Page 72 - Improving Machinery Reliability

44 Improving Machinery Reliability

Major Machinery Turnaround Documentation
Efficient and effective future machinery maintenance should be planned at the
inception of any given project. While this statement holds true in any industry, it
takes on added importance in the petrochemical plant environment where downtime
for unspared major machinery can cost staggering amounts of money.
Assembly and disassembly procedures for machinery or critical machine sub-
assemblies and tabulations of critical machine dimensions will have to be acquired
well before turnaround maintenance can be performed. The logical time for defining
and assembling all these data is prior to equipment delivery.
The critical-dimension diagram shown in Figure 1-30 is typical of size and toler-
ance information which must be cataloged for axial as well as radial dimensions of
turbomachinery rotors, bearings, seals, admission valves, governors, etc. Many of
these data must be obtained during initial assembly of the equipment and cannot be
retrieved once the machine leaves the manufacturer’s facilities. This makes it again
appropriate to require the equipment vendor to carefully record these dimensions at
initial assembly and to furnish these data to the contractor and ultimate owner before
the machinery is commissioned at the plant.
A photographic record of machinery assembly and disassembly is of similar
importance to process plants. Figure 1-31 depicts a random page taken from the
illustrated reassembly manual developed for a large mechanical-drive steam turbine.
Each step is documented both pictorially and in writing. A margin column lists the
time it takes a designated maintenance crew to perform the task. The number in
parentheses gives the cumulative total crew-hours expended.

TURNAROUND k WllHlLNANCE INFOIW\lION
ROTOR CLEAFANCEI
MACHINETAQNO C-103 (Ethylene)

Figure 1-30. Turnaround
and maintenance informa-
tion: rotor clearances.