JP7103124B2 - Basic test equipment for threaded joints for steel pipes - Google Patents

Description

The present disclosure relates to a basic test apparatus for a threaded joint for steel pipes, and more particularly, a test piece having an annular convex surface simulating a sealing surface of a threaded joint for steel pipes and a through hole arranged inside the annular convex surface. It relates to a basic test apparatus for basic evaluation of the sealing performance of a sealing surface.

In oil wells, natural gas wells, etc. (hereinafter collectively referred to as "oil wells"), many steel pipes called oil well pipes are used to mine underground resources. These well pipes are connected to each other by threaded joints.

The types of threaded joints for oil country tubular goods are roughly classified into integral type and coupling type. In the case of the integral type, each well pipe has a male threaded portion at one end and a female threaded portion at the other end. The well pipes are connected by screwing the male threaded portion of one well pipe into the female threaded portion of the other well pipe and fastening the well pipes. In the case of the coupling type, the well pipes are connected to each other by using a coupling. The coupling is a steel pipe different from the oil well pipe to be connected, and has female threaded portions at both ends. Male threaded portions are provided at both ends of each well pipe. The male threaded portions of the oil well pipes are screwed into and fastened to each of the female threaded portions of the coupling, so that the oil well pipes are connected to each other. Generally, the end of the well pipe having a male threaded portion is referred to as a pin, and the end of the well pipe or coupling having a female threaded portion is referred to as a box.

Threaded joints are required to have excellent sealing performance in oil wells under high temperature and high pressure environments. As a threaded joint for improving sealing performance, a threaded joint that forms a sealed portion by metal-metal contact in a fastened state is known. In this threaded joint, a sealing surface is provided on each of the pin and the box. In the non-fastened state, the diameter of the sealing surface of the pin is slightly larger than the diameter of the sealing surface of the box. Therefore, when the pin and the box are fastened and the sealing surfaces come into contact with each other, the diameter of the sealing surface of the pin is reduced and the diameter of the sealing surface of the box is expanded. An elastic recovery force that tries to return to the original diameter is generated on the sealing surface of the reduced-diameter pin and the sealing surface of the expanded box. As a result, the contact force between the sealing surfaces is increased, and the sealing surfaces are brought into close contact with each other all around, and the sealing performance is exhibited.

In order to determine whether or not the required sealing performance is ensured at the design stage of the threaded joint having the sealing portion, it is preferable that the sealing mechanism of the sealing portion has been elucidated in advance. Further, when creating a design formula for a threaded joint having a seal portion, it is preferable that the sealing mechanism of the seal portion is clarified in order to correctly create a model that is a premise of the design formula. Non-Patent Documents 1 to 3 report basic research aimed at clarifying the sealing mechanism of the sealing portion.

Non-Patent Document 1 discloses gas sealing tests I to III simulating a contact state of a sealing surface in an oil country tubular goods threaded joint. In particular, Test III is carried out in consideration of the sliding of the sealing surface that occurs during fastening and the deterioration of the lubricant (grease) due to high temperature. Specifically, the upper test piece is compared with the lower test piece while increasing or decreasing the pressing force from the metal seal surface of the upper test piece to the metal seal surface of the lower test piece by simulating the fastening and disassembling of the screw joint. Rotate and slide. Grease is applied to each sealing surface. Next, the upper and lower test pieces are heated while simulating the high temperature environment in the oil well and maintaining the pressing force of the upper test piece against the lower test piece at a predetermined value. After that, high-pressure gas is introduced into the inner space of the annular seal contact portion formed by the seal surfaces of the upper and lower test pieces, and a gas leak is confirmed.

Non-Patent Document 2 discloses a technique for in-situ observation of a sealing surface during a gas sealing test using a test piece having a metal sealing surface and a sapphire glass plate. In Non-Patent Document 2, a non-sliding seal test and a post-sliding seal test are carried out. The non-sliding seal test is a test in which a sapphire glass plate is pressed against a seal surface coated with a lubricant (grease) to load a high-pressure gas. The post-sliding seal test is a test in which a sapphire glass plate is pressed against a seal surface that has been slid in advance with grease applied to load a high-pressure gas.

In each test of Non-Patent Document 2, a sapphire glass plate is pressed against the sealing surface of the test piece to form a sealing contact portion. While maintaining the pressing force of the sapphire glass plate against the sealing surface, a mixed high-pressure gas of nitrogen and helium is loaded in the space formed between the sealing surface and the sapphire glass plate. After that, the pressing force of the sapphire glass plate is gradually reduced while maintaining the gas pressure. During each test, the behavior of grease on the sealing surface in the process leading to a gas leak is observed through the sapphire glass plate by an endoscopic microscope inserted above the sapphire glass plate. In each test, the presence or absence of slow leak before the occurrence of a rapid decrease in gas pressure (instantaneous leak) is confirmed by a helium leak detector.

Similar to Non-Patent Document 2, Non-Patent Document 3 also discloses a technique for in-situ observation of the sealing surface during a gas sealing test. In Non-Patent Document 3, the test apparatus for the gas sealing test includes a load frame, a heating furnace, and a high-pressure gas generator. The load frame is configured to hold the test piece and the sapphire glass plate. The load frame includes an actuator that generates axial force and rotational force.

In Non-Patent Document 3, in order to confirm the effect of high temperature deterioration of the lubricant (grease) on the sealing performance, the test piece is heated as a pretreatment for the gas sealing test. Specifically, the test piece is heated in a heating furnace with grease applied to the metal seal surface thereof. During the heating of the test piece, the sapphire glass plate is pressed from above by the load frame against the greased sealing surface. The test piece is heated at a predetermined temperature for a predetermined time and then naturally cooled.

Further, in Non-Patent Document 3, in order to confirm the influence of sliding of the sealing surface on the sealing performance, as a pretreatment for the gas sealing test, a sliding body made of the same steel pipe as the test piece is used as a test piece by a load frame. Rotately slide with respect to the sealing surface of. Specifically, the sliding body is pressed against the grease-coated seal surface to rotate it. A manganese phosphate film treatment is applied to the flat surface of the sliding body that is pressed against the sealing surface. The pressing force of the sliding body against the sealing surface increases to a predetermined value during rotational sliding. After that, the sliding body is removed from the test piece, and a sapphire glass plate is placed on the sealing surface of the test piece. The sapphire glass plate is pressed against the sealing surface by the load frame.

