Storage and Handling Techniques

Like most materials, lubricating grease gradually will deteriorate with time. The rate and degree of deterioration depends on the storage and handling conditions to which the grease is exposed.

Grease may change its characteristics during storage. The product may oxidize, bleed, change in appearance, pick up contaminants or become firmer or softer. The amount of change varies with the length of storage, temperature and nature of the product.

Depending on the storage conditions, some greases can undergo age hardening, which results in the product becoming firmer and increasing in consistency or even softening. These changes in consistency can cause the grease to slip out of its original consistency grade. This behavior can be further aggravated by prolonged storage conditions. Because of this aspect, extended storage periods should be avoided.

If a grease is more than a year old, the National Lubricating Grease Institute (NLGI) recommends that it be inspected and the worked penetration tested to ensure that the grease is still within its intended NLGI grade.

Another recommended industry practice specifies that whenever any type of lubricant is received, the usage and storage methods must follow the first-in/first-out inventory system. This simply requires the user of the lubricating grease to use the grease that was put into the storage system first. In addition, grease manufacturers place a date code or bath number on the individual packages or cartons that can help determine the month, day and year the grease was made.

As previously mentioned, greases tend to bleed and release their base oils during storage. The rate of oil released from the grease will increase with time and vary based on the temperature at which it is stored. Ideally, grease should be stored in a cool, dry indoor area that does not exceed 86 degrees F (30 degrees C) and remains above 32 degrees F (0 degrees C).

It is not unusual to find grease containers in storage areas that have temperatures as high as 130 degrees F (54 degrees C). These storage areas also can be exposed to contaminants such as dust, dirt, moisture or rainwater, which can severely deteriorate the quality of the grease.

A grease container should never be exposed to direct sunlight or be stored in an area directly near a heat source such as a steam pipe, furnace, cab of a truck in hot weather, etc. This will only aggravate the rate of oil release that can occur.

Always store grease in its original packaging and keep the container closed until it is time for it to be used. Wipe the lid or cover of the container before opening and always use clean tools and dispensing equipment when handling or pumping the grease. After use, the container should be closed immediately and kept closed. Before placing the lid back onto the container, wipe off any dust, dirt or excess grease that may have accumulated.

Cartridge tubes of grease should be stored upright at all times. If a cartridge tube is left in a grease gun, the grease gun should be depressurized, wiped with a clean cloth to remove any contaminants and stored in a horizontal position inside a clean, cool, dry area to keep the oil from bleeding out of the grease.

To further ensure a grease’s original quality and cleanliness, as well as to prevent excessive oil separation, the following storage and handling techniques are recommended:

• Do not use lubricating greases that have been stored for long periods of time unless their condition and cleanliness can be verified by a laboratory analysis.
• If accidental mixing is suspected or has occurred, consult the lubricant supplier or conduct compatibility tests.
• The storage room should be separated from areas of contamination such as metal debris, dust, dirt, chemical fumes or moisture. The room should be heated, well-ventilated and contain clean accessories, dispensing equipment and other necessities. Personnel also should be properly trained in storage techniques and inventory control to prevent contamination.
• Grease containers should be clearly labeled with the date they were received, the type and brand of grease, etc. These markings should be kept in a position where they can be easily read.
• Store grease in its original container until it is used. Drums, pails, kegs and boxes should be kept off the floor and supported by a rack, platform or blocks at least several inches high.
• Never leave grease containers improperly covered, uncovered or open. Keep them tightly sealed between uses. If the containers are stored outside, a heavy canvas tarpaulin, plastic sheet or lean-to can be used to keep off water or dirt. Drums, kegs and pails should be raised off the ground and stored either on their sides or tilted at a 45-degree angle to prevent any moisture or dirt from being drawn into the product.
• Any tools used to handle or dispense grease should be cleaned before they are used.
• Never use wooden paddles or spatulas to remove or transfer grease from containers to grease guns or other types of dispensing systems. This practice poses a high risk of contamination.
• If a barrel warmer is used, it should have some type of temperature-regulating mechanism. The grease should never be heated above 75 degrees F, and the barrel warmer should not be left on overnight or unattended. This can cause the grease to readily release its base oils or even thicken in consistency due to oxidation and thermal stress.
• Never use a torch or open flame to warm a grease container. This poses a fire hazard.
• Maintain a separate inventory and utilization record for each product. Tracking how much grease is used and on which machine or piece of equipment will help you keep an accurate inventory of lubricants.
• Use the oldest container received first.
• Before storing or using a grease, inspect the received containers for any damage such as severe dents, corrosion or moisture.
• Some type of coding and tagging system should be used to identify the contents of different lubricant containers, transfer/pumping systems, tools and pipes that carry grease throughout the plant. Make sure all transfer valves, hoses and dispensing equipment are kept clean. Seals and gaskets also should be maintained in proper condition.
• All transfer containers should be filled under clean conditions.
• Grease containers should be completely emptied before being discarded.