Page 61 - Machinery Component Maintenance

46 Machinery Component Maintenance and Repair

Specific Preparation and Planning
When preparing for an overhaul of a major piece of turbomachinery, it
is important to know as much as possible about the machine and why it
needs to be taken out of service. There are several obvious sources of
information, including the operating and maintenance personnel, the
equipment file folder and the vibration history record. If sufficient infor-
mation is not found in the file folder, which is all too often the case, this
fact should reinforce the resolve to do a proper job of documenting the
planned overhaul in a special manual or “machinery T/A package.”
Before proceeding, one question usually arises: Is a complete overhaul
really necessary? To properly answer this question, you will need to eval-
uate the symptoms. Has the vibration steadily increased over a long pe-
riod of time or have you witnessed a step change? What does an analysis
of the vibration signature reveal? Has the performance gradually fallen
off or taken a dramatic drop? Problems such as a locked gear coupling or
soluble deposits inside the machine can sometimes be corrected without
opening the machine and at a considerable savings of time and effort.
Another obvious source of information is the manufacturer’s manual.
The good ones provide detailed, step-by-step instructions with clear il-
lustrations; others assume prior knowledge or place undue reliance on the
manufacturer’s service representative. Consequently, it is prudent to de-
velop procedures, installation instructions, or even detailed commission-
ing instructions for inclusion in the turnaround package. See Figure 2-10
for typical requirements.
Since a detailed manual is often too bulky for constant reference, we
might reduce portions of it to a critical item list. Certain steps, clear-
ances, and methods are vital to doing a good job. These items should be
summarized and kept for ready reference during the course of the over-
haul. In fact, one complete turnaround package should be on the com-
pressor platform and should be used while the job is in progress.
It is important to assign the responsibility for the overhaul to one per-
son so that conflicting positions do not occur. As indicated earlier, we
recommend the appointment of a turbotrain T/A engineer to oversee the
job and believe that all decisions and compromises should be made by
him. He should be responsible for the engineering coverage, interface
with the maintenance and operating departments, interface between user
company and original equipment manufacturer, and for documenting the
overhaul. It is a responsible assignment, one that requires judgment, ma-
turity, and initiative on the part of the engineer. It is strongly recom-
mended that the turbotrain T/A engineer assume responsibility for the
development of data packages and checklists, some of which are shown
later in sample form, but which must of course be adapted to fit a specific
machine or turnaround situation.