KR102800168B1 - Improved water tight connecting structure with protecting ring for coated steel pipe end for water supply - Google Patents

Abstract

The connection structure of a water-use coated steel pipe equipped with a double watertight pipe end protection ring according to the present invention comprises: a first coated steel pipe having an expansion portion with an inner diameter expanded on one side; a second coated steel pipe having an insertion portion fitted into the expansion portion of the first coated steel pipe; a sealing member interposed between the insertion portion fitted into the expansion portion and the expansion portion, and provided in the shape of a ring as a whole to primarily form a watertight structure between the first coated steel pipe and the second coated steel pipe; a fastening assembly provided to press the sealing member between the expansion portion and the insertion portion and prevent the expansion portion and the insertion portion from being separated; and, a pipe end protection cap provided in the pipe end area of the insertion portion, wherein a portion that surrounds the pipe end of the insertion portion is provided to have a cross-sectional shape of the letter 'ㄷ' and is provided in the shape of a ring as a whole to secondary form a watertight structure between the first coated steel pipe and the second coated steel pipe;
The above sealing member and the above pipe end protection cap are characterized in that they are made of a material including an EPDM rubber material.
Accordingly, by providing double watertight members at the portions where water-tight clad steel pipes are connected to each other, the hydraulic performance for maintaining watertightness is improved, cross-sectional corrosion is prevented, and a connection structure for water-tight clad steel pipes equipped with a double watertight pipe end protection ring can be provided that prevents the cladding layer inside one steel pipe from being damaged by the end of one steel pipe inserted when the other steel pipe is inserted into the other steel pipe.

Description

{Improved water tight connecting structure with protecting ring for coated steel pipe end for water supply}

The present invention relates to a connection structure for a water-supply coated steel pipe having a double watertight end protection ring, and more specifically, to a connection structure for a water-supply coated steel pipe having a double watertight end protection ring, in which a double watertight member is provided at a portion where water-supply coated steel pipes are connected to each other, thereby improving the hydraulic performance for maintaining watertightness, preventing cross-sectional corrosion, and preventing the coating layer inside one steel pipe from being damaged by the end of one steel pipe inserted into the other when the other steel pipe is inserted.

Steel pipes are widely used for the purpose of transporting fluids such as water, sewage, gas, and crude oil, or for accommodating cables such as electric wires and communication lines, as they have superior mechanical properties and are lightweight compared to cast-iron pipes or synthetic resin pipes.

In general, steel pipes are used as coated steel pipes, which have a coating material applied to the inner and outer surfaces with excellent corrosion resistance and adhesiveness. Therefore, a coated steel pipe includes a steel pipe and a coating layer, and may include an inner coating and an outer coating applied to the inner and outer surfaces of the steel pipe, respectively, as a coating layer for protecting the steel pipe from the outside.

These coated steel pipes may further include an end coating that is applied in a separate process from the inner and outer surface coating process on the end faces of the pipe section. However, since the importance of the end coating is lower than that of the inner and outer surface coating, the quality of the end coating is relatively poor, and the area of the end face of the pipe section is narrow, the end coating may easily be lifted or torn and peeled off, thereby making it impossible to protect the pipe section from the outside, and thus physical damage or chemical damage (e.g., corrosion) may easily occur on the end face of the pipe section.

Meanwhile, the coated steel pipes can be connected to each other by insertion. Therefore, if the end surface of the pipe section is not coated or the end surface coating is peeled off to expose the end surface of the pipe section, when the coated steel pipes are inserted and connected, the sharp edge of the end surface of the pipe section may cause the inner surface coating or outer surface coating of another coated steel pipe to be damaged.

In addition, when connecting the clad steel pipes by inserting them, there is a problem that the watertight structure is weak and therefore, when used for water supply, the watertight state cannot be firmly maintained, which may result in a decrease in the water pressure performance.

Republic of Korea Patent Publication No. 10-1037586 (May 27, 2011) Republic of Korea Patent Publication No. 10-1924450 (December 3, 2018) Republic of Korea Patent Publication No. 10-2095325 (2020.03.31.)

