Prepare for Winter Colds
Industry manufacturers offer advice on how to immunize your operation against the harmful effects of winter cold.
by Tina Grady Barbaccia, News/Digital Editor
Failure to prepare your aggregate processing equipment for winter can be like a small cut that turns into a serious infection, then adversely affects both your health and finances.
A tremendous amount of money is lost each year in the aggregates industry because of corrosion, a.k.a. rust, of iron and steel aggregate processing equipment. Because U.S. winters have recently been milder than in years past, producers are trying to run their plants longer. This has resulted in shorter “winter shutdown,” notes Mark Kennedy, senior after sales training instructor for Metso Mining and Construction Technologies. However, he notes that most plants he deals with don’t take the time, money, or effort to winterize their crushing or screening equipment when they do shut down for the winter.
“Most customers simply turn the equipment off and hope for the best when they start back up in spring,” Kennedy adds, warning that “once rust develops, it can spread like an infection, until before you know it, you have a worthless, ineffective component on your hands. Rust is not only unappealing to the eye, it can damage the safety and health of that equipment part or component. Rusted bolts, fasteners, gear teeth, bearings, shafts, and other parts may cause the equipment to malfunction, fail, or lead to personal injury.”
What’s more, Kennedy says, is that under some conditions, rust may strike quickly, while other times, it takes its time and slowly erodes the component. “When oxygen and moisture come into contact with exposed metal, rust is the unfortunate result,” he says. “While corrosion is removable in many cases, it is much better to prevent the rust rather than deal with its aftermath.”
The problem with iron, as well as many other metals, is that the oxide formed by oxidation does not firmly adhere to the surface of the metal and flakes off easily causing “pitting.” Extensive pitting eventually causes structural weakness and disintegration of the metal.
The tell-tale sign that the piece of equipment has been affected by corrosion — i.e. the “wearing away” of metals due to a chemical reaction — is “an unattractive burnt orangey-brown mess that clearly indicates rust is present,” Kennedy points out. “The appearance is particularly unattractive when it attacks the outside of a piece of equipment, where speedy attention is needed to prevent further damage and the spread of rust.”
It’s also important to keep in mind that rust is permeable to air and water, therefore, the interior iron that is already affected will continue to corrode, Kennedy says. “Rust prevention thus requires coatings that preclude rust formation,” he says. “Coatings such as oil, wax, rust preventers, or paint will isolate the part from the environment.”
Electrical panels also need to be properly sealed to prevent water or moist air from entering. “Moisture absorbing packets can be used to reduce the moisture level within the panel,” Kennedy explains.
Spare crusher parts and assemblies are also often forgotten about when it comes to seasonal storage. If the components are going to be stored outdoors, they also need to be protected from the elements, he says. Without proper winterization, an unprotected crusher’s locking collar could become rusted (like the one pictured here).
To reduce the production cost of finished aggregates, an operation’s staff needs to understand exactly how their rock crushers are supposed to be maintained and exactly how they should be prepared for seasonal storage, Kennedy says.
“If rock crusher operator personnel do not have a thorough and complete understanding of their rock crusher maintenance requirements,” he adds, “frequent periods of downtime along with subsequent lost production due to unexpected crusher failures are inevitable.”
To protect against inevitable failures and to help you prepare your equipment to keep it at its best during a winter shutdown, implement the following guidelines. (It is always a good idea to refer to your specific equipment instruction manual for exact “winterization” details.)
12 tips to equipment storage and preparations
Mark Kennedy, senior after sales training instructor for Metso Mining and Construction Technologies, offers “protective measures” for cone crusher seasonal storage. By adhering to the following recommendations, a crusher stored outdoors should have six to 12 months of rust protection.
- Remove the bowl, feed plate, head, socket, and eccentric assemblies. Disconnect the oil drain line at the bottom of the crusher and the oil pressure inlet at the bottom of the main shaft. Make sure that all piping and the hole in the bottom of the main shaft are sealed with pipe plugs.
- Use a wide paint brush to paint all inside surfaces of the main frame with a rust preventative lubricating oil.
- Use a lubricant which has a rust preventative blend designed for the protection of internal parts of enclosed assemblies. The rust preventatives function by displacing water from the metal surfaces, by forming strong water-resistant films on the surfaces. These products provide as much as 30 to 40 times the protection against rust as high-quality lubricating oils that have not been specially formulated to prevent rust. In most applications, the residual rust preventative film need not be flushed away or otherwise removed when the crusher is to be filled with lubricating oil and put back into service. The viscosity of the oil should be in the 150 to 300 SSU at 100 degrees Fahrenheit range. Fifty-five gallons should be sufficient to coat the entire crusher.
