JPH054631Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention relates to a connection structure between steel pipes used mainly for supplying and draining industrial water, domestic water, etc., and piping equipment such as valves and pipe fittings. ,
In particular, the present invention relates to a connection structure that prevents rust from forming on the end surface of the pipe at the connection between the internally coated steel pipe and piping equipment, and solves the problem of red water and water leakage.

(Prior art) The end surface of the internally coated steel pipe that is connected to the piping equipment is rusted because it is not coated with anti-corrosion coating.
It is necessary to prevent this from occurring, as red water may occur or water may leak due to damage to the connections.

For this reason, many developments have been made, but most of these are related to pipe joints, and very few are related to valves. For this reason, when connecting an internally coated steel pipe to a corrosion-resistant valve made of bronze or stainless steel, a nipple made of blue, brass, or stainless steel must be connected to the valve, and the above-mentioned corrosion-resistant pipe fitting must be connected to this nipple. However, equipment costs and piping work costs are high, and the space required to connect the valve is also large. Structure was needed.

Furthermore, various types of the above-mentioned pipe end corrosion-proof pipe joints have been proposed, but each has one or more of the following problems as a drawback, and it is difficult to completely solve these problems. The reality is that a connection structure that solves this problem has not yet been proposed.

(Problems to be solved by the invention) The present invention has been devised in view of the above-mentioned circumstances, and aims to solve all of the following conventional problems.

The gasket easily comes off from the pipe end when connecting.
It is not possible to completely prevent corrosion.

The gasket bulges into the pipe due to the compressive force during connection and the fluid flowing inside the pipe, and eventually falls into the pipe, making it impossible to prevent corrosion.

The inner diameter of the core is small and the flow loss is large.

Sometimes people forget to insert the core, or sometimes they connect without noticing that the core once inserted has fallen off, making it impossible to completely prevent corrosion.

If the flatness or perpendicularity of the tube end surface is poor, or if there are scratches, curls, or burrs on the tube end surface, the tube end surface will not be completely protected and corrosion protection will be incomplete.

If the length of the male thread on the outer circumferential surface of the tube end is long and the screw length of the tube end is long, the gasket will be damaged and the screw connection will be incomplete, resulting in incomplete corrosion protection, sealing, and even the connection itself. become.

If the length of the male thread provided on the outer circumferential surface of the tube end is short and the threaded length of the tube end is short, the tube end surface will not reach the gasket, or the surface pressure with the gasket will be insufficient, making it impossible to prevent corrosion. or become incomplete.

The precision required for machining the tube end surface and male threaded portion of the tube end is high, and it is usually difficult to meet this requirement, resulting in incomplete sealing, corrosion protection, etc.

The core is tilted and deformed at the threaded end of the tube, resulting in incomplete sealing and corrosion protection.

It cannot be commonly applied to piping equipment such as pipe fittings and valves.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention employs the following configuration.

In other words, it is a connection structure between an internally coated steel pipe having a male thread on the outer circumferential surface of the pipe end and piping equipment such as a valve or a pipe fitting having a female thread on the inner circumferential surface of the pipe fitting. A step part formed by a cylindrical surface and an annular plane is formed at the inner part of the female thread part of the pipe joint part, and a circular hole part which is a flow path for piping equipment is formed following this step part, while the first cylindrical part and The first cylindrical part of the tube end anticorrosion core made of a thin corrosion-resistant metal with a flange formed in the middle of the second cylindrical part is inserted into the circular hole described above, and the flange has a flange on both sides of the flange. An annular elastic gasket is fitted across the cylinder, an annular groove is formed on at least one side of the outer circumferential surface and the inner circumferential surface of the portion compressed in the axial direction of the elastic gasket, and the above-mentioned cylindrical The connecting portion between the surface and the annular plane is formed to have an arcuate cross section, and the corners of the elastic gasket that contact this connecting portion are formed to have an arcuate cross section. When inserting the second cylindrical part and screwing the male threaded part of the pipe end into the female threaded part of the pipe fitting part, the elastic gasket described above is compressed between the annular plane and the pipe end surface of the inner-coated steel pipe. The annular plane and the tube end surface were brought into sealed contact.

