Piston ring wear

Residual fuel oils and heavy marine fuels are composed of high-boiling-petroleum fractions, gas oils and cracked components. Residual and clarified oil streams from the FCC process can contain degraded alumina/silica catalyst fines. These 20- to 70-micron-diameter fines are known to contribute to a variety of problems in fuel injection and combustion systems. In marine engines, excessive injector pump wear, piston ring wear, and cylinder wall wear can all be due to the abrasive action of catalyst fines on these fuel system parts. 

Cylinder and piston ring wear have been observed when using alcohol fuels. Metal loss could be due to wear caused by removal of the lubricating oil film by liquid alcohol during cold starting or by the corrosive action of formic acid or other acids formed during the combustion process. Use of more corrosion- and wear-resistant metal alloys in engine construction have helped resolve this problem. 

The use of water-contaminated oil causes an increase in piston ring wear by a factor of two. The deposition rate of carbonaceous matter on the cylinder-piston group parts is increased by a factor of 2-3 when water contaminated oil is used as compared to uncontaminated oils (Kozhekin et al., 1978 Shishigin and Belganovich, 1976 Somov et al., 1978). After 100 hrs of shipboard engine operation at 80% rated power with water contaminated oil, its TBN value dropped by 58%, whereas that value only dropped 22% for the dry oil. Similarly, the benzene insoluble contaminant content was 2.8% and 0.7%, respectively. 

Fig. 13.3 Sulzer integrated piston ring wear detecting arrangement, redrawn and adapted from...

High-speed beatings, wear f piston rings Wear pads, piston rings... 

Four cycle diesel engines generally need fuU-fiow and bypass filters together. Bypass filtration helps to reduce rod and main bearings wear and piston ring wear. A bypass system is shown in Figure 5.10. Here, the oil pump feeds the main gallery... 

Eunctional or hard chromium plating (169,175) is a successfljl way of protecting a variety of industrial devices from wear and friction. The most important examples are cylinder liners and piston rings for internal combustion engines. Eunctional chromium deposits must be appHed to hard substrates, such as steel, and are appHed in a wide variety of thicknesses ranging from 2.5 to 500 ]Am. 

FIG. 10-94 Piston equipped with carbon piston and wearing rings for a non-hibricated cylinder. 

Butterfly Valves These valves (Fig. 10-155) occupy less space in the line than any other valves. Relatively tight sealing without excessive operating torque and seat wear is accomphshed by a variety of methods, such as resilient seats, piston rings on the disk, and inclining the stem to limit contact between the portions of disk closest to the stem and the body seat to a few degrees of curvature. 

Figure 3-8. Piston rings and wear band. (Courtesy ofNuovo Pignone)...

Figure 11-11. Piston rings and wear bands are made of material that is softer than the c inder wall with which they are in constant contact, so they must be replaced regularly. [Courtesy of Dresser-Rand Company.]...

Diesel fuel may contain ash-forming materials in the form of abrasive solids or soluble metallic soaps. These solids cause wear of injection equipment, pistons, piston rings, and liners as well as increasing engine deposits. Ash content is expressed as a percentage of the weight of the original test sample of the fuel when burned to completion m an open container. 

Figure 12-8A. Piston rings. The piston rod is manufactured from heat-treated stainless steel and is coated with wear-resistant overlays, such as ceramic, chromium oxide, and tungsten carbide applied by plasma techniques. Piston rod cross-head attachment has mechanical preloading system for the threads. Rider rings and seal rings are manufactured from PTFE filled resins fillers are matched to the gas, piston speed, and liner specifications. Typical fillers are glass, carbon, coke, or ceramic. (Used by permission Bui. BCNA-3P100. Howden Process Compressors Incorporated. All rights reserved.)...

Mack T6 assesses oil oxidation, piston deposits, oil consumption and ring wear. 

One effect of valve sleeve, piston ring, and cylinder wall wear is leakage of lubricating oil into the combustion chamber. When lubricating oil accumulates in the combustion chamber and bums with fuel, the exhaust smoke appears blue in color. Wear due to abrasion or corrosion has the same effect. At times, unbumed fuel can also appear as blue smoke if fuel droplets are finely dispersed in the exhaust. Blue smoke is a symptom of a mechanical problem rather than a fuel performance problem. 

In marine fuel applications, injector deposits and the corrosive wear of piston rings have been linked to fuel sulfur and sulfur bearing acid formation. 

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