Page 417 - Improving Machinery Reliability

Maintenarm for Continued Reliability 381

information? When do we throw it away? and Who should be trained? Detailed task
descriptions of maintenance processes do not always receive proper attention, but they
are an important ingredient for an effective maintenance organization.
A proactive approach to maintenance should be common ground for anyone
involved in plant reliability. For that reason, predictive, preventive, proactive, relia-
bility-centered, total productive and all other maintenance philosophies that focus on
prevention will be referred to throughout this section of our text as proactive mainte-
nance or simply PM. This section describes a process for developing a PM program
to a level of detail that is really dictated by the equipment itself. There are three
aspects to developing the PM program: defining the plant; understanding, evaluating
and selecting PM technologies; and documenting the PM program, which is where
important details are captured. The next step is implementation, which is accompa-
nied by measure and improve. The measure and improve step is an evolutionary
process. It is never really complete.

Develop The PM Programs

Development of PM programs for a plant must begin by defining the plant. In
other words, by defining the systems that exist within the plant and the components
that make up the system, and then further defining the components or parts that
make up the equipment. It is through selective application of PM technologies that
preservation of component and thus system function can be ensured.

Define the Plant. In a hydrocarbon processing plant, one can typically find systems
that provide plant air, electrical distribution, cooling water, boiler feedwater, steam,
and nitrogen, just to name a few. This view of the plant might be called the “process
sort” because the names of the systems describe the process or function that the sys-
tem serves or supports in the production process. Every plant can be divided into its
own unique series of systems.
Just as each plant can be broken up into systems, every system can be further
divided into components. For example, a typical cooling water system might consist
of the cooling tower, cooling tower basin, pumps, piping, and water treatment sys-
tem. This view of the plant might be called the “component sort,” because it
describes the components that make up the system.
Advancing this concept one step further, each component in a system can be
divided into still another set of components or parts. The cooling tower pump is an
assembly of bearings, a rotor, the casing, the seals, a coupling, and the motor. If you
are following the logic so far, you are probably asking yourself, “Okay, where does
this end?’ The answer to the question is, When you reach a point in the hierarchy
where one of the PM technologies applies. For this cooling tower pump example, it
is probably not necessary to go any further.

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*Contributed by Richard Ellis and Mark Galley, the Dow Chemical Company, Freeport, Texas. Pre-
sented at the 5th International Process Plant Reliability Conference, Houston, Texas, 1996.