The purpose of the present invention is to provide a connection structure for water pipes having a double watertight pipe end protection ring, which can improve the hydraulic pressure performance for maintaining watertightness, prevent cross-sectional corrosion, and prevent the coating layer inside one of the steel pipes from being damaged by the end of one of the steel pipes inserted into the other when the other steel pipe is inserted, by providing a double watertight member at the part where the water pipes are connected to each other.

In order to achieve the above object, the connection structure of a water supply coated steel pipe equipped with a double watertight pipe end protection ring according to the present invention comprises: a first coated steel pipe having an expansion portion whose inner diameter is expanded on one side; a second coated steel pipe having an insertion portion fitted into the expansion portion of the first coated steel pipe; a sealing member interposed between the insertion portion fitted into the expansion portion and the expansion portion, the sealing member having a ring shape overall to primarily form a watertight structure between the first coated steel pipe and the second coated steel pipe; a fastening assembly provided to press the sealing member between the expansion portion and the insertion portion and prevent the expansion portion and the insertion portion from being separated; And, a pipe end protection cap provided in the pipe end area of the insertion part, wherein the part that wraps the pipe end of the insertion part is provided to have a cross-sectional shape of the letter ‘ㄷ’ and is provided to have a ring shape overall, so that a second watertight structure is formed between the first cladding steel pipe and the second cladding steel pipe;

The above sealing member and the above pipe end protection cap are characterized in that they are made of a material including an EPDM rubber material.

And, the expansion member includes an expansion body formed by expanding one end of the first cladding steel pipe, and an expansion end formed to have an inclined shape by splaying outward from a tip of the expansion body, and it is preferable that the outer periphery of the expansion end is provided with at least one spike formed inclined on an inner periphery having an incline corresponding to the expansion end, and a socket ring that is inserted into the outer periphery of the expansion end.

According to the present invention, by providing double watertight members at the portions where water-tight clad steel pipes are connected to each other, the hydraulic pressure performance for maintaining watertightness is improved, cross-sectional corrosion is prevented, and a connection structure for water-tight clad steel pipes equipped with a double watertight pipe end protection ring can be provided, which can prevent the cladding layer inside one steel pipe from being damaged by the end of one steel pipe inserted when the other steel pipe is inserted into the other steel pipe.

In addition, by safely protecting the end surface of a clad steel pipe from the outside, where the end surface is exposed without coating material or coated with coating material, the end surface coating of the end surface of the clad steel pipe can be maintained intact for a long period of time or the exposed end surface can be prevented from corrosion. In addition, even if the end surface of the clad steel pipe is corroded, the rate at which the corroded portion spreads can be delayed, and the fluid flowing along the pipe can be prevented from being contaminated by the corroded portion.

Figure 1 is a side cross-sectional view showing a watertight connection structure of a water-coated steel pipe according to the present invention.
Figure 2 is a perspective view showing the insertion portion of the second cladding pipe of Figure 1 and the end protection cap surrounding the end of the insertion portion.
Figure 3 is an exploded perspective view showing the state before the pipe end protection cap is attached to the second cladding pipe of Figure 2.
Figure 4 is a perspective view of a tube protection cap according to the present invention.
Figure 5 is a perspective view of the tube protection cap of Figure 4 viewed from the opposite side.
Figure 6 is a perspective view showing a portion of a socket ring according to the present invention cut away.
Figure 7 is an exploded perspective view of a socket ring according to the present invention.
Figure 8 is a test performance certificate of the material forming the sealing member and the pipe end protection cap according to the present invention.
Figure 9 is a diagram showing the results of an insulation resistance test of a coated steel pipe with a double watertight tube end protection ring attached according to the present invention.
Figure 10 is a diagram showing the results of a leakage resistance test of a coated steel pipe with a double watertight pipe end protection ring according to the present invention.
Figure 11 is a diagram showing the results of a test on the resistance to salt water corrosion of a clad steel pipe with a double watertight pipe end protection ring according to the present invention.
Figure 12 is a diagram showing the results of a hydraulic pressure test of a coated steel pipe with a double watertight pipe end protection ring according to the present invention.
Figure 13 is a diagram showing the results of a coating breakage test of a coated steel pipe to which a double watertight pipe end protection ring according to the present invention is attached.