(Function) In the connection structure between the internally coated steel pipe and piping equipment of the present invention, first, an annular elastic gasket is fitted to the flange of the tube end corrosion-protecting core so as to straddle the flange on both sides.
In this case, the elastic gasket may be fixed to the flange using an adhesive or the like. When this is attached to the stepped part of piping equipment such as a valve or pipe fitting, the elastic gasket is held by the stepped part and the first cylindrical part is inserted into the circular hole of the pipe fitting, so it can be used for pipe end corrosion protection. The core is fixed concentrically to a pipe joint part of piping equipment such as a valve or a pipe joint. Therefore, when an internally coated steel pipe is screwed into this, the pipe end anti-corrosion core will not be improperly contacted and deformed by the internally coated steel pipe, and the elastic gasket will reliably contact the pipe end surface. , sealing and corrosion protection are ensured. Of course, it is possible to completely protect the tube end surface from corrosion without forgetting to insert the tube end corrosion prevention core or connecting it without noticing that the tube end corrosion prevention core once inserted has fallen off.

Further, the elastic gasket does not bulge into the skein pipe or fall out into the pipe due to compressive force during connection or fluid flowing inside the pipe.

In addition, the pipe end corrosion protection core is usually formed from a stainless steel pipe or stainless steel plate, either integrally or by mechanically joining multiple parts, or joining them by welding or brazing. The inner diameter of the anticorrosive core can be made relatively large, and the flow loss is small.

Furthermore, the elastic gasket has a 1.1 mm diameter on the outer circumferential surface and the inner circumferential surface of the portion compressed between the flange and the tube end surface.
When an annular groove with a sawtooth cross section of 5 to 5 grooves is formed, the supporting distance over which the elastic gasket can be compressed and deformed at the end surface of the internally coated steel pipe increases, and it is necessary to provide the elastic gasket on the outer circumferential surface of the pipe end of the internally coated steel pipe to be connected. Even if the length of the external threaded part is long or short, and the threaded length of the pipe end is long or short, the elastic gasket deforms accordingly and comes into contact with the pipe end surface to prevent corrosion. I can do it. Additionally, the internally coated steel pipe can be completely screwed into the pipe joint.

In addition, elastic gaskets are made of rubber or the like with sufficient elasticity, and as mentioned above, the deformation distance is long, so the flatness and perpendicularity of the tube end surface may be poor, and the tube end surface may be scratched, curled, or burred. Even if there is a problem, the pipe end face is completely protected and corrosion protection of the pipe end face is complete. Therefore, the accuracy required for machining the tube end surface and male threaded portion of the tube end may be relatively loose.

Furthermore, if the connecting part between the cylindrical surface of the stepped part and the annular plane is formed to have an arcuate cross-section, and the corner of the elastic gasket that contacts this is also formed to have an arcuate cross-section to strengthen the contact at this part, Leakage between the stepped portion and the elastic gasket can be more reliably prevented.

Furthermore, by providing an annular protrusion in a part of the second cylindrical part, by providing an annular gasket groove and attaching or fixing the second gasket thereto, or by changing the outer diameter of a part or substantially all of the second cylindrical part. Since the second cylindrical part is formed in a size that is in sealing contact with the pipe hole, and a part or almost all of the second cylindrical part is brought into sealing contact with the pipe hole, either directly or indirectly, the fluid flowing inside the pipe is It is blocked by the edible core and does not come into contact with the tube end surface. Therefore, even if the contact between the tube end surface and the elastic gasket is poor, the tube end surface will not corrode. Furthermore, even if there is rust on the end surface of the tube, it will not dissolve into the fluid. Furthermore, as mentioned earlier, if the elastic gasket is fixed to the annular plane of the stepped portion, even if the tube end surface and the elastic gasket do not contact each other and there is a gap, the tube end surface will not come into contact with the fluid and corrosion will not occur. do not.

Further, the connection structure of the present invention can be applied not only to pipe joints but also to piping equipment such as valves.

(Example) Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial sectional view showing an embodiment of the connection structure between the inner-coated steel pipe and piping equipment of the present invention.

In the figure, 1 is an inner-coated steel pipe, 1a is a steel pipe portion thereof, 1b is an inner coating portion, 1c is an end portion of the tube, and 1d is a male threaded portion provided on the outer circumferential surface of the tube end portion 1c. 1e is a tube hole, and 1f is a tube end surface.

