JPS594985A - Method for coating corrosion and abrasion resistant metallic material on inside surface of steel pipe - Google Patents

Abstract

PURPOSE:To coat a corrosion resistant and abrasion resistant metallic material suited for practicable use on the inside surface of a long sized or small diameter steel pipe by coating a desired metallic material on the outside surface of a thin walled pipe, inserting the same into the steel pipe and expanding and heating the pipe. CONSTITUTION:A corrosion and abrasion resistant metallic material 12 such as an Ni alloy for coating the inside surface of a steel pipe 1 is coated by plasma melt spraying or the like on the outside surface of a thin walled pipe 2. The pipe 2 is inserted into the pipe 1 to form a superposed pipe, and after sealing caps 3 are welded to both ends of the pipe 2, the pipe is put into a tubular electric furnace 5 or the like. While the superposed pipes are heated, the inside of the pipe 2 is maintained at a prescribed pressure and the pipe is expanded. When the pressure is reduced after cooling, the pipe 2 is joined thoroughly to the inside surface of the pipe 1 through the metal 12. The pipe 2 remaining in the pipe 1 is removed by a mechanical or chemical means.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coating the inner surface of a steel pipe with a metal material having corrosion resistance and/or wear resistance.

Pipes made of metal materials are required to have various properties depending on their use, and are manufactured using materials that satisfy these properties. In recent years, with the development of industry, especially the chemical industry and its peripheral or related technologies, the characteristics required of the pipes have become diverse and severe, and seven types of pipe materials have been developed to satisfy all of the required characteristics. for,
At present, very expensive materials must be used.

For example, metal materials with high corrosion resistance or high wear resistance are generally expensive and difficult to process, so they have the drawback of lacking versatility as metal materials for pipes.

w4IF! Various surface treatment methods for steel pipes have been proposed and used as methods for improving the corrosion resistance and/or wear resistance of steel pipes. Among them, plating and ion brating, for example, have drawbacks such as poor reliability due to thin coatings, and difficulty in applying to long steel pipes. Further, although the thermal spraying technology that has been widely used in recent years is useful, it requires specially designed thermal spraying equipment to coat the inner surface of long steel pipes, and it has the disadvantage that it cannot be applied to small-diameter steel pipes in particular.

An object of the present invention is to provide a surface treatment method that eliminates and improves the above-mentioned drawbacks found in conventional surface treatment methods for the inner surface of steel pipes. can be achieved.

The present invention provides a method for coating the inner surface of a steel pipe with a metal material having corrosion resistance and/or wear resistance, in which a thin walled pipe having an outer diameter slightly smaller than the inner diameter of the steel pipe is prepared, and the outer surface of the thin walled pipe is coated with a metal material having corrosion resistance and/or wear resistance. The target metal material is coated, the coated thin-walled tube is inserted into the steel tube, the tube is expanded and heated at high temperature, and the metal material coated on the outer surface of the thin-walled tube is coated on the inner surface of the steel tube. The thin-walled tube is bonded by melting and/or diffusion, and if necessary, the thin-walled tube bonded to the inner surface of the steel tube is bonded by at least one of mechanical means and chemical means.
The present invention relates to a method for coating the inner surface of a steel pipe with a corrosion-resistant and wear-resistant metal material, which is removed by two means. According to this method, it becomes possible to coat the inner surface of a long steel pipe or the inner surface of a small diameter steel pipe with a corrosion-resistant and wear-resistant metal material, which has been difficult to implement using conventional surface treatment techniques.

Next, the present invention will be explained in detail.

The present inventors previously proposed a method of coating the inner surface of a steel pipe with a corrosion-resistant and wear-resistant metal material in Japanese Patent Application No. Sho-kA-1g797. The method proposed above involves inserting an inner tube made of a corrosion-resistant and wear-resistant metal material into an outer tube, filling the gap between the inner and outer tubes with metal solder, and then pressurizing the inner tube from the inside.
The method involved heating the outer tube and brazing the inner and outer tubes.

