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Characteristics of Cork, and Marine Applications LTHOUGH cork products are widely used in marine work, the origin of this unique material may be somewhat of a mystery even to many in the maritime industry who have used cork in one form or another for years. The following description of its nature and prac- tical application was prepared by the Armstrong Cork Co., Lancaster, Pa. Cork is made up of mililons of tiny cells, each filled with air. The cell walls are composed of thin but very strong tissues of cellulose. The cells are held together with a sort of natural gum or resin. Fifty-three per cent of the total cork volume is air, which accounts for its buoyancy and lightness. This structure, and its composition of almost pure cel- lulose and air, explains the resilience of cork and its compressibility, its low absorption of liquids, and_ its resistance to the passage of heat. Cork’s low heat conductivity makes it an ideal insulating mate- rial. Corkboard insulation is made of pure clean granules of cork com- pressed in molds and baked. The baking process liquifies the natural gum and so cements the granules in a solid mass without any foreign binder. Between 50 and 60 per cent of the world’s annual stripping of cork- wood is used for insulation purposes. Much of this corkboard insulation is used to protect cargoes of foodstuffs and other perishable commodities transported in ships. Corkboard in- sulation also is used in ships, par- ticularly below the waterline, to pre- vent condensation. Cork covering for cold pipes sup- plements the insulation in board form. The cork granules are com- pressed and baked in molds of the necessary shapes and sizes to cover standard pipes and fittings. By in- sulating the pipes which convey the refrigerant such as brine, ammonia, ete., 85 per cent of the refrigeration is saved that would be lost if the pipes were left bare. Cork also is used in the manufac- ture of the insulating brick used to reduce heat leakage in boilers. Cargo Handling, Warping HE S. S. ManHatTran has a novel (Rares in two Of her cargo winches. These winches are made to serve as warping winches when a gear shifting lever is placed in the slow speed position. The movement of the lever actuates a waterproof control switch which, in turn, changes the circuit of the magnetic panel below deck to suitable per- formanee for warping duty. The winch will exert a pull of 10,000 pounds at a rope speed of 80 feet per minute and a pull of 20,000 pounds at 65 feet per minute when set for warping. The control switch that is auto- matically operated when the lever is moved from the position for cargo winch performance to that for warp- ing performance adds the usual step back or jamming feature and also make ineffective the lowering side of the master switch. The hoisting portion only of the cargo winch per- Cargo Handling or Warping formance is made available for warp- ing duty. In order to pay out rope, the lever must be thrown for cargo winch performance in which case a choice of speeds range from 5 to 250 per cent of the rated speed. Small Size Limit Stop NEW small size crane limit safety stop, with standard mill type blowouts and contact tips, has been developed by Cutler-Hammer, Inec., Milwaukee, Wis. These stops are used to prevent over-travel of the hoist on electric cranes. Rated for 40 horsepower and under, it is claimed the new stop is unusually small and compact for this rating, taking only 9-inch head Small Size Crane Limit Stop room. The stop is supplied com- plete with leads equipped with sold- ering lugs. The cover is removable for inspections and repairs. The new 14,800 liner, PRESIDENT DouMER, was launched at the _ ship- yard of the Messageries Maritime at Marseilles, France, on Jan. 22. MARINE REVIEwW—March, 1933 Unique Heating Elements In New Oil Heater STORAGE tank oil heater re- A cently developed by The Gris- com-Russell Co., New York, has a unique type of heating element which makes the unit particularly compact, effective and economical. The patented G-fin heating ele- ments in this apparatus consist of a number of U-shaped steel pipes hav- ing longitudinal fins along the ex- terior surface of the straight por- tions of each pipe. These fins are equally spaced about the cireumfer- ence of the pipe, and are securely fastened by a mechanical process without tinning or similar bond which would limit the operating temperature. The purpose of the longitudinal fins is to increase the heat-trans- mitting surface on the outside of the pipes in contact with the oil to be heated for withdrawal from the tank. The total surface of the fins on each pipe is from 4 to 6% times greater than that of a bare pipe of the same length and diameter, so that the cold viscous oil is heated sufficiently to flow readily in a frac- tion of the time required by a bare tube heater of the same dimensions. Therefore, this design permits a more compact and economical unit for a given heating duty. This unit is also more economical in steam consumption than pipe coils located in the bottom of the tank because it heats the oil locally at the point of withdrawal from the tank. The heater is installed with the shell and heating elements extend- ing into the tank and the steam, drain and oil connections outside the tank. Special provisions in the de- sign of the unit facilitate flow of oil into and out of the shell. No eross baffles are necessary in the _ shell, thereby resulting in minimum pres- sure drop of the oil. The construc- tion of the unit throughout is sim- ple, sturdy and leakproof. Ejector Refrigeration HERE was recently tested at the South Philadelphia works of the Westinghouse Electric & Mfg. Co., a piece of refrigerating equipment of large capacity using steam ejectors to produce the cooling effect. In this test a tank of several hundred gallons of water at room temperature was frozen to a slush ice in a few minutes, indicating the great effectiveness of this type of equipment. Except for some small pumps, there was no rotating apparatus in this equipment, and the complete unit was simple and relatively small in size. The ejector itself was developed by Westinghouse engineers from those used in connection with condensers for large steam turbines which this company has built for many years.