In Non-Patent Document 3, a gas sealing test is performed after a pretreatment that simulates high-temperature deterioration of grease or a pretreatment that simulates sliding of a sealing surface. That is, the high-pressure gas generator introduces high-pressure gas into the sealing surface of the test piece and the inner space of the annular seal contact portion formed of the sapphire glass plate. The state of the seal contact portion during the gas sealing test can be observed through the sapphire glass plate by an endoscope-type microscope inserted above the sapphire glass plate. Gas leaks from the seal contacts are detected by the helium leak detector.

Keita Inose, 2 others, "Influence of Grease on High-Pressure Gas Tribology-to-Metal Sale Tribology , Tribology Online, Japan Tribology Society, 2016, Vol. 11, No. 2, p. 227-234 Keita Ise and 2 others, "In-situ observation during airtightness test of grease applied to metal seal", Tribology Society 2016 Autumn Niigata Proceedings, Japan Tribology Society, 2016 Keita Inose, 2 others, "Investigation of Grease Behavior on Metal Seal Surface under High Pressure Pressure Gear Gear situ Observations) ”, 6th World Tribology Conference Extended Abstracts Session 83 Track 7 (World Tribology Congress 2017 extended abstract session 83 track 7), September 17-22, 2017

In order to elucidate the sealing mechanism of the sealing portion, it is preferable to perform in-situ observation of the sealing surface as in Non-Patent Documents 2 and 3. In the in-situ observation, it is important to make the contact state of the seal surface as close as possible to the actual contact state of the seal surface of the threaded joint.

Non-Patent Documents 2 and 3 propose a method of simply pressing a sapphire glass plate against the sealing surface of a test piece to form a sealing contact portion. However, this method does not consider the sliding of the sealing surface that occurs in the process of fastening the threaded joint. The sliding of the sealing surface greatly affects the sealing performance of the sealing portion. In order to accurately evaluate the sealing performance of the sealed portion, it is necessary to carry out in-situ observation in consideration of the sliding of the sealing surface.

Non-Patent Document 3 proposes a method in which a sliding body is rotationally slid with respect to a sealing surface of a test piece, and then a sapphire glass plate is pressed against the sealing surface to form a sealing contact portion. In this method, although the sliding of the sealing surface is taken into consideration, it is necessary to separate the sliding body from the sealing surface of the test piece when observing in-situ. As a result, the contact state of the sealing surface changes. Therefore, it is difficult to accurately evaluate the sealing performance of the sealing portion.

An object of the present disclosure is to provide a basic test apparatus capable of accurately evaluating the sealing performance of a sealed portion of a threaded joint for steel pipe.

The basic test apparatus according to the present disclosure is a test apparatus for testing the sealing performance of the sealing surface of a threaded joint for steel pipes using a test piece. The test piece has an annular convex surface simulating the sealing surface of a threaded steel pipe joint, and a through hole arranged inside the annular convex surface. The basic test apparatus includes a transparent plate, a jig, an endoscope apparatus, and a gas supply apparatus. The transparent plate has a polygonal shape or an elliptical shape in a plan view. The transparent plate is arranged so as to face the annular convex surface. The jig has a recess. The recess has a shape corresponding to the shape of the transparent plate and accommodates the transparent plate. The jig is configured so that the transparent plate in the concave portion can be pressed against the annular convex surface. The jig is configured to be rotatable around a rotation axis. The axis of rotation passes through the central portion of the annular convex surface and extends in the thickness direction of the transparent plate in the concave portion. The endoscope device has an endoscope. The endoscope is inserted into the jig. The endoscope device images the seal contact portion through the transparent plate. The seal contact portion is formed of an annular convex surface and a transparent plate. The gas supply device supplies gas at a predetermined pressure from the through hole to the inner space of the seal contact portion.

According to the basic test apparatus according to the present disclosure, the sealing performance of the sealed portion of the threaded joint for steel pipe can be evaluated with high accuracy.

FIG. 1 is a front view of the basic test apparatus according to the embodiment. FIG. 2 is a plan view and a side view of the transparent plate included in the basic test apparatus shown in FIG. FIG. 3 is a vertical cross-sectional view and a bottom view of the jig included in the basic test apparatus shown in FIG. FIG. 4 is a schematic view showing a test evaluation unit of the basic test apparatus shown in FIG. 1 and its peripheral configuration. FIG. 5 is a schematic view showing the test evaluation unit and its peripheral configuration in a plan view. FIG. 6 is another schematic view showing the test evaluation unit and its peripheral configuration in a plan view. FIG. 7 is a front view showing a part of the basic test apparatus according to the modified example of the basic test apparatus shown in FIG. FIG. 8 is a diagram for explaining a test procedure of Examples. FIG. 9 is an image of the seal contact portion observed in Test 1 in the examples. FIG. 10 is an image of the seal contact portion observed in Test 3 in the examples.

The basic test device according to the embodiment is a test device for testing the sealing performance of the sealing surface of a threaded joint for steel pipes using a test piece. The test piece has an annular convex surface simulating the sealing surface of a threaded steel pipe joint, and a through hole arranged inside the annular convex surface. The basic test apparatus includes a transparent plate, a jig, an endoscope apparatus, and a gas supply apparatus. The transparent plate has a polygonal shape or an elliptical shape in a plan view. The transparent plate is arranged so as to face the annular convex surface. The jig has a recess. The recess has a shape corresponding to the shape of the transparent plate and accommodates the transparent plate. The jig is configured so that the transparent plate in the concave portion can be pressed against the annular convex surface. The jig is configured to be rotatable around a rotation axis. The axis of rotation passes through the central portion of the annular convex surface and extends in the thickness direction of the transparent plate in the concave portion. The endoscope device has an endoscope. The endoscope is inserted into the jig. The endoscope device images the seal contact portion through the transparent plate. The seal contact portion is formed of an annular convex surface and a transparent plate. The gas supply device supplies gas of a predetermined pressure from the through hole to the inner space of the seal contact portion (first configuration).