Further, 2 is a pipe joint part of piping equipment such as a valve or a pipe joint, 2a is a female thread part, 2b is a step part, 2
C is a circular hole portion, and a female thread portion 2a, a step portion 2b, and a circular hole portion 2c are sequentially formed on the inner peripheral surface of the pipe joint portion 2 from the outer end. In addition, 2d is a cylindrical surface, 2e is an annular plane, and the step part 2b is comprised of the cylindrical part 2d and the annular plane 2e.

3 is a tube end anti-corrosion core made of corrosion-resistant metal, and 3a
3b is a flange portion, 3b is a first cylindrical portion, and 3c is a second cylindrical portion, and the tube end anticorrosion core 3 is provided on the flange portion 3a and one side of the flange portion 3a and inserted into the circular hole portion 2c. A first cylindrical portion 3b and a tube end portion 1c provided on the other side of the collar portion 3a.
and a second cylindrical portion 3c inserted into the tube hole 1e.

Note that the tube end anticorrosion core 3 is usually made from a stainless steel pipe or a stainless steel plate, but even if it is formed into an integral shape, it may be formed by mechanically joining multiple parts, or by welding or brazing. It may be formed by

FIG. 2 is a partial sectional view showing an example of this,
Figure 2 a shows the one molded in one piece, Figure 2 b shows the 2
A product formed by mechanically joining two separate parts, a second
Figure c is formed by joining two parts by welding or brazing.

Reference numeral 4 denotes an elastic gasket made of rubber or the like, and this elastic gasket 4 is an annular gasket fitted across both sides of the flange portion 3a, and is formed between the annular plane 2e of the stepped portion 2b and the tube end portion 1c. It is compressed between the tube end surface 1f and is provided so as to be in sealing contact with the annular plane 2e and the tube end surface 1f.

3a and 3b are partial sectional views showing examples of the shape of the elastic gasket 4, in which 4a is a groove for fitting across both sides of the flange 3a,
4b is a first contact surface that comes into contact with the annular plane 2e, 4c
is a second contact surface that contacts the tube end surface 1f of the tube end portion 1c. Further, 4b is the flange portion 3 of the elastic gasket 4.
This is an annular groove with a sawtooth cross section provided on the outer and inner circumferential surfaces of the portion compressed between a and the tube end surface 1f.
Reference numeral 4e denotes a corner of the elastic gasket 4 that contacts the connection between the cylindrical surface 2d of the stepped portion 2b and the annular plane 2e, and is formed to have an arcuate cross section as shown in the figure.

Figure 3a shows an annular groove 4d with three grooves on the outer peripheral surface and one groove on the inner peripheral surface, and Figure 3b shows the annular groove 4d.
Four stripes of d are provided on each of the outer circumferential surface and the inner circumferential surface.

Further, a part or substantially all of the second cylindrical portion 3c of the tube end anticorrosion core 3 is brought into direct or indirect sealing contact with the tube hole 1e. FIG. 4 is a partial cross-sectional view showing this, and in FIG.
was brought into sealing contact with the inner circumferential surface of the inner surface coating portion 1b. In FIG. 4b, an annular gasket groove 3e is provided in a part of the second cylindrical portion 3c, and a second annular gasket 3f is attached or fixed to this gasket groove 3e, so that the second cylindrical portion 3c is connected to the second gasket. It was brought into sealed contact with the tube hole 1e via 3f. Also, Figure 4 c and Figure 4
In Figure d, almost the entire second cylindrical part 3c is shown in Figure d.
In this case, a part of the second cylindrical portion 3c was formed to a size so as to come into sealing contact with the tube hole 1e.

Next, the operation of the embodiment shown in FIGS. 1 to 4 will be explained.