Hereinafter, the present invention will be described in detail with reference to the attached drawings.

The connection structure of the water-tight coated steel pipe equipped with a double watertight pipe end protection ring according to the present invention comprises, as shown in FIGS. 1 to 3, a first coated steel pipe (100) having an expansion portion (110) with an inner diameter expanded on one side, a second coated steel pipe (200) having an insertion portion (210) fitted into the expansion portion (110) of the first coated steel pipe (100), a sealing member (300) interposed between the insertion portion (210) fitted into the expansion portion (110) and the expansion portion (110) and formed to have a ring shape overall so as to primarily form a watertight structure between the first coated steel pipe (100) and the second coated steel pipe (200), and a sealing member (300) that presses between the expansion portion (110) and the insertion portion (210) and seals the expansion portion (110) and the second coated steel pipe (200). It includes a fastening assembly (400) provided to prevent the insertion part (210) from being separated, and a pipe end protection cap (500) provided in the pipe end area of the insertion part (210) so that a portion that wraps around the pipe end of the insertion part (210) has a ‘ㄷ’ cross-sectional shape and is provided to have a ring shape overall so that a second watertight structure is formed between the first cladding steel pipe (100) and the second cladding steel pipe (200).

Here, it is preferable that the sealing member (300) and the pipe end protection cap (500) are made of a material including EPDM rubber material.

Accordingly, by providing double watertight members at the parts where the water-tight clad steel pipes are connected to each other, the hydraulic performance for maintaining watertightness is improved, cross-sectional corrosion is prevented, and a connection structure of water-tight clad steel pipes equipped with a double watertight pipe end protection ring can be provided that prevents the cladding layer inside one steel pipe from being damaged by the end of one steel pipe inserted when the other steel pipe is inserted into the other steel pipe.

For example, in the past, when connecting clad steel pipes by inserting them, the watertight structure was weak and, when used for water supply, it could only withstand a water pressure of about 2.5 MPa. However, according to the watertight connection structure of the clad steel pipe for water supply according to the present invention, the water pressure performance can be improved to withstand a water pressure of about 3.5 MPa.

In addition, since the existing pipe end protection cap is simply made of high-density polyethylene material, the hardness is higher than the coating layer on the surface of the cladding steel pipe, so the coating layer can be easily damaged by the pipe end protection cap when connecting the insertion part to the expansion part, and if the pipe end protection cap is not tightly sealed to the cladding steel pipe when fastening due to the worker's carelessness, etc., water or foreign substances can penetrate through the gap, easily causing pipe corrosion, etc., and deformation can easily occur due to temperature changes in winter and summer, making maintenance difficult. However, the pipe end protection cap (500) according to the present invention is made of EPDM rubber material (a polymer made of ethylene propylene diene rubber) together with the sealing member (300), so that watertightness does not depend on only one sealing member such as the conventional rubber ring, but forms a double watertight structure together with the sealing member (300), thereby solving all of the above problems and further improving watertightness.

More specifically, the sealing member (300) and the tube end protection cap (500) are made of a material including an EPDM rubber material, and it may be more preferable to make the material having a composition ratio of 30 to 45 wt% of a polymer material made of ethylene propylene diene rubber, 25 to 45 wt% of carbon black, 8 to 15 wt% of calcium carbonate, 4 to 13 wt% of a foaming agent, and 0.1 to 3 wt% of an ultraviolet stabilizer or antioxidant.

In addition, the foaming agent is a component that provides elasticity and heat resistance, and its type is not limited as long as it is commonly used or known. Considering compatibility with other components, ease of commercial availability, foaming property, etc., it is preferable that it be composed of at least one selected from azodicarbonamide or sodium bicarbonate, and azodicarbonamide is more preferable.

