KR101150166B1 - Drinking water pipe and connector applied nitro-oxidation process and derail controlling clamping method - Google Patents

Abstract

PURPOSE: A water pipe using nitro-oxidation and separation-prevention methods is provided to prevent a steel pipe from becoming separated from the other steel pipe by processing the steel pipes and a connector through nitro-oxidation. CONSTITUTION: A water pipe using nitro-oxidation and separation-prevention methods comprises steel pipes(1) and a connector(2). The connector is composed of a joint pipe(21), pressure wheels(22), pakcings(23), and multiple coupling bolts(24). The joint pipes connect the steel pipes to each other. The pressure wheels are installed in both ends of the joint pipe and receive separation prevention protrusions(11) therein. The packings are adhered to the steel pipes and the joint pipe and prevent fluid leakage. The coupling bolts couple the pressure wheels to the joint pipe.

Description

Drinking Water Pipe and Connector Applied Nitro-Oxidation Process and Derail Controlling Clamping Method

The present invention relates to a water supply pipe to which the nitriding invasion method and the anti-leaving pressure technique are applied. More particularly, the present invention relates to a steel pipe for supplying water consumed for drinking water, living water, public use and industrial use, and a connector connecting the steel pipe and the steel pipe. In the configured water pipe, the use of the connector applying the release prevention compression technique to solve the problem of the pipe being broken and the pipe falling off when the water pipe is prevented from being tightened and misfitted, and the tensile strength and corrosion resistance of the steel pipe and the connector are heat treated by heat treatment. The present invention relates to a water pipe using a nitriding invasion method for increasing the cost and lowering the cost.

In general, water pipes have excellent impact resistance and chemical resistance, corrosion resistance and corrosion resistance, but have low impact resistance. Ductile Cast Iron Pipe KSD 4311, which has high internal and external pressure strength but may cause cracking when sudden pressure is applied Steel pipes coated with epoxy + adhesive + PE and coated with liquid epoxy on the outside are used.

Ductile Cast Iron is cast iron in which graphite is crystallized by adding Mg, Ca, Ce, etc. to molten metal, also called spheroidal cast iron or nodular cast iron. It is similar to steel, and has twice the ductility and several times the impact value compared to the cast iron. It is close to malleable cast iron, has improved cutting ability, and has excellent castability and strong mechanical properties. Widely used for

However, the ductile cast iron pipe (Ductile Cast Iron Pipe) has a problem of good corrosion resistance but expensive unit price, there is a problem that the connection between the pipe and the pipe is a lot of problems if the tube is detached or incorrectly tightened, the tube is destroyed and the tube is missing.

In general, a water supply pipe using a ductile cast iron pipe (Ductile Cast Iron Pipe) has a wide diameter portion having a wide inner diameter at the rear end thereof, and can be connected by fixing the front end portion of the water supply pipe to the expansion diameter portion of another water supply pipe.

In addition, a packing fitted between the front end portion and the enlarged diameter portion of the interconnected water pipes is installed at the connection portion of the connected water pipes, and the outside of the pressure-retaining pressure ring for firmly and firmly fixing the water pipes is coupled to the outside thereof.

According to KSD 3565, steel pipe coated with epoxy + adhesive + PE on the inside and liquid epoxy on the outside has a low corrosion resistance when coating is broken, and the use of welding for pipe-to-pipe connection leads to high labor costs and especially corrosion on the welded area. There is a weak problem.

In order to reinforce the corrosiveness of the steel pipe, a pipe lined with a synthetic resin of rubber, hard vinyl chloride or polyethylene is used on the inner surface, but there is a problem that it is expensive and causes a problem in the lining treatment of the connection site and labor costs.

The use of pressure rings as a method of connection to a water supply pipe includes a pressure preventing ring for the separation of the water supply pipe and a pressure preventing ring for the separation of the water supply pipe, but a ductile cast iron pipe is used. The wide diameter part with wide inner diameter is formed at the rear end, and the front end part of the water supply pipe can be inserted into the expansion diameter part of another water supply pipe to be fixed and connected for a long time. Therefore, it is difficult to apply when using the steel pipe without the diameter part (hub). have.

The present invention for solving the above problems is to apply the nitriding invasion method to improve the tensile strength, elongation, elastic modulus and corrosion resistance by densifying the structure of the metal in the steel pipe and connector and forming an oxide film, steel pipe and steel pipe A joint pipe connecting the joint pipe, the separation preventing jaw is accommodated therein, and the pressure ring is coupled to the steel pipe and the joint pipe, respectively, and is installed at both ends of the joint pipe, and is inserted into the outside of the steel pipe and inserted into both ends of the joint pipe. The pipe is connected to the steel pipe and the fitting pipe by the pressure ring to prevent leakage of internal fluid, and a water pipe for inserting the steel pipe into a connector composed of a plurality of coupling bolts coupling the pressure ring and the fitting pipe. Nitride invasion method and prevention of pull-out technique to prevent the falling of water pipes and improve corrosion resistance and tensile strength It is to provide the applied water pipe.

The water supply pipe to which the nitriding invasion method and the anti-leaving pressure technique of the present invention are applied comprises a steel pipe for supplying water consumed for drinking water, domestic water, public use and industrial use, and a connector connecting the steel pipe and the steel pipe.

The steel pipe and the connector are treated by nitriding invasion to improve the tensile strength, elongation, modulus of elasticity and corrosion resistance by densifying the metal structure and forming an oxide film.

A ring-shaped separation prevention jaw is formed on an outer circumference of a portion of the steel pipe to prevent the connector from being separated from the steel pipe and to limit the coupling position of the connector.

The connector is a joint pipe connecting the steel pipe and the steel pipe; A pressure ring accommodated in the separation prevention jaw and coupled to the steel pipe and the fitting pipe, respectively installed at both ends of the fitting pipe; A packing inserted into an outside of the steel pipe and inserted into both ends of the fitting pipe to be in close contact with the steel pipe and the fitting pipe by the pressure ring to prevent an internal fluid from leaking; Composed of a plurality of coupling bolts for coupling the pressure wheel and the joint pipe.

