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The Importance of Visual Inspections
Buckets are important when changing oil, but when the bottom of the bucket is not visible, another route must be taken.
The condition-based maintenance team recently collected an oil sample on a No. 2 condensate booster pump motor as part of a routine sample collection. While pulling the sample, the oil was observed to be dirty. Due to high vibration on another booster pump and the fact that the unit was coming off in a couple of days, the team decided to let it run.
A few days later, vibration data was collected on the No. 2 motor. Because there were no indications of a vibration problem and a unit outage was scheduled in three days, maintenance personnel decided to let it go and changed the oil on the scheduled outage.
While changing the oil, a unique situation occurred that reiterates the importance of using a clean bucket every time an oil change is performed. During routine procedure, at the conclusion of draining the oil into a clean bucket, the oil is visually inspected for any debris or unusual matter. In this case, the oil was so dirty that the bottom of the bucket could not be seen and a visual inspection was not possible. However, being aware of the importance a visual inspection has on the life of the equipment as well as the possible monetary savings of any findings encountered, we transferred the dirty oil into another clean bucket so visual inspection could be achieved. During this inspection, a steel pin was found.
A maintenance supervisor was contacted, and after examination, he suspected this was an alignment pin from the bearing housing. With this information, further inspection was necessary and upon pulling the sight glass, another pin was found. As a result, maintenance pulled the bearing out and observed that the dowel pins came from the bearing halves.
As a result of routine procedures, utilizing clean buckets and innovative thinking, condition-based maintenance had a great save!Check the Flow Rate
The flow can be checked in one of two ways. With the hydraulic system off and the pressure at zero PSI, the line can be removed and run into a container of known size. If possible, secure the line to the container because holding the line may create a safety hazard. Turn the pump on and record the amount of oil that flows into the container for one minute.
The second method is to temporarily or permanently install a flow meter in the case drain line. This will provide an easy, accurate method of checking the flow rate while the machine is operating.
When the case flow reaches 10 percent of the maximum pump volume, the pump should be changed. In this example, the pump should be replaced when the flow rate is three GPM.
Find the Leak
Label Placement Helps
It was discovered that one of the gearboxes retained sludge deposits in its casing, while another one was noisy. It was noted that one gearbox was grease-lubricated, while the others were oil-lubricated.
Preventive maintenance was performed on two gearboxes with the same oil, which wasn't even the correct viscosity oil. Not only were we lubricating this hoist incorrectly, but we also employ eight others which were lubed in the same manner. This created a safety hazard in addition to lost production.
Bottom line: Double-check the validity and accuracy of all PMs. Just because a PM exists doesn't mean that it's correct.
Oil Mist for Contamination Control
In bearing applications where high contamination levels are a concern, consider converting grease lubrication systems to oil mist lubrication. Oil mist systems are slightly pressurized, which helps to exclude contaminants. Use a pure mist system for rolling element bearings and purge mist for gearboxes and journal bearings.
Seal it Out
To keep the end of your grease gun clean and prevent contamination from entering a bearing when lubing the bearing, place a plastic cap over the end of the lube head. Caps come in all sizes and the half-inch provides a tight seal to keep out everything from dirt to water.
Purge Before Installing
Purge all new grease fittings with a grease gun before installing them on the machine. Use the same type of grease that will be used later for regreasing. This practice removes any dust, burrs and other debris that has collected inside the grease fitting. It also reduces the risk of cross-contamination between different grease products.
Paper Thermometer Reveals Temperature Spikes