Applied Industrial Technologies
Many facilities shut down when the weather gets too cold to work or during the annual slow season. But an operation cannot simply turn off the machinery and hibernate for the shutdown period. Here are 10 tips on how to prepare equipment for its seasonal “vacation” to ensure that it will run reliably on restart.
Tip 1 – Prepare the Staff
Prior to the shutdown, gather maintenance and support staff to review the shutdown procedure. Make a list of all personnel with up-to-date contact information, and inform them if they may be on 24-hour call during the shutdown.
Tip 2 – Inspect Electric Motors and Bearings
Outdoor operations can be especially hard on electric motors
. Bearings in critical applications should be inspected where dust, dirt and water are everywhere and can enter a bearing through shaft seals, causing excessive wear. In addition, the heavy loads, shock and vibration common to many operations can cause severe bearing damage and potential failure. There are many new monitoring tools available where the bearing can be tested for excessive heat or vibration to help determine if a bearing will need to be replaced at start-up.
Electric motors should also be inspected due to the harsh conditions. Motor efficiency can be enhanced through regular maintenance, which will not only improve reliability but also prolong motor life. A basic motor maintenance program requires periodic inspection and correction of unsatisfactory conditions. Items to check during inspection are: lubrication, vibration, ventilation and the presence of dirt or other contaminants; alignment of motor and load; possible changing load conditions; belts, sheaves and couplings; and tightness of hold-down bolts.
When an electric motor fails, the question is whether to repair it or replace it with a new one. Operating cost is a primary consideration in making this decision because the cost of a motor is insignificant compared to the cost of the electricity required to operate it.
When a motor must be replaced, either a standard EPAct or NEMA Premium®
design can be used. EPAct motors generally are less expensive; however, they usually are less energy efficient, run hotter and have higher operating costs. NEMA Premium motors cost more initially, but some utilities offer rebates to help offset the cost difference. The motors are 0.5 to 4 percent more efficient than standard motors. They also run cooler, require less maintenance, experience less downtime and are available with extended warranties. NEMA Premium motors can save thousands of dollars in annual energy costs, and payback time can be as short as six months.
Tip 3 – Inspect Conveyor Belts, Idlers, Pulleys and Skirting
Conveyor belts, idlers, head and tail pulleys and skirting
take a beating during the busy summer months and these items seldom get replaced unless there is a breakdown. Now is the time to thoroughly inspect all these moving parts and replace worn and damaged items to avoid costly downtime next season. Order an extra set of spare parts for those items that exhibit the most wear. Smart planning now could save valuable time and money next year.
Tip 4 – Inspect Drive Belt Sheaves and Belt Tension
Most facilities routinely replace drive belts
when they become worn or damaged, but they often neglect to check sheave
condition. Eroded sheave sidewalls can cause up to 12 percent loss in V-belt drive efficiency. Rough and worn sidewalls can reduce belt life by up to 50 percent. Worn sheaves are often compensated for by over-tensioning of belts to transmit power, which can overload the motor and gearbox shafts. An inexpensive sheave can result in downtime and motor or bearing replacement costing several thousand dollars. A sheave in a typical quarry application should be replaced every 2 to 4 V-belt replacements, depending on the abrasiveness of dust in the air, installation accuracy, load, and other operating conditions. Belt manufacturers can supply sheave gauges to help assess sheave condition and make smart decisions about maintenance.
In addition, sprocket and sheave
alignment plays an important role in maintaining belt drive efficiency. Misalignment can cause excessive wear on sheaves, resulting in similar inefficiencies and reduction in belt life. Alignment tools are available from belt manufacturers to assist in correctly positioning sheaves and sprockets.
Improper tensioning – either too tight or too loose – leads to inefficient power transmission and reduced belt life. In a severe environment, belts can be loosened due to shock and vibration. To help ensure proper belt tensioning, manufacturers offer a variety of tools at costs ranging from free to $1200. For example, the Goodyear TensionRite™ Gauge is designed for use on select Goodyear belts. The tool adheres to belts during installation. Users locate the correct tension listed on the back of the TensionRite card that corresponds to the belt and sheave diameter being used. They then tighten the belt to the setting indicated in the gauge window.
Tip 5 – Inspect Gearbox Breathers
Breathers are an important part of any gearbox
. They allow heat to escape and cooling air to enter to help prevent the gearbox from overheating. They also allow for expansion and contraction of the air in the reservoir in repose to temperature fluctuations. However, in dirty or harsh environments, breathers can become clogged or damaged, or completely disappear.
When breathers become clogged, internal gearbox pressure can build up until it escapes through oil seals, creating a false impression that the seal has failed. A clogged breather can also cause internal gearbox temperature to rise, leading to lubricant failure. This can be more problematic during summer months.
