Introduction

This chapter deals with the art of periodically monitoring the condition of various important pieces of rotating machinery in a plant to determine the present health of the equipment. Another common term for this endeavor is predictive maintenance. The reasons for carrying out such a program are given below:

Eliminate Unnecessary Disassembly Any time a machine is tampered with, there is a possibility that it will be damaged. Under the old philosophy of preventative maintenance, for instance, the bearings might be replaced every 2 years whether they needed to be or not. This led to a real possibility that

• The new bearing would fail in a short time due to manufacturing errors in the bearing itself (infant mortality) or due to improper installation

• A lock washer, lock nut, or lock wire might be forgotten, causing the machine to fall apart after just a few hours of operation

• Poor assembly clearances could cause rubs, premature wear, or operating inefficiency

• Poor alignment of the rebuilt machine or improper lubrication could cause bearing or coupling failure in a short time

• A forgotten part of the machine or a tool could be sucked into the inlet of either the rebuilt machine or another machine in the system, wrecking it.

These kinds of experiences led to the sage advise, "If it ain't broken, don't fix it." A machine that is exhibiting no sign of wear or faulty operation should be left alone to do its job for as long as possible.

Reduce...