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New heat resisting alloy
CURRENT
TOPICS.
Lateral Steel Reinforcement Strengthens Brick Columns.(Iron Age, Vol. 136, No. 7.) A series of tests recently conducted in the department of mechanics of the University of Wisconsin determined the properties of reinforced brick masonry columns. The tests showed that the effective strength of a reinforced brick masonry column equals the sum of three components: the strength of the plain masonry, the strength of the longitudinal steel at its yielding point and the lateral restraint given by steel hoops placed in the horizontal joints of a brick column. Lateral hoops in every joint served to increase the toughness and to some extent the strengths of the columns. The yield point of the g in. steel rounds used in the hoops was 53,800 lb. per sq. in. The strength of the fillett and spot welds in the IO in. hoops after heating to 900 deg. C. (1652 deg. F.) and straightening while hot averaged 58,900 lb. per sq. in. of bar cross-section. Spot welds alone did not prove satisfactory. R. H. 0. New Heat Resisting Alloy.-A new development of the A. 0. Smith Corporation is announced in Steel for September 2. It is a heat resisting alloy of chromium-iron-aluminum type, known as Smith No. IO. It is now being used in heat treating furnaces for industrial and laboratory use, making available electric heat with metallic resistors for operation to 2400 deg. F. The new alloy may be rolled into wire from which it is possible to wind coils or make reverse bands and other shapes of heating elements. It may also be cast into resistors or furnace parts of any desired form. Accurate life tests indicate commercial life at 2300 to 2400 deg. F. Electrical After passing resistance is about 1000 ohms per circular mil foot. through a maximum at about 1700 deg. F. its resistance falls gradually and at 2300 deg. F. it is about IO per cent. and at about 2600 deg. F. it is about 7 per cent. above the resistance at room temperature. These temperatures are black body temperatures of the wire in air. By determining the temperature to which sample must be heated to start fusion it was found the new alloy begins to melt at 2830 deg. F. Its density is 6.9 grams per cubic centimeter. The formation of a protective alumina film on the new alloy makes it highly resistant to the penetration of oxygen and it is due largely to this that the new alloy owes its excellent performance at high 682
Nov., 1935.3
operating temperatures. of the nickle-chromium
CURRENT TOPICS.
683
It can be welded to itself or to other leads alloy by using wire as a filler rod. R. H. 0.
Plant to Make Rubber at IOO Degrees Below.-(Iiefrigerating Engineer, Vol. 30, No. 3.) Down to - 100“ F. will go the temperatures in one section of a new plant for manufacturing artificial rubber, it was announced by the duPont company in Wilmington early in August. Several years laboratory experiments have proved the commercial feasibility of this cold, the most intense to be used It is a part of a scientific trend toward on a large scale in industry. lower and lower temperatures, where important chemical changes can be made more readily than with heat which has so long been the chief source of man’s mechanical domination over natural forces. The 100’ cold will be used to separate from acetylene the substance mono vinyl acetylene, which is the base of synthetic rubber. R. H. 0.
The Passamaquoddy Tidal-Power Project.-(mechanical Engineering, Vol. 57, No. 9.) Capt. HUGH J. CASEY furnishes a brief statement on the largest utilization of power from the tides the world has seen. Located in the vicinity of Eastport, Maine, the project will provide for the generation of power by creating and maintaining a low level pool about 37 sq. miles in area in Cobscook Bay, by the construction of a series of dams, a power house, and an emptying-gate structure between Cobscook Bay and the Bay of Fundy. It is planned that the interior basin shall be maintained at or near low tide levels. As the tide rises and the difference in head between the sea and the basin exceeds 5 ft. the power house will be opened and power generated from the rising tide. The mean range of tide at this locality is approx. 18 ft. Power is likewise generated during falling tide. In the absence of an auxiliary means of generation of power, this arrangement would provide no primary power, due to the necessity of shutting down the power house during lower tide levels for 5 hr. intervals twice a day. Provision is made for a pumped storage plant near Haycock Harbor, 15 miles distant. Surplus peak power generated at the main tidal power plant at and near high tide is transmitted to a large pumping plant located on the sea near Haycock which pumps water into a large reservoir 125 to 135 ft. above sea level. During the shut-down periods of the main tidal power plant, this stored water is used to generate power at the Haycock power plant. The initial development will be adaptable to a much larger two basin development utilizing both Passamaquoddy and Cobscook Bays. R. H. 0.
