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Conveying


to totally enclose hazardous spaces as a way of protecting employees and visitors using walkways and inspection points, with heavy guards fabricated from metal mesh or screen that permits observation of moving parts without posing an opportunity for injury. Detailed safety guidelines for the U.S. are published in ASME Standard B-2.1-2006: Safety Standard for Conveyors and Related Equipment and in B15.1: Safety Standard for Mechanical Power Transmission Apparatus. While virtually every nation has individual requirements that apply to the placement of guards, local and general industry standards should also be consulted and implemented.


SCHEDULED INSPECTION & MAINTENANCE


It’s easy to focus on the fact that companies make money only when the conveying system is loaded and running, especially if employee compensation is tied to plant performance. As a result, there’s a reluctance to shut down a running line until there’s a compelling reason, which creates a “We’ll fix it when it breaks” attitude.


What some managers fail to recognise is that this approach will change their conveyor service from scheduled maintenance to crisis management. Such short-term thinking is an almost certain path to component failure -- probably catastrophic -- which will ultimately cause more system downtime, higher repair costs and more labour investment than if a sensible plan had been created and followed from the outset. It’s critical that the production schedule allows adequate system downtime to perform necessary inspections and maintenance. A formal inspection and service schedule must be developed for the material handling system and followed religiously. This program should include review of emergency switches, lights, horns, wiring and warning labels, as well as the conveyor’s parts and accessories, such as chutes, cleaners and other components. There are certain conveyor safety practices that should always be observed, regardless of the size, design or operating environment. Lockout / tagout / blockout / testout procedures must be established for all of the belt’s energy sources, as well as accessories and associated process equipment. Bulk material handling systems can still present a hazard from the energy that is stored in a stretched belt after its motion has stopped, which can cause the conveyor to move suddenly, even when the system is de-energised. Lockout and tagout alone may not be


22 September 2014 Solids and Bulk Handling


enough to ensure a worker’s safety, so it’s imperative that the conveyor be blocked and tested to confirm that it cannot move. These procedures should be followed before beginning any work in the area, whether it be construction, installation, maintenance or inspection.


SAFETY BY DESIGN


The most efficient way to address conveyor safety and maintenance is by building the system from the outset with those features in mind. But even without that luxury, a thorough evaluation of the conveyor system will help identify potential problems and upgrades, whether performed by a qualified staff member or by an experienced independent supplier.


While any conveyor supplier can build a system to transfer material from one place to another, adding safety and fugitive material control as critical elements will complicate the equation for some manufacturers. For optimum safety and productivity, a conveyor system should be designed for easy installation, maintenance, repair and cleanup. Specifiers should look for standardised components that can be easily serviced; maintenance access points at strategic locations; comprehensive barrier guards at all pinch points; and upgradability options to meet future requirements.


The design should provide adequate walkways, platforms and utilities such as water, electricity and compressed air to facilitate maintenance and service. Modular components such as track-mounted pulleys can deliver slide-in / slide-out convenience. Even if a procedure is only required infrequently, the time and money savings can be significant. Dust-resistant structures, engineered flow chutes and properly designed skirtboards all contribute to fugitive material control, helping to reduce maintenance and downtime. Common features such as wear liners, seals and belt cleaners help minimise waste and maintain consistent belt tracking, while customised designs may include specialised chutes and belt-washing systems. Modern 3-D drafting and fabrication techniques now allow conveyor suppliers to build and arrange components in non-traditional ways, without greatly increasing the costs.


CONTRACT SERVICES


When the economy lags, plants often reduce their head count. In an effort to concentrate the efforts of remaining staff on core activities


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and stabilise maintenance costs, many bulk materials handlers are entrusting their conveyor installation and service to outside contractors. Most will find the best success with specialty contractors whose sole focus is conveyor systems and bulk material flow. These specialists, employed by a proven manufacturer, trained and certified to specific standards, will have conveyor expertise which exceeds that of a general contractor. Having an outside expert opinion often helps to identify problem areas that plant personnel may have come to view as normal. Some suppliers will offer to “walk the belt” and provide a state-of-the-system report from observing it in operation. While no repairs should ever be attempted with the belt in motion, watching and listening to the system will help an experienced conveyor mechanic to identify components in need of attention, often before a catastrophic failure or safety incident occurs. Trustworthy parts/service providers will provide upfront quotes on the equipment and labour they supply, as well as performance guarantees to ensure customer satisfaction. They should be skilled in conveyor science and safety, able to identify opportunities for system improvements and quantify the potential benefits. Some will also offer operator training programs and continuing education, helping to facilitate a company- wide commitment to safety and preventive maintenance, while fostering a culture of continuously reducing risk and enhancing plant performance. All forms of bulk material movement carry their own risks and safety concerns, but properly designed, maintained and operated conveyor systems remain one of the most effective modes of material transport. Rather than view them purely as an operating expense, owners and crews would be better served to investigate the opportunities to improve both safety and productivity. Thorough planning by well-trained personnel will help maximise efficiency by eliminating fugitive material and minimising hazards as much as humanly possible. The result will be healthier, happier employees and an improved bottom line. n


For more information contact Martin Engineering on tel: 01159 464746 or visit: www.martin-eng.co.uk


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