Page 217 - Boiler_Operators_Handbook,_Second_Edition

202 Boiler Operator’s Handbook

equipment drawing samples of the oil for testing is a that was in the bearing is going. That frequently results
predictive maintenance measure. It falls on the opera- in the bearing shaft seals failing because the grease
tor to ensure that every piece of moving equipment is forced them to upset (Figure 6-3) and additional grease
properly lubricated. With the increased use of synthetic is forced out around the shaft or into the equipment
lubricants that portion of the job is becoming more housing.
complex. Synthetic oils can save thousands of dollars Combine that with the common over-lubrication
in power cost for operating large pieces of equipment. associated with grease bearings and it promotes equip-
On the other hand, adding the wrong oil to a crankcase ment failure because the grease eventually blocks cool-
can result in an instantaneous breakdown of the equip- ing air flow passes within the equipment. Invariably
ment because the two oils are incompatible and one oil there is a plug or cap that can be removed to provide a
causes the other to break down. Keeping an up-to-date passage for the old grease and that opening should be
lubrication chart that covers everything in the plant is provided before pressing new grease into the bearing.
important. Paying some attention to proper lubrication Don’t forget to put the plug or cap back after the bearing
schedules can save you time in the long run. is lubricated and, when the manufacturer recommends
I’ve discovered that lubrication is one of the main- it, the equipment is operated to stabilize the volume of
tenance activities that is always a mixed bag. Most grease in the bearing.
plants seem to have a program that consists of over- Use of the proper grease is also important. I’ve
lubrication of some equipment and insufficient atten- observed some facilities simply use the highest grade
tion to the lubrication of other equipment. Many grease of grease required to simplify their activities thinking
lubricated bearings need lubrication infrequently but that if they use the best in everything they won’t have
are lubricated regularly simply because the program a problem. There are two problems with that thinking,
doesn’t provide for a proper schedule; that results in first it’s expensive because the high quality grease is
unnecessary lubrication and over-lubrication of that very expensive and secondly that high priced grease
equipment. If your program doesn’t allow for lubrica- may not work well in the bearings that can function with
tion schedules over periods as long as five years that the less expensive material.
will happen. Grease is not cheap nor is the labor that’s Grease requirements are a function of load on
required to move around the plant and lubricate equip- the bearing and speed so a grease designed for a high
ment unnecessarily so developing a suitable program speed low load bearing will not adequately support the
normally pays for itself. larger loads of a low speed bearing. A lubrication pro-
Lubrication is a function of operating hours more gram that’s designed to be simple or make life easy for
than anything else so a program for scheduling it sug- personnel can result in shorter bearing and equipment
gests installation of recording operating hours of the life. So… give up on the concept that you can use one
equipment to determine when lubrication is necessary. grade of grease and lubricate the bearings in accordance
I’m in favor of installing operating hour meters on ev- with the manufacturer’s instructions or the recom-
erything. Tracking when equipment is in service in a log mendations of your lubrication specialist. Painting a
book is another way to determine operating hours. circle around each fitting with special colors to denote
Frequency of operation is also a factor and equip- the grease to be used and applying similar paint to the
ment that is started and stopped frequently should be
lubricated more often than those that run continuously
because the constant heating and cooling of the bear-
ing results in swell and shrinkage of the lubricant and
can result in air and moisture mixing with it to degrade
the lubricant and rust the bearing. Systems that are oil
lubricated also have a requirement for replacing the oil
at frequencies that are based on the greater of operating
hours or time. Grease is replaced with each lubrication
so there’s no additional scheduling to replace it.
It’s that replacing of grease that many operators
fail to consider. I don’t know how many times I’ve seen
someone slap a grease gun onto a fitting and pump
away with no thought or concern for where the grease Figure 6-3. Grease seal upset by overpressure