JPS60109687A - Joint for tubular article made of metal of different kind - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coupling for connecting two or more tubular bodies of dissimilar metals, such as a water well casing knob and a well screen.

Deep wells, especially water wells, have a structure that combines a casing nozzle a (hereinafter referred to as a casing) and a well screen b (hereinafter referred to as a screen) as shown in FIG. Casing a prevents the well from collapsing due to earth pressure,
The screen b has the function of conveying water, and the screen b has the function of collecting water while preventing the well from collapsing due to earth pressure and preventing the inflow of earth and sand. The casing a is often made of iron, but the screen b is now mainly made of stainless steel. In order to prevent the inflow of fine sand, the screen must be small in X IJ knots, and since screens with small slits are prone to clogging due to corrosion, in order to minimize such corrosion, This is because stainless steel is preferable as the material for the screen b.

Conventionally, the iron casing a and the stainless steel screen b are connected by directly welding them together, or by using an iron or stainless steel metal joint C with threads on the inside as shown in Figure 1. This is done by either screwing or threading.

However, in the combination structure of the casing a and the screen b connected in this way, a problem arises in that corrosion of the iron casing progresses at an abnormally fast rate.

This occurs in environments with a lot of water and humidity, such as water wells.
Because there is a natural electrode potential difference between the iron casing a and the stainless steel screen that are in direct contact, there is a greater tendency for ionization. It became a tragedy,
This is because corrosion due to electrolytic corrosion is accelerated.

Therefore, in order to connect the casing made of dissimilar metals and the screen in an environment with a lot of water and moisture, it is conceivable to insulate the two by inserting an insulating material between them instead of bringing them into direct contact. However, since the casing and screen joints used in deep wells are used directly above the screen,
Usually from several tens of meters underground to a depth of more than 1000771g
It must be able to withstand the conditions of use. In other words, since earth pressure is applied to the joint according to its depth, it goes without saying that it has a structure that can withstand strong earth pressure at depth, but in addition, it has a structure that can withstand the heavy earth pressure of the screen and casing, and the weight of the screen and casing when pulled out. It is required to have tensile strength to withstand the load of .

The present invention provides a corrosion protection system for connecting and using two or more tubular objects made of dissimilar metals, such as an iron casing and a stainless steel screen, in a usage environment where strong external pressure, tensile load, and compressive load are generated as described above. The purpose is to provide a preventive fitting.

According to the present invention, the first short tube is connected to one metal tubular object, is made of the same metal as the tubular object, and has a bulge formed in a part; A second short tube connected to the other metal tubular object made of a different metal than the object, made of the same metal as the other tubular object, and having a bulge formed in a part. The -1 short pipes are arranged facing each other with a space between them. By arranging an insulating tube to surround the first short tube and the second short tube, it is possible to completely insulate dissimilar metals and to protect against strong external pressure, tensile load, and compressive load in deep places such as deep wells. A joint for a tubular object having sufficient strength is provided.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the accompanying drawings.

FIG. 2 is a perspective view showing the external appearance of one embodiment of the joint according to the present invention, and FIG. 3 is a sectional view taken along line A--A in FIG. 2.

In this embodiment and the embodiments shown in FIGS. 6 and 7 described later, a typical example will be described in which the joint according to the present invention is used to connect an iron casing for a deep water well and a stainless steel screen. .

The joint 1 includes a first short pipe 2, a second short pipe 3, and an insulating pipe 40.
It consists of three parts. The first short pipe 2 is connected to an iron casing located above the joint at the top of the well, and is made of iron, which is the same material as the casing. Uniform part 2a connected to the casing of the short pipe 2
is formed in a cylindrical shape, but the part following this is formed so that the entire tube is gradually expanded outward as it moves away from the cylindrical part 2a, forming a truncated conical bulge part 2b. has been done. The second short pipe 3 is connected to a stainless steel screen located below the joint in the well, and is made of stainless steel, which is the same material as the screen. The portion 3a of the short tube 3 on the side connected to the screen is formed in a cylindrical shape, and this Kh:
In the < section, the entire tube is gradually expanded outward, and the third threats 3b are arranged facing each other at intervals.