Regarding the above proposal, the present inventors inserted an inner tube whose outer surface was sprayed with four N1 particles into an outer tube, and while conducting an experiment to create a double tube by pressurizing and heating, the inner tube It was discovered that interfacial peeling occurred between N10 and N10, and this was the inspiration for the present invention.

Since the N10 layer itself is a corrosion-resistant and wear-resistant metal, the present inventors first formed a Ni wax layer on the outer surface of a temporary thin-walled inner tube as a coating layer, and then formed a thin-walled inner tube with this coating layer. Insert the tube into the steel tube and pressurize and heat it to the N10
The present invention was completed based on the finding that it is possible to coat the inner surface of a steel pipe with N10 by melting and/or diffusion bonding a fatigue coating layer made of Y to the inner surface of the steel pipe. That is, according to the present invention, a steel pipe having a corrosion-resistant and wear-resistant coating layer is manufactured by a method in which N10 coated on the outer surface of a thin-walled pipe is transferred and pasted onto the inner surface of the steel pipe. I can do it.

The method of the present invention does not directly coat the inner surface of a steel pipe with a corrosion-resistant and wear-resistant metal material as in the conventional method, but instead uniformly coats the outer surface of a thin-walled pipe, which is easy to coat, with the metal material. The coated thin-walled pipe is inserted into a steel pipe to form a stacked pipe, and then the stacked pipe is expanded from the inner surface of the thin-walled pipe to bring the metallic material into close contact with the inner surface of the steel pipe, while the stacked pipe is expanded. By heating at high temperature and performing melting and/or diffusion treatment of the metal material, the metal material is bonded to the inner surface of the steel pipe, and the coating is completed by cooling, and then the thin wall remaining inside the steel pipe is removed if necessary. This method involves removing the pipe by chemical or mechanical means such as pickling or polishing. By doing this, it becomes as if the corrosion-resistant and wear-resistant metal material has been transferred and pasted onto the inner surface of the steel pipe.

Next, the invention will be explained with reference to the figures.

FIG. 1 is a longitudinal sectional view of a tubular electric furnace containing stacked tubes. The desired corrosion-resistant and wear-resistant metal material/
, 2, and insert this coated thin-walled tube into the inside of the steel pipe to form an overlapping tube.Both ends of the thin-walled tube are sealed with seal caps 3, and connected to a gas cylinder of air or inert gas. do. A tubular electric furnace using stacked tubes! The stacked tubes are expanded by applying pressure to the thin-walled tube λ with gas supplied from the gas cylinder while heating it in the tubular electric furnace S. The heating temperature in the electric furnace is the diffusion bonding temperature between the steel pipe and the metal material coated on the thin-walled pipe,
Alternatively, the temperature may be near the melting temperature of the metal material. Due to this tube expansion and heating, the steel pipe l and the thin-walled pipe co are made of the metal material/
, 2. The joined stacked pipes are taken out from the tubular electric furnace 3, cooled, and the pressure is released to complete the coating construction.

FIG. 2 is a longitudinal sectional view of a zone heating electric furnace containing stacked tubes. The stacked tubes prepared in the same manner as shown in FIG. A gas or reducing gas is introduced into the atmosphere adjustment chamber 6 from a gas cylinder/liter of atmosphere adjustment gas, and air or an inert gas is pressurized from the gas cylinder holder into the thin-walled tube sealed with a seal cap J to make the thin-walled tube. Pressurize the inside of the heating coil 7, energize the heating coil 7 from the induction heating power supply, and then press the heating coil moving device. band-heating the overlapped tubes while moving the heating coil 7, and expanding the thin-walled tube by heating and pressurizing the thin-walled tube in the heating section at each position during the movement of the heating coil 7. They are bonded via the metal material 12.