The pressure wheels are divided into upper and lower pressure wheels in a semicircle of the same shape so as to be inserted into the release prevention jaw, and each of the upper pressure wheels and the lower pressure wheels has two positions so as to bolt the upper pressure wheels and the lower pressure wheels to each other. The upper and lower pressure coupler is formed, a plurality of coupling bolt insertion holes for coupling the coupling pipe is inserted into the pressing wheel, a ring-shaped packing adhesion protrusion for pressing the packing, and the release prevention jaw is accommodated Departure prevention jaw accommodation groove is formed.

The coupling bolt is used to rotate the bolt and the bolt head and the bolt body that is penetrated through the coupling bolt insertion hole and the nut so that the pressure wheel and the coupling tube is not separated when the contact with the fitting pipe is tightened. It is composed.

The coupling bolt is composed of a bolt body penetrating the insertion bolt insertion and coupled to the nut, and the bolt head in contact with the joint pipe when the nut is tightened.

On both outer circumferences of the joint pipe, flanges are fastened to the bolt heads of the coupling bolts, and both ends of the joint pipes are provided with packing inserts for inserting the packings. An insertion restricting ring is formed that restricts further insertion.

The nitriding invasion method includes a washing step of washing and removing contaminants on the surfaces of the steel pipe and the connector, and a preheating step of putting the washed steel pipe and the connector into a furnace to preheat the treatment. Low temperature nitriding the preheated steel pipe and connector in a mixed gas atmosphere of ammonia, nitrogen, and carbon dioxide; A purging step of discharging the gas in the furnace after the nitriding treatment to the outside of the furnace; An oxide film forming step of forming an oxide film on the nitrided steel pipe and the connector by injecting steam into the furnace; It is composed of a quenching step of quenching and then quenching the steel pipe and connector formed with an oxide film from the furnace.

The packing is hollow and has the same shape as the space formed by the packing insert of the fitting pipe when the steel pipe is inserted, and includes a cylindrical part contacting the outer side of the packing insert and a conical part contacting the inside of the packing insert. .

The bolt head protrudes only one side such that only the joint pipe is in contact with the packing fitting protrusion so as to easily contact the packing, and a joint pipe contact part is formed, and the inclination of the joint pipe contact part is an outer surface of the flange to increase the contact force. It has the same slope as the slope.

The end of the coupling bolt is a structure that is fastened with a nut so that the coupling bolt is not loosened.

It is possible to solve the problem to be solved of the present invention by the water supply pipe to which the above-mentioned nitriding invasion method and the separation prevention pressure technique are applied.

According to the water supply pipe to which the nitriding invasion method and the anti-leaving pressure technique of the present invention is applied, the pipe joint is easy, and the separation of the water supply pipe can be prevented, and the problem of the tube being broken and the tube falling out due to the wrong tightening can be solved, and the nitriding invasion method By processing steel pipes and connectors, corrosion resistance, which is a weak point of steel pipes, is increased, and tensile strength is also increased, thereby lowering the installation cost of water pipes.

1 is an overall front view and a cross-sectional view AA according to the water supply pipe to which the nitriding invasion method and the separation prevention pressure technique of the present invention is applied
Figure 2 is an overall perspective view according to the water supply pipe to which the nitriding invasion method and the separation prevention pressure method of the present invention is applied
Figure 3 is a perspective view of the whole cross section according to the water supply pipe to which the nitriding invasion method and the separation prevention pressure method of the present invention is applied
Figure 4 is an overall cross-sectional view according to the water supply pipe to which the nitriding invasion method and the separation prevention rolling method of the present invention is applied
5 is a perspective view and a schematic view of a steel pipe according to the water supply pipe to which the nitriding invasion method and the anti-deviation pressing method are applied according to the present invention.
Figure 6 is a perspective view of the connector according to the water supply pipe to which the nitriding invasion method and the separation prevention pressure method of the present invention is applied
7 is a cross-sectional view of the connector according to the water supply pipe to which the nitriding invasion method and the separation prevention pressure method of the present invention is applied.
8 is an exploded view of a connector according to the water supply pipe to which the nitriding invasion method and the anti-release pressure technique of the present invention are applied.
9 is a plan view and a side view of a joint pipe according to a water supply pipe to which the nitriding invasion method and the anti-separation pressure technique of the present invention are applied.
10 is a perspective view of a joint pipe according to the water supply pipe to which the nitriding invasion method and the separation prevention pressure technique of the present invention are applied.
11 is a cross-sectional view of a joint pipe BB according to the water supply pipe to which the nitriding invasion method and the anti-separation pressing technique of the present invention are applied.
12 is a perspective view of the rolling wheel according to the water supply pipe to which the nitriding invasion method and the separation prevention pressing method of the present invention is applied.
13 is a detailed view of the pressure wheel according to the water supply pipe to which the nitriding invasion method and the separation prevention pressure method of the present invention is applied.
14 is a cross-sectional view of the pressure C-C according to the water supply pipe to which the nitriding invasion method and the separation prevention pressure technique of the present invention are applied.
15 is a schematic diagram of the packing according to the water supply pipe to which the nitriding invasion method and the separation prevention pressure technique of the present invention is applied
16 is a schematic view of the coupling bolt according to the water supply pipe to which the nitriding invasion method and the anti-deviation pressing method of the present invention is applied.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In addition, the terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users or operators, and the definitions refer to "a nitriding invasion method and a separation prevention rolling technique" according to the present invention. It should be made on the basis of the contents throughout this specification to describe the "water conduit".