The insulating tube 4 has a cylindrical appearance with a swollen central portion compared to both ends, and one half of the inside thereof is the bulged portion 2 of the first short tube 2.
The outer shape of b and the other part are shaped to match the outer shape of the bulging portion 3b of the second short tube 3, respectively. ! However, the insulating tube 4 has a radial direction from approximately the center thereof.
A spacer portion 4a is formed that protrudes and fits into the gap between the first short tube 2 and the second short tube 3, thereby holding both the short tubes 2 and 3 apart from each other. The insulating tube 4 may be made of a wide range of materials, such as plastic, ceramic, glass, or composite materials thereof, as long as it has electrical insulation properties and has sufficient strength under the conditions in which the joint is used. % [FRP is a preferred material. When the insulating tube is made of FRP, for example, the insulating tube 4 is formed by holding the short tubes 2 and 3 facing each other as shown in the figure and wrapping VcFRP around them. In addition, when the insulating tube 4 is made of ceramic, for example, each cylindrical short tube member is inserted into the insulating tube that has been previously formed into the shape of a finished product, and a portion of each short tube member is plastically molded using a die or the like. It is deformed to form the bulges 2b and 3b.

When connecting the joint 1 constructed as described above to a casing or screen, the cylindrical portion 2 of the short pipe 2 is connected to the casing (or screen) 5 as shown in FIG.
Alternatively, a male thread 2c may be provided at the end of the cylindrical portion 3a) of the short pipe 3, and screwed into a corresponding female thread 5c provided at the end of the casing (or spout 11-5), or as shown in FIG. Casing (or screen) as shown
An appropriate method can be used, such as bathing the end of the cylindrical portion 2a of the short tube 2 (or the cylindrical portion 3a of the short tube 3) with the end of the short tube 5.

FIG. 6 is a perspective view showing the outside M of another embodiment of the joint according to the present invention, and FIG. 7 is a sectional view taken along line BB in FIG. 6. In FIGS. 6 and 7, the same components as in FIGS. 2 and 31\81 are designated by the same symbols.

In this embodiment, the first short tube 2 connected to the casing and made of the same material has a cylindrical portion 2a connected to the casing;
The portions are formed with bulging portions 2b, 2b in such a way that after the entire tube is expanded outward, it is recessed at a trough portion 2cf having an inner diameter approximately the same as the inner diameter of the cylindrical portion 2a. A second short pipe 3 connected to the screen and made of the same material is also formed with bulges 3b, 3b'M and troughs 3c, 3e in the same way as the return pipe 2. The short tube v2 and the short tube 3 are arranged opposite to each other with an interval between them.

In the illustrated embodiment, the short tubes 2 and 3 each have two bulges, but each short tube may have at least one bulge, and three or more bulges may be provided. The insulating tube 4 is the valley bulge portion 2b of the short tubes 2 and 3.

It has an inner shape that matches the outer shape of 3b.

In this embodiment, unlike the embodiments shown in FIGS. 2 and 3, the bulging portions 2b and 3b are formed in a shape that protrudes outward from the tube and is recessed to its original position. .3 can be held apart from each other even without the spacer 4a in Figures 2 and 3, but if the spacer is provided to fit into the gap between the short tubes 2 and 3, the structure will be even stronger. desirable.

The method of manufacturing the joint of this embodiment and the method of contacting it with the casing or screen are the same as those of the embodiment shown in FIGS. 2 and 3, so detailed explanations will be omitted.

If a joint with even greater strength is required depending on the usage conditions, as shown in FIG. can be provided. In this case, the reinforcing tube 5, the iron casing, and the stainless steel 9A screen I) must be completely electrically insulated at ℃.