In the first configuration, the jig presses the transparent plate housed in the concave portion against the annular convex surface simulating the sealing surface of the threaded joint for steel pipe. As a result, the seal contact portion is formed by the annular convex surface and the transparent plate. Further, the jig rotates around a rotation axis extending in the thickness direction of the transparent plate in the recess through the center of the seal contact portion. The recess has a shape corresponding to a transparent plate having a polygonal or elliptical shape in a plan view. According to this configuration, when the jig rotates around the rotation axis, a sufficient torque acts on the transparent plate from the inner surface of the recess to rotate the transparent plate in the same direction as the jig, so that the transparent plate is transparent. The plate rotates with the jig. That is, since the relative rotation between the transparent plate and the jig is restricted by the polygonal or elliptical transparent plate and the concave portion, the transparent plate can be used with the jig without slipping between the transparent plate and the jig. It rotates integrally. Therefore, the transparent plate can be rotationally slid with respect to the annular convex surface. The seal contact portion formed of the annular convex surface and the transparent plate can be imaged as it is through the transparent plate that has been rotated and slid by the endoscope device. Therefore, the gas sealing test can be started by supplying gas to the inner space of the seal contact portion by the gas supply device without changing the contact state of the annular convex surface, and the seal contact portion under test can be observed on the spot. .. Therefore, in-situ observation is possible in consideration of the sliding of the sealing surface that occurs in the fastening process of the threaded joint, and it is possible to accurately evaluate the sealing performance of the sealed portion of the threaded joint for steel pipes.

In the above basic test apparatus, a lubricant or a lubricating film may be present between the annular convex surface and the transparent plate (second configuration).

In the second configuration, a lubricant or a lubricating film is present between the annular convex surface and the transparent plate by applying a lubricant in advance to the annular convex surface or forming a lubricating film in advance. This makes it possible to observe the behavior of the lubricant or the lubricating film on the annular convex surface. Therefore, the influence of the lubricant or the lubricating film on the gas sealing performance can be confirmed by in-situ observation.

The basic test device having the second configuration preferably further includes a heating device. The heating device can accommodate and heat the test piece and the transparent plate in a state where the seal contact portion is formed (third configuration).

According to the third configuration, the heating device heats the lubricant or the lubricating film at the seal contact portion. Therefore, in-situ observation, the influence of high temperature deterioration of the lubricant or the lubricating film on the gas sealing performance can be confirmed.

In the second or third configuration, the endoscope device may include an ultraviolet light source. The ultraviolet light source can irradiate the seal contact portion with observation light including ultraviolet rays through the transparent plate. In this case, it is preferable that a lubricating oil or grease is present as a lubricant between the annular convex surface and the transparent plate. A fluorescent agent is preferably added to the lubricating oil or grease. The fluorescent agent absorbs ultraviolet rays and emits fluorescence (fourth configuration).

According to the fourth configuration, the seal contact portion is irradiated with observation light including ultraviolet rays in a state where the lubricating oil or grease to which the fluorescent agent is added is present between the annular convex surface and the transparent plate. As a result, the fluorescent agent in the lubricating oil or grease fluoresces, so that the behavior of the lubricating oil or grease can be grasped more accurately in the in-situ observation.

In the fourth configuration, the ultraviolet light source preferably irradiates the seal contact portion with observation light via a long wavelength cut filter. The long wavelength cut filter can attenuate light having a wavelength longer than that of visible light (fifth configuration).

In the fifth configuration, the long wavelength cut filter attenuates light having a wavelength longer than that of visible light, and irradiates the seal contact portion with light having a wavelength shorter than that of visible light. That is, unnecessary light is not incident on the seal contact portion. Therefore, the visibility of the seal contact portion in in-situ observation can be improved.

The basic test apparatus preferably further includes a shield and a helium leak detector. The shield covers the test piece and the transparent plate in which the seal contact portion is formed. The helium leak detector is connected to the shield. The gas supply device supplies gas containing helium to the inner space (sixth configuration).

According to the sixth configuration, the shield captures the gas leaked from the inner space of the seal contact portion, and the helium leak detector detects the helium in the leaked gas. As a result, even when a gas leak occurs in a portion other than the portion observed by the endoscope device in the seal contact portion, the gas leak can be detected.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each figure, the same or equivalent configurations are designated by the same reference numerals, and the same description is not repeated.

[Test equipment configuration]
(overall structure)
FIG. 1 is a front view of the basic test apparatus 100 according to the embodiment. The basic test apparatus 100 is used for testing the gas sealing performance of the sealing surface of the threaded joint for steel pipes. In the test by the basic test apparatus 100, the test piece 200 is used. The material of the test piece 200 is preferably the same as the material of the threaded joint for steel pipe to be tested. However, the material of the test piece 200 does not have to be exactly the same as that of the threaded joint for steel pipe to be tested, and may be a material corresponding to the material of the threaded joint for steel pipe. The test piece 200 has an annular convex surface 201 that simulates the sealing surface of a threaded joint for steel pipes. The test piece 200 has a through hole 202 extending in the vertical direction.

As shown in FIG. 1, the basic test apparatus 100 includes a main body frame 10, an elevating / rotating mechanism 20, jigs 30 and 40, a gas supply device 50, a gas leak detection mechanism 60, and a transparent plate 70. ..

The main body frame 10 includes a table 11, a pair of columns 12, and a crosshead 13. Each column 12 extends upward from the upper surface of the table 11. The crosshead 13 extends in the horizontal direction and spans a pair of columns 12. The crosshead 13 is attached to the pair of columns 12 so as to be able to move up and down. The crosshead 13 is fixed to each support column 12 by, for example, a clamp. In this case, by loosening the clamp, the crosshead 13 can be moved up and down along each support column 12.

The elevating and rotating mechanism 20 is arranged between the columns 12. The elevating and rotating mechanism 20 is attached to the crosshead 13. Therefore, when the crosshead 13 moves up and down with respect to the support column 12, the elevating and rotating mechanism 20 moves up and down together with the crosshead 13.

The elevating / rotating mechanism 20 is a mechanism for elevating and lowering the jig 30, which will be described later, and rotating the jig 30 around a rotation axis X extending in the vertical direction. The elevating and rotating mechanism 20 includes a linear actuator 21, a motor 22, and a pair of guide rods 23.

The linear actuator 21 has a cylinder 211 and a rod 212. The cylinder 211 is fixed to the upper surface of the crosshead 13. The rod 212 is inserted into the cylinder 211. The rod 212 extends downward from the cylinder 211 through the crosshead 13. The rod 212 is configured to be able to move up and down with respect to the cylinder 211 and the crosshead 13.

