- They are hard, abrasive particles.
- It is also possible to contaminate a clean marine residual fuel oil with catalyst particles during transport. For example, if steamship fuel (frequently containing catalyst particles) has been transported by barge prior to moving a clean heavy fuel oil for a diesel powered ship, the barge bottom sediment will be mixed with the clean fuel oil and will contaminate it.
- Cat-fines are generally small, very hard, and quite abrasive to pumps, atomizers, piston rings and liners.
- (30 ppm) of alumina in the bunkered fuel oil is the upper limit for successful treatment and engine operation.
- The average particle size, as well as the concentration, greatly impacts the wear rate of engine components.
- Small sized catalyst particles (1-10) micron range typically cause accelerated wear in injection pumps and injectors and only moderate increases in cylinder assembly wear, such as piston rings, piston grooves, and liners.
- The larger sized catalyst particles, in the ten to seventy (10-70) micron range, typically causes very accelerated wear rates in the cylinder assembly area. Also on injection pump inlet valves, exhaust valve seating areas, and turbocharger turbine blading.
1. High cost: Manganese bronze is a costly alloy, making it less economical for large propellers. 2. Low strength-to-weight ratio: Compared to other propeller materials like nickel-aluminum bronze or stainless steel, manganese bronze has a lower strength-to-weight ratio. 3. Susceptible to corrosion: Manganese bronze can corrode in seawater, especially when exposed to high velocities and turbulence. 4. Poor cavitation resistance: Manganese bronze is more prone to cavitation damage than other materials. 5. Difficult to cast and machine: Manganese bronze is challenging to cast and machine, making it less desirable for complex propeller geometries. 6. Limited weldability: Manganese bronze has poor weldability, making repairs and modifications difficult. Nickel-aluminum bronze or stainless steel are commonly used for propellers due to their: - High strength and durability - Excellent corrosion resistance - Good cavitation resistance - Ease of casting and machining - Weldability
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