TOPICS.
Lateral Steel Reinforcement Strengthens Brick Columns.(Iron Age, Vol. 136, No. 7.) A series of tests recently conducted in the department of mechanics of the University of Wisconsin determined the properties of reinforced brick masonry columns. The tests showed that the effective strength of a reinforced brick masonry column equals the sum of three components: the strength of the plain masonry, the strength of the longitudinal steel at its yielding point and the lateral restraint given by steel hoops placed in the horizontal joints of a brick column. Lateral hoops in every joint served to increase the toughness and to some extent the strengths of the columns. The yield point of the g in. steel rounds used in the hoops was 53,800 lb. per sq. in. The strength of the fillett and spot welds in the IO in. hoops after heating to 900 deg. C. (1652 deg. F.) and straightening while hot averaged 58,900 lb. per sq. in. of bar cross-section. Spot welds alone did not prove satisfactory. R. H. 0. New Heat Resisting Alloy.-A new development of the A. 0. Smith Corporation is announced in Steel for September 2. It is a heat resisting alloy of chromium-iron-aluminum type, known as Smith No. IO. It is now being used in heat treating furnaces for industrial and laboratory use, making available electric heat with metallic resistors for operation to 2400 deg. F. The new alloy may be rolled into wire from which it is possible to wind coils or make reverse bands and other shapes of heating elements. It may also be cast into resistors or furnace parts of any desired form. Accurate life tests indicate commercial life at 2300 to 2400 deg. F. Electrical After passing resistance is about 1000 ohms per circular mil foot. through a maximum at about 1700 deg. F. its resistance falls gradually and at 2300 deg. F. it is about IO per cent. and at about 2600 deg. F. it is about 7 per cent. above the resistance at room temperature. These temperatures are black body temperatures of the wire in air. By determining the temperature to which sample must be heated to start fusion it was found the new alloy begins to melt at 2830 deg. F. Its density is 6.9 grams per cubic centimeter. The formation of a protective alumina film on the new alloy makes it highly resistant to the penetration of oxygen and it is due largely to this that the new alloy owes its excellent performance at high 682
Nov., 1935.3
operating temperatures. of the nickle-chromium
CURRENT TOPICS.
683
It can be welded to itself or to other leads alloy by using wire as a filler rod. R. H. 0.
Plant to Make Rubber at IOO Degrees Below.-(Iiefrigerating Engineer, Vol. 30, No. 3.) Down to - 100“ F. will go the temperatures in one section of a new plant for manufacturing artificial rubber, it was announced by the duPont company in Wilmington early in August. Several years laboratory experiments have proved the commercial feasibility of this cold, the most intense to be used It is a part of a scientific trend toward on a large scale in industry. lower and lower temperatures, where important chemical changes can be made more readily than with heat which has so long been the chief source of man’s mechanical domination over natural forces. The 100’ cold will be used to separate from acetylene the substance mono vinyl acetylene, which is the base of synthetic rubber. R. H. 0.
The Passamaquoddy Tidal-Power Project.-(mechanical Engineering, Vol. 57, No. 9.) Capt. HUGH J. CASEY furnishes a brief statement on the largest utilization of power from the tides the world has seen. Located in the vicinity of Eastport, Maine, the project will provide for the generation of power by creating and maintaining a low level pool about 37 sq. miles in area in Cobscook Bay, by the construction of a series of dams, a power house, and an emptying-gate structure between Cobscook Bay and the Bay of Fundy. It is planned that the interior basin shall be maintained at or near low tide levels. As the tide rises and the difference in head between the sea and the basin exceeds 5 ft. the power house will be opened and power generated from the rising tide. The mean range of tide at this locality is approx. 18 ft. Power is likewise generated during falling tide. In the absence of an auxiliary means of generation of power, this arrangement would provide no primary power, due to the necessity of shutting down the power house during lower tide levels for 5 hr. intervals twice a day. Provision is made for a pumped storage plant near Haycock Harbor, 15 miles distant. Surplus peak power generated at the main tidal power plant at and near high tide is transmitted to a large pumping plant located on the sea near Haycock which pumps water into a large reservoir 125 to 135 ft. above sea level. During the shut-down periods of the main tidal power plant, this stored water is used to generate power at the Haycock power plant. The initial development will be adaptable to a much larger two basin development utilizing both Passamaquoddy and Cobscook Bays. R. H. 0.