Page 212 - Boiler_Operators_Handbook,_Second_Edition

Chapter 6

Maintenance

Operating a system is not as simple as starting and little cooling fan motor (normally they have permanent
stopping equipment and opening and closing valves. An lubrication) when its replacement costs less than the la-
operator not only operates, he ensures operability. That bor to check it once; that’s a situation where breakdown
is the function of maintenance. maintenance applies. On the other hand lubrication of a
steam turbine can include testing the oil and operation
of equipment that continuously cleans the oil because a
MAINTENANCE failure would represent a significant cost.
A small 1/2 horsepower feed pump for a little
You’ll recall I said that maintenance of the boiler heating boiler isn’t eligible for much more than break-
plant is an operator’s responsibility. You can be called down maintenance. A 2,000-horsepower feed pump for
upon to do everything from sweeping the floor to re- a super-critical boiler plant will have vibration and tem-
building a turbine, the simplest job to one of the most perature sensors at every bearing, speed sensor, suction
complex, and everything in between. In a small plant and discharge pressure and temperature sensors and
with little equipment you might be expected to do it all probably its own flow meter.
yourself. As the size of the plant increases those duties Between those two extremes are all sorts of varia-
will increasingly be performed by others but you still tions on monitoring and maintenance but most of them
have a responsibility to make sure they don’t interfere rely on the skill and dedication of you, the boiler opera-
with the continuous safe operation of the boiler plant. tor. Each round of the boiler plant you will look and lis-
The purpose of maintenance is reliability and cost ten to the feed pump, noting its condition, look for signs
control. We ensure reliability of the equipment and sys- of vibration or shaft leakage, possibly feel the motor and
tems in the boiler plant by limiting or preventing wear, pump bearing housings to get a sense of their tempera-
vibration, erosion, corrosion, oxidation, and breakdown. ture; all that is predictive maintenance. When you add
Proper maintenance prevents failures of equipment that oil or grease to bearings you’re performing preventive
can result in significant repair costs. Maintenance in- maintenance.
cludes many activities but the most important are moni- Breakdown maintenance has the advantage of
toring and testing performed by the boiler operator. low cost because we basically do nothing to prevent a
There are many forms of maintenance and, contrary failure. Preventive and predictive maintenance require
to many opinions, each one has its place. You choose an expenditure of effort and materials which represent
which form of maintenance to use depending on the an investment in reliability. There are varying degrees of
degree of reliability you want or can afford. Maintenance effort expended in those activities depending on the cost
methods fall into three general categories, breakdown of failure, the cost of maintenance, and the probability of
maintenance, preventive maintenance, and predictive failure.
maintenance. Despite what you may have heard, all three The only caution here is to remember that some
methods should be used to maintain your boiler plant. equipment becomes obsolete. It pays to think about
There are many items that you simply won’t pay any at- the condition of something that would normally only
tention to until they fail, then you’ll replace them. That’s deserve breakdown maintenance but could be irreplace-
breakdown maintenance and it applies to things like light able and force a major expense if it isn’t taken care of.
bulbs, sump pumps, and other items that cost so little An example would be a special bolt on a turbine speed
to replace and are so easy to obtain that any time spent control; the bolt might be easy to replace, if you could
maintaining them is a waste. Some, like light bulbs, only find one, but its loss would produce hours of turbine
allow breakdown maintenance. down time.
Maintenance requirements vary but should repre- Preventive maintenance is performed on a regular
sent a cost relative to the potential loss. You wouldn’t schedule to, as the name implies, prevent damage to
spend a considerable amount to check lubrication of a equipment or systems. Water treatment and lubrication
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