As the linear actuator 21, a commercially available or known linear actuator can be adopted. The linear actuator 21 may be an electric actuator or a fluid pressure actuator such as hydraulic pressure. The amount of movement of the rod 212 with respect to the cylinder 211 can be adjusted by controlling a drive source such as an electric motor or a fluid pressure pump with a control device (not shown).

The motor 22 is arranged above the linear actuator 21. The motor 22 is connected to the rod 212. The drive shaft of the motor 22 is connected to the rod 212 via a speed reducer 24 or the like. Therefore, the rotational force of the motor 22 is transmitted to the rod 212, and the rod 212 rotates around the rotation axis X. The motor 22 is preferably a servomotor whose rotation angle and rotation speed are automatically controlled in response to a command from a control device (not shown).

The pair of guide rods 23 are arranged on both sides of the linear actuator 21. Each guide rod 23 is fixed to the upper surface of the crosshead 13. Each guide rod 23 extends upward from the crosshead 13. One of the guide rods 23 is attached to one of the columns 12 via the linear guide bearing 25. The other side of the guide rod 23 is attached to the other side of the support column 12 via the linear guide bearing 25. The guide rod 23 guides the elevating and rotating mechanism 20 to move along the support column 12 when the elevating and rotating mechanism 20 moves up and down together with the crosshead 13.

The jig 30 is attached to the lower end of the rod 212. The jig 30 is detachably attached to the rod 212 via the holder 31. The jig 30 extends downward from the rod 212. When the rod 212 moves up and down with respect to the cylinder 211, the jig 30 moves up and down together with the rod 212. When the rod 212 rotates around the rotation axis X, the jig 30 rotates around the rotation axis X together with the rod 212.

The jig 30 is a component for positioning the transparent plate 70. The jig 30 has a recess 32. The recess 32 is provided on the bottom surface of the jig 30. The recess 32 is configured to accommodate the transparent plate 70.

Here, a detailed configuration of the transparent plate 70 and the jig 30 will be described with reference to FIGS. 2 and 3. FIG. 2 is a plan view and a side view of the transparent plate 70. FIG. 3 is a vertical sectional view and a bottom view of the jig 30.

With reference to FIG. 2, the transparent plate 70 has a polygonal shape or an elliptical shape in a plan view. The polygonal shape means that it is generally a polygonal shape. That is, the polygons include not only polygons formed only by straight lines, but also polygons with rounded corners and polygons with rounded sides and corners (so-called equi-diameter strain circles). included. The elliptical shape means that the shape is generally elliptical. That is, the elliptical shape is not only an elliptical shape in a geometrical sense, but also a shape defined by a pair of parallel line segments and a pair of arcs connecting the line segments (so-called track shape). Is also included. In the present embodiment, the transparent plate 70 has a square shape in a plan view. The planar shape of the transparent plate 70 is a quadrangle with rounded corners. The transparent plate 70 is preferably symmetrical with respect to the rotation axis X in any cross section including the rotation axis X.

The hardness of the transparent plate 70 is preferably high to some extent. The material of the transparent plate 70 can be selected from, for example, tempered glass, quartz, sapphire glass and the like. The Vickers hardness of tempered glass is about 640, the Vickers hardness of quartz is about 1100, and the Vickers hardness of sapphire glass is about 2300. The transparent plate 70 preferably has a Vickers hardness of 1000 or more. The transparent plate 70 is preferably a sapphire glass plate.

With reference to FIG. 3, a recess 32 is formed on the bottom surface of the jig 30. The recess 32 has a shape corresponding to the shape of the transparent plate 70. That is, the shape of the recess 32 is substantially the same as the planar shape of the transparent plate 70 when viewed from the bottom of the jig 30. When the transparent plate 70 has a polygonal shape in a plan view, the recess 32 has a polygonal shape in a bottom view of the jig 30. When the transparent plate 70 has an elliptical shape in a plan view, the recess 32 has an elliptical shape in a bottom view of the jig 30. In the present embodiment, the recess 32 has a quadrangle with rounded corners when viewed from the bottom of the jig 30. The size of the recess 32 is slightly larger than the size of the transparent plate 70. The recess 32 is formed in a size that allows the transparent plate 70 to fit exactly.

Returning to FIG. 1, the jig 40 is arranged between the jig 30 and the table 11. The jig 40 is a component for positioning the test piece 200, which will be described later. The jig 40 includes a holding portion 41 and a load cell 42. The holding portion 41 sandwiches and holds the test piece 200 from above and below. The test piece 200 held by the jig 40 comes into contact with the transparent plate 70 in the recess 32 of the jig 30. The load cell 42 is arranged below the test piece 200 held by the holding portion 41.

The gas supply device 50 generates gas at a predetermined pressure. The gas supply device 50 generates the high-pressure gas required in the gas sealing test of the sealing surface of the threaded joint for steel pipes. The gas supply device 50 has a supply path 51. The supply path 51 penetrates the table 11 and the jig 40, extends along the rotation axis X, and is connected to the through hole 202 of the test piece 200. The gas supply device 50 supplies high-pressure gas between the test piece 200 and the transparent plate 70 via the supply path 51. The gas supplied by the gas supply device 50 is preferably helium gas or helium mixed gas.

The gas leak detection mechanism 60 detects a leak of gas supplied between the test piece 200 and the transparent plate 70 by the gas supply device 50. The gas leak detection mechanism 60 includes a shield 61 and a helium leak detector 62.

The shield 61 covers the test piece 200 and the transparent plate 70 housed in the recess 32 of the jig 30. The shield 61 captures the gas leaked from between the test piece 200 and the transparent plate 70. However, the shield 61 does not need to form a completely enclosed space. The shield 61 should be able to cover at least the test piece 200 and the transparent plate 70 from above and from the side. That is, the lower surface of the shield 61 may be open. The shield 61 is detachably configured in the basic test apparatus 100.

The helium leak detector 62 is connected to the shield 61 via a tube 63. The helium leak detector 62 sucks the gas in the shield 61 through the tube 63 by a built-in pump (not shown). The helium leak detector 62 detects the flow rate of helium in the sucked gas. As the helium leak detector 62, a commercially available or known helium leak detector can be used.

