Failure of turbine blades

There are two identical turbines operating in India of 16.5 MW rating since 1977. In one turbine, turbine blades have failed five times while there is no failure in the other. The blade's strenght and other testing were carried out but no abnormality was observed. Normally, one turbine is in service and other turbine is on stand by. This is a back pressure turbine which supplies steam to the process of a chemical industry. There are two extraction lines, one is controlled extraction and other is un controlled extraction. Extraction steam going to the HP and LP heaters. HP and LP heaters and deareator are common for both the machine. What could be the reasons of frequent failure ? Is it is process oriented or manufacuring related ? Kindly reply
(A.K.Sinha)

 

[VibrationSpecialist]

Dear Mechanical Engineer,
What is the failure type?
What is the operating scenario in terms of turn around?
What is the piping lay out? Any differences?

These are just questions that you may start find reasons through the course of investigation.

Take Care

 

[Franko]

Mr. Sinha
Are these variable speed mechanical drives for compressors/pumps or are they generator drives? Which turbine stage failed in the five failures? Have the failures been confirmed to be due to high cycle fatigue? Does the unit that fails have either much more standby or operating time?
fkushner@elliott-turbo.com

 

Dear Mr. Franko,
Thanks for your response.
This machine is not variable speed drive.
In this machine, there is a single rotor having HP and LP section.
There are 15 reaction stages and one curtis stage in LP section. Failure is taking place after curtis stage. There is one extraction line after curtis stage.
Yes the unit in which failure take place mostly remain on stand by.

 

[walkerny]

Could you tell me the name of the Plant, and a contact?
joe.walker@storkhe.com