In addition, UV stabilizers and antioxidants are components that prevent the elastic roll sheet from aging or oxidation due to UV rays, oxygen, etc. when it is constructed and exposed to sunlight, air, moisture, etc. for a long time. The type is not particularly limited as long as it is commonly used or known. UV stabilizers have the function of blocking or absorbing UV rays, and considering their performance as a UV stabilizer and compatibility with other ingredients, they are preferably HALS-based materials. Hindered Amine Light Stabilizers (HALS) refer to materials in which an amine group is surrounded by a three-dimensional structure and used as a light stabilizer. Commercial products of UV stabilizers include Tinuvin TM (BASF), etc. Also, specific examples of antioxidants include 2,2',2",6,6',6"-hexa-(1,1-dimethylethyl)-4,4',4"-[(2,4,6-trimethyl-1,3,5-benzenetriyl)-trismethylene]-triphenol, 1,3,5,tris[3,5-di(1,1-dimethylethyl)-4-hydroxybenzyl]-1H,3H,5H-1,3,5-triazine-2,4,6-trione, pentaerythrityl tetrakis[3-[3,5-di(1,1-dimethylethyl)-4-hydroxyphenyl]-propionate], octadecyl-3-[3,5-di(1,1-dimethylethyl)-4-hydroxyphenyl]-propionate, Tris[2,4-di(1,1-dimethylethyl)-phenyl]phosphite, 2,2'-di(octa-decyloxy)-5,5'-spirobi(1,3,2-dioxaphosphorinane), dioctadecyl disulfide, didodecyl-3,3'-thiodipropionate, dioctadecyl-3,3'-thiodipropionate, butylhydroxytoluene, ethylenebis[3,3-di[3-(1,1-dimethylethyl)-4-hydroxyphenyl]butyrate], octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate, tris(2,4-di-tert-butylphenyl)phosphite There is a back.

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Accordingly, by making the sealing member (300) and the pipe end protection cap (500) made of a material including an EPDM rubber material, a double watertight structure is formed at the connection part of the water-coated steel pipe by the sealing member (300) and the pipe end protection cap (500), so that the watertight state is firmly maintained and the hydraulic performance is improved.

Figure 8 is a test performance report of the material forming the sealing member (300) and the pipe end protection cap (500) according to the present invention. Looking at this, it can be seen that the EPDM rubber material forming the sealing member (300) and the pipe end protection cap (500) according to the present invention exhibits excellent characteristics in terms of tensile strength and elongation, etc.

Meanwhile, as another embodiment of the present invention, the sealing member (300) and the tube end protection cap (500) may be prepared from a material including an EPDM rubber material, but may be prepared from a material including an additional 5 to 15 parts by weight of nanomagnet powder per 100 parts by weight of the material.

Accordingly, even if radioactive materials such as cesium are mixed in water that comes into contact with the sealing member (300) and the tube end protection cap (500), they can be cleanly purified by the nanomagnet component.

Here, if the nanomagnet powder is included in an amount less than 5 parts by weight, the purification ability of radioactive materials may be reduced, and if it is included in an amount exceeding 15 parts by weight, the elasticity inherent in the EPDM rubber material may be reduced, affecting the watertightness and significantly increasing the cost.

In the case of the existing pipe end protection ring, it was impossible to fasten it by hand, so a tool was used to fasten it. In the case of the double watertight pipe end protection ring, it was easy to fasten it by forcing it in by stretching only the end.

Meanwhile, instead of the nanomagnet powder included in the EPDM rubber material forming the sealing member (300) and the tube end protection cap (500), a magnetite-graphene oxide compound powder having a size of 10 nanometers may be included.

Accordingly, even if water coming into contact with the sealing member (300) and the tube end protection cap (500) is contaminated with carcinogens such as arsenic or other heavy metals, the carcinogens or heavy metals can be cleanly removed by the magnetite-graphene oxide compound component, thereby purifying the water quality.

Meanwhile, the first clad steel pipe (100) and the second clad steel pipe (200) each include a steel pipe and a clad layer, and the clad layer includes an inner coating and an outer coating provided on the inner and outer surfaces of the steel pipe, respectively. For example, the inner coating and the outer coating may be made of a coating material including polyethylene (PE) and may have a certain elasticity. The first clad steel pipe (100) and the second clad steel pipe (200) may be straight pipes or may be irregular pipes such as bent pipes or T-shaped pipes.