The present invention is a water pipe consisting of a steel pipe for supplying water consumed for drinking water, living water, public and industrial use, and a connector (2) connecting the steel pipe (1) and the steel pipe (1), the steel pipe (1) and The connector 2 is treated with a nitriding invasion method to densify the metal structure and form an oxide film to improve tensile strength, elongation, modulus of elasticity and corrosion resistance. A ring-shaped separation prevention jaw 11 is formed to prevent the connector 2 from being separated from the steel pipe and to limit the coupling position of the connector 2.

The connector (2) is a joint pipe (21) connecting the steel pipe (1) and the steel pipe (1); The separation prevention jaw (11) is accommodated therein and combines the steel pipe (1) and the joint pipe (21), the pressing ring 22 is installed on both ends of the joint pipe (21); Inserted to the outside of the steel pipe 1 and inserted into both ends of the fitting pipe 21 is in close contact with the steel pipe 1 and the fitting pipe 21 by the pressure wheel 22 to prevent the internal fluid from leaking Packing 23 to be made; Composed of a plurality of coupling bolts 24 for coupling the pressure wheel 22 and the joint pipe 21.

The pressure wheel 22 is divided into an upper pressure wheel 22a and a lower pressure wheel 22b in a semicircle of the same shape so as to be inserted into the release prevention jaw 11, and each of the upper pressure wheel 22a and the lower pressure wheel 22b. In the upper and lower pressure wheel 22a and the lower pressure wheel 22b, two upper and lower pressure wheel coupling holes 221 are formed to be coupled to each other by a bolt 2211.

A plurality of coupling bolt insertion holes 222 are inserted into the pressing wheel 22 to couple the fitting pipe 21 to the fitting pipe 21, and a packing packing protrusion having a ring shape pressing the packing 23. 223, and the departure prevention jaw receiving groove 224 is accommodated is the departure prevention jaw (11) is formed.

The coupling bolt 24 is used to rotate the bolt and the bolt head 241 to prevent the pressure wheel 22 and the coupling pipe 21 is coupled and separated when contacted and tightened to the coupling pipe 21; The bolt body 242 penetrates the coupling bolt insertion hole 222 and is coupled to the nut 244.

The outer periphery of the both ends of the fitting pipe 21 is formed with a flange 211 is fastened to the bolt head 241 of the coupling bolt 24, the packing 23 is inserted into the inner periphery of both ends of the fitting pipe 21 A packing inserting portion 212 is formed, and an insertion restriction ring 213 is formed on the central inner circumference of the fitting pipe 21 to restrict the insertion of the end of the steel pipe 1.

The nitriding invasion method includes a washing step of washing and removing contaminants on the surfaces of the steel pipe 1 and the connector 2, and a preheating step of putting the cleaned steel pipe 1 and the connector 2 into a furnace. Wow; Low temperature nitriding the preheated steel pipe (1) and the connector (2) in a mixed gas atmosphere of ammonia, nitrogen, and carbon dioxide; A purging step of discharging the gas in the furnace after the nitriding treatment to the outside of the furnace; An oxide film forming step of forming an oxide film on the steel pipe (1) and the connector (2) which is nitrided by injecting steam into the furnace; The steel pipe 1 and the connector 2 on which the oxide film is formed are drawn out of the furnace, and then quenched and quenched.

The packing 23 is hollow for the steel pipe 1 to be inserted, and has the same shape as the space formed by the packing inserting portion 212 of the joint pipe 21 when the steel pipe 1 is inserted. It is composed of a cylindrical portion 231 in contact with the outside of the packing inserting portion 212 and a conical portion 232 in contact with the inside of the packing inserting portion 212.

The coupling bolt 24 passes through the coupling bolt insertion hole 222 and the bolt body 242 coupled with the nut 244, and the bolt contacting the fitting pipe 21 when tightening the nut 244. Head 241.

The bolt head 241 protrudes only one side such that only the joint pipe 21 is in contact with the packing 23 to facilitate the packing contact protrusion 223, and a joint pipe contact portion 2413 is formed. The inclination 2411 of the joint contact portion 2413 has the same inclination as the outer surface inclination 2111 of the flange 211 to increase the contact force.

The end of the coupling bolt 24 is a structure that is fastened with a nut 244 so that the coupling bolt 24 is not loosened.

Hereinafter, with reference to the drawings a preferred embodiment of the "water supply pipe to which the nitriding invasion method and the separation prevention rolling technique applied" according to the present invention will be described in detail. The following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

1 is an overall front view and a cross-sectional view according to the water supply pipe to which the nitriding invasion method and the release prevention compression method of the present invention is applied, FIG. 3 is an overall cross-sectional perspective view of the water supply pipe to which the nitriding invasion method and the anti-release pressure technique are applied, and FIG. 5 is a perspective view and a schematic view of a steel pipe according to the water supply pipe to which the nitriding invasion method and the release prevention compression method of the present invention is applied, and FIG. 6 is a perspective view of the connector according to the water supply pipe to which the nitriding invasion method and the release prevention compression method are applied. 7 is a cross-sectional view of a connector according to the water supply pipe to which the nitriding invasion method and the release prevention pressure technique of the present invention are applied, and FIG. 8 is a nitride of the present invention. Connector exploded view according to the water supply pipe applying the wet process and the escape prevention pressing method, Figure 9 is a plan view and a side view of the joint pipe according to the water supply pipe applying the nitriding invasion method and the escape prevention pressing method of the present invention, Figure 10 is a view of the present invention Fig. 11 is a perspective view of a joint pipe according to the water supply pipe to which the nitriding invasion method and the release prevention compression method are applied, and FIG. 11 is a cross-sectional view of a joint pipe BB according to the water supply pipe to which the nitride invasion method and the release prevention compression method are applied. Fig. 13 is a perspective view of a rolling conduit according to a nitriding invasion method and a release prevention pressing technique, FIG. 13 is a detailed view of a pressing conduit according to the nitriding invasion technique and a release prevention pressing technique, and FIG. Fig. 15 is a sectional view taken along the C-C of the water supply pipe to which the nitriding invasion method and the release prevention pressing method are applied. Fig. 16 is a schematic diagram of a packing according to a water supply pipe to which the method is applied.