An annular elastic gasket 4 is fitted to the flange 3a of the tube end anticorrosion core 3 so as to straddle the annular portion 3a. When this is attached to the stepped part 2b of piping equipment such as a valve or a pipe fitting, the elastic gasket 4 is held by the stepped part 2b, and the first cylindrical part 3b is attached to the circular hole part 2 of the pipe fitting part 2.
c, the pipe end corrosion protection core 3 is fixed concentrically to the pipe joint part 2 of piping equipment such as a valve or pipe joint. Therefore, the inner coated steel pipe 1 is added to this.
When the tube end corrosion protection core 3 is screwed in, the tube end corrosion prevention core 3 will not be inappropriately contacted with the internally coated steel tube 1 and deformed, and the second contact surface 4c of the elastic gasket 4 will surely come into contact with the tube end surface 1f. As a result, sealing and corrosion protection are ensured. Of course, the tube end surface 1f can be completely protected against corrosion without forgetting to insert the tube end corrosion prevention core 3 or without noticing that the tube end corrosion prevention core 3 once inserted has fallen off.

Note that if the first contact surface 4b of the elastic gasket 4 is fixed to the annular plane 2e of the stepped portion 2b using an adhesive or the like, the sealing performance and prevention of falling off will be further ensured.

In addition, since the elastic gasket 4 is compressed by the tube end surface 1f of the internally coated steel tube 1 while being surrounded by the stepped portion 2b and the tube end corrosion protection core 3, the elastic gasket 4 is compressed by the compressive force at the time of connection and by the fluid flowing inside the tube. The gasket 4 will not bulge into the pipe or fall out into the pipe.

In addition, the pipe end corrosion protection core 3 is usually formed from a stainless steel pipe or a stainless steel plate, either integrally or by mechanically joining a plurality of parts, or joining them by welding or brazing. The inner diameter of the end corrosion protection core 3 can be made relatively large, and the flow loss is small.

Furthermore, when the elastic gasket 4 is compressed, the annular plane 2e and the tube end surface 1f are brought into sealing contact, and the elastic gasket 4 is brought into sealing contact with the outer and inner circumferential surfaces of the portion compressed between the flange 3a and the tube end surface 1f. 1 to 5 each
When the annular groove 4d with a sawtooth cross section is formed, the elastic gasket 4 is compressed and deformed by the end face 1f of the inner-coated steel pipe 1, and the deformation distance becomes longer, and the length of the deformation distance at which the elastic gasket 4 can be deformed becomes longer. Regardless of whether the length of the male threaded portion 1d provided on the outer circumferential surface is long or short, and whether the length of the pipe end portion 1c to which the tube end portion 1c is screwed is long or short, the elastic gasket 4 deforms accordingly, and the second abutment The contact surface 4b can reliably contact the tube end surface 1f to prevent corrosion. Moreover, the inner surface coated steel pipe 1 can be completely screwed into the pipe joint part 2.

In addition, the elastic gasket 4 is made of rubber or the like having sufficient elasticity, and has a long deformation distance as described above, so that the flatness and perpendicularity of the tube end surface 1f may be poor, and the tube end surface 1f may have scratches or bulges. , burrs, etc., the tube end surface 1f is completely protected by the second contact surface 4c of the elastic gasket 4, and the tube end surface 1f is completely protected from corrosion. Therefore, the required accuracy for machining the tube end surface 1f and the male threaded portion 1d of the tube end 1c is as follows:
It should be relatively gentle.

Further, the connecting portion 2f between the cylindrical surface 2d of the stepped portion 2b and the annular plane 2e is formed to have an arcuate cross-section, and the corner portion 4e of the elastic gasket 4 which is in contact with this portion is also formed to have an arcuate cross-section. By making the contact stronger, leakage between the stepped portion 2b and the first contact surface 4b of the elastic gasket 4 can be more reliably prevented.

Furthermore, an annular protrusion 3d is provided in a part of the second cylindrical part 3c, an annular gasket groove 3e is provided and a second gasket is attached or fixed thereto, or a part or almost all of the second cylindrical part 3c is The outer diameter of the second cylindrical portion 3c is formed to a size that allows sealing contact with the tube hole 1e, and a part or almost all of the second cylindrical portion 3c is brought into sealing contact directly or indirectly with the tube hole 1e, so that the fluid flowing inside the tube has elasticity. It is blocked by the gasket 4 and the tube end corrosion prevention core 3, and does not come into contact with the tube end surface 1f. Therefore, even if the contact between the tube end surface 1f and the second contact surface 4c of the elastic gasket 4 is incomplete, the tube end surface 1f will not corrode. Furthermore, even if there is rust on the tube end face 1f, it will not dissolve into the fluid. Furthermore,
As mentioned earlier, the elastic gasket 4 is connected to the stepped portion 2b.
If it is fixed to the annular plane 2e of the tube end surface 1,
Even if the second abutting surface 4c of the elastic gasket 4 does not abut and there is a gap, the tube end surface 1f will not corrode.