As illustrated in FIG. 1, an expansion body (111) having an inner diameter larger than the outer diameter of an insertion portion (210) is formed so that an insertion portion (210), which is an end portion of a second cladding pipe (200), can be inserted into at least one end portion of a first cladding pipe (100), and an expansion end (113) extending from the end portion of the expansion body (111) is formed at the end portion of the expansion body (111).

That is, the expansion part (110) of the first cladding steel pipe (100) includes an expansion body (111) formed by expanding one end of the first cladding steel pipe (100), and an expansion end (113) formed to have an inclined shape by expanding outwardly from the tip of the expansion body (111).

In addition, a socket ring (600) is provided on the outer circumference of the expansion end (113) with at least one spike (611) formed at an angle corresponding to the angle of the expansion end (113) and fitted into the outer circumference of the expansion end (113).

Accordingly, as force is applied in the direction of separation of the first cladding steel pipe (100) and the second cladding steel pipe (200), the socket ring (600) presses in a direction of suppressing separation, so that separation and separation can be reliably prevented after the connection construction of the first cladding steel pipe (100) and the second cladding steel pipe (200) together with the fastening force of the fastening assembly (400).

The socket ring (600) is positioned so as to be fitted to the outer periphery of the expansion tube end (113), as shown in FIG. 1, and includes at least one spike (611).

The insertion portion (210) of the second cladding pipe (200) is inserted into the expansion body (111). The expansion end (113) is provided in a shape that gradually spreads outward as it goes toward the end, so that the inner and outer peripheral surfaces each have a sloped surface at a constant angle, and a ring-shaped sealing space is formed as an empty space between the insertion portion (210) inserted into the expansion body (111).

At this time, a sealing member (300) made of an airtight material such as EPDM rubber is inserted and installed in the sealing space.

The fastening assembly (400) fastens a first cladding pipe (100) with a socket ring (600) positioned on the outer periphery of an expansion end (113) and a second cladding pipe (200) with an insertion portion (210) inserted into the expansion portion (110) to each other, thereby preventing the first cladding pipe (100) and the second cladding pipe (200) that are connected to each other from being separated.

More specifically, the fastening assembly (400) includes, as illustrated in FIG. 1, a pressure ring (410) fitted to the outer circumference of the second cladding pipe (200), a pipe fastening mechanism (420) that fastens the socket ring (600) and the pressure ring (410), and a position fixing mechanism (430) that fixes the position of the pressure ring (410) with respect to the second cladding pipe (200).

Here, the pipe fastening mechanism (420) is configured to bring the socket ring (600) and the pressure wheel (410) close together by tightening the bolt. The pressure wheel (410) has a pressing surface that presses the sealing member (300) against the sealing space when the bolt is tightened by the pipe fastening mechanism (420). According to the pressing action by the pressing surface of the pressure wheel (410), the sealing member (300) is received in a press-fit state in the sealing space.

The pipe fastening mechanism (420) is composed of a plurality of pairs of fastening bolts and fastening nuts that are screw-connected to each other. The fastening bolts have their bolt heads hooked on the engaging projections (621) formed on the outer ring (620) of the socket ring (600), respectively. The pressure ring (410) has through holes through which the bolt bodies of the fastening bolts pass, respectively. The through holes may be arranged at intervals so as to be spaced apart from each other along the circumferential direction based on the center of the pressure ring (410). The fastening nuts are connected to the bolt bodies of the fastening bolts that have passed through the through holes of the pressure ring (410), respectively, while being hooked on the engaging projections (621). The fastening bolts may be hook bolts.

The position fixing mechanism (430) is composed of a plurality of spike bolts. The spike bolts are screw-connected while being arranged radially on the pressure wheel (410) and are spaced apart from or approached by the outer surface of the second cladding pipe (200) depending on the direction of rotation. Of course, when the spike bolts approach the outer surface of the pressure wheel (410), the position of the pressure wheel (410) is fixed. The spike bolts may be arranged between each of the through holes of the pressure wheel (410).