1, 2, 3 and 4, the water pipe of the present invention is a steel pipe for supplying water consumed for drinking water, domestic water, public and industrial use, and the steel pipe (1) and steel pipe (1 It is composed of a connector (2) for connecting.

The connector (2) is a joint pipe (21) connecting the steel pipe (1) and the steel pipe (1); The separation prevention jaw (11) is accommodated therein and combines the steel pipe (1) and the joint pipe (21), the pressing ring 22 is installed on both ends of the joint pipe (21); Inserted to the outside of the steel pipe 1 and inserted into both ends of the fitting pipe 21 is in close contact with the steel pipe 1 and the fitting pipe 21 by the pressure wheel 22 to prevent the internal fluid from leaking Packing 23 to be made; Composed of a plurality of coupling bolts 24 for coupling the pressure wheel 22 and the joint pipe 21.

On the outer periphery of the end of the steel pipe (1) is formed a ring-shaped release prevention jaw (11) for preventing the connector (2) from being separated from the steel pipe and limiting the coupling position of the connector (2) do.

The pressing technique, which is a method of connecting the steel pipe 1 and the connector 2, is as follows.

1. The joint pipe 21 of the components of the steel pipe 1 and the connector 2 is arranged in a straight line.

2. Insert the packing 23 into the steel pipe to a certain distance away from the separation prevention jaw (11).

3. Insert the steel pipe 1 into which the packing 23 is inserted into one side of the joint pipe 21 up to the insertion limit ring 213.

4. The lower pressure wheel 22b is installed below the release stop 11 part of the steel pipe 1, and the upper pressure wheel 22a is installed on the lower pressure wheel 22b so that the upper and lower pressure couplers 221 coincide with each other. After the bolt 2211 is inserted, the nut 22111 is screwed into the lower part of the bolt 2211, and the bolt 2211 is tightened to fully integrate the upper pressure wheel 22a and the lower pressure wheel 22b. .

5. The pressure wheel 22 is brought into close contact with the fitting pipe 21, and the coupling bolt 24 is inserted into the coupling bolt insertion hole 222 of the pressure wheel 22, and the fitting pipe contact portion of the bolt head 241 ( 2413 is brought into contact with the flange 211 of the fitting tube 21, and then the nut 244 is inserted into the coupling bolt 24 and tightened.

6. The other side of the pipe 21 may be piped while continuing the steel pipe 1 by the above-described method.

The above-mentioned rolling method, which is a method of connecting the steel pipe 1 and the connector 2, is flexible, so that the connector part can be prevented from being separated in the pipe by the settlement of the road or the load of the upper part. In addition, it can prevent pipes from being broken and pulled out due to the wrong tightening.

The steel pipe 1 and the connector 2 are treated with nitriding invasion to improve the tensile strength, elongation, elastic modulus and corrosion resistance by densifying the metal structure and forming an oxide film. It is a new process that reinforced the corrosion resistance.

In other words, nitrocarburizing is a method in which iron-based metals are heated in a furnace containing ammonia, carbon monoxide, and carbon dioxide, and nitrogen and carbon penetrate the iron surface to create a wear resistant layer. However, even though the strength is high, pores were formed due to excess nitrogen that penetrated the surface during the heat treatment process, resulting in poor corrosion resistance. Because of the early disadvantages, anti-rust treatment such as zinc or chromium plating was essential after heat treatment.

On the other hand, nitriding invasion allows the formation of oxygen-rich compound layers on the iron surface by heating propane gas, ammonia and air from the bottom. The key feature of this technology is that the oxide fills the pore layer to smooth the surface. To prevent corrosion.

As a result of comparing the corrosion resistance, the use of nitriding invasion method improved the corrosion resistance by 4 ~ 5 times and the durability more than 2 times. Also, since the nitriding invasion method does not have plating process, there is no need to worry about environmental pollution, Can be lowered by more than%.

Compound layers formed by the nitriding invasion method are as follows.

In the treatment by the nitriding infiltration method, C and N are diffused and penetrated into the compound layer, only N is diffused into the diffusion layer, and the treatment temperature thereof is in the range of 560 to 600 ° C., so there is no change of structure even after cooling after treatment. In the diffusion layer, nitrogen and carbon are present in iron nitride or solid solution by low temperature cooling.

1. Consists mainly of Fe ₃ (C, N), some Fe ₄ N is formed, the two phases coexist.

2. The compound layer appears as a white layer in Nital corrosion solution (3% HNO ₃ + 97% Methanol), and pores are formed in the outermost surface to a depth of 3 ~ 10㎛.

3. The compound layer is mainly responsible for corrosion resistance and abrasion resistance, and its hardness value is 550 ~ 700Hv when the material is SPHC (hot rolled steel sheet), and similar hardness value in steel pipe, and the hardness value of compound layer is 15㎛ In case of abnormality, it is possible to measure the micro hardness (Micro Vickers, Hv) with 25-50g Load, and the hardness value of the outermost surface layer has low hardness value due to pore and shows the highest hardness value in the inner direction at the middle part of the layer.

Oxide layer formed by nitriding invasion method is formed on the outer layer (most surface) of the compound layer, and the dark blue Fe ₃ O ₄ Oxide is formed, which is about 0.2 ~ 1㎛, and the red color and corrosion resistance In addition, it increases 72% at 5% NSST (Cu 54 ^ 58% / Pb 0.1% or less / Fe 0.25% or less / Zn remainder / Mn 0.5% or less / Ni 16.5 ^ 19.5%) depending on the treatment conditions. Anticorrosive property of about 300hr.

When the nitriding invasion method is applied to the water pipe of the present invention, the corrosion resistance is 150Hr or more (5% N.S.S Test), and the wear resistance can be improved by the compound layer surface hardness of 600Hv or more, the yield strength by 3 to 5 times, and the tensile strength by 2 to 3 times.

