Corrosive plant environments are among the most serious threats to many industries today, contributing to extensive production downtime and exorbitant maintenance costs. According to a recent report, the annual cost of corrosion for the U.S. industrial market was expected to reach more than $500 billion in 2015.
Among the most devastating effects of corrosion is its destructive impact on the load-bearing surfaces of plant equipment, which are supported by many types of bearing components such as rollers, spines, gears, ball bearings or other moving parts. Unless these components receive proper lubrication, they will be subjected to excessive heat and wear, leading to premature failure.
With today's equipment running at higher speeds and longer periods, it is more important than ever to ensure that lubrication systems provide efficient, timely applications of lubricating oil or grease. For this reason, many manufacturers are opting for automating their lubrication systems.
The Multi-point Challenge
Food and beverage manufacturing operations often have hundreds or even thousands of lubrication points in a single facility. Although automatic lubrication systems have been around for decades, much of this work is still conducted using manual labor, particularly when the lubricant is grease.
While the food and beverage industry is moving toward higher-speed, higher-volume automated equipment, it is becoming increasingly impractical for the industry to depend on labor-intensive manual grease gun lubrication.
"Bearing giant SKF has estimated that 57 percent of all bearing failures are lubrication-related," explains Richard Hanley, president of Lubrication Scientifics. "That rate can be reduced dramatically by automating the lubrication process, which ensures that the right amount and type of lubrication are delivered to every equipment bearing point."
Automated lubrication systems can be used in a wide variety of industries in addition to food processing, including the pulp and paper, chemical processing, steel, petrochemical and mining industries. From an economic point of view, the payback period for most of these systems is less than a year. In some cases, engineered lubrication systems with advanced monitoring capabilities can save millions of dollars in downtime costs per year.
Automated lubrication systems eliminate the cost and sometimes hazardous task of manually applying controlled amounts of lubricant to multiple equipment locations at frequent time intervals while the equipment is operating.
"More frequent delivery of smaller amounts of lubricant is particularly important to bearing points on high-speed equipment," Hanley says. "This prevents overheating the bearings due to excessive lubricant buildup and ensures longer operating life."
Harsh Environments
Food-processing plants are exposed to some of the harshest environmental factors, including extreme room temperatures and mandatory wash-down procedures. U.S. Food and Drug Administration regulations require all processing lines and equipment be adequately sanitized as often as necessary.
This requirement is typically met by a full equipment wash-down with an approved cleaning agent. These wash-downs create serious corrosion problems for any non-stainless-steel components used in the processing line.
Corrosive damage from exposure to caustic wash-down fluids can severely compromise the performance and service life of lubricating system metering valves. These valves dispense oil or grease in controlled proportions to each connected lube point and are constructed of zinc- or nickel-plated carbon steel.
"In such an environment, the corrosion-resistant life of a plated-carbon-steel metering valve or system component will only be weeks to months," Hanley says. "Although the initial corrosion will look much like rust, it will eventually cause the lubrication metering valve to lose its effectiveness long before normal wear and tear would compromise that part."
In the food-processing industry, corrosion problems are normally prevented through the use of equipment made of stainless steel. However, since a broad offering of stainless-steel metering valves has not been readily available, the only effective anti-corrosion solution for automatic lubrication system components has been to enclose the plated-carbon-steel metering valves into stainless-steel enclosures.
With the cost of the enclosure, bulkhead fittings and installation labor, it is easy to spend $2,000 to protect a $500 plated-carbon-steel metering valve, and yet the space required to mount such an enclosure may not be available on or near the processing line.
In such cases, the installation of stainless-steel metering devices that can be mounted directly to plant equipment is the most cost-effective solution for maintaining sanitary standards and ensuring long-term production reliability.
Although stainless-steel metering valves cost between 1 1/2 to three times the price of a carbon-steel-plated metering valve, this is typically 40 to 60 percent less expensive than enclosing plated-carbon-steel valves in a stainless-steel enclosure.
System Types
While there are several different types of automated lubrication systems, a typical system consists of a controller or timer, pump with reservoir, supply line, metering valves and feed lines.
One of the most common lubrication systems is the single-line parallel, which is also referred to as an injector-type of lubrication delivery method. This system is known for its ease of installation, adjustable metering of valves (or injectors) and applicability to up to six lube points per device.
Lubrication points may be added or removed without redesigning the system. On the downside, it is difficult to verify that each lubrication point is constantly being serviced.
Another common system is the dual-line parallel. This system is also easy to install and features adjustable metering valves. With this type of system, a maximum of eight lube points may be serviced from each device, and points may be added or subtracted without a system redesign.
Heavy greases can also be delivered over very long distances, but it is difficult to verify that each lubrication point is constantly being serviced.
The single-line progressive system is a third type of automated system. It is engineered to deliver exact lubricant amounts to each point. However, with this system, the lubrication amounts and points may not be altered, and initial installation costs are higher.
The primary advantage of these systems is that performance can be easily and inexpensively monitored to verify that each lube point is constantly being serviced. This type of system also prevents unauthorized interference with system settings, so workers cannot inadvertently change the precise lubrication amounts and intervals.
Whatever their design, automated lubrication systems can be beneficial for plants that need to supply precise lubricant amounts to many points, ensuring longer machine life, safe operation, reduced unscheduled downtime and more economical operating costs.