The tube protection cap (500), as illustrated in FIGS. 4 and 5, has a through opening formed in the center, and a ring-shaped receiving groove formed around the through opening to receive the tube section area of the insertion portion (210) and protect the exposed end surface of the tube section area. That is, it is configured to have a through opening in the center and a receiving groove around it. At this time, the receiving groove is configured to be expandable and deformable within an elastic range depending on the thickness of the tube section area when the tube section area is received. Accordingly, the receiving groove can prevent water as a fluid flowing along the pipe from flowing between the receiving groove and the tube section area by receiving the tube section area in a close state.

More specifically, such a tube protection cap (500) includes, as illustrated in FIGS. 4 and 5, a central inner ring (510) providing a through opening, an outer ring (520) arranged around the inner ring (510), and a connecting ring (530) shielding a rear portion between the inner ring (510) and the outer ring (520). At this time, the connecting ring (530) connects the inner ring (510) and the outer ring (520), and a receiving groove is formed between the inner ring (510) and the outer ring (520). The inner ring (510), the outer ring (520), and the connecting ring (530) are all made of an elastic material such as EPDM rubber. It is preferable that the inner ring (510), the outer ring (520), and the connecting ring (530) are formed integrally.

The inner ring (510) and the outer ring (520) are formed in a shape inclined at a constant angle toward the receiving groove, so that when the end region is received in the receiving groove, the receiving groove can expand within an elastic range due to the thickness of the end region, thereby receiving the end region in a close state.

Here, the inner ring (510) has an outer surface that adheres to the inner surface of the tube end region. The outer ring (520) has an inner surface that adheres to the outer surface of the tube end region. The outer ring (520) positioned between the expansion portion (110) and the insertion portion (210) can prevent the inner surface coating of the expansion portion (110) and the outer surface coating of the insertion portion (210) from being damaged during the process of connecting the first cladding steel pipe (100) and the second cladding steel pipe (200).

As one embodiment of the present invention, it is preferable that the outer ring (520) be formed to be about 0.5 to 1.5 mm thicker than the gap between the expansion portion (110) and the insertion portion (210).

Accordingly, by providing an outer ring (520) in a forced fit form by elasticity as a part that is secondarily watertight by the tube end protection cap (500), the second watertightness by the tube end protection cap (500) can be made more solid.

At this time, if the outer ring (520) is formed thicker than 0.5 mm, the secondary watertight structure may become somewhat loose, and if it is formed thicker than 1.5 mm, the construction process of inserting and connecting the second cladding pipe (200) into the first cladding pipe (100) may become somewhat difficult.

Meanwhile, the tube end protection cap (500) is coupled to the tube end area and when the tube end area is received in the receiving groove, the receiving groove expands by the thickness of the tube end area due to elastic deformation and is closely attached to the tube end area. Of course, when the tube end protection cap (500) is separated from the tube end area, the receiving groove is restored to its original state.

The spike (611), as illustrated in FIG. 1, is formed on the inner surface of the socket ring (600), and when force is applied in the direction of separation of the first cladding steel pipe (100) and the second cladding steel pipe (200), it is embedded in the outer surface coating forming the outer surface of the expansion end (113) and prevents separation of the first cladding steel pipe (100) and the second cladding steel pipe (200) together with the fastening assembly (400).

The spike (611) of such a socket ring (600) may be formed with a sharp shape including a tip so that it can be easily inserted into the outer surface of the expansion tube end (113), and may be formed so that the protruding length and width are constant. In addition, the spike (611) may be formed to have a closed ring shape.

Meanwhile, a concave portion having a shape corresponding to the shape of the spike (611) may be formed on the outer surface of the expansion end (113) as the spike (611) is embedded therein. That is, the concave portion may be formed in the shape of a closed ring along the outer surface direction of the expansion end (113).

As one embodiment of the present invention, as shown in FIGS. 6 and 7, a socket ring (600) includes an inner ring (610) and an outer ring (620). The inner ring (610) has a spike (611) formed on the inner periphery, and a joining protrusion (613) formed in a shape of a groove along the outer periphery direction on the outer periphery at the rear end.

