Modification of Bearing Pedestals
Modification of Bearing Pedestals
(OP)
I recently reviewed a consultants report concerning our steam driven boiler feed pumps at one of our generating stations. We have had vibration problems with these pumps over the years. The pumps were supplied by Byron Jackson and are 14X14X16 4 stage boiler feed pumps.
The recent evaluation consisted of gathering vibration/impact data to generate an operating deflection shape (ODS) under operating speed conditions.
The main conclusion from their study is that the pump pedestals are twisting from a natural frequency imparted by the operating speed range of the pump. To correct for this problem, it was recommended to stiffen the pedestal support legs by welding stiffener plates or filling the cavity in the hallow legs with concrete.
My question is... what type of concrete should be used because I am concerned regarding shrinkage and flexing strength. Is their a recommended concrete for this type of specific application?
The recent evaluation consisted of gathering vibration/impact data to generate an operating deflection shape (ODS) under operating speed conditions.
The main conclusion from their study is that the pump pedestals are twisting from a natural frequency imparted by the operating speed range of the pump. To correct for this problem, it was recommended to stiffen the pedestal support legs by welding stiffener plates or filling the cavity in the hallow legs with concrete.
My question is... what type of concrete should be used because I am concerned regarding shrinkage and flexing strength. Is their a recommended concrete for this type of specific application?





RE: Modification of Bearing Pedestals
This is only my opinion,
Roy Gariepy
Maintenance and Reliability Dept.
Dorlastan Fibers LLC.
Goose Creek, South Carolina USA
RE: Modification of Bearing Pedestals
RE: Modification of Bearing Pedestals
daveleo
RE: Modification of Bearing Pedestals
I'd be real careful not to interfere with any of the manufacturer's provisions for thermal expansion.
I doubt you can get the manufacturer to bless any design change. Have you checked to see if they offer any special service revisions you can buy?
RE: Modification of Bearing Pedestals
Having said that, my experience has been minimal effect from filling the pedestal with concrete or other material. Stiffening with steel is probably better but keep in mind that the stiffness value is dominated by the most flexible member in the system and stiffen accordingly.
RE: Modification of Bearing Pedestals
RE: Modification of Bearing Pedestals
RE: Modification of Bearing Pedestals