The basics of contamination control
The steps that mines can take to control contamination range from the straightforward — such as good housekeeping — to the less common, such as particle counting. The basic procedures focus on clean facilities, clean components, clean processes and clean fluids.
Simon Bishop, contamination control market professional at Caterpillar, shares best practices for sites to begin reaping the benefits of this important activity.
- An ongoing training program for all shop and parts personnel (including management and labor) must be in place. Classroom and on-the-job training are required to ensure all those who have an impact are thoroughly familiar with all of the processes and procedures of a successful contamination control program.
- All machines and components should be washed using high-volume, high-pressure wash equipment before entering the shop. The intent is to remove dirt and oils that could contaminate the machine being worked on as well as to keep the shop clean. Once the machine has been washed, it is equally important to have a clean concrete or crushed stone/gravel path from the wash bay to the shop and a concrete apron to prevent dirt entry in the shop. Underside water nozzles at the entrance or in the center of the wash bay complement high-volume water cannons, reducing machine wash time and freeing time for planned maintenance, backlog repairs or a faster return to production.
- Hoses and tubes require special care. All hose / tube ends should be appropriately capped or plugged and all hoses and tubes that are removed during the repair process must be cleaned prior to reinstallation. A supply of clean caps, plugs and plastic wrap or bags should be in a readily accessible area where they are protected from shop and parts warehouse contamination. A portable cart that is easy to move to the machine and around the machine makes it more likely that proper caps and plugs will be used and reduces time wasted retrieving the right cap or plug.
- A preventive maintenance cart is recommended. The contents should be staged prior to a planned maintenance activity and outfitted for the specific machine being serviced. This ensures the necessary equipment is available and the contents are clean and protected. Contents may include items such as clean exchange magnetic plugs and screens, vacuum pump and tubing (for fluid samples that cannot be taken live), fluid sample bottles, filter cutting tool, digital camera, low-lint towels, etc. All should be bagged and protected.
- Oil spills should be cleaned immediately using a vacuum or absorbent pads specifically designed for collecting oil. Final cleaning is with a clean water mop and degreaser; hot water is preferred. The use of oil-absorbing granular material is not recommended as it creates airborne dust, which contaminates other areas of the shop and makes a mess during disposal. Granular materials have a high probability of being tracked throughout the shop and becoming a source of contamination.
- Parts must be kept clean until installation. They should be kept inside the original packaging until they are ready to be installed. This will significantly reduce contamination problems.
- Filter boxes should be kept clean and unopened, and filters that are shrink wrapped should remain in the shrink wrap until installed.
- O-rings require two levels of clean protection, which could include storing in re-sealable plastic bags and a clean cabinet. Contaminated O-rings have the potential to create a leak path when installed and in service.
- All fluid-carrying hoses and tubes should be stored with end caps in place. When an uncapped hose or tube end is found, the hose or tube should be cleaned before being capped. It is important that the right-sized cap or plug is used to cap the hose or tube.
- Components and parts must be protected when work is in process. During system invasion repairs or during component remove and install, all of the machine’s exposed cavities should be covered with plugs, metal or magnetic covers, plastic wrap with tape, or guards. Contamination-sensitive parts should also be protected with clean drop cloths or plastic during periods of inactivity such as breaks, meals, shift changes and overnight.
- Housekeeping makes a big difference to contamination control efforts. If the shop environment is clean and uncluttered, it will reduce the chances of contaminating equipment being serviced and repaired, as well as increase repair and maintenance efficiencies. Seal floors and clean them daily or more often if needed, keep tools and equipment clean and organized, maintain work benches, install material on work surfaces to protect sensitive parts, and store parts off the floor.
- Protect bulk fluids.
- Start with clean bulk storage tanks.
- Filter fluids entering the tank to keep the tank clean and to allow the filtering of fluids exiting the tank to be more effective.
- Equip bulk tanks with 4 micron breathers with the ability to remove water. As temperatures change from day to night and/or fluid levels drop, the fluid is replaced by outside air. This air must be filtered and moisture removed to keep fluids free of contaminants.
- Implement a tank preventive maintenance program that includes periodic draining of water and debris, tank inspection and cleaning, filter and breather inspection and replacement dates, etc.
- Filter oil at the point of use and dispense into machines at ISO –/16/13. Depending on the cleanliness of the oils delivered / received there could be a need to clean the oils to the recommended cleanliness levels using kidney loop (off-line) filtration.
- All machines should be enrolled in a scheduled oil sample program (S.O.S.SM) to include particle count technology (portable or lab) and monitored at PM intervals and during system invasion repairs such as component removal and installation. Kidney loop filtration may be needed to restore the system to the recommended cleanliness target.
- Protect bulk fuels.
- Clean fueling ports prior to fueling and ensure they are covered with the standard cover.
- Maintain machine fuel tanks, routinely draining them of sediment and water.
- Filter bulk distillate fuels at both entrance and exit/dispensing points. Exit filtration should have the ability to remove water in order to dispense fuel at the recommended target of ISO 18/16/13.
- Equip and maintain lubrication and fuel trucks just like bulk storage tanks.
- A good rule of thumb is that any time fluid is transferred, it should be filtered.