Dear all 

We have an issue  high vibration on BRG #2&3 ,  finish the Major Inspection on this unit when we start the unit , at FSNL ( 3000 RPM ) the vibration for BRG # 2&3 stable not exceed (6 mm/s ) , when the unit is loaded the vibration increase on BRG 2&3 Only , at full load the Vibration reach on BRG # ( 9- 13 mm/s fluctuating ) and BRG #3 ( 7- 8.5 mm/s ) , and in the MI inspection we made casing Alignment as recommended from  manufacturer GE because when open the unit we found the BRG # 2 is damage from Upper haif and BRG # 3 is damage on lower haif and there is oval on AFT compressor casing and before open unit the vibration on BRG # 2 reached ( up to 19mm/s ) , all bearing replaced BY new ones and the vibration still , please to advice me to know what is the cause of vibration .

note : all vibration on BRG # 4 & 5 are smooth not exceed  (2mm/s )at Full load 

thanks in advance 

Original Post
Ahmad alfakeer posted:

Dear all 

We have an issue  high vibration on BRG #2&3 ,  finish the Major Inspection on this unit when we start the unit , at FSNL ( 3000 RPM ) the vibration for BRG # 2&3 stable not exceed (6 mm/s ) , when the unit is loaded the vibration increase on BRG 2&3 Only , at full load the Vibration reach on BRG # ( 9- 13 mm/s fluctuating ) and BRG #3 ( 7- 8.5 mm/s ) , and in the MI inspection we made casing Alignment as recommended from  manufacturer GE because when open the unit we found the BRG # 2 is damage from Upper haif and BRG # 3 is damage on lower haif and there is oval on AFT compressor casing and before open unit the vibration on BRG # 2 reached ( up to 19mm/s ) , all bearing replaced BY new ones and the vibration still , please to advice me to know what is the cause of vibration .

note : all vibration on BRG # 4 & 5 are smooth not exceed  (2mm/s )at Full load 

thanks in advance 

please to help me ???

First, I think you should give us some data (APHT trend, waterfall, SCL, orbit... if any)for review and also the arrangement of machine. I do not know where is bearing#2 or 3 and so on. 

You said that the casing have done bore alignment due to center of bearing housing 2 and 3 is not coincided. How about the alignment result and how about the rotor center position check (done at some hole on casing). how about labyrinth clearance at both side of bearing? how about the phase?

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