Many older gearboxes still have an open tube for breathing, although newer units now incorporate a vent plug. While these types of breathers may stop large contaminants from falling into the gearbox, they will not stop destructive particles from entering.
During shutdown, replace clogged or missing breathers with devices incorporating a 1-µm filter to remove as much airborne particulate as possible. If the gearbox operates in a damp environment, use a desiccant breather to trap the moisture in the incoming air, which can cause corrosion on gears and reservoir walls.
For applications where volume changes are minimal, a bladder type breather is an option. This device effectively seals the inside of the gearbox from the atmosphere while still allowing for expansion and contraction of the air in the casing due to temperature changes.
Tip 6 – Check Hydraulic Hoses
A shutdown is a good time to inspect hydraulic hoses
for damage or leakage and take corrective action. Damaged hoses should be replaced to avoid costly environmental cleanups, potential injury, unscheduled downtime and damage to other components in the system.
If a hose must be replaced, the installation should be examined to determine if the failure is due simply to age or if steps can be taken to prevent future failures. For example, if the hose is abraded, install abrasion protection such as spiral wrapping, sleeves and guards. Also, install guards and shields around heat sources (exhaust manifolds, turbochargers, mufflers, etc.) and around operator areas to keep out fluid if a hose fails.
Although it may seem obvious, check that hoses carry the proper rating (working pressures are printed on the hose body). In addition, verify that the correct hose fittings are installed and that hose length is correct. Finally, check hose routing to eliminate abrasion damage and exposure to ignition and electrical sources, and install hose clamps where appropriate to prevent excessive free motion.
Remember, when replacing hoses, clean or blow out the interior to remove debris or pieces of metal left over from manufacturing so it does not contaminate your system.
Tip 7 – Inspect the Hydraulic Fluid
Like a car, a hydraulic system cannot run optimally on low or dirty oil. Dirt and heat, which are present in abundance in outdoor or underground operations, are the principal enemies of a hydraulic fluid
. Failure to maintain proper oil levels and quality will rapidly reduce equipment life.
The ideal operating temperature for a hydraulic system is about 120°F. If you can hold your hand on the reservoir during normal system operation, temperature is probably within that range. However, if the reservoir is too hot to touch, temperature is too high and the fluid is probably breaking down. If the system is too hot, ask two questions: Has it always run hot? Or has it been getting hotter over time? If system temperature has been rising over the years, check for internal leakage or failing components. If the system always ran hot, consider adding a heat exchanger or oil cooler.
should be sampled and tested annually to ensure contamination and fluid properties are within acceptable levels, and a planned shutdown is an ideal time to perform this analysis. The tests measure particulate level, water content and the oil’s lubricity properties. The analysis will also indicate if oil filters are being changed at proper intervals and if the filtration level is correct.
If fluid must be replaced or topped off, use hydraulic filter carts
to transfer new oil to the system. This will reduce the potential for contaminants to enter the system and cause problems later.
Tip 8 – Prepare Gearboxes and Pumps
Any equipment that is filled with grease or oil needs special attention during a shutdown. Gearbox
casings should be filled so that gears and bearings are completely covered with oil to prevent corrosion while they sit idle. The same holds true for hydraulic pumps
housings. Remember to drain the oil and refill to the proper level before restarting the equipment.
Tip 9 – Consider Installing Shaft Sensors and Automatic Lube Systems
Rocks and debris can cause jams and overloads, leading to drive failures that quickly spread to other equipment. Rotating shaft sensors placed on strategic drives can alert personnel of sudden speed changes or stoppage of drives, or belt slippage. Corrective actions can then be taken to prevent further breakdowns and avoid chain reaction failures.
The MS1 Sensor from Applied Innovative Solutions mounts magnetically, eliminating the need for machining and welding. They are suitable for any equipment with a rotating steel shaft of 1-15/16 in. or larger in diameter and rotating at less than 300 rpm.
Tip 10 – Winterize Pneumatic Lines
At temperatures below freezing, water in pneumatic lines can freeze, potentially ruining equipment or bursting lines. These problems can be minimized in
total-loss lubrication systems by adding a lubricant such as Total USA's Kilfrost 400 to the system.
Kilfrost 400 absorbs up to four times its own weight of water in the air, depressing the freezing point of the solution formed to prevent freezing. Before restarting the system, the Kilfrost should be replaced by the usual lubricant because it cannot be used at temperatures above 40°C.
The annual or seasonal shutdown is the perfect time to inspect equipment, make necessary repairs, and prepare it for the layoff. Following a step-by-step inspection, repair and maintenance procedure can ensure a safe and reliable restart. Now is the best time to ensure higher productivity goals for next year. Additional information is available by contacting Applied Industrial Technologies at www.Applied.com