The nitriding invasion method includes a washing step of washing and removing contaminants on the surfaces of the steel pipe 1 and the connector 2, and a preheating step of putting the cleaned steel pipe 1 and the connector 2 into a furnace. Wow; Low temperature nitriding the preheated steel pipe (1) and the connector (2) in a mixed gas atmosphere of ammonia, nitrogen, and carbon dioxide; A purging step of discharging the gas in the furnace after the nitriding treatment to the outside of the furnace; An oxide film forming step of forming an oxide film on the steel pipe (1) and the connector (2) which is nitrided by injecting steam into the furnace; The steel pipe 1 and the connector 2 on which the oxide film is formed are drawn out of the furnace, and then quenched and quenched.

At this time, the connector 2 is dismantled and nitriding only the steel part except the packing.

In the washing step, it is preferable to wash the contaminants by using ultrasonic waves for 30 to 60 minutes at 50 ~ 70 ℃ by adding a cleaning agent.

The preheating step is a preliminary step of nitriding treatment, preheating an empty furnace to inject the steel pipe 1 and the connector 2 at 540 to 550 ° C., and nitrogen to 4 to 6 m 3 N to prevent oxidation of the product. Feed into the furnace at a rate of ₂ / m ₃ / hr. At this time, nitrogen was added again until the temperature lowered by the injected hot rolled steel sheet or cold rolled steel sheet reached the point where the temperature in the furnace reached 490 ~ 520 ° C, and then ammonia was added to 4 ~ 6㎥ NH ₃ / ㎥ Preheating to 560 ~ 580 ℃ while discharging the gas by opening only 1/3 of the gas outlet while inputting ~ 4㎥ N ₂ / ㎥ at hr and carbon dioxide at 0.3 ~ 0.7㎥ CO ₂ / ㎥ at hr Do.

When the temperature of the furnace is less than 540 ° C. when the steel pipe 1 and the connector 2 are introduced into the furnace, the cold steel pipe 1 and the connector 2 are introduced into the furnace, and the nitriding treatment step is 560 to 580 ° C. It takes a long time to reach, if the temperature of the furnace exceeds 550 ℃, the steel pipe (1) and the connector (2) due to the heat too high, the scale is formed in the product, not only the hardness and corrosion resistance, but also aesthetic appearance may occur .

And in the above nitrogen injection rate "4 ~ 6 ㎥ N ₂ / ㎥ to hr" means that the nitrogen of 4 ~ 6 ㎥ N2 per hour is supplied to the furnace of 1 ㎥. When the amount of nitrogen supplied from the above is insufficient, the steel pipe 1 and the connector 2 are oxidized due to the lack of nitrogen, and scale is formed during nitriding. When the amount of nitrogen supplied is excessive, the amount is excessive. Depending on the amount of nitrogen, the oxide layer may be thick and the corrosion resistance may be deteriorated.

And the temperature to above 490 ~ 4 ~ 6㎥ the ammonia from the time that is 520 ℃ NH ₃ / ㎥ in · hr, 2 ~ 4㎥ nitrogen N ₂ / ㎥ · hr, carbon dioxide 0.3 ~ 0.7㎥ CO ₂ / ㎥ and hr, and the gas outlet is opened only 1/3 to discharge the gas so that the gas in the furnace is not quickly discharged to the outside of the furnace, can be in contact with the steel pipe (1) and the connector (2) in the furnace for a long time. As a result, even in the presence of a small amount of gas, the surface structure of the hot rolled steel sheet or the cold rolled steel sheet can be made very dense, thereby improving tensile strength, yield point, elongation, and bending test results.

When the preheating temperature of the steel pipe 1 and the connector 2 is less than 560 ° C., the steel pipe 1 and the connector 2 may not be sufficiently preheated, and thus, the nitride layer may not be formed properly during the nitriding treatment. And, if the preheating temperature exceeds 580 ℃, due to the overheating of the hot or cold rolled steel sheet, the nitride layer is not densely formed during the nitriding treatment, the numerical values such as tensile strength, yield point, elongation, modulus of elasticity may be low. have.

Unlike the conventional nitriding treatment method, the nitriding treatment step supplies ammonia (NH ₃ ) -nitrogen (N ₂ ) -carbon dioxide (CO ₂ ) mixed gas to a 20-25 m ³ mixed gas / m ³ . While feeding into the furnace at a speed of 2.5 to 3.5 hours at a temperature of 560 to 580 ° C, lowering the temperature again and then nitriding for 20 to 40 minutes at a temperature of 560 to 580 ° C for 30 to 80 minutes at a temperature of 530 to 550 ° C. desirable.

As described above, the steel pipe 1 and the connector 2 are gradually nitrided at a temperature lower than a temperature of 580 to 600 ° C., which is a normal nitriding temperature, and 530 to 530 ° C. after nitriding at a temperature of 560 to 580 ° C. By lowering the temperature to 550 ℃ and nitriding it again, increasing the temperature to 560 ~ 580 ℃ and nitriding, ammonia is decomposed by the temperature in the furnace at high temperature during purging, so that red stain does not occur and it has a clean steel surface. The structure of the steel pipe 1 and the connector 2 is densely nitrided so that the tensile strength is sharply improved.

If the steel pipe 1 and the connector 2 are nitrided at a normal nitriding temperature of 580 to 600 ° C., the nitride compound layer is well formed but the structure of the nitrided steel pipe 1 and the connector 2 is As the density of is lowered, the properties of tensile strength are not improved properly. In addition, when the nitriding treatment is generally performed at a temperature of 560 to 580 ° C., and then the temperature is lowered to 530 to 550 ° C., the ammonia decomposition does not occur completely, resulting in staining of the steel pipe 1 and the connector 2, and rusting. Red color will be visible to the naked eye.

