Routine Maintenance Helps Prevent Losses

Leaks in compressed air pipelines can cost thousands of dollars a year, making air loss one of the mining industry’s most costly problems. Leaks, which can occur at any point along the pipeline, have a number of causes. Regular mining activities expose the lines and hoses to vibration, impact and harsh materials, all of which could lead to leaks. Improperly installed pipe couplings and unsuitable gasket material are also culprits. Fortunately, coupling and gasket installation issues are easily fixed, resulting in cost savings and productivity improvement.

Air loss and the bottom line

According to the Ontario Mining Association’s (OMA) compressed air leak management program report, “Implementing a Sustainable Compressed Air Leak Program,” compressed air systems typically consume 20 to 40 percent of the electricity used in mines. Anywhere from 30 to 70 percent of that air is wasted through leaks. Although these numbers are impressive, the dollar figures associated with this wasted energy is much more dramatic.

The OMA’s report includes a chart showing the staggering costs of a variety of leak sizes. Assuming energy cost of $0.10/kWh, a single 1/16-inch diameter leak can result in $200 worth of wasted energy for a one-shift operation, and up to $750 for a three-shift operation each year. That amount increases exponentially as the leak size increases. A single -inch diameter leak can cost $12,820 for a one-shift operation, and as much as $47,850 for a three-shift operation each year. Considering an average mine can have hundreds of air line leaks, the cost in wasted energy easily reaches into the hundreds of thousands of dollars, a figure sure to catch anyone’s attention.

The costs of air loss are not limited to wasted energy; productivity is also affected. A leak in a compressed air line can lead to a drop in system pressure, affecting the performance of tools and equipment that rely on compressed air. Operation time may need to be increased to make up for the lower pressure, which can increase maintenance requirements and potentially shorten the equipment’s life expectancy. The mounting costs of air loss certainly make it a problem worth addressing.

Causes of and solutions for air loss

Leaks can occur at multiple points along a compressed air line, and a number of causes have been identified for those leaks. The predominant cause of leaks is an improperly installed pipe coupling. In fact, the OMA report estimates that 60 to 80 percent of the air loss a mine incurs can be attributed to couplings.

Now, this doesn’t mean mines need to replace their grooved piping systems. As the report describes, mines rely on grooved systems for their ease-of-use, robustness and ability to accommodate the constantly changing landscape. The Pumps, hoses and pipes need routine inspections and service to help ensure performance and prevent accidents.

solution is actually quite simple, and requires just a bit of education.

Pinched gaskets are often the cause of leaks. This occurs when the coupling is installed without applying lubricant to the gasket. Despite the fact that it takes only a few seconds to apply lubricant to the gasket, skipping this step is seen as a time-saver. If a mine uses gaskets that require lubrication on-site, it should educate its pipe installers as to the economic losses that could result from a leak if not properly lubricated.

Another method to reduce pinched gaskets is to use an installation-ready coupling, such as the new Victaulic Style 177 QuickVic Flexible Coupling. Installation-ready couplings do not require disassembly prior to installation. They can simply be positioned on the pipe ends and tightened using standard hand tools. By keeping the coupling assembled, the risk of pinching the gasket is reduced. In addition, these couplings reduce installation time compared to couplings that need to be disassembled.

Another cause of air loss is gasket deterioration, which occurs when the gasket grade selected does not suit the application. Many mines use only one type of gasket material for both water and air piping systems, usually Grade “E,” or EPDM. However, this material is not recommended for air exposed to oil vapors. Oil separating filters are generally not used on compressed air systems in mines, so the air lines may carry oil vapors. These vapors can degrade the EPDM compound, leading to leaks. Grade “T,” or Nitrile, gaskets are designed specifically for air with oil vapors, and should not be used on water lines. This means that a mine should use two types of gaskets: EPDM for water services and Nitrile for air lines. The OMA report suggests replacing EPDM gaskets with Nitrile gaskets during repairs on existing gasket leaks, and using the Nitrile gaskets during the installation of new compressed air lines. It classifies this solution as having a high impact on energy savings.

Whereas gasket leaks are not the only cause of air loss in compressed air systems, proper selection and installation of couplings plays a major role in reducing the costs associated with leaks.

Air loss results in more than just unnecessary energy expenditures; it can increase maintenance requirements, leading to prolonged downtime and reduced productivity. Repairing leaks can reduce air loss to less than 10 percent of the mine’s compressed air output, which will result in immediate cost savings.

*Rob Bonsall, Regional Manager for North Central Canada, is a 14-year Victaulic veteran. Victaulic is a leading producer of mechanical pipe joining systems. The company develops products for a full range of industrial, commercial and institutional piping system applications.

For more information, visit www.victaulic.com.