SU918815A1 - Method of testing hollow article for strength under cryogenic temperatures - Google Patents

Description

(S) TEST METHOD FOR EMPTY PRODUCTS FOR DURABILITY UNDER CRYOGENIC TEMPERATURES

This invention relates to testing the strength of hollow articles operating under pressure at cryogenic temperatures. -

The known method of testing products for strength, which consists in supplying a cryogenic liquid into the product cavity and creating the necessary fluid pressure 1.

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The disadvantage of this method is the high cost of testing. The research institute is associated with the need to build protective devices that occupy large production areas.

The closest technical. The essence and the achieved result of the invention is the method of testing hollow products for strength at cryogenic temperatures, which means that the product is placed in a cryostat and the cryogenic liquid is fed into the product under pressure 2}.

The disadvantages of this method are the differences in the test conditions from the natural conditions, due to the significant heat leakage to the external surface of the product and to the cryogenic liquid supplied to it, as well as the insufficient safety of the tests, associated with high explosion energy during the destruction of the product.

The purpose of the invention is to increase the safety of the tests and to bring them closer to natural conditions.

This goal is achieved by the fact that, according to the method of testing hollow articles for strength at cryogenic temperatures, which consists in placing the product in a cryostat and feeding a cryogenic liquid under pressure into the product, cryogenic liquid is transferred from the product to the cryostat cavity during the test.

Claims (2)

G 7 / aEi where q is the specific tag flow through the walls of the cryostat, kJ / cm, the surface area of the cryostat, m is the heat obtained by the cryogenic liquid, feeding it into the product, kJ / s; g - specific heat of vaporization of a cryogenic liquid, kJ / kg, cryogenic; The fluid supplied to the product is transferred through the accumulated cryogenic liquid in the cryostat in the cavity of the latter above the liquid surface and an overpressure is maintained, the value of which does not exceed 0.2 atm. The pressure of the product is irrigated with a cryogenic liquid bypassed into the cryostat. . The method is carried out as follows. The product is placed in a cryostat, a cryogenic liquid, for example liquid nitrogen, is fed into the product, while this liquid is transferred from the product to the cryostat cavity, irrigating the product, with a flow rate G, ... where q is the specific heat gain through the cryostat wall kJ / cm; F — cryostat surface area, m2-; uQ is the heat obtained by the cryogenic liquid when supplied to the product, kJ / s; (d) specific heat of vaporization of a cryogenic liquid, kJ / kg. Thus, the heating of the cryogenic liquid due to heat conduction to the external surface of the product from the walls of the cryostat is eliminated. The vapor of the cryogenic liquid from the cryostat is vented to the atmosphere, while in the cavity of the cryostat above the surface of the cryogenic liquid, an overpressure is maintained, the value of which does not exceed 0.2 atm, for example, by adjusting the drain valve of the cryostat, which leads to a decrease in the temperature of the cryogenic liquid in the product, and, therefore, The potential energy of the fluid at the pressure of the test is practically the same as its potential energy at normal pressure. The non-evaporated part of the cryogenic liquid supplied to the cryostat from the product is collected in parts of the cryostat and transferred through the products, collected in parts of the cryostat and transferred through it the cryogenic liquid supplied to the product, which ensures heat removal in the cryogenic liquid supply system. The invention makes it possible to significantly reduce the explosion energy at the time of the destruction of the product during cryogenic hydraulic tests, which leads to an increase in their safety. In addition, cooling the cryogenic liquid and circulating it in the cavity of the product eliminates the possibility of boiling it in the cavity of the product, the formation of gas bubbles and the geyser effect, which brings the test conditions closer to natural ones. Claim 1. A method for testing hollow articles for durability at cryogenic temperatures, which means that the product is placed in a cryostat and a cryogenic liquid is fed into the product under pressure, characterized in that, in order to increase the safety of the tests and bring them closer to natural conditions, cryogenic liquid in the process of testing is bypassed from the product into the cavity of the cryostat with a flow rate where the specific heat gain through the walls of the cryostat, kJ / cm; the surface area of the cryostat, the heat obtained by the cryogenic liquid when it is fed into the product, kJ / s; the specific heat of vaporization of the cryogenic liquid kJ / kg, the cryogenic liquid supplied to the product is passed through the accumulated cryogenic liquid in the cryostat; in the cavity of the latter above the liquid surface, an overpressure is maintained, the value of which does not exceed 0.2 atm. 2. The method according to claim 1, about t l and h a and y and with the fact that the product irrigate 9188156 cryogenic fluid, bypass 1, USSR Copyright Certificate in a cryostat, No. 18809, cl. G 01 M 3/30, 19b5 .. Sources of information, 2, Problems of strength, Vf 12, taken into account in the examination of 1971, p.26-29 (prototype).