For the drum, producers can inspect the drum liners, shell and flights, especially the veiling flights. The area between the material inlet and the asphalt injection point is where the majority of the wear occurs. Liquid asphalt serves as a lubricator and, therefore, reduces wear on the flights past the injection point.
When planning for drum wear, producers must keep in mind the type of aggregate being used in the mix designs. "A producer from West Virginia using granite in the mix will experience more wear than the producer from Missouri working with limestone," says Garbelman.
Another high wear, big ticket item that should be serviced during the winter months is the drag conveyor. The drag chain, flights and floor are all subject to wear throughout the paving season and are more efficiently serviced during the off-season. Garbelman offers maintenance personnel a tip when servicing the drag conveyor. "Lay the conveyor on the ground when working on it. It's safer, and it saves the crew time, since it eliminates the need to constantly go up and down when replacing parts.
To enhance loading safety, any wear uncovered in the silo cone liners should be addressed during the shutdown. The cone area withstands a great deal of weight from stored asphalt and properly servicing the liners will help to avoid a catastrophic event.
Wintertime is also a good time to rebuild large plant gear boxes. Drive gears for the drums, drag chains and pugmills serviced during the off-season will limit the possibility of unscheduled downtime during the paving season. Oil samples taken throughout the paving season will aid in the detection of gear boxes that need to be rebuilt.
The production shutdown is also the time to perform thorough inspections of items that don't typically get checked during the paving season. Items such as the ductwork, cyclone/pre-cleaner and drum shell thickness should be inspected for wear and repaired as required. In addition, replacement of baghouse bags and repairs to silo transfer conveyors should be made during the off-season.
Although drive sprockets and chains may need replacing throughout the paving season, winter also gives maintenance crews ample time for inspection, repair or replacement. Garbelman suggests maintenance technicians make a template of a new sprocket for fast wear inspection. "With a template, they can easily see the wear on a sprocket. More than a quarter-inch wear means it needs to be replaced."
Finally, Garbelman advises producers to not forget about the controls. The computer controls are the quickest items to become obsolete on a plant. Unfortunately, many producers don't find out that their controls are obsolete until a problem occurs. Then it is a more costly problem to fix.
For many asphalt producers and paving contractors, the South holds promise for year-round work. While this boosts the bottom line, it can wreak havoc on a plant. Producers in the southern states don't have the climatic off-season to service big wear items.
Since these producers do not have the luxury of shutting down for a month or more to repair wear items, they must schedule multiple shorter-duration downtime periods throughout the year. This makes the routine plant inspection all the more critical. These examinations must flag those components that need replacement, and the maintenance crews must have the repair parts on hand prior to the scheduled downtime period.
"Planning downtime is critical for producers operating in the South. This allows them to whittle away at maintaining the plant a week at a time, replacing bags over a weekend or shutting down for a short time to rebuild a drag chain," says Garbelman.
Whether operating in the southern or northern United States, it is essential for a producer's longevity in the business to keep a well maintained asphalt plant. Routine inspections, scheduled downtime and keeping inventory of wear parts will keep a producer operating efficiently and profitably, minimizing the potential for unscheduled downtime.
"Downtime is the ugliest word in the business for producers. Very few contractors have a spare asphalt plant, and if they do, trucking costs will probably be too high to justify using the other plant," says Garbelman. And if you're not producing asphalt, you're not making money.