When the amount of mixed gas injected into the furnace is insufficient, when the nitriding treatment time is short or when the nitriding temperature is low, less activated nitrogen (NO) is generated or the gas nitriding time is short to form a sufficient nitride layer. There is a possibility that the tensile strength of the steel pipe (1) and the connector (2) does not improve, and if the amount of mixed gas is excessive, the gas nitriding time is long, or the temperature is high, the hot rolled steel sheet or the cold rolled steel sheet Too much activated nitrogen (NO) is generated relative to the amount, or the nitriding time is too long, so that the thickness of the nitride layer is formed so thick that nitriding stains may be formed on the nitride surface of the hot rolled steel sheet or the cold rolled steel sheet.

The composition ratio of the mixed gas is preferably 70 ± 2% by volume, 20 ± 1% by volume of nitrogen, and 10 ± 1% by volume of carbon dioxide.

When the mixed amount of ammonia is less than 68% by volume, the amount of activated nitrogen is less than the mixed amount of nitrogen and carbon dioxide, so that the nitride layer may not be formed properly. When the mixed amount of ammonia exceeds 72% by volume, Since there is a relatively large amount compared to the mixed amount of nitrogen and carbon dioxide, the nitride layer is formed to an excessive thickness, there is a fear that nitride staining occurs.

The gas reaction in the furnace is as follows.

1.2NH _3- > 2 [N} Fe + 6H-> N ₂ + 3H ₂

2.C ₃ H ₈ + O _2- > (CO + CO ₂ ) + H ₂ O

3.CO ₂ + H _2- > CO + H ₂ O

4.NH ₃ + CO-> HCN + H ₂ O

5. HCN-> [N] Fe + [C] Fe + 1 / 2H ₂

6.CO + H _2- > [C] Fe + H ₂ O

_{7. 2M + 2H 2 O ->} 2MO + 2H 2

2M + O _2- > 2MO

The purging step is a step of discharging the remaining amount of gas such as ammonia in the furnace to the outside of the furnace, by discharging the gas in the furnace at a temperature of 560 ~ 580 ℃ the same as the nitriding treatment step to decompose the remaining amount of ammonia in the furnace Since it is discharged, it has a clean surface without the phenomenon of red color on the surface of the steel sheet by ammonia.

If purging at the usual purge temperature of 530 ~ 550 ℃ undecomposed in the furnace and remaining ammonia reacts with the steam introduced in the oxide film forming step, the surface of the steel sheet exhibits a red color to reduce the productability and corrosion resistance.

In the oxide film forming step, steam is introduced into a furnace to oxidize the surface of the nitride layer of the nitrided steel pipe 1 and the connector 2 to form an oxide film (Fe ₃ O ₄ ) at an outer surface thereof. As the steam to be introduced at this time, it is preferable to oxidize at a temperature of 560 to 580 ° C. for 40 ± 2 minutes while supplying the steam at 240 to 260 ° C. at a rate of 2 to 4 m 3 steam / m 3. At this time, if the amount of steam supplied into the furnace is small, and the oxidation time is short or the oxidation temperature is low, there is a possibility that a sufficient oxide film is not formed on the outside of the nitride layer, and the amount of steam supplied into the furnace is large and oxidized. When the time is long or the oxidation temperature is high, an excessive oxide film is formed on the outer side of the nitride layer, which may cause severe deformation of the appearance of the steel pipe 1 and the connector 2. Such an oxide film enhances the surface color of the steel pipe 1 and the connector 2, thereby improving product quality.

At this time, the thickness of the iron oxide film layer formed on the outer side of the nitride layer is preferably 1 ~ 2㎛.

In the quenching step, unlike water cooling or air cooling, which is a conventional quenching method, it is preferable to spray spray quenching, which is a method of slowly spraying water on the nitrided steel pipe 1 and the connector 2 from the furnace.

When the nitrided steel sheet is slowly cooled, such as the quenching method according to the present invention, tensile strength is not only improved, but there is no deformation of the nitrided steel pipe 1 and the connector 2 at all.

Therefore, the steel pipe (1) and the connector (2), which is nitrided by the nitriding invasion method, the metal structure is very dense, the tensile strength, yield point, elongation, bending test and the modulus of elastic modulus are improved and corrosion resistance is improved. do.

As shown in FIG. 5, the steel pipe is a pipe based on ASTM A carbon grade steel pipe A53 Grade A SCH40 to 80 as a pipe for supplying water consumed for drinking water, living water, public use, and industrial use.

On the outer periphery of the end of the steel pipe (1) is formed a ring-shaped release prevention jaw (11) for preventing the connector (2) from being separated from the steel pipe and limiting the coupling position of the connector (2) do.

The release prevention jaw 11 is formed by welding to the steel pipe (1).

As shown in FIGS. 6, 7 and 8, the connector 2 includes a joint pipe 21 connecting the steel pipe 1 and the steel pipe 1; The separation prevention jaw (11) is accommodated therein and combines the steel pipe (1) and the joint pipe (21), the pressing ring 22 is installed on both ends of the joint pipe (21); Inserted to the outside of the steel pipe 1 and inserted into both ends of the fitting pipe 21 is in close contact with the steel pipe 1 and the fitting pipe 21 by the pressure wheel 22 to prevent the internal fluid from leaking Packing 23 to be made; Composed of a plurality of coupling bolts 24 for coupling the pressure wheel 22 and the joint pipe 21.

The pressure wheel 22 is divided into an upper pressure wheel 22a and a lower pressure wheel 22b in a semicircle of the same shape so as to be inserted into the release prevention jaw 11, and each of the upper pressure wheel 22a and the lower pressure wheel 22b. In the upper and lower pressure wheel 22a and the lower pressure wheel 22b, two upper and lower pressure wheel coupling holes 221 are formed to be coupled to each other by a bolt 2211.

9, 10 and 11, the fitting pipe 21 serves to connect the steel pipe 1 and the steel pipe 1, and is preferably made of cast steel.

