Page 399 - Improving Machinery Reliability

Spare Parts and Their Effect on Service Factors 363

Table 9-1 (Continued)

Bearings 2 2 sets 1 set
Turbine rotor 2 full rotor full rotor
Fuel controls 3 partial set partial set
Speed controls 2 partial set partial set
Cos expanders
See applicable parts of steam turbines
Key: No. Evenflrain-Year
5 One every 1-2 years
4 One every 2-3 years
3 One every 3-4 years
2 One every 4-5 years
1 One every 6-8 years

enced, preserved, or labeled with the vendor’s parts and drawing numbers in addition
to the owner’s spare parts identification.
The advent of sophisticated electronic controls for machinery-related instrumenta-
tion (e.g., electronic governors) makes it necessary to pay very special attention to
appropriate preservation and storage. Dust, moisture, and crush-proof packaging are
indispensable. While spare parts for major machinery should be stored in designated
areas clustered in close proximity, sensitive electronic components for the same
machine are best not located in the same bin with heavy mechanical components.
The storage of large turbomachinery rotors presents special problems and many
opportunities for good or bad solutions. Modern user plants generally opt for the
highly satisfactory storage method shown in Figure 9-1. Here, the rotors are pre-
served with an oil-derived coating and hung vertically from large cross beams. The
building is humidity controlled, but does not require heating or cooling.
Storage and retrieval methods must represent a logical compromise satisfying sever-
al critical requirements. For instance, the night-shift repair crew must have access to
spare parts without the help of daytime personnel. At the same time, procedures should
be in place which give assurance that the removal of parts from stores is recorded so as
to have an up-to-date reading of true inventory levels and reorder requirements.

Spare Parts Documentation

Money spent in documenting spare parts locations, inventory levels, and reorder-
ing quantities, and in cross referencing vendor designations, drawing numbers, bills
of materials, owner’s storage codes, etc. is money well spent. Cross-sectional draw-
ings of major machinery should be combined with component number designations
and all other relevant cross references to enable mechanical work forces to locate
parts without wasted time or motion.
Complex spare parts documentation, time-consuming retrieval, and ineffective
“automatic reordering” procedures have been shown to catalyze illicit substores. An
illicit substore is the foreman’s desk drawer. This is where he squirrels away special
tools, a handful of Kairez@’ O-rings, and an occasional stationary bellows mechanical