(Test evaluation department and its surroundings)
In the present embodiment, the test piece 200 and the transparent plate 70 that come into contact with each other are referred to as a test evaluation unit Pt. Hereinafter, the test evaluation unit Pt and its peripheral configuration will be described in detail with reference to FIGS. 4 to 6. 4 to 6 are schematic views showing the test evaluation unit Pt and its peripheral configuration. 4 to 6 show an endoscope device 80 and a heating device 90, which are not shown in FIG. 1, as a part of the peripheral configuration of the test evaluation unit Pt. That is, the basic test device 100 according to the present embodiment further includes an endoscope device 80 and a heating device 90.

First, referring to FIG. 4, the test piece 200 has an annular convex surface 201 and a through hole 202. The annular convex surface 201 is formed by simulating the sealing surface of the threaded joint for steel pipe to be tested. The annular convex surface 201 forms an annular shape centered on the rotation axis X. The annular convex surface 201 is formed so as to draw a convex curve on the transparent plate 70 side when viewed in a cross section including the rotation axis X. However, the annular convex surface 201 may be formed so as to draw a trapezoid protruding toward the transparent plate 70 when viewed in a cross section including the rotation axis X. That is, the annular convex surface 201 is formed by a top surface that is substantially parallel and flat to the lower surface of the transparent plate 70 when viewed in a cross section including the rotation axis X, and an inclined surface that is inclined downward from both ends of the top surface. It may have a substantially trapezoidal shape. The through hole 202 extends downward along the rotation axis X from the center of the annular convex surface 201 and penetrates the test piece 200.

The transparent plate 70 faces the annular convex surface 201 in a state of being housed in the concave portion 32 of the jig 30. When the jig 30 descends together with the rod 212 (FIG. 1) of the linear actuator 21, the lower surface of the transparent plate 70 is pressed against the annular convex surface 201. As a result, the transparent plate 70 forms an annular seal contact portion Ps together with the annular convex surface 201. The seal contact portion Ps is the contact center of the annular convex surface 201 with respect to the transparent plate 70.

Since the annular convex surface 201 is convex toward the transparent plate 70 and the lower surface of the transparent plate 70 is flat, the inside of the annular seal contact portion Ps is inside between the test piece 200 and the transparent plate 70. Space S is formed. The gas supply device 50 supplies the gas adjusted to a predetermined pressure to the inner space S. The gas from the gas supply device 50 passes through the supply path 51 and the through hole 202 in order, and is supplied to the inner space S.

The jig 30 has an insertion hole 33 for inserting the endoscope device 80 above the recess 32. The endoscope device 80 images the seal contact portion Ps through the transparent plate 70 in the recess 32. The endoscope device 80 includes an industrial endoscope 81, a camera 82, a microscope 83, and an ultraviolet light source 84.

The industrial endoscope 81 is a commercially available or known borescope, fiberscope, videoscope, or the like. The tip of the industrial endoscope 81 is inserted into the insertion hole 33 of the jig 30. The tip of the industrial endoscope 81 has an optical system for forming an image of the seal contact portion Ps. The industrial endoscope 81 transmits an image of the seal contact portion Ps from the tip portion to the camera 82. When the industrial endoscope 81 has an imaging element built-in, the industrial endoscope 81 converts the image of the seal contact portion Ps into an electric signal to generate image data, and the image data of the seal contact portion Ps. Is transmitted from the tip to the camera 82.

The camera 82 is typically a CCD camera. The camera 82 is connected to an industrial endoscope 81, as is commonly done in internal observations using a borescope or the like. The camera 82 converts the image of the seal contact portion Ps input from the industrial endoscope 81 into an electric signal to generate image data, and performs necessary image processing for recording. Alternatively, the camera 82 receives the image data of the seal contact portion Ps from the industrial endoscope 81, performs necessary image processing, and records the image data.

The microscope 83 is connected to the camera 82. The microscope 83 is a known display device that displays an enlarged image on a display screen. The microscope 83 enlarges and displays an image corresponding to the image data of the seal contact portion Ps generated by the camera 82 on the display screen.

The microscope 83 is also connected to the industrial endoscope 81. The microscope 83 incorporates a visible light source (not shown) such as a halogen light. This visible light source can be used as an external light source for the industrial endoscope 81. The visible light output from the visible light source of the microscope 83 is emitted from the tip of the industrial endoscope 81 to the seal contact portion Ps via the transparent plate 70.

The ultraviolet light source 84 is used as an external light source for the industrial endoscope 81. The ultraviolet light source 84 is connected to the industrial endoscope 81 instead of the visible light source of the microscope 83. The ultraviolet light source 84 outputs observation light including ultraviolet rays. The ultraviolet light source 84 is, for example, a commercially available or known ultraviolet (UV) light. The observation light from the ultraviolet light source 84 is emitted from the tip of the industrial endoscope 81 to the seal contact portion Ps via the transparent plate 70.

The ultraviolet light source 84 is preferably configured to irradiate the seal contact portion Ps with the observation light via the long wavelength cut filter 85. The observation light from the ultraviolet light source 84 passes through the long wavelength cut filter 85 before entering the industrial endoscope 81. In the present embodiment, the observation light is focused by the convex lens 86 and incident on the long wavelength cut filter 85. However, the observation light may be focused by the convex lens 86 after passing through the long wavelength cut filter 85. The long wavelength cut filter 85 attenuates the observation light output by the ultraviolet light source 84, which has a wavelength longer than that of visible light. The long wavelength cut filter 85 transmits light having a wavelength substantially shorter than the wavelength of visible light, specifically, ultraviolet rays having a wavelength of approximately 385 nm (± 5 nm) or less.

Next, the heating device 90 will be described with reference to FIGS. 5 and 6. As shown in FIGS. 5 and 6, the heating device 90 includes a constant temperature bath 91, a heater 92, and a rail 93.

The constant temperature bath 91 has a tank body 911 and a door 912. The constant temperature bath 91 moves on the rail 93 together with the heater 92. That is, the constant temperature bath 91 and the heater 92 are configured so as to be able to move forward and backward toward the test evaluation unit Pt along the rail 93. The constant temperature bath 91 approaches the test evaluation unit Pt with the door 912 open, and accommodates the test evaluation unit Pt in the tank body 911. When a gap is generated between the tank body 911 and the jigs 30, 40, etc. (FIG. 1), the gap may be closed by the spacer 94. When the constant temperature bath 91 and the heater 92 are moved to the test evaluation unit Pt, the shield 61 (FIG. 1) covering the test evaluation unit Pt is removed from the basic test apparatus 100. In the heater 92, the tank body 911 accommodates the test evaluation unit Pt, and after the door 912 is closed, the air in the constant temperature bath 91 is heated to raise the temperature.

