Application Bulletin       Increasing the Reliability of Hot Gas Fans       Chrome carbide weld overlay on gas recirculation fan blade after four months of service.   Conforma Clad tungsten carbide fan blade liner in the same application after twelve months of service. Severe wear caused by fly ash colliding with gas recirculation, hot primary air, induced draft, scrubber boosters, and other dirty gas fans, can result in costly downtime, repairs, and availability limitations. Failures triggered by high velocity ash impingement can occur in many areas, including leading and trailing edges, centerplate weldment areas, and fan inlet hubs. These failures often result in reduced gas flow and fan efficiency, sudden fan imbalance, and the catastrophic detachment of blades; all of which can lead to significant collateral damage and forced outages or deratings. Equipment operators have attempted to improve the reliability of high speed fans by applying various protective coating technologies. Several factors, however, limit the success of most protective coatings on fan applications. These factors include extreme operating conditions, fan instability caused by the increase in weight, insufficient or unpredictable coating performance, safety concerns raised by potential material disbonding, limited motor horsepower, fan dynamics and geometry, and the need to substantially extend run times between maintenance outages Conforma Clad infiltration brazed tungsten carbide cladding has successfully conquered these obstacles, and has helped dozens of operators increase their hot gas fan run times by a factor of four or more. Conforma Clad substantially boosts equipment productivity and reduces maintenance costs and unplanned downtime. Case Study A Northeastern production facility experienced several induced draft fan and scrubber booster failures as a result of hot fly ash erosion. Failures of hard chrome liners typically occurred at six to nine month intervals. Due to the unpredictable wear characteristics of hard chrome, the failure interval was unpredictable and represented an extreme risk during the peak summer production season. In an attempt to lessen the risk of excessive downtime, the facility routinely stocked 1,000 chrome blade liners to facilitate rapid repairs. The failure of a 640MW unit occurred during the late summer months, causing an unscheduled outage that lasted 96 hours. In order to meet its committed power supply, the facility was forced to wheel 61GW-hour at a cost of $60/MW-hour. This single unplanned outage cost the facility nearly $3.7M in lost generation alone. Now, using Conforma Clad infiltration brazed blade and wheel hub protection liners, the facility operates its hot gas fans without the fear of unplanned failures between scheduled outage windows. The Conforma Clad liners are replaced every 36 months, during scheduled outages. What is Conforma Clad Infiltration Brazing? Conforma Clad blends hard tungsten carbide particles and tough nickel chrome particles which are spun together and rolled with organic binders in a proprietary process to create flexible and homogenous high-density metal composite cloths. These flexible cloths are applied to industrial equipment components in an environmentally controlled brazing furnace. During the brazing process, the tungsten carbide particles are bonded to the nickel chrome lattice, which also infiltrates the substrate component, forming a true metallurgical bond that precludes spalling, chipping, and peeling, even under extreme operating conditions. Erosion Test Results   Homer City Fly Ash     Black Beauty Fine Grit Coal Slag     Conforma Clad Wear Protection vs. Alternate Materials Properties Conforma Clad Thermal Spray Weld Overlay Ceramic Tiles AR Plate High Chrome Cast Bond Strength Very High Very Low High Low N/A Low Complex Geometries Yes No Difficult Difficult Very Low Low Abrasion Resistance Very High Moderate High Very High Very Low Low Erosion Resistance Very High Low-Moderate Low Low Very Low Low Corrosion Resistance High Low Low Low Low Low Impact Resistance Moderate Low Moderate Very Low Low Low Oxidation Resistance Low High Low Low Low Low Formability High Moderate Low Very Low High Low Heat Tolerance High Moderate Low Very Low High Low Susceptibility to Channeling High Moderate Low Very Low High Low Predictable Life High Moderate Low Very Low High Low Erosion: Weight Ratio High Moderate Low Very Low High Low Available Thickness High Moderate Low Very Low High Low For more information on how you can use Conforma Clad solutions to increase the reliability and productivity of your hot gas fans, contact your local representative, call us directly at (888) 289-4590, or email us at newalbany.contact@kennametal.com.  Download PDF here. (182 KB)