RU1815600C - Method of leak testing of hollow articles at cryogenic temperatures - Google Patents

Abstract

Usage: control hermetically; sti products cryogenic - vacuum technology. SUBSTANCE: cryochamber is installed over a test zone of a welded joint of a product evacuated by a pump. Klypse- | The indicator gas is supplied through 1 blower. The cryochamber is filled with liquid 1 refrigerant, creating a shock thermal effect on the test zone, and the blower is moved along the test compound, supplying indicator gas through the refrigerant layer. The degree of tightness of the product during the cooling period, when the temperature of the test zone is higher than the crisis temperature of the film boiling point of the refrigerant, is judged by a leak detector connected to the evacuated cavity of the product; Under these conditions, the probable leaks are not blocked by liquid refrigerant. 1 ill.

Description

The invention relates to a test technique and can be used to localize leaks in evacuated shells. kah working at cryogenic temperatures, for example, in pipelines of cryogenic-vacuum installations.

An object of the invention is to increase reliability in locating a leak.

The drawing shows a diagram of a device for implementing the method,

A detachable cryochamber 3 is installed above the test zone of compound 1 of product 2, into which a blower 4 is inserted in the form of a tube for supplying indicator gas to compound 1 through a layer of refrigerant 5 during low-temperature blowing. A vacuum-CUI pump 6 and a leak detector 7 are connected to the cavity of the product 2, and a heater 8 is installed on the product in the immediate vicinity of the test zone. mi 11 and st chickpeas bandages 12.i

A method for testing hollow articles for: tightness at cryogenic temperatures: pax is as follows. ;

A cryochamber 3 is mounted above the test zone of compound 1 and the cavity of the product 2 is evacuated by pump 6. A blower 4 is connected to cryochamber 3 to compound 1 and indicator gas is supplied to it from an external source (not shown in the drawing). Then the cryochamber 3 is filled with liquid refrigerant 5, for example, liquid nitrogen, from an external source (not shown in the drawing), providing cooling with the creation of thermal shock, accompanied by 00

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with the appearance of tensile temperature stresses reaching 0.5 Ohm. By moving the blower along the test compound 1, it is low-temperature blown during exposure to temperature stresses. In this case, the test gas flowing out from the blower enters the vapor film of the refrigerant above the test surface, and from it through probable through defects to the evacuated cavity and leak detector7, by which the degree of leakage of article 2 is judged. With this test variant, only during the cooling period at the temperature of the test zone above the crisis temperature of the film boiling point of the refrigerant, when through defects are not covered by the refrigerant in the liquid phase.

If it is necessary to increase the cooling time in order to increase the reliability of detection of leaks, low-temperature blowing is used with heating of the test zone. For this purpose, a heater 8 is installed on the product 2 in the immediate vicinity of this zone with the cryochamber 3 mounted on it and provide a constant supply of heat. Then the cryochamber 3 is filled with refrigerant and low-temperature indicator gas is blown at a temperature of the test zone above the crisis temperature of film boiling of the refrigerant with simultaneous detection of leaks through the leak detector 7. Under conditions of constant heating of the test zone, stationary film boiling of the refrigerant is ensured, eliminating the overlap of the leaks its liquid phase and after the zone reaches a stable lower temperature level. Due to this, the low temperature blowing time is not limited.

An example of a specific implementation of the method.

Around the test area of the annular weld joint 1 with a width of 80 mm pipe5

5

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5

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5

pipelines 2 D 56x2 install a detachable box-shaped cryochamber 3 and vacuum the cavity of the pipeline with a pump 6. Indicator gas is supplied to connection 1

helium through a blower in the form of a thin-walled tube brought into contact by the surface of the product. Liquid nitrogen is poured into the cryochamber, providing thermal shock to the test zone, and the blower is moved along the test compound 1. The leak rate is determined by the leak detector 7 connected to its cavity. Under these conditions, airflow is possible only during the five-minute cooling process, until the temperature of the test zone reaches the temperature of the film boiling point of nitrogen (about 120 K).

To increase the cooling time in the immediate vicinity of the cryochamber

0 an electric heater is installed in the pipeline, with which the test zone is continuously heated. The cryochamber is filled with liquid nitrogen and low-temperature blowing is performed at the temperature of the test zone by 10-15 degrees; more than 120 K, at which, due to the film mode of boiling of the liquid refrigerant, the leakage does not occur.

Claims (1)

SUMMARY OF THE INVENTION A method for testing hollow articles for tightness at cryogenic temperatures, in which the article is comfortable on one side of a vacuum wall, it is cooled with liquid refrigerant on the other side of the wall in thermal shock mode, indicator gas is supplied to the product wall and determined The concentration of this gas on the other side of the wall is measured through a leak detector, so that, in order to increase the reliability of the leak and localize the leak, the indicator gas is supplied simultaneously with the cooling of the wall idkim refrigerant through its fiber article at a temperature above the temperature of the coolant film boiling crisis, j