[How to use the test equipment]
Hereinafter, a typical method of using the basic test apparatus 100 configured as described above will be described mainly with reference to FIG. However, the method of using the basic test apparatus 100 is not limited to the method of use described in this embodiment.

With reference to FIG. 1 again, first, a test piece 200 made of the same material as the threaded joint for steel pipe to be tested is prepared. The annular convex surface 201 of the test piece 200 is formed by simulating the sealing surface of the threaded joint for steel pipe to be tested.

Next, the test piece 200 is placed on the jig 40 with the annular convex surface 201 facing upward. A lubricant may be applied to the annular convex surface 201, or a lubricating film may be formed on the annular convex surface 201. The lubricant or lubricating film is a lubricant or lubricating film that is expected to be actually used in the threaded joint for steel pipes to be tested. The lubricant is, for example, a lubricating oil or grease. Examples of the grease include compound grease of the American Petroleum Institute (API) standard containing heavy metal particles, graphite and the like. A fluorescent agent that absorbs ultraviolet rays and emits fluorescence may be added to the lubricating oil or grease. The lubricating film is, for example, a solid lubricating film formed by applying a fluidizing lubricant and then performing a curing treatment.

Further, the transparent plate 70 is arranged in the recess 32 of the jig 30 and temporarily fixed with an adhesive tape or the like. After adjusting the position of the elevating and rotating mechanism 20 by raising and lowering the crosshead 13 as necessary, the linear actuator 21 is driven to lower the rod 212. As a result, the jig 30 is lowered together with the rod 212, and the lower surface of the transparent plate 70 in the recess 32 is pressed against the annular convex surface 201 of the test piece 200.

The transparent plate 70 presses the annular convex surface 201 with a pressing force predetermined according to the purpose of the test or the like. The pressing force acting on the annular convex surface 201 is detected by the load cell 42 arranged below the test piece 200.

When the motor 22 is driven while the transparent plate 70 presses the annular convex surface 201, the transparent plate 70 rotates and slides with respect to the annular convex surface 201. That is, the rod 212 rotates around the rotation shaft X in conjunction with the drive shaft of the motor 22. As a result, the jig 30 and the transparent plate 70 pressed against the annular convex surface 201 also rotate around the rotation axis X. The transparent plate 70 receives torque for rotating in the same direction as the jig 30 from the inner surface of the recess 32, and rotates together with the jig 30. The jig 30 rotates with respect to the annular convex surface 201 at a predetermined rotation speed and rotation speed. The pressing force from the transparent plate 70 to the annular convex surface 201 during rotational sliding may be gradually increased in consideration of the gradual increase in the contact surface pressure of the sealing surface during the fastening process of the threaded joint for steel pipe.

After the rotational sliding of the transparent plate 70 with respect to the annular convex surface 201 is completed, the test evaluation unit Pt (FIGS. 5 and 6) composed of the transparent plate 70 and the test piece 200 is heated. As shown in FIGS. 5 and 6, the constant temperature bath 91 with the door 912 open and the heater 92 are tested and evaluated along the rail 93 while maintaining the pressing force from the transparent plate 70 to the annular convex surface 201. The door 912 is closed by accommodating the test evaluation unit Pt in the tank 911 so as to approach the unit Pt. The temperature inside the constant temperature bath 91 is raised to a predetermined temperature by the heater 92, and the test evaluation unit Pt is heated at this temperature for a predetermined time. The heating of the test evaluation unit Pt is performed with the shield 61 (FIG. 1) removed from the basic test apparatus 100. The heating temperature and heating time of the test evaluation unit Pt can be a temperature and time conforming to ISO 13679 (2011). After that, the door 912 is opened and the test evaluation unit Pt is naturally cooled to room temperature.

Next, referring to FIG. 4, the high-pressure gas is supplied from the gas supply device 50 to the inner space S of the seal contact portion Ps while maintaining the pressing force from the transparent plate 70 to the annular convex surface 201. When the high-pressure gas is supplied to the inner space S, a shield 61 (FIG. 1) covering the test evaluation unit Pt is attached to the basic test apparatus 100. In addition, the observation of the seal contact portion Ps by the endoscope device 80 is started. That is, the image of the seal contact portion Ps is enlarged and displayed on the display screen of the microscope 83, and the state of the seal contact portion Ps is observed.

When the lubricating oil or grease to which the fluorescent agent is added is applied to the annular convex surface 201, the ultraviolet light source 84 is connected to the industrial endoscope 81, and the observation light including ultraviolet rays is emitted from the ultraviolet light source 84 to the seal contact portion Ps. Irradiate to. As a result, the fluorescent agent in the lubricating oil or the base oil of the grease fluoresces, making it easier to confirm the behavior of the lubricating oil or the base oil. When no fluorescent agent is used, the microscope 83 is connected to the industrial endoscope 81, and the visible light source irradiates the seal contact portion Ps with visible light.

The high-pressure gas is supplied until the gas pressure in the inner space S of the seal contact portion Ps reaches a predetermined value. Then, while maintaining the gas pressure in the inner space S, the pressing force from the transparent plate 70 to the annular convex surface 201 is gradually reduced.

The display screen of the microscope 83 also shows how the gas from the gas supply device 50 flows into the vicinity of the seal contact portion Ps. When the annular convex surface 201 is previously coated with lubricating oil or grease, the display screen of the microscope 83 shows that the base oil or solid particles in the lubricating oil or grease are swept from the inside to the outside of the seal contact portion Ps by the gas pressure. The situation can be projected. In addition, the display screen of the microscope 83 can also display the distribution of solid particles and the like.

When a gas leak occurs during gas pressurization or tapering of pressing force, the gas leak can be detected by the image of the seal contact portion Ps displayed by the microscope 83 or the helium leak detector 62.

