LABORATORY DEVICE FOR DETERMINING HYDROGEN IN STEELS

Abstract

This utility model relates to corrosion testing, specifically testing steel for the presence of hydrogen. The technical result is improved accuracy in determining the amount of dissolved hydrogen in a hydrogenated sample. This is achieved by constructing the device's housing in the shape of a U-shaped tube with the anode working area positioned horizontally upward, eliminating the influence of hydrogen bubbles rising from the cathode on electrolyte access to the plate surface. Furthermore, all surfaces except the working area are coated with a protective varnish, ensuring uniform dissolution of the hydrogenated sample.

Description

[0001] The utility model relates to corrosion testing, namely to testing steels for the presence of hydrogen in them.

[0002] A device and method for measuring hydrogen penetration are known (RU Patent No. 2646801, published on September 10, 1997), which is a probe containing a means for capturing hydrogen spontaneously flowing out of a part dissolved in it, an inlet passage for a measuring gas, which can be ambient air, a mixing chamber for mixing the measuring gas with hydrogen flowing out of the part, a solid-state sensor for measuring the concentration of hydrogen in the resulting gas mixture, a means for creating a flow of measuring gas from the inlet passage to the solid-state sensor, a fastening means for hermetically connecting the device to the analyzed structure (threaded means, flanged means, welded means).

[0003] The disadvantage of the device is that its fastening means provides a sealed contact only with structures that have mating threaded, flanged or welded elements, which structurally does not allow the device to be attached to surfaces of arbitrary shape.

[0004] A device for determining the hydrogen content in metal is known (Author's Certificate No. SU 1065775A, published January 7, 1984), comprising a test structure, a measuring device with a sealed cavity and a measuring instrument connected to it, and an additional measuring device, formed as part of the test structure, consisting of two mating parts whose contact surface is stepped, and a sealed cavity with a measuring instrument connected to it is located on each step. When hydrogen under pressure is passed inside the test structure, it diffuses through the wall, solidifies at the interfaces of the parts, collects in the cavities, and is fed to the measuring instruments, where its content in different layers of the cross-section is assessed.

[0005] The disadvantage of this device is the stepped contact surface of the mating parts, which allows the hydrogen content to be determined only in a structure of a given shape and only on specially manufactured parts during their hydrogenation, without the possibility of determining hydrogen in already hydrogenated structures of arbitrary shape.

[0006] An electrochemical cell for measuring hydrogen content in metal is known (US Patent No. 4,221,651, published September 9, 1980). Its working surface has a hole leading to a cavity inside the cell containing a sponge for electrolyte, and an anode is inserted into the cavity itself. After the cell is pressed magnetically against the metal being measured, a current is generated between the anode and the contact electrode, caused by the oxidation of hydrogen released from the metal. A circuit is provided for measuring the hydrogen oxidation current and calculating its content based on diffusion equations.

[0007] The disadvantage of the design is that the means for pressing the cell to the measured metal is made only in the form of a magnet, which structurally does not allow for hermetic contact and measurements to be taken on surfaces made of non-magnetic metals, as well as on ferromagnetic metals with a rough or oxidized surface, where the force of magnetic attraction is insufficient for sealing.

[0008] A device for determining the local hydrogen content in solid materials is known (RU Patent No. 26133, published November 10, 2002). The device comprises a pulsed laser, a system for focusing and directing the beam onto a sample, the solid material to be analyzed, a reference sample of the same composition but with a known hydrogen content, a working chamber with an optical window hermetically sealed to the surface of the material or reference sample, and a sensor that generates a signal proportional to the amount of hydrogen released. Microareas of the surface of the substance and the reference sample are irradiated with a laser pulse, the pulse of which heats and evaporates the surface layer of the substance, with the hydrogen contained therein transitioning to a gas phase within the chamber. The content of the gas is determined by the ratio of the sensor signals for the substance being analyzed and the reference sample.

[0009] The disadvantage of the device is the working chamber, which is made in the form of a rigid volume, the tightness of which is ensured by pressing its end edge to a flat section of the surface of the product, which structurally does not allow the device to be attached to surfaces of arbitrary shape.

[0010] A device for the anodic dissolution of hydrogenated samples is known (Beloglazov S.M. Hydrogenation of Steel in Electrochemical Processes / S. M. Beloglazov; Moscow State University of Higher and Secondary Specialized Education, 1975. - 411 p.), adopted as a prototype, which includes a housing containing a porous ceramic cup. Between the walls of the housing and the cup is a copper cathode connected to the negative pole of a direct current source. Inside the cup there is a holder with a screw onto which the steel sample to be dissolved, the anode, made in the form of a cylinder with a threaded hole in its lower end for screwing onto the holder screw, is screwed. The holder with the sample is connected to the positive pole of a direct current source. A glass gas burette is fixed above the sample, where hydrogen bubbles released during the dissolution of the anode sample are collected through a bell-shaped expansion.Separating the cathode and anode zones of the electrolyte with a porous wall prevents products formed at the cathode from entering the gas collection burette. An aqueous solution of NaCl with added Rochelle salt is used as the electrolyte.

[0011] The disadvantage of the device is the vertical position of the analyzed cylindrical sample, which does not ensure uniform dissolution of its surface due to rising hydrogen bubbles, which prevent the supply of electrolyte to the upper part of the sample, and, as a result, sufficient accuracy in determining the amount of dissolved hydrogen in the hydrogenated sample.

