High-Temperature Shops

industrial premises in which the technological processes performed are accompanied by the generation of considerable amounts of heat or by other industrial hazards. High-temperature shops include blast-furnace, open-hearth, convertor, electrical steel-casting, and sintering and rolling shops in the metallurgical industry; casting and forging shops in the machine-building industry; annealing shops in nonferrous metallurgy; glass and ceramics production; and steam power plants. In many high-temperature shops the amount of heat generated sometimes reaches 800 or more kilojoules per hour (kJ/hr) per cubic meter of volume, a condition under which a worker’s heat-exchange system may not function efficiently. Under normal weather conditions the emission of the heat constantly being produced by a worker’s body takes place through the skin by three main methods: convection (about 30 percent), radiation (about 45 percent), and evaporation (about 25 percent). As a result of high-temperature shops’ increased heat inputs compared to the workers’ heat losses, the workers’ heat equilibrium can be upset and body temperatures may rise to 40° C; severe overheating may lead to heat strokes. In addition, excessive water loss through perspiration (up to 10 liters or more) will disturb a worker’s water-salt metabolism.

In the USSR a great deal of attention is being focused on problems of improving working conditions in high-temperature shops. Mechanized and automated production processes are being introduced on a broad scale in order to provide favorable working and hygienic conditions and to prevent occupational illnesses. The optimum parameters within the working zones of production facilities, depending on the quantity of excess heat and the category of work during various times of the year, are set forth in the Construction Standards and Rules (SNiP II-G.7–62) and Health Standards for the Planning of Industrial Enterprises (SN 245–63). The basic requirements for production processes and equipment that are characterized by the generation of heat are set forth by the Ministry of Health of the USSR (Health Rules for the Organization of Technological Processes and Hygiene Requirements for Production Equipment, 1966).

Sources of heat (heating and smelting furnaces, pipelines, and so on) are usually equipped with devices to prevent or limit heat emission—for example, the surface temperature of insulating or shielding materials according to the Health Standards (SN 245–63) must not exceed 45° C. The openings in heating furnaces and equipment with open gates for servicing these furnaces are equipped with devices to protect workers from heat exposure (water curtains, ventilation with water vapor, and so on). Blowers or spot ventilators are used to increase heat dissipation by perspiration and convection in situations involving the strong exposure of the body or its parts (arms or chest). High-temperature shops have appropriate places where workers can relax (for example, rooms or offices with radiation cooling systems involving cooled walls) in order to restore their efficiency during breaks.

Special drinking-water systems (soda water containing 0.5 percent NaCl) may be used to prevent disruption of the body’s water-salt equilibrium.

In addition to large amounts of heat, almost all high-temperature shops have some connection with the generation of dust and gas, which also has deleterious effects on workers and structures. The necessary hygienic conditions of the air and the content of gas, dust, and water vapor in the air in working and service zones are provided by technical measures aimed at decreasing the incidence of production hazards by the rational location of high-temperature shops relative to the direction of the prevailing winds and by appropriate volume-design and planning decisions concerning structural complexes with ventilating and airconditioning systems. The most efficient method of ventilating such shops is controlled ventilation, or aeration.

High-temperature shop buildings may be unheated or heated, with heated or unheated enclosing structures. The selection of the type of building and enclosure is based on technical and economic comparisons, taking into account the area of the construction. The selection of construction materials is based on the degree of structural heating. In addition, such requirements as the inadmissibility of condensation on the internal surfaces of enclosures and the maximum slope of a roof are taken into consideration. In developing volume design and construction solutions for high-temperature shops, consideration is given the need for the fastest possible removal of hot or polluted air from a building. Measures are provided for the structure’s protection against the effects of heat (both radiated and convected) by the use of shields, linings, and protective paints. In cases when the influence of heat on a structure is associated with other factors (for example, increased moisture or the presence of corrosive substances in a shop’s atmosphere), anticorrosion protection is used. A radical solution to problems related to the design and construction of high-temperature shops involves the future replacement of cyclical processes with continuous processes, full mechanization and automation of technological processes, reliable hermetic sealing of equipment, and the development of a means of transporting hot semifinished products (including iron and steel) through closed pipelines.