In the above explanation, iron and stainless steel have been cited as typical examples of dissimilar metals, but the present invention is not limited to this, and is applicable to any type of dissimilar metal tubular material that is susceptible to electrolytic corrosion due to the existence of a natural electrode potential difference. It is a good idea to apply VC. Furthermore, the joint of the present invention can be used not only for joints between casing pipes and Werne Clean, but also for connecting casings or screens or other tubular members. I cited water wells as a good example;
It can also be used for other wells and for purposes other than wells.

As described above, the joint of the present invention is connected to two different metal tubular objects, the short tubes 2 and 3 are arranged apart from each other, and the bulges 2b and 3b are formed in these short tubes 2 and 3. Since the short tubes 2 and 3 are connected by the insulating tube 4 whose internal shape matches the external shape of these bulges, the short tubes 2 and 3 are held in place by the insulating tube 4. , the two different citrus metal X tubes are connected in a completely electrically insulated state, and corrosion due to electrolytic corrosion can be prevented from occurring in one of the tubes. The material of the insulating tube generally has a lower tensile strength than metal, but according to the structure of the present invention, the inner surface of the insulating tube 4 is in close contact with the outer surface of the bulges of the short tubes 2 and 3, and the tensile strength is lower than that of metal. The load is not unevenly distributed in one place, but is applied uniformly to the entire inner surface of the insulating tube, so it can exhibit great strength.

In addition, for compressive loads, in the embodiments shown in FIGS. 2 and 3, the spacer 4a is used, and in the embodiments shown in FIGS. Since the troughs provide resistance, it can exhibit sufficient strength against buckling. Therefore, according to the present invention, by appropriately adjusting the wall thickness, length, size and number of bulges of each short tube and insulating tube and the material of the insulating tube according to the usage conditions, the external pressure can be maintained under all conditions. It is possible to design a joint that has sufficient strength against tensile and compressive loads. Furthermore, since no fastening members such as bolts, nuts, or rivets are required, there is no reduction in the strength of the member due to perforation, and there are advantages in that it is easy to manufacture.

[Brief explanation of the drawing]

In the attached drawings, Figure 1 shows how to connect the casing pipe and well screen at a water well temperature of 16°C.
FIG. 2 is a perspective view showing an embodiment of the joint according to the present invention;
FIG. 3 is a sectional view taken along the line A-A in FIG. 2, FIGS. 4 and 5 are diagrams showing a method of connecting the joint to a casing or a screen, and FIG. 6 is a diagram showing another embodiment of the joint according to the present invention. FIG. 7 is a sectional view taken along the line B--B in FIG. 6, and FIG. 8 is a diagram showing still another embodiment of the joint according to the present invention. DESCRIPTION OF SYMBOLS 1... Joint, 2, 3... Short pipe, 2b, 3b... Swelling part, 4... Insulating tube, 4a... Spacer.

Claims (1)

[Scope of Claims] 1. A first short tube connected to one metal tubular object, made of the same metal as the V-tubular object, and having a bulge formed in a part thereof; and the one metal tube. The tubular product is connected to the other tubular product made of a different metal, and the second short pipe is made of the same metal as the other tubular product and has a bulge formed in a portion thereof. Insulating tubes made of an electrically insulating material and having an inner shape that matches the outer shape of each of the bulging portions of the first short tube and the second short tube are arranged facing each other with a space between them. A joint for a tubular object made of different metals, the joint being arranged so as to surround the first short pipe and the second short pipe. 2. A first short tube that is connected to one metal tubular object, is made of the same metal as the tubular object, and has a bulge formed in a part, and is different from the one metal tubular object. A second short tube connected to another metal tubular object made of metal, made of the same metal as the other tubular object, and having a bulge formed in a part thereof, with a distance between them. An insulating tube made of an electrically insulating material and having an inner shape matching the outer shape of each bulge of the first short tube and the second short tube is placed between the first short tube and the second short tube. A spacer portion is arranged to surround the tube 2 and the second short tube, and further projects inward from the insulating tube and fits into the gap between the first short tube and the second short tube. A joint for dissimilar metal tubular objects.