Page 477 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

454 Major Process Equipment Maintenance and Repair

be rectified while the unit is running, and such activities as online com-
pressor cleaning. Although there are many different types of maintenance
and inspection activities which are commonly discussed, we will simplify
them into two major classifications: combustion inspection and major
overhaul. Not all comments will apply to every turbine. Primarily we
will focus on industrial type turbines commonly used for mechanical
drive applications in process plants. These are generally between 15-
35,000 HP and are either one- or two-shaft designs.
A combustion inspection for our purposes is defined as an inspection
and/or replacement of the major components of the combustion system.
These include fuel nozzles, combustors , transition pieces, cross-flame
tubes, and in some cases even first stage nozzles! Wious other work is
also carried out with this inspection (Table 9-2), but the work stops short of
the removal of any of the upper casings. Borescope inspections are carried
out into the various portions of the hot gas path which is not directly visible
except by this method. Stationary vane surfaces should be inspected for:

Foreign object damage
Corrosion
Cracks
Trailing edge bowing

Table 9-2
InspectionMaintenance Task List

Combustor Major
item Action Performed inspection Overhaul
1 Inspect fuel nozzles X X
2 Inspect ignitors X X
3 Inspect combustors and cross flame tubes X X
4 Inspect combustion transition pieces X X
5 Inspect 1st stage nodes and blades X X
6 Check all field transducers X X
7 Replace faulty thermocouples X X
8 Check control calibration X X
9 Check back-up SYS~IUS X X
-UPS system
-Lube/control oil system
-Fire protection system
10 Inspect compressor IGV’s X X
11 Inspect all compressor stages X
12 Inspect all turbine stages X
13 Check bearings and seals X
14 Inspect and check alignment X