Corrosive wear occurs when a machine surface is damaged by chemical attack. The responsible corrosive chemical could be either vaporous or liquid, which might be found in a plant that mixes or handles strong acid or alkali materials. Often the damage to lubricated surfaces come from acidic by-products generated by the deterioration of the lubricant itself.

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From the book "Lubrication and Maintenance of Industrial Machinery":

Contamination is a particular concern with greases. Unlike lubricating oils where contaminants can be readily removed via filtration, once a grease is contaminated, it is a virtual certainty that these contaminants will be introduced into equipment if the grease is used. This can result in premature equipment failure due to abrasion and fatigue.

Similarly, cross contamination of different greases through using transfer tools or grease guns for two different products should be avoided. Many different grease thickeners are considered to be incompatible and can lead to excessive softening or thickening once the cross contaminated grease is put into service. Just like lubricating oils, greases should be stored with pertinent information such as date of manufacture, date of receipt, "used-by" date (based on Table 7.3), and product data including manufacturer and brand.

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"I've heard the term 'slumpability' used when referring to
greases. Can you explain what this is and why it is important?"

Yes, the word 'slumpability' sounds strange and may conjure thoughts of your 3rd grade teachers repeated reminders to sit-up and quit 'slumping' in your desk.

The meaning of the word as it applies to greases is similar. The slumpability of a grease relates to how feedable it is, or its ability to be drawn into a pump. For example, if grease is pumped from the bottom of a supply tank through a pipe, it is essential for further grease to continually take its place for the pumping to be able to continue. Otherwise, the pump will lose its prime. The grease must be able to fall or 'slump' from the sides of the tank to the pumping zone.

Fibrous or stringy greases typically have better feedability or slumpability characteristics than greases that are buttery (not fibrous). However, these same greases on occasion can prove more difficult to push downstream of the pump through piping.

Currently there is no standard test for slumpability.

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