Furthermore, the connection structure of the present invention can be applied not only to pipe joints but also to other piping equipment such as valves.

(Effects of the Invention) Since the connection structure between the internally coated steel pipe and piping equipment of the present invention is constructed as described above, extremely excellent effects can be obtained as described below.

Threaded joints and internal fluid do not come into contact with each other.
Ensure that the gasket properly contacts the pipe end surface when connecting.
It is possible to reliably protect the pipe end surface from corrosion.

The gasket will not bulge into the pipe due to compressive force during connection or the fluid flowing inside the pipe, and will not eventually fall into the pipe, resulting in loss of corrosion protection.

The inner diameter of the core can be made relatively large,
Low flow loss.

Corrosion protection will not be lost due to forgetting to insert a core or not realizing that the core once inserted has fallen off.

Even if the flatness or perpendicularity of the tube end surface is poor, or the tube end surface has scratches, curls, burrs, etc., the tube end surface can be reliably protected from corrosion.

Even if the length of the external thread provided on the outer circumferential surface of the tube end surface is long or short, the tube end surface can be reliably protected from corrosion.

The required precision for machining the male thread on the end surface of the tube is low, making the work easy.

Corrosion protection can always be ensured without damaging the core during connection.

Can be commonly applied to piping equipment such as pipe fittings and valves.

[Brief explanation of drawings]

Fig. 1 is a partial sectional view showing an embodiment of the connection structure between the internally coated steel pipe and piping equipment of the present invention, and Fig. 2a
3A to 3C are partial sectional views showing an embodiment of the pipe end corrosion-protecting core in the connection structure of the present invention, FIG. Figures a to d are partial cross-sectional views showing an embodiment of a portion where a tube end anticorrosion core makes sealing contact with a tube hole of an inner-coated steel tube in the connection structure of the present invention. 1... Internally coated steel pipe, 1c... Pipe end, 1d...
...Male thread part, 1e...Pipe hole, 1f...Pipe end surface, 2
...Pipe joint part, 2a...Female thread part, 2b...Stepped part, 2c...Cylindrical hole part, 2d...Cylindrical surface, 2e...
Annular plane, 3... core for tube end corrosion protection, 3a... flange, 3b... first cylindrical part, 3c... second cylindrical part,
3d... Annular projection, 3e... Gasket groove, 3
f...Second gasket, 4...Elastic gasket,
4d... annular groove, 4e... corner.

Claims (1)

[Scope of utility model registration request] A connection structure between an internally coated steel pipe with a male thread on the outer circumferential surface of the pipe end and piping equipment such as a valve or a pipe fitting with a female thread on the inner circumference of the pipe fitting, the pipe fitting described above. At the back of the female threaded part of the part, a stepped part formed by a cylindrical surface and an annular plane, and a circular hole part that is a flow path for piping equipment is formed following this stepped part, and on the other hand,
The first cylindrical part of the tube end corrosion-proofing core made of a thin corrosion-resistant metal with a flange formed midway between the first cylindrical part and the second cylindrical part is inserted into the circular hole described above, and the flange is , an annular elastic gasket is fitted across both sides of the flange, and an annular groove is formed on at least one side of the outer circumferential surface and the inner circumferential surface of the portion compressed in the axial direction of the elastic gasket. Furthermore, the connecting portion between the cylindrical surface and the annular plane described above is formed to have an arcuate cross section, and the corners of the elastic gasket that contact this connecting portion are formed to have an arcuate cross section, and the tube hole at the end of the tube described above is formed to have an arcuate cross section. When inserting the second cylindrical part of the core described above and screwing the male threaded part of the pipe end into the female threaded part of the pipe joint part, the above-mentioned A connection structure between an internally coated steel pipe and piping equipment, characterized by compressing an elastic gasket to bring an annular plane into sealing contact with the pipe end surface.