Additionally, the inner ring (610) is formed so that the inner surface has an inclined surface corresponding to the inclined surface on the outer surface of the expansion tube end (113).

This inner ring (610) has a configuration in which it is divided into a plurality of units arranged along the circumferential direction, as illustrated in FIG. 7.

The outer ring (620) is positioned on the mating jaw (613) of the inner ring (610), as shown in FIGS. 6 and 7, and is formed to have a larger inner circumference than the maximum outer circumference of the expansion end (113).

A socket ring (600) like this can be simply and quickly placed on the outer circumference of the expansion end (113) by first fitting the outer ring (620) on the expansion end (113) side, then placing a plurality of units forming the inner ring (610) on the outer circumference of the expansion end (113), and then placing the outer ring (620) on the engaging jaw (613) of the inner ring (610).

Test Example 1: Fastening Test

A fastening test was conducted with respect to the above product. In the case of the existing pipe end protection ring, it was impossible to fasten it by hand, so a tool was used to fasten it. In the case of the double watertight pipe end protection ring of the present invention, it was easy to fasten it by a forced fastening method by stretching only the end.

In addition, a double watertight pipe end protection ring was attached to the water pipe and the tolerances on the inner and outer surfaces of the water pipe and the pipe end protection ring were checked, and it was confirmed that both the inner and outer surfaces were in close contact.

Test Example 2: Insulation Test

For third-party products, existing products, and the products of the present invention, after connecting four 3m 300A water pipes, the covering was removed to a size of 5cm X 5cm at a point 1.5m from the water pipes. After filling the water pipes with water more than halfway, insulation was checked for each product when 1kV electricity was applied using a pinhole tester. The results are shown in Fig. 9.

Pinholes occurred in third-party products and existing products, but no pinholes occurred in the product of the present invention. Accordingly, it was confirmed that the improved product made of rubber had an insulating effect.

Test Example 3: Leakage resistance test according to bending angle

In the initial test plan, the center of the specimen was lifted by a crane to measure the bending angle due to its own weight, but it was judged that measurement due to load would yield more accurate results, so a universal material testing machine was used to check the bending angle at the point where leakage occurred when a load was applied. The results are shown in Fig. 10.

The existing product had leakage at 6˚, while the product of the present invention had leakage at 8˚, confirming a 33% performance improvement effect compared to the existing product.

Test Example 4: Pipeline salt water corrosion resistance test

According to KS D 9502, 5% brine (275 L of tap water, 13.8 kg of sea salt) was prepared. This brine was sprayed on a third-party product, an existing product, and an improved product, and the results were confirmed after 14 days. The results are shown in Fig. 11. The third-party product and the existing product were corroded at the cross-section, but the product of the present invention did not corrode because the inner surface, cross-section, and outer surface were all covered.

Test Example 5: Hydraulic Test

After cutting the expansion and straight pipe sections of a 300A water pipe to 0.7 m, specimens of existing and improved products were produced and a hydraulic pressure test was performed. The results are shown in Fig. 12.

Existing products leak when pressure exceeding 2.5 MPa is applied, while the product of the present invention does not leak even at water pressure exceeding 3.0 MPa. Accordingly, a 20% performance improvement effect compared to existing products was confirmed.

Test Example 6: Internal Covering Breakage Test by Impact

When a straight pipe section with a pipe end protection ring attached was inserted into an expanded pipe section for a third-party product, an existing product, and the product of the present invention, and a vertical load of 100 kN was applied using a universal testing machine (UTM), it was checked whether the inner covering of the water pipe was damaged. The results are shown in Fig. 13. In the case of the third-party product and the existing product, a circular band was formed on the inner covering because the pipe end protection ring could not absorb the impact, whereas in the product of the present invention, there was no damage other than foreign substances being attached to the rubber.

The results of the above tests are shown in Table 1 and Figures 9 to 13.