[0012] The technical result is to increase the accuracy of determining the amount of dissolved hydrogen in a hydrogenated sample.

[0013] The technical result is achieved in that the housing is made in the form of a U-shaped tube, a graphite rod-cathode is fixed inside the left sleeve of the tube, in the right sleeve of the tube below the constriction there is a branch, at the end of which a sealing unit made of a corrosion-resistant material is installed, inside which a conductor-holder is installed with the possibility of removal, one end of which is fixed to the anode plate, which is made of the analyzed steel, while the surfaces of the conductor-holder and the anode plate, with the exception of the working area, are covered with a protective corrosion-resistant varnish.

[0014] The device is explained by the following drawing:

[0015] Fig. 1 - general view of the device;

[0016] 1 - body;

[0017] 2 - graphite rod cathode;

[0018] 3 - DC power supply;

[0019] 4 - microburette;

[0020] 5 - three-way valve;

[0021] 6 - branch;

[0022] 7 - sealing unit;

[0023] 8 - conductor holder;

[0024] 9 - anode plate;

[0025] 10 - working area;

[0026] 11 - electrolyte.

[0027] The laboratory device for anodic dissolution of hydrogenated plates of pipe steels consists of a housing 1 (Fig. 1), which is made in the form of a U-shaped tube, which is made of a dielectric material resistant to corrosion and having low adhesion to hydrogen bubbles, for example, glass. Inside the left sleeve of the tube of the housing 1, a graphite rod-cathode 2 is fixed, connected to the negative pole of a direct current source 3. The right sleeve of the tube in the upper part is made with a constriction, to which a microburette 4 calibrated by the gas volume is fixed, on which a three-way valve 5 is fixed. In the right sleeve of the tube below the constriction, a branch 6 is made, at the end of which a sealing unit 7 is installed made of a material resistant to corrosion, for example, acid-resistant rubber. A conductor-holder 8 is installed inside the sealing unit 7 with the possibility of being removed, one end of which is fixed to the anode plate 9, which is made of the steel being analyzed.The other end of the conductor-holder 8 is connected to the positive pole of the DC source 3. The surfaces of the conductor-holder 8 and the anode plate 9, with the exception of the working area 10, are covered with a protective corrosion-resistant varnish.

[0028] The laboratory apparatus for anodic dissolution of hydrogenated pipe steel plates operates as follows. An electrical conductor holder 8 is connected to a hydrogenated steel sample—anode plate 9 (Fig. 1). The surface of the holder, like the entire surface of plate 9, with the exception of the working area 10, is coated with a corrosion-resistant varnish.

[0029] Then the anode plate 9 (Fig. 1) in a horizontal position with the working area 10 upwards is placed in the branch 6 of the right sleeve of the U-shaped housing 1, where it is connected to the positive pole of the direct current source 3 through the conductor holder 8 and the sealing unit 7. The negative pole of the direct current source 3 is connected to the graphite rod 2, located inside the left sleeve of the U-shaped housing 1.

[0030] Open three-way valve 5 and fill tube 1 with electrolyte 11 through the left sleeve of the U-shaped tube - an aqueous solution of NaCl with a concentration of 10 to 15% with the addition of Rochelle salt with a concentration of 2 to 3%. Tube 1 is filled to a level that ensures complete immersion of graphite rod 2 in electrolyte 11. Then, a rubber bulb is connected to the end of microburette 4, with the help of which electrolyte 11 is sucked out of U-shaped tube 1, raising its level above three-way valve 5, after which three-way valve 5 is closed. Electrolyte is added to the left sleeve of U-shaped tube 1 to a level that ensures complete immersion of graphite rod 2 in it.

[0031] Turn on DC power source 3. By passing electric current, the surface metal layer of the working zone 10 of the anode plate 9 undergoes anodic dissolution, and the hydrogen contained in this layer is released as rising bubbles, which are collected in a calibrated microburette 4. The volume of released hydrogen is recorded and related to the mass of dissolved metal, determining the hydrogen concentration in the metal of the hydrogenated plate. Based on the determined hydrogen concentration in the metal of the anode plate 9, a conclusion is drawn about the hydrogenation susceptibility of the pipe steel from which the plate is made.

[0032] Increased accuracy in determining the amount of dissolved hydrogen is achieved by manufacturing the device body in the form of a U-shaped tube with the anode working area positioned horizontally upwards, which eliminates the influence of hydrogen bubbles rising from the cathode on the access of the electrolyte to the plate surface, as well as by coating all surfaces except the working area with a protective varnish, which ensures uniform dissolution of the hydrogenated sample.

Claims

A laboratory device for determining hydrogen in steels, comprising a housing in which there is a cathode connected to the negative pole of a direct current source, a holder with a sample connected to the positive pole of the current source, a glass gas burette with a bell-shaped expansion and an electrolyte, which is an aqueous solution of NaCl with the addition of Rochelle salt, characterized in that the housing is made in the form of a U-shaped tube, a graphite rod-cathode is fixed inside the left sleeve of the tube, in the right sleeve of the tube below the constriction there is a branch, at the end of which a sealing unit made of a material resistant to corrosion is installed, inside which a conductor-holder is installed with the possibility of removal, one end of which is fixed to an anode plate, which is made of the steel being analyzed, wherein the surfaces of the conductor-holder and the anode plate, with the exception of the working area, are covered with a protective corrosion-resistant varnish.

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