, with cylinderical type, there is a deviation from API 546 regarding not keeping 15% critical speed margin, they are saying it is normally damped although this 2nd critical is just 5% above 1800 RPM?!
The good point about the 2-lobe bearings, it will comply with API requirement for 15% separation margin, but it requires 2-2.5 bar pressure which we can't acheive during machine cost down, unless we add oil ring which will boost the pressure during cost down??
Cylindrical bearing will not comply with API requirement for 15% separation margin, but it requires less pressure; typically 0.7 bar.
I hope someone can give me some inputs on my following question.
25 MW motor, which has common lube oil system with a compressor and a gear unit.
Supplier is saying that we will have as good properties with cylindrical bearings as with 2-lobe bearings.The cylindrical bearing is robust, requires lower flow and pressure?
However, with cylinderical type, there is a deviation from API 546 regarding not keeping 15% critical speed margin, they are saying it is normally damped although this 2nd critical is just 5% above 1800 RPM?!
The good point about the 2-lobe bearings, it will comply with API requirement for 15% separation margin, but it requires 2-2.5 bar pressure which we can't acheive during machine cost down, unless we add oil ring which will boost the pressure during cost down??
Cylindrical bearing will not comply with API requirement for 15% separation margin, but it requires less pressure; typically 0.7 bar.