In the central portion of the joint pipe 21, the steel pipe inserting portion 214 into which the steel pipe 1 is inserted is formed at both sides, and the steel pipe 1 is inserted at both sides.

The outer periphery of the both ends of the fitting pipe 21 is formed with a flange 211 is fastened to the bolt head 241 of the coupling bolt 24.

The inclination 2111 of the outer side of the flange 211, that is, the portion where the coupling tube contact portion 2413 of the bolt head 241 of the coupling bolt 24 comes into contact is the joint tube contact portion 2413 of the bolt head 241. It is the same as the inclination of the 2411 so that the coupling bolt 24 and the fitting tube 21 is completely in contact.

A packing inserting portion 212 into which the packing 23 is inserted is formed at both inner peripheries of the fitting pipe 21.

The packing inserting portion 212 has a cylindrical contact surface 2121 in surface contact with the cylindrical portion 231 of the packing 23 and a conical contact surface 2122 in surface contact with the conical portion 232 of the packing 23. ) Is formed.

The packing inserting part 212 is an empty space formed when the steel pipe 1 is inserted, and a packing 23 having the same shape as the empty space is inserted therein, and the packing contact protrusion 223 has the coupling bolt 24. And the packing 23 is in close contact with the steel pipe 1 and the fitting pipe 21 when tightened with the nut 244 to prevent leakage of fluid between the steel pipe 1 and the fitting pipe 21.

In the center inner circumference of the joint pipe 21 is formed an insertion restriction ring 213 to restrict the insertion of the end of the steel pipe (1) any longer, the steel pipe inserted into the left and right by the insertion restriction ring 213 The length of (1) is the same, and the ground subsidence is prevented from falling to one side by the load.

As shown in FIGS. 12, 13, and 14, the pressure wheel 22 accommodates the release preventing jaw 11 therein and couples the steel pipe 1 and the fitting pipe 21 to each other. 21) are installed at both ends.

The pressure wheel 22 is separated into an upper pressure wheel 22a and a lower pressure wheel 22b in a semicircle of the same shape so as to be inserted into the release preventing jaw 11.

In each of the upper pressure wheel 22a and the lower pressure wheel 22b, two upper and lower pressure wheel coupling holes 221 are formed to couple the upper pressure wheel 22a and the lower pressure wheel 22b to each other with bolts 2211. do.

When the pressure wheel 22 is coupled to the steel pipe 1, the pressure wheel 22 is separated into the upper pressure wheel 22a and the lower pressure wheel 22b to be coupled to the release prevention jaw 11 of the steel pipe 1, and the upper and lower pressure wheel coupling holes. The bolt 2211 is inserted into the 221 and tightened with the nut 22111.

A plurality of coupling bolt insertion holes 222 are inserted into the pressing wheel 22 to couple the fitting pipe 21 to the fitting pipe 21, and a packing packing protrusion having a ring shape pressing the packing 23. 223, and the departure prevention jaw receiving groove 224 is accommodated is the departure prevention jaw (11) is formed.

As shown in FIG. 15, the packing 23 is inserted into the outside of the steel pipe 1 and inserted into both ends of the fitting pipe 21 to be jointed with the steel pipe 1 by the pressure wheel 22. It adheres to the pipe 21 and prevents the internal fluid from leaking.

The packing 23 is hollow for the steel pipe 1 to be inserted, and has the same shape as the space formed by the packing inserting portion 212 of the joint pipe 21 when the steel pipe 1 is inserted. The cylindrical portion 231 is in contact with the cylindrical contact surface 2121 of the outer side of the packing inserting portion 212 of the fitting pipe 21 and the conical contact surface 2122 of the inner side of the packing inserting portion 212 Cones 232.

The packing 23 is provided with a packing adhesion protrusion contact surface 234 in which a steel pipe through-hole 233 having a hollow inside and the packing adhesion protrusion 223 are in close contact with the steel pipe 1 to be inserted therein.

When the packing adhesion protrusion 223 is tightened by the coupling bolt 24 to the packing adhesion protrusion contact surface 234, the packing 23 is compressed to pack the steel pipe 1 and the fitting pipe 21. It adheres to the contact surface to prevent leakage of water in the steel pipe.

The packing contact surface includes a cylindrical contact surface 2121 and a conical contact surface 2122.

As shown in FIG. 16, the coupling bolt 24 couples the pressure wheel 22 and the fitting pipe 21 so that the steel pipe 1 does not fall out of the connector 2, and the steel pipe of 80 mm to 700 mm. At least four to twenty or more can be fastened.

The coupling bolt 24 is used to rotate the bolt and the bolt head 241 is in contact with the joint pipe 21 to prevent the pressure wheel 22 and the joint pipe 21 to be coupled and separated, and the coupling It consists of a bolt body 242 penetrated through the bolt insertion hole 222 and coupled to the nut 244, the bolt head 241 to facilitate the packing 23 in close contact with the packing adhesion protrusion 223 Only the joint pipe 21 is projected to one side relative to the bolt body 242 so that the joint pipe contact portion 2413 is formed.

That is, when the bolt head 241 is tightened, the packing contact protrusion 223 of the pressure ring 22 presses the packing 23 when the bolt head 241 is not in contact with the pressure ring 22. The outer periphery of 1) and the cylindrical contact surface 2121 and the conical contact surface 2122 of the joint pipe 21 are in close contact with each other so that the water in the steel pipe 1 does not leak.

The inclination 2411 of the joint contact 2424 has the same inclination as the outer surface inclination 2111 of the flange 211 to increase the contact force.

The end of the coupling bolt 24 is a structure for fastening with a nut 244 so that the coupling bolt 24 is not loosened, it may be fastened with a double nut.

