STEEL MILLS AND HFCS
Tony LeBarge, director of technology, KOST USA, Inc., says that today’s steel mills need HFCs with a number of key characteristics, including the following:
OPTIMAL WATER CONTENT. The water content provides the primary fire resistance. A minimum of 35 percent water is typically required to maintain optimum fire resistance. Too much water can adversely affect pump performance and cause premature failure. For this reason, less than 41 percent water is recommended.
SHEAR STABILITY. As machine and maintenance practices improve, there are greater demands on fluid. The higher pressures, temperatures and flow rates, along with reduced down times, expose the fluid to more shearing stress. This can result in permanent viscosity loss, which can make equipment more susceptible to premature failure. The correct choice of customized or optimized polymer thickeners will become increasingly important.
CORROSION CONTROL. Because they contain a high proportion of water, HFCs have a greater tendency to corrode ferrous parts. A fluid properly formulated with corrosion inhibitors will reduce or prevent this. However, the area of most concern is where the fluid does not come in contact with the parts needing corrosion protection. Due to elevated operating temperature and the volatility of water in the fluid, water vapor tends to condense into the cooler-head space of components such as reservoirs and storage tanks. This is why many fluids contain vapor-phase corrosion inhibitors. The challenge is to maintain the proper levels throughout the fluid life. These inhibitors are designed to evaporate and protect the metal surfaces from corrosion due to water vapors. The challenge is to select a corrosion inhibitor that volatizes slowly enough to maintain protection over an extended service application.
Sidebar 2 from Fire-Resistant Fluids Cover Story from July 2013 TLT