December 1, 2010
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.
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:
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:
A checklist for winter shutdown:
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.”