Corrosive plant environments are among the most serious threats to the pulp and paper industry, contributing to extensive production downtime and exorbitant maintenance costs. Assets are allowed to operate to failure before repairs are planned. In many instances, bearing maintenance is performed using reactive maintenance – after bearings have incurred serious damage or have already failed.
According to the most recent NACE (National Association of Corrosion Engineers) study, the harsh processing environments of facilities in the pulp, paper and allied products sector make corrosion control especially costly and challenging. The direct annual cost is over $6 billion.
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 are provided proper lubrication, they will be subjected to excessive heat and wear, both 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 are providing bearing devices with efficient, timely applications of lubricating oil or grease in order to ensure wear life, safe operation, reduced unscheduled downtime of processing machinery, and more economical operating costs.
“More frequent delivery of smaller amounts of lubricant is particularly important to bearing points on high-speed equipment,” says Richard Hanley, president of Lubrication Scientifics (Irvine, CA). “This prevents overheating the bearings due to excessive lubricant buildup, and ensures longer operating life.” For that reason many manufacturers are opting for automating their lubrication systems.
Lubrication Scientifics engineers and manufactures a variety of automated lubrication systems and components that are installed on equipment used in a wide variety of industries including the pulp & paper, chemical processing, steel, petrochemical, food processing and mining industries.
The multi-point challenge
When paper mills roll emulsion, it can travel through progressive rollers on a machine that is perhaps 200 ft. in length. During that process there is considerable caustic water and glue that is squeezed from the final product and flows all over the machine. When the equipment is washed down with high-pressure hoses, the lubrication oil or grease often gets blown out of the lube points and has to be replaced.
“Re-lubricating all of the hundreds or sometimes thousands of points manually is a very difficult and time consuming job that will create substantial, unnecessary downtime for the paper mill resulting in a huge expense that any company would want to avoid,” says Hanley.
Although automatic lubrication systems have been around for decades, it is estimated that 80% of all lube points are manually lubricated.
From an economic point of view, automatic lubrication systems provide users with very quick return on investment. In addition to reducing grease consumption up to 33%, optimum lubrication reduces energy consumption, maintenance intervals, waste disposal, and unplanned downtime. In some cases, engineered lubrication systems with advanced monitoring capabilities can easily save elaborate processes millions of dollars in operating costs per year.
Automated lubrication systems also eliminate the potential human risk costs associated with manually lubricating critical lube points on running equipment.
Automated system basics
There are several different types of automated lubrication systems, but a typical system consists of controller/timer, pump with reservoir, supply line, metering valves and feed lines.
Whatever the design, automated lubrication system metering valves - the valves that dispense oil or grease in controlled proportions to each connected lube point - must stand up to the rigors of harsh plant environments.
One of the most common lubrication systems is the Single-Line Parallel, which is also referred to as the Injector-type of lubrication delivery methodology. This system is known for its ease of installation, adjustable metering of valves (or injectors) and applicability to a minimum of one and maximum of six lube points per device. Lubrication points may be added or removed without redesign of the system. On the down side, 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 minimum of one and maximum of eight lube points may be serviced from each device, and lubrication points may be added or subtracted without system redesign. Also, heavy greases may be delivered over very long distances. However, with this system it is difficult to verify that each lubrication point is constantly being serviced.
A third type of automated system, the Single-Line Progressive System (aka the Divider Valve System), is precisely engineered to deliver exact lubricant requirements to each point. However, with this system lubrication amounts and points may not be altered, and initial installation costs are higher than with other systems. A primary advantage of these systems is that system performance can be easily and inexpensively monitored to verify that each lube point is constantly being serviced.
In order to overcome the various threats of corrosive and caustic environments, Lubrication Scientifics makes all three types of system and components available in 303 and 316 stainless steel, most of which are available within days rather than months.
Verifiable system advantages
Plants that have the verifiable automated system normally have the need to deliver precise amounts of lubrication to many points. This requirement is so stringent that is critical that workers could not normally adjust the amount or type of lubricant that being delivered to the equipment.
The biggest advantage of the Single-Line Progressive type of system is that every lubrication point is monitored, ensuring that each point is receiving the proper lubrication, thereby maximizing production uptime.
In addition, this type of system prevents unauthorized interference with system settings, so that workers cannot inadvertently change the precise amounts and intervals of lubrication sent to various points.
Avoiding failure of metering valves
Pulp & paper industry plants are exposed to some of the harshest environmental factors, including the wash-down procedures that occur at frequent intervals.
Corrosive damage from exposure to caustic emulsions and wash-down fluids can severely compromise the performance and service life of lubricating system metering valves. These are often 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.”
One answer to preventing corrosion damage is the use of stainless steel. However, as 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. Including the cost of the enclosure, the bulkhead fittings, and the installation labor, it is easy to spend $2,000 to protect a $500 hundred dollar plated carbon steel metering valve.
Rather than wasting precious capital enclosing carbon steel metering devices in stainless steel enclosures, Lubrication Scientifics produces and stocks stainless steel metering devices and accessories, for every type of lubrication delivery system. The company has a full offering of metering devices, specifically designed to meet the reliability and cost needs of the paper and pulp industry. These metering devices can be directly mounted onto the equipment being lubricated and all critical points can be economically monitored. If paper and pulp is your business, and corrosion and improper lubrication are hurting your bottom line, stainless steel lubrication systems are the answer to the problem.