According to the water supply pipe to which the nitriding invasion method and the anti-leaving pressure technique of the present invention is applied, the pipe joint is easy, and the separation of the water supply pipe can be prevented, and the problem of the tube being broken and the tube falling out due to the wrong tightening can be solved, and the nitriding invasion method By processing steel pipes and connectors, corrosion resistance, which is a weak point of steel pipes, is increased, and tensile strength is also increased, thereby lowering the installation cost of water pipes.

1: Steel pipe 11: Breakaway prevention jaw
2: connector 21: fittings
211 flange 2111 slope
212: packing insertion part 2121: cylindrical contact surface
2122: cone contact surface 213: insertion limit ring
214: steel pipe insertion portion 22: pressure ring
22a: upper pressure wheel 22b: lower pressure wheel
221: up-and-down pressure coupler 2211: bolt
22111: Nut 222: Coupling bolt insertion hole
223: packing adhesion protrusion
224: departure prevention jaw accommodation groove 225: outer ring
23: packing 231: cylindrical portion
232: cone portion 233: steel pipe penetration portion
234: packing close contact surface 24: coupling bolt
241 bolt head 2411 slope
2413: joint pipe contact portion 242: bolt body
2421: external thread 244: nut

Claims (4)

In the water supply pipe consisting of a steel pipe for supplying water consumed for drinking water, living water, public and industrial use, and a connector (2) connecting the steel pipe (1) and the steel pipe (1),
The steel pipe (1) and the connector (2) is treated by nitriding invasion to improve the tensile strength, elongation, elastic modulus and corrosion resistance by densifying the metal structure and forming an oxide film.
On the outer periphery of the end of the steel pipe (1) is formed a ring-shaped release prevention jaw (11) for preventing the connector (2) from being separated from the steel pipe and limiting the coupling position of the connector (2) ,
The connector (2) is a joint pipe (21) connecting the steel pipe (1) and the steel pipe (1);
The separation prevention jaw (11) is accommodated therein and combines the steel pipe (1) and the joint pipe (21), the pressing ring 22 is installed on both ends of the joint pipe (21);
Inserted to the outside of the steel pipe 1 and inserted into both ends of the fitting pipe 21 is in close contact with the steel pipe 1 and the fitting pipe 21 by the pressure wheel 22 to prevent the internal fluid from leaking Packing 23 to be made;
Composed of a plurality of coupling bolts 24 for coupling the pressure wheel 22 and the joint pipe 21,
The pressure wheel 22 is separated into an upper pressure wheel 22a and a lower pressure wheel 22b in a semicircle of the same shape so as to be inserted into the separation prevention jaw 11.
In each of the upper pressure wheel 22a and the lower pressure wheel 22b, two upper and lower pressure wheel coupling holes 221 are formed to couple the upper pressure wheel 22a and the lower pressure wheel 22b to each other with bolts 2211. Become,
The combination of the upper pressure wheel 22a and the lower pressure wheel 22b is such that the lower pressure wheel 22b is installed below the release stop 11 of the steel pipe 1, and then the upper pressure wheel 22a is connected to the lower pressure wheel 22b. After the upper and lower pressure coupler 221 is installed to coincide with the bolt 2211, the nut 22111 is screwed into the lower part of the bolt 2211, and the bolt 2211 is tightened to tighten the upper pressure wheel 22a. ) And the lower pressure wheel (22b) to be integrated,
A plurality of coupling bolt insertion holes 222 are inserted into the pressing wheel 22 to couple the fitting pipe 21 to the fitting pipe 21, and a packing packing protrusion having a ring shape pressing the packing 23. 223, and the separation prevention jaw receiving groove 224 is formed, the accommodation prevention jaw (11) is accommodated,
The coupling bolt 24 is used to rotate the bolt and the bolt head 241 to prevent the pressure wheel 22 and the coupling pipe 21 is coupled and separated when contacted and tightened to the coupling pipe 21 and The bolt body 242 penetrates the coupling bolt insertion hole 222 and is coupled to the nut 244.
The outer periphery of the both ends of the fitting pipe 21 is formed with a flange 211 is fastened to the bolt head 241 of the coupling bolt 24,
A packing inserting portion 212 into which the packing 23 is inserted is formed at both inner peripheries of the fitting pipe 21.
In the center inner circumference of the joint pipe 21 is formed an insertion restriction ring 213 for restricting the end of the steel pipe 1 is no longer inserted,
The nitriding invasion method includes a washing step of washing and removing contaminants on the surfaces of the steel pipe 1 and the connector 2, and a preheating step of putting the cleaned steel pipe 1 and the connector 2 into a furnace. Wow;
Low temperature nitriding the preheated steel pipe (1) and the connector (2) in a mixed gas atmosphere of ammonia, nitrogen, and carbon dioxide;
A purging step of discharging the gas in the furnace after the nitriding treatment to the outside of the furnace;
An oxide film forming step of forming an oxide film on the steel pipe (1) and the connector (2) which is nitrided by injecting steam into the furnace;
The steel pipe (1) and the connector (2) formed with an oxide film is composed of a quenching step of withdrawing and then quenching and processing from the furnace,
The packing 23 is hollow for the steel pipe 1 to be inserted, and has the same shape as the space formed by the packing inserting portion 212 of the joint pipe 21 when the steel pipe 1 is inserted. Is composed of a cylindrical portion 231 in contact with the outside of the packing inserting portion 212 and a conical portion 232 in contact with the inside of the packing inserting portion 212,
The bolt head 241 is protruded to one side relative to the bolt body 242 so that only the joint pipe 21 is in contact with the packing 23 to facilitate the packing tight protrusion 223, the joint contact portion 2413 is formed,
The inclination 2411 of the joint tube contact portion 2413 has the same inclination as the outer surface inclination 2111 of the flange 211 to increase the contact force,
The end of the coupling bolt 24 is a water supply pipe to which the nitriding invasion method and the separation prevention pressure rolling method is applied, characterized in that the coupling bolt 24 is fastened with a nut 244 so as not to loosen.
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