[Effect of Embodiment]
In the present embodiment, the transparent plate 70 in the concave portion 32 of the jig 30 is pressed against the annular convex surface 201 simulating the sealing surface of the threaded joint for steel pipe, and presses the annular convex surface 201. As a result, the annular convex surface 201 and the transparent plate 70 form the seal contact portion Ps. The jig 30 rotates around the rotation axis X together with the transparent plate 70 in a state where the transparent plate 70 is pressed against the annular convex surface 201. Therefore, the transparent plate 70 can provide rotational sliding to the annular convex surface 201 in consideration of the fastening process of the threaded joint for steel pipes.

In the present embodiment, the transparent plate 70 has a polygonal shape or an elliptical shape in a plan view, and the recess 32 has a shape corresponding to the plan shape of the transparent plate 70 in a bottom view of the jig 30. Therefore, when the jig 30 rotates around the rotation axis X, a sufficient torque is applied to the transparent plate 70 to rotate in the same direction as the jig 30, and the transparent plate 70 rotates together with the jig 30. That is, since the relative rotation between the transparent plate 70 and the jig 30 is restricted by the polygonal or elliptical transparent plate 70 and the similarly polygonal or elliptical concave portion 32, the transparent plate 70 and the jig 30 are combined. The transparent plate 70 rotates integrally with the jig 30 without slipping between them. Therefore, the transparent plate 70 can be rotationally slid with respect to the annular convex surface 201.

In the present embodiment, the seal contact portion Ps can be observed with the endoscope device 80 through the transparent plate 70 without removing the rotating and sliding transparent plate 70 from the annular convex surface 201. Therefore, the high-pressure gas is supplied to the inner space S of the seal contact portion Ps by the gas supply device 50 without changing the contact state of the annular convex surface 201, and the seal contact portion Ps loaded with the high-pressure gas is observed on the spot. Can be done. Therefore, the sealing performance of the sealed portion of the threaded joint for steel pipe to be tested can be evaluated accurately.

In the present embodiment, the annular convex surface 201 may be coated with a lubricant in advance or a lubricating film may be formed in advance. In this case, when observing the seal contact portion Ps on the spot, a lubricant or a lubricating film is present between the annular convex surface 201 and the transparent plate 70. Therefore, the behavior of the lubricant or the lubricating film at the seal contact portion Ps can be observed by the endoscope device 80. Therefore, the influence of the lubricant or the lubricating film on the gas sealing performance can be confirmed by in-situ observation.

The basic test apparatus 100 according to the present embodiment includes a heating apparatus 90. The heating device 90 can accommodate and heat the test piece 200 and the transparent plate 70 in a state where the lubricant or the lubricating film is held between the annular convex surface 201 and the transparent plate 70. Therefore, in-situ observation, the influence of high temperature deterioration of the lubricant or the lubricating film on the gas sealing performance can be confirmed.

In this embodiment, the endoscope device 80 has an ultraviolet light source 84. The observation light from the ultraviolet light source 84 includes ultraviolet rays and is applied to the seal contact portion Ps. When a lubricating oil or grease containing a fluorescent agent is present between the annular convex surface 201 forming the seal contact portion Ps and the transparent plate 70, the fluorescent agent fluoresces. Therefore, the behavior of the lubricating oil and the grease can be grasped more accurately in the in-situ observation.

In the present embodiment, the ultraviolet light source 84 irradiates the seal contact portion Ps with observation light via the long wavelength cut filter 85. The long wavelength cut filter 85 attenuates light having a wavelength longer than the wavelength of visible light, and substantially, light having a wavelength shorter than the wavelength of visible light, specifically, approximately 385 nm (± 5 nm) or less. Transmits ultraviolet light having the wavelength of. As a result, the seal contact portion Ps is not irradiated with visible light, so that the visibility of the seal contact portion Ps in in-situ observation is improved.

The basic test apparatus 100 according to the present embodiment includes a shield 61 that covers the test evaluation unit Pt, and a helium leak detector 62 that is connected to the shield 61. Therefore, when the gas supplied to the inner space S of the seal contact portion Ps contains helium, the gas leaked from the inner space S can be captured by the shield 61, and the gas leakage can be detected by the helium leak detector 62. .. As a result, even if a gas leak does not occur in the portion of the annular seal contact portion Ps that can be observed by the endoscope device 80 and the gas leak cannot be visually confirmed, the occurrence of the gas leak can be detected. can.

In this embodiment, the test piece 200 is positioned by the jig 40. This jig 40 may have a tilt correction unit 43, for example, as shown in FIG. 7. The tilt correction unit 43 is arranged below the holding unit 41. The tilt correction unit 43 has an elastic modulus smaller than that of the holding unit 41, and is composed of, for example, duralumin or the like. When the jig 30 is tilted with respect to the rotation axis X, the tilt correction portion 43 is elastically deformed so that the holding portion 41 and the test piece 200 follow the tilt of the jig 30. Therefore, even if the jig 30 is tilted with respect to the rotation axis X, the transparent plate 70 in the recess 32 of the jig 30 can be evenly pressed against the annular convex surface 201. In the example shown in FIG. 7, the load cell 42 is arranged below the tilt correction unit 43.

Although the embodiment according to the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various changes can be made as long as the purpose is not deviated.

Hereinafter, the present disclosure will be described in more detail by way of examples. However, the present disclosure is not limited to the following examples.

Using the basic test apparatus 100 shown in FIG. 1, a gas sealing test was carried out on the sealing surface of the threaded joint for steel pipes. In this embodiment, the material of the jig 30 is SNCM439, and the hardness was adjusted to Rockwell hardness (HRC) 35 to 40 by heat treatment. Further, the jig 40 is provided with an inclination correction unit 43 (manufactured by duralumin (A2017)) shown in FIG. 7.

