Engineering & Mining Journal

JUN 2013

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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Page 84 of 171

MAINTENANCE management selected Chevron's Delo 400 Multigrade 15W-40 as the standard engine oil for these haulers. Chevron's senior consulting scientist, Jim McGeehan, visited the mine recently to inspect one hauler's MTU 20V 4000 engine that had racked up 21,900 hours of operation, and had been serviced at 500-hour intervals. The engine was torn down and the findings, according to McGeehan, were impressive. Wrist pin bushings on the 20V 4000's 20 pistons were found to be in excellent condition. The lands were free of deposits, while the crowns showed minimum deposits. When looking at the rings of one piston, McGeehan said, "The oil ring groove is absolutely clean. ... The top ring is in a good wear pattern. ... Then the oil scraper ring, all the rails are in perfect condition." The main bearings also were in excellent condition with no overlay removal. "It's important to remember that this engine is operated at 3,650 brake horsepower, with oil drain intervals of 500 hours…These bearing are in excellent condition. In fact, you can put these back in the engine," said McGeehan. According to Jerry Martinez, customer support manager for W.W. Williams, which provides service and support for Asarco's heavy-duty equipment, being able to extend the life of key engine components in vehicles like these can save "hundreds of thousands of dollars" across the whole fleet. "In today's market, these engines go new for somewhere between $550,000 to $560,000. They probably overhaul for about $480,000 per engine, said Martinez. "When you can add 15% or 20% to the life cycle of an engine, then the customer is going to get a return. "I'm not going to [have to] replace all these rocker arms, I'm not going to replace the camshaft or the swingers. I'm going to put in a set of pistons, bearings and gaskets and put this engine back to work for another 25,000 hours or so," he said. According to Senior Maintenance Planner Scott Jackson, the benefits of increasing engine life from 20,000 to 27,000 hours are clear to the mine. "We are actually saving approximately $160,000 per engine per year. The mine runs a fleet of 21 trucks, so you are looking at roughly $3,000,000 in savings per year and 7,000 hours equates to more than a year's operating time at the mine." Eliminate Grease-grade Guesswork The benefits of proper lubrication choice and an attentive vendor aren't limited to engine applications. Bel-Ray Company, a New Jersey, USA-based supplier of industrial and retail lubricants, recently assisted a large quarry operation in Trinidad in solving an ongoing problem related to grease supply in its screen installations, which use large double spherical bearings. The company was using a lithium complex NLGI 2 grade with a base oil viscosity of 144 cSt at 40°C and 11.7 cSt at 100°C, in a pneumatic lubrication system. The NLGI 2 grease wouldn't slump into the suction tube of the grease pump and, consequently, the bearings were not getting greased sufficiently—and even when they were getting the proper amount of lubrication, they didn't last long due to the grease's low base oil viscosity. Bel-Ray, working with the Trinidad distributor, found that the bearings had an inside diameter of 140 mm and an outside diameter of 300 mm, and operated at 200 rpm. Operating temperature was 70°C. Based on this information, Bel-Ray Technical Services calculated the Ndn value and minimum base oil viscosity, which was 55 cSt at operating temperature. To provide the correct base oil viscosity, the Kappa value was calculated, which determines the correct base oil viscosity at operating temperature under the type of load to which the bearing is being exposed. In this application, Bel-Ray determined a heavy load Kappa value of 4 would be appropriate—four times the minimum base oil viscosity. After calculating that the viscosity of the base oil at 70°C was 196 cSt, the Kappa value was determined to be 196 / 55 = 3.56—very near to the desired Kappa value of 4. Bel-Ray Molylube Extreme Pressure High Viscosity Grease 1000-1 was then selected due to its heavy (1000 cSt at 40°C) base oil viscosity. The recommended high-viscosity grease was applied via the screen's auto lube system, with good results: The NLGI 1 grade provided the correct slumping performance, and the heavy base oil of the grease provided the required lubrication. Quick On-site Analysis Even when the correct lubricant has been selected, eventual "lubrication abnormalities" can occur and cause unexpected equipment downtime. To prevent those costly occurrences, Spectro Inc. claims its FluidScan Q1100 handheld infrared oil analyzer enables users to determine when oil is no longer fit for use due to liquid contamination or degradation. The compact instrument provides direct, immediate measurement of water, total acid number (TAN), oxidation, glycol, total base number (TBN), and other parameters via Spectro's patented Direct Infrared Spectroscopy (DIR) technology. The route-based capability of the FluidScan Q1100's operation allows the device to mostly eliminate mislabeled samples and long wait times for laboratory analysis. The results highly correlate to TAN and TBN laboratory tests conducted with ASTM D664 and D4739 titration methods and water tests with the ASTM D6304 Karl Fischer Titration method. Routes, similar to thermography or vibration routes, can be downloaded from Emerson Process Management's AMS Suite's OilView software to the Q1100. Results can be uploaded back into OilView. Oil data can be analyzed, along with data from other predictive maintenance techniques, in the Emerson AMS software for Machinery Health Management. The Q1100 includes a large and expandable reference library of industrial mineral and synthetic lubricants for gearboxes, compressors and hydraulic systems. Emerson Process Management and Spectro joined forces in this sector last year, announcing in September an exclusive alliance to combine technical innovation and expertise to deliver expanded oil analysis solutions. Under the agreement, Spectro gained rights to a suite of Emerson-developed and patent protected intellectual property in the field of oil analysis for predictive machine maintenance. Included in the IP portfolio are Emerson's AMS Suite oil analysis software module Spectro Inc. claims its FluidScan Q1100 as well as the CSI 5200 handheld infrared oil analyzer enables users machinery health oil analyz- to determine when oil is no longer fit for use er—a multi-functional ana- due to contamination or degradation. JUNE 2013 • E&MJ 83

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