GE MS6001B, Maintenance Instructions Manual

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Inspection and Maintenance — GEK 107048 Scheduled Turbine Maintenance
STM-12
SPECIAL INSPECTIONS
Provisions have been built into the GE MS-6001B heavy duty gas turbines to facilitate the conducting of sever-
al special inspection procedures. These special procedures provide for the inspection and measurement of
some of the critical internal turbine components without requiring removal of the turbine outer casings.
Nozzle Clearance Measurements
A one-inch diameter hole has been provided through the turbine shell and shrouds at a location between
the afterside of the second-stage nozzle and the forward side of the second-stage turbine wheel and at the
afterside of the third-stage nozzle and the forward side of the third-stage turbine wheel. The 2F1 and 3F1
clearances found at these locations, can be measured using a special taper gauge in conjunction with a
borescope.
The 2F1 and 3F1 clearance measurement and monitoring service can be obtained by contacting your local
GE Company Field Service Representative.
Eddy Current Testing
GE Company has developed an inspection method utilizing the proven eddy current and borescope tech-
niques for detection and determination of cracks in turbine buckets.
GE Power Generation Service has been designated as the qualified GE Company agent for conducting
the eddy current and borescope inspection of all bucket stages. Selected teams of personnel have under-
gone extensive training leading to their qualification and certification to perform the inspection following
procedures developed by the Gas Turbine Department.
Arrangements can be made with your local GE Company Field Service Representative.
The inspection should normally require one week or less to complete. While it is preferred that the unit
be made available for this inspection for a continuous period, it could be returned to service within one
hour’s notice.
BORESCOPE INSPECTIONS
Source Document — GEK 28159
General
The gas turbine incorporates provisions in both turbine and compressor casings for visual inspection of
an intermediate compressor rotor stage or stages, first-, second- and third-stage turbine buckets and nozzle
partitions by means of the optical borescope.
These provisions, consisting of radially aligned holes through the casings and internal stationary turbine
shrouds, are designed to allow the penetration of an optical borescope into the gas or air-flow path regions
of a non-operating gas turbine. Optical borescopes are utilized to provide visual inspection of the rotating
and stationary parts without removing the upper compressor and turbine casings.