In this example, as the industrial endoscope 81, the microscope 83, the ultraviolet light source 84, the long wavelength cut filter 85, and the helium leak detector 62, commercially available ones were used as shown below.
-Industrial endoscope (borescope): Made by KEYENCE Co., Ltd., Real bore lens, VH-B40 (maximum observation magnification 140 times)
-Microscope (including camera): Digital microscope, VHX-1000 manufactured by KEYENCE CORPORATION
-Ultraviolet light source: Made by Hayashi Clock Industry Co., Ltd., LED-UV spot lighting, HD3133-260
-Long wavelength cut filter: Asahi Spectroscopy Co., Ltd., long wavelength cut filter, SH0385
-Helium leak detector: ULVAC, Inc., leak tester, HELIOT 100 series model 102+

The transparent plate 70, the test piece 200, and other test conditions are as follows.
-Transparent plate: Square sapphire glass plate (25 mm x 25 mm, R5 fillet processing at the four corners, thickness 5 mm)
-Test piece (metal seal test piece): Carbon steel specified as L80 in the API standard (manufactured by carving from an oil well pipe)
-Lubricant: API standard grease (API modified threat compound)
-Fluorescent agent: SPECTRONICS CORPORATION, fluorescent agent for oil / oil system, OIL-GLO44
-Gas: Helium mixed gas (95% nitrogen, 5% helium)

FIG. 8 is a diagram for explaining a test procedure in this embodiment. With reference to FIG. 8, the sliding process is a process of rotating the jig 30 by 2160 degrees while pressing the transparent plate 70 against the annular convex surface 201 to 25 kN in 144 seconds to give rotational sliding to the annular convex surface 201. (Sliding distance: 226.08 mm, sliding speed: 1.57 mm / s, average Hertz contact pressure: equivalent to 700 MPa). In the baking process, the transparent plate 70 and the test piece 200 are heated by the heating device 90 at 180 ° C. for 12 hours in accordance with ISO 13679 (2011) while maintaining the pressing force (pressing pressure) of 25 kN, and then the baking process is performed. It is a process of allowing to cool to room temperature. In the gas sealing test, a high-pressure gas is supplied from the gas supply device 50 to the inner space S of the seal contact portion Ps while maintaining a pressing force of 25 kN, the gas pressure is increased to 150 MPa, and then a gas pressure of 150 MPa is applied. This is a test for confirming a gas leak by gradually reducing the pressing force at 0.04 kN / s (reducing from 25 kN to 1 kN in 600 sec) while maintaining the pressure.

In this example, tests 1 to 4 shown in Table 1 were carried out. In each of Tests 1 to 4, a lubricant to which a fluorescent agent was added was applied in advance to the annular convex surface 201 of the test piece 200.

In test 2, a baking process was performed without performing a sliding process, and then a gas sealing test was performed. In test 3, after the sliding treatment, the gas sealing test was carried out without the baking treatment. In test 4, a gas sealing test was carried out after performing a sliding treatment and a baking treatment in order. In Test 1, a gas sealing test was carried out without performing either a sliding treatment or a baking treatment for comparison with Tests 2 to 4. During the gas sealing test, a part of the annular seal contact portion Ps was observed by the endoscope device 80.

As shown in Table 1, in Test 1 in which the sliding treatment and the baking treatment were not performed, a gas leak occurred at a pressing force of 10.0 kN in the gas sealing test. In Test 2 in which only the baking treatment was performed, a gas leak occurred when the gas pressure was increased to 132 MPa in the gas sealing test. In Test 3 in which only the sliding treatment was performed, a gas leak occurred with a pressing force of 11.0 kN in the gas sealing test. In Test 4 in which the sliding treatment and the baking treatment were performed, a gas leak occurred when the gas pressure was increased to 142 MPa in the gas sealing test. From this result, the gas sealing test of the sealing surface of the steel pipe threaded joint differs depending on the presence or absence of the sliding process considering the fastening process of the steel pipe threaded joint and the baking process considering the high temperature usage environment of the steel pipe threaded joint. It can be seen that In particular, in this example, it was confirmed that the gas sealing test was lowered when the baking treatment was carried out.

FIG. 9 shows an image of the seal contact portion Ps observed in Test 1. FIG. 10 shows an image of the seal contact portion Ps observed in Test 3. In each of FIGS. 9 and 10, the image on the left side is an observation image of the seal contact portion Ps by visible light, and the image on the right side is an observation image of the seal contact portion Ps by ultraviolet rays. In FIG. 10, it can be confirmed that the seal contact portion Ps is worn due to rotational sliding (scratches).

100: Basic test equipment 30: Jig 32: Recess 61: Shield 62: Helium leak detector 70: Transparent plate 80: Endoscope equipment 81: Endoscope 84: Ultraviolet light source 85: Long wavelength cut filter 90: Heating equipment 200 : Test piece 201: Circular convex surface 202: Through hole Ps: Seal contact part S: Inner space

Claims (6)

A basic test device for testing the sealing performance of the sealing surface using a test piece having an annular convex surface simulating the sealing surface of a threaded joint for steel pipe and a through hole arranged inside the annular convex surface. There,
A transparent plate having a polygonal shape or an elliptical shape in a plan view and arranged so as to face the annular convex surface.
A jig having a shape corresponding to the shape of the transparent plate and having a concave portion for accommodating the transparent plate, the transparent plate in the concave portion can be pressed against the annular convex surface, and the annular convex surface can be pressed. A jig configured to be rotatable around a rotation axis extending in the thickness direction of the transparent plate in the recess through the central portion of the above.
An endoscope device having an endoscope inserted into the jig and imaging a seal contact portion formed by the annular convex surface and the transparent plate via the transparent plate.
A gas supply device that supplies gas of a predetermined pressure from the through hole to the inner space of the seal contact portion, and
A basic test device. The basic test apparatus according to claim 1.
A basic test apparatus in which a lubricant or a lubricating film is present between the annular convex surface and the transparent plate. The basic test apparatus according to claim 2, further
A heating device that accommodates and heats the test piece and the transparent plate in a state where the seal contact portion is formed.
A basic test device. The basic test apparatus according to claim 2 or 3.
The endoscope device has an ultraviolet light source that irradiates the seal contact portion with observation light including ultraviolet rays through the transparent plate.
A basic test apparatus in which a lubricating oil or grease to which a fluorescent agent that absorbs ultraviolet rays and emits fluorescence is added as the lubricant is present between the annular convex surface and the transparent plate. The basic test apparatus according to claim 4.
The ultraviolet light source is a basic test apparatus that irradiates the seal contact portion with the observation light via a long wavelength cut filter that attenuates light having a wavelength longer than that of visible light. The basic test apparatus according to any one of claims 1 to 5, further comprising:
A shield covering the test piece and the transparent plate in a state where the seal contact portion is formed, and
A helium leak detector connected to the shield,
With
The gas supply device is a basic test device that supplies a gas containing helium to the inner space.

Images