- Using a paint brush, coat the lower thrust bearing, the outer surface of the main shaft, and all exposed surfaces of the pinion with the rust preventative oil. Remove the countershaft box oil feed hose from the top of the countershaft box. Place a funnel in the hole and pour oil into the countershaft box while rotating the countershaft. About 5 gallons will be required. When complete, reattach the oil feed hose to the countershaft box.
- Fill the lubricating hole in the main shaft until the hole is filled with oil, and then drain it.
- Coat the outer surface of the eccentric, the eccentric bushing bore, the gear, and the upper thrust bearing with rust preventative oil.
- Brush oil over the head ball, the bore of the upper and lower head bushings, and all areas of the head adjacent to the “T” seal.
- Reinstall the eccentric assembly and the socket assembly. Apply a coat of the rust preventative oil to the bearing surface of the socket liner and the exposed surfaces of the socket. Reinstall the head assembly and then the feed plate.
- Brush or spray a light-bodied petroleum solvent containing a substantial amount of polar rust-preventative additive having strong attraction for metal surfaces, on the bowl threads, adjustment ring threads, and the clamping ring threads. The solvent should evaporate quickly and leave a thin, transparent greasy film. The film need not be removed when the crusher is placed back in service. At that time, the threads will be liberally coated with lithium-based grease NLGI No. 1 with 5 percent to 10 percent molybdenum disulfide.
- Reinstall the bowl assembly into the crusher.
- Cover the entire adjustment cap and bowl hopper with a sheet of 8-mil black polyethylene to prevent water from seeping into the crusher and corroding the threads. Black is recommended as transparent sheeting will deteriorate four times faster than black. The end of the countershaft should also be covered. Steel strapping or banding is an ideal method of holding the polyethylene sheeting in place.
- Reconnect the oil inlet and oil drain lines. The oil adhering to the metal surfaces is all that is needed for proper rust protection. When seasonal shutdown results in months of equipment inactivity, not weeks, the aforementioned steps will result in a more reliable crusher come springtime. At the same time that the “winterization” takes place, a complete yearly crusher inspection should take place.
8 tips to better vibrating screen storage
If a vibrating screen will be stored for an extended period of time — longer than two weeks — a rust treatment plan should be renewed every three months, following the date stamped on the paper label affixed to each side of the vibrator shipment, according to Metso’s Mining and Construction Technologies.
Vibrators in service that are to remain idle for periods longer than two weeks should also be given some storage treatment to prevent rusting of internal metal parts and drying of seals. Additionally, rust preventative oils are recommended because the parts need not be cleaned of this compound before placing the unit in operation. Simply drain the excess and refill to the proper oil level with your operating lubricant.
Before shutting down, Metso’s Mining and Construction Technologies recommends the following steps if the vibrator is to be idle for an extended period and power is available to drive it while it is attached to the live frame:
- Drain the operating oil and refill to the proper oil level with Mobil-Kote 501 or 503 (or equivalent).
- Run the unit for one hour before shutting down.
- After shutdown, coat the exposed portion of the oil flinger sleeve on the drive shaft with grease.
- Keep the rust preventative in the vibrator during the idle period, and put the unit in operation every three months for one hour.
- When operations are resumed, drain the rust preventative and refill with the proper oil.
- Vibrating screens can vary from model to model, so make sure to refer to your specific vibrating screen instruction manual for exact “winterization” details.
Tip sheet for winter operations and shutdown:
Here’s a tip list from Chris Wade, FLSmidth Pekin general manager of crushing services, and Ken Olson, FLSmidth director of manufacturing, to help you with winter operations at your aggregates plant whether you run through the winter months or completely shut down your operation.
A checklist for operating during the winter:
- Make sure the package lubrication systems and the hydraulic power units have the proper viscosity oil for ambient temperature conditions that will be encountered. Operating with high oil viscosity will shorten pump life and can affect the function of solenoid and relief valves on the hydraulic power units
- Make sure that all oil immersion heaters are functional, as highly viscous cold oil has an adverse effect on pump life. The additional viscosity will result in an increase in viscosity head, which can result in too much oil by-pass and not enough lubricating oil getting to the crusher. Note that some operators insulate the lube oil and hydraulic power unit oil reservoirs in very cold climates.
- Hydraulic power unit canister breathing elements for the reservoirs often have a desiccant and should be changed out as sub-freezing temperatures approach.
