SU1774294A1 - Device for checking dielectric coats on cylindrical metal parts for continuity - Google Patents

Description

The invention relates to defective. FDI dielectric coatings of metal objects and can be used to control continuous ™ of these coatings on the inner surface of cylindrical products, such as pipes and pipelines.

The aim of the invention is to simplify the regulation of pressure.

The goal according to the invention is achieved in that in a device for monitoring the continuity of dielectric coatings on the inner surface of metal cylindrical products, containing an electrospark defectoscope with an annular probe located on a piston moved by a displacement unit in the controlled product, one of the ends of which is closed by a lid forming between it and a piston inside the controlled product, a separate volume of the gas medium c. reduced electric strength due to the regulated (by means of the appropriate unit) pressure, the pressure control unit is made in the form of a valve-regulator installed in the cover, and the displacement unit is made so that the piston (together with the annular probe) moves from the cover to the opposite end during monitoring ^ controlled product.

To ensure control of the continuity of the coating at the ends of the controlled product, the device can be equipped with a nozzle with the same internal diameter as the controlled product, _{l l} coaxially attached to the free end of the product, and the lid is made in the form of a glass with a cylindrical shell, also having the same internal diameter as the controlled product and coaxial with the product. In this case, the control valve is located in the end part of the cover. The piston displacement unit may have different designs depending on the length of the items to be controlled. For instance. for not very long products (up to several meters long), the indicated assembly can be made in the form of a rod (in particular, a telescopic one) with one or another drive (for example, hydraulic).

For extended pipelines, the piston displacement assembly can be made in the same way as in the prototype, i.e. in one direction (preparatory stage), the piston can move under the action of pressure created between it and an additional second cover that closes the free end of the pipeline. To the other side (the working stage), the piston can be moved with a cable. wound on a winch drum and electrically connecting an annular probe with a flaw detector. It is understood that the second cover has a hole with a seal for the passage of the cable.

The drawing schematically depicts a controlled product and interacting with it the nodes of the proposed device.

The controlled metal product 1 of a cylindrical shape with a dielectric coating 2 is closed on one side by a cover 3, and on the other hand is continued by a pipe 4. The control device includes a piston 5 with an annular probe 6, electrically connected to the flaw detector 7 and moved by a rod 8 along the product 1. In the end part of the cover 3, a pressure regulating valve 9 is installed.

The device operates as follows.

On the controlled product 1, on one side, a cover 3 with a pressure regulating valve 9 is fixed, and on the other hand, a pipe 4 with a piston 5 located therein and an annular probe 6. Then, the preparatory operation of moving the piston 6 from its initial position in the pipe 4 to the initial operating position in the cover 3. This movement is performed using the rod 8. moreover, with this movement of air from the controlled product 1 is displaced by the piston 5 through the check valve (not shown in the drawing), built into the end part of the cover 3 l for the piston 5 itself. Next, the flaw detector 7 is turned on, as a result of which an electric voltage of the order of 500 V is supplied to the annular probe 6 (it is understood that if the cover 3 and the nozzle 4 are made all-metal, then the flaw detector 7 allows a short circuit of the probe. Otherwise, the cover 3 and the pipe 4 must have a dielectric inner coating similar to that of the product under control). Next, the piston 5 (together with the probe 6) is moved by means of a rod 8 in the direction of the open end of the product 1 being monitored. In this case, due to the expansion of the volume of the gas medium between the ends of the piston 5 and the cover 3 facing each other, the pressure rises to the value that the control valve is adjusted to 9 (corresponding to the minimum electric breakdown voltage of air according to the Paschen law for a given coating thickness). As soon as the indicated vacuum level is reached, the control valve 9 will open slightly for a short time and let a portion of air into the adjustable volume, as a result of which the pressure will increase and the control valve 9 will close. These procedures will be repeated until the piston 5 moves. It is understood that the accuracy and speed of the control valve 9 have acceptable values that are consistent with the permissible limits of pressure change in the product and the speed of the probe.

When probe 6 approaches a possible defect of coating 2 in the form of a violation of its continuity (pore, puncture, etc.), between the probe 6 and the metal base of the controlled product 1, an electrical breakdown of air occurs, which is fixed by a flaw detector 7. The location of the defect can be determined by the position rods 8 relative to the edge of the product 1. After moving the piston 5 to the final position (in the pipe 4), the continuity control of the coating 2 is considered complete, the flaw detector 7 is turned off (the voltage is removed from the probe 6), the cover 3 together with the product m 1 are moved away from the nozzle 4 located therein with the piston 5 (to facilitate this operation pipe 4 is provided in the channel connecting the cavity with its internal atmosphere at the extreme position of the piston 5). Then, the cover 3 is separated from the product

1. after which the device is ready to control the continuity of the coating of another similar product.

The use of the device allows to significantly simplify the control of the continuity of dielectric coatings on the inner surface of metal cylindrical products and objects by the most effective spark method with significantly reduced (tens of times) the voltage values on the probe.

Claims (2)

Claim 1. A device for monitoring the continuity of dielectric coatings on the inner surface of metal cylindrical products, containing an electrospark flaw detector with an annular probe located on a piston moved by a displacement unit in the controlled product, one of the ends of which is closed by a lid, which forms a separate between it and the piston inside the controlled product the volume of the gaseous medium with reduced electric strength due to the regulated (by means of the corresponding unit) pressure, which differs That, for the purpose of simplification, the pressure control unit is formed as a valve set in the cover regulator. 2. The device according to claim 1, with the fact that, in order to ensure control of the continuity of the coating at the ends of the controlled product, it is equipped with an additionally introduced pipe having the same internal diameter as the controlled product and attached coaxially to the free end of the aforementioned product, and the lid is made in the form of a glass with a cylindrical shell, also having the same inner diameter as the controlled product and located coaxially with the said product, the control valve being installed from the end part Ryshkov. Compiled by M. Khaenko Editor T. Yurchikova Tehred M. Morgenthal Corrector M. Petrova Order 3925. Circulation Subscribed VNIIIPI of the State Committee for Inventions and Discoveries at the State Committee for Science and Technology 113035, Moscow, Zh-35. Raushskaya nab., 4/5 Production and Publishing Plant “Patent, Uzhhorod, 101 Gagarin St.