FIG. 9 is a diagram showing the results of an insulation resistance test of a coated steel pipe having a double watertight pipe end protection ring attached according to the present invention, FIG. 10 is a diagram showing the results of a water leakage resistance test of a coated steel pipe having a double watertight pipe end protection ring attached according to the present invention, FIG. 11 is a diagram showing the results of a salt water corrosion resistance test of a coated steel pipe having a double watertight pipe end protection ring attached according to the present invention, FIG. 12 is a diagram showing the results of a hydraulic pressure test of a coated steel pipe having a double watertight pipe end protection ring attached according to the present invention, and FIG. 13 is a diagram showing the results of a coating breakage test of a coated steel pipe having a double watertight pipe end protection ring attached according to the present invention.

Measurement items Achievement criteria Test method Insulation resistance test Third party products: Not insulated
Existing product: Non-insulated
The invention product: Insulating Certified institution test report According to the bending angle
Leakage resistance test Existing product: 6˚
Product of the present invention: 8˚
※ Plan: 20% performance improvement → 13% additional improvement Homologous Corrosion of the crown salt water
Resistance test Third party products: Greening
Existing product: Green and red occurrence
Product of the present invention: No red or green occurrence Homologous hydraulic test Existing product: 2.5MPa
Product of the present invention: 3.0MPa
※ Plan: 20% performance improvement → Goal achieved Homologous Internal by shock
Covering failure test Third party products: Cover damage
Existing product: Cover damage
Product of the invention: No damage Homologous

From the above test results, it was found that the coated steel pipe with the double watertight pipe end protection ring according to the present invention showed significantly improved results in insulation resistance, water leakage resistance, salt water corrosion resistance, import test, and coating breakage test.

Although the technical aspects have been described above and in the attached drawings, the technical idea of the present invention is for the purpose of explanation and not limitation, and a person having ordinary technical knowledge in the technical field of the present invention will be able to understand that the technical idea of the present invention can be variously modified and changed within the scope that does not depart from the technical scope described in the claims to be described hereinafter.

100: 1st cladding pipe 110: Expansion pipe
111: Expanded body 113: Expanded end
200: 2nd cladding pipe 210: Insertion part
300: Sealing member 400: Fastening assembly
410: Press wheel 420: Pipe fastening mechanism
430 : Position fixing device 500 : Tube protection cap
510: Inner ring 520: Outer ring
530 : Connecting ring 600 : Socket ring
610 : Inner ring 611 : Spike
613 : Combination jaw 620 : Outer ring

Claims (3)

A first clad steel pipe (100) having an expanded portion (110) with an inner diameter expanded on one side;
A second cladding steel pipe (200) having an insertion portion (210) that is fitted into the expansion portion (110) of the first cladding steel pipe (100);
A sealing member (300) interposed between the insertion member (210) fitted into the above-mentioned expansion member (110) and the above-mentioned expansion member (110), and having a ring shape overall, to primarily form a watertight structure between the first cladding steel pipe (100) and the second cladding steel pipe (200);
A fastening assembly (400) provided to press the sealing member (300) between the expansion member (110) and the insertion member (210) and prevent the expansion member (110) and the insertion member (210) from being separated; and
A pipe end protection cap (500) provided in the pipe end area of the insertion portion (210) so that a portion surrounding the pipe end of the insertion portion (210) is provided to have a cross-sectional shape of the letter 'ㄷ' and is provided to have a ring shape overall, so that a second watertight structure is formed between the first cladding steel pipe (100) and the second cladding steel pipe (200);
The above sealing member (300) and the above pipe end protection cap (500) are made of a material including an EPDM rubber material, and are prepared with a material having a composition ratio of 30 to 45 wt% of a polymer material made of ethylene propylene diene rubber, 25 to 45 wt% of carbon black, 8 to 15 wt% of calcium carbonate, 4 to 13 wt% of a foaming agent, and 0.1 to 3 wt% of an ultraviolet stabilizer.
A connection structure of a water pipe-clad steel pipe equipped with a double watertight pipe end protection ring, characterized in that the sealing member (300) and the pipe end protection cap (500) further include 5 to 15 parts by weight of nanomagnet powder or 5 to 15 parts by weight of magnetite-graphene oxide compound powder having a size of 10 nanometers per 100 parts by weight of a material including an EPDM rubber material. delete delete