- Air/oil heat exchangers continue to cause cooling of the oil even without the fan moving air over the radiator core. Cover the front of the radiator to block air flow, if necessary.
- Make sure that the reservoir oil temperature is up to 80 degrees Fahrenheit before starting the lubrication pump.
- Make sure that the return oil temperature is up to at least 60 degrees Fahrenheit before feed is introduced to the crusher.
- Winter operations can result in frost on the feed and discharge conveyor belts. Operate the conveyors without load for an extended period of time to warm the belts and increase the flexibility. Ensure that any belt slip detection is functional. A slipping discharge conveyor can cause serious damage to a cone crusher if product backs up into the crusher.
- Keep walkways and decks free from ice and snow build up for safety.
A checklist for winter shutdown:
- Unless the oil is relatively new, change the lubrication oil and circulate it through the crusher. Old oil can contain contaminants and may have lost its ability to lock up water, which can lead to corrosion of both the steel journal surfaces and bronze bushings.
- Make sure that all oil reservoirs are properly sealed, and change out/clean out all reservoir breathers. Some reservoir breathers have a desiccant inside, and these should always be changed out prior to sub-freezing temperatures.
- If possible, start up the crusher and run it at no load until a return oil temperature of 100 degrees Fahrenheit is achieved.
- Crushers with water/oil heat exchangers will need to be drained and left open. It is often advisable to place an anti-freeze mixture in the heat exchangers. Make sure that all piping is drained or blown out with compressed air. This also goes for any dust suppression systems used with the crushing plant.
- Air/oil heat exchangers should have the outboard protective grill covered to keep air from blowing through. This will stop the windmill turning of the fan and motor and also stop wind-blown dust and sand from eroding the radiator core.
- Relax the tension on the crusher drive belts. The belts contract with cold, and the already tensioned belts could cause excessive tension to the countershaft, motor rotor shaft, and all bearings and bushings.
- Cover the crusher feed hopper to keep the chimney effect from moving dust through the crusher discharge and crushing cavity. Excessive dust-laden air flow can cause a venture effect that will pull air out of the lower sealing area and into the upper sealing area.
- Any outside junction boxes with plastic windows and any automation control features such as HMIs should be covered to reduce UV damage and wind-blown erosion (frosting).
Keep it Clean
Although it may seem like common sense, properly cleaning all the equipment and components in your plant can mean the difference between protecting your equipment and having it ready to go at spring startup in the spring and having downtime because you didn’t take the time to do proper maintenance.
Dust suppression system: For example, it’s critical to blow out the dust suppression system on your plant, says Bill Maccini, a service technician with Telsmith who also managed a plant for nearly 20 years. “Before it gets too cold, you want to clean the equipment so you can perform maintenance on it,” Maccini says. “You’ll want to wash down everything completely when you shut down so you’re not chipping frost off to clean [the equipment].”
Air cooler: You want to wash out any moisture and condensation in the equipment, particularly air coolers, Maccini says. “That way, it’s not sitting there causing corrosion in your cooler. When you start up in the spring, you want a clean sheet,” he says. “Once everything freezes, you can’t move equipment for repair. It’s much more cost effective to clean things and be prepared to do maintenance. You don’t want to have to bring a plant online while having to make several repairs that are difficult to do because the machines weren’t shut down properly.”
Electrical components: Maccini notes that working on electrical components that have not been cleaned properly is problematic. “If you have to work on electrical components, but you can’t get to them because they are buried in dirt, that’s going to affect your whole plant,” he says. “The same goes for hydraulic units. It comes down to housekeeping and preparing for both winter shutdown and spring start up.”
Gear boxes: Be sure to drain the oil when it’s still warm. “It’s easy to drop the oil out when it’s hot,” Maccini says. “You need to do it while it’s still flowing. When the oil is cool, it is thick.” Maccini also suggests resealing the gear boxes that need it prior to any winter shutdown.
Components, etc.: Disassemble any components that can be put in the shop. Replace any “time-consuming” items. Replace/change any return pulleys or head pulleys that need to be changed.
Maccini suggests that each plant operator develop a daily checklist specific to his or her operation. In putting together the checklist, Maccini says the plant superintendent needs to think about “what will cause us to go down in the middle of the day.” Tasks should be prioritized by “what will keep us from starting up in a few months.”
A month prior to shutdown, make a list of everything that is needed for parts, Maccini advises. “Make a list of everything you need for parts, prioritize the list, and make sure you have the parts and a timeline to do it.”