Inside the inner-coated steel pipe l obtained by the method shown in Fig. 11.2, a thin-walled pipe remains with a layer of corrosion-resistant and wear-resistant metal material l interposed therebetween. This remaining thin-walled pipe does not necessarily have to be a pipe with corrosion resistance and wear resistance, and may be a steel pipe with a wall thickness of O*Zm or less. It can be removed by polishing, grinding or other mechanical means, or pickling, chemical polishing or other chemical means, but if there is no inconvenience in use depending on the purpose of the coated steel pipe, it will remain and will not corrode during use. Alternatively, there may be cases in which the material disappears naturally due to wear and there is no need to remove it by the above-mentioned means.

Next, the present invention will be explained with reference to examples.

Example 1 Steel pipe/Carbon steel pipe (5TBA 22) (7,) Wall thickness 3
．． Qm.

A thin-walled pipe with an outer diameter of SO, and a cylindrical shape are used for the thin-walled pipe.The outer diameter of the thin-walled pipe is 39 drunkenness. A self-fusing nickel alloy (A) having the components shown in Table 1 was sprayed onto the outer surface of the thin-walled tube as a metal material for coating using a plasma spraying device. Thermal spraying thickness is approximately o, 1
IIs. The inner surface of the steel pipe 1 was coated according to the following procedure. That is, as shown in Fig. 1, a coated thin-walled tube is inserted into the inside of a steel pipe 1 to form a stacked tube, seal caps 3 are TIG welded to both ends of the thin-walled tube, and then the stacked tube is connected to a tubular electric tube. Furnace! The inside of the sealed thin-walled tube was kept at a pressure of 〃atmosphere by pressurized gas from an argon gas bomber while heating it to /lOo''C.

After holding at 1iooC for 3 minutes, the stacked tubes were placed in a tubular electric furnace! After cooling, the pressure was reduced. As a result of the above treatment, it was confirmed by inspection of a cross section perpendicular to the axial direction that the thin-walled pipe was completely joined to the inner surface of the steel pipe through the corrosion-resistant and wear-resistant leek alloy. The microstructure after chemically polishing the thin-walled pipe inside the steel pipe l with hydrofluoric acid is shown in Figure 3, where a is the steel pipe and b is the self-fusing nickel coating, which is a corrosion-resistant and wear-resistant metal coating. It was observed that a sufficient coating was formed.

Example 2 Steel pipe l is the wall thickness g of carbon steel pipe (5TBA, 2.1),
Q vmν outer diameter! 0. The thin-walled tube is made of tea with a wall thickness of 0. kII11? A '1' IG welded pipe made of /1% Or stainless steel with an outer diameter of 3 mm was used. A self-fusing cobalt alloy (B) having the components shown in Table 1 was thermally sprayed onto the outer surface of the thin-walled tube. The spraying thickness is approximately Q, 7m. The inner surface of the steel pipe 1 was coated according to the following procedure. That is, after making the stacked tubes as shown in Figure 1 and TIG welding the seal caps 3 to both ends of the thin-walled tubes, the stacked tubes are placed in an atmosphere of 111 t%.
It was set in a chamber 6, and after the chamber 6 was evacuated by a vacuum exhaust device lo, argon gas was introduced from a gas cylinder for atmosphere adjustment.

While pressurizing the inside of the thin-walled tube to 70 atmospheres with argon gas from a gas bomb pedal, the zone heating filter 7 was moved over the entire length of the tube at a speed of 301 LwL/min, and the heated portion of the tube was The stacked tubes were heated to 0.degree. C. to 0.degree. C., and after the entire length of the tubes had been treated, the stacked tubes were taken out from the atmosphere adjustment chamber 6. It was confirmed by inspection of a cross section perpendicular to the axial direction that the above treatment had completely adhered the thin-walled pipe to the inner surface of the steel pipe via the corrosion-resistant and wear-resistant cobalt alloy. The microscopic structure of the cross-sectional cut of the stacked pipes is shown in Figure 3, where a is a steel pipe, d is a thin-walled pipe, and C is a self-fusing cobalt coating, which is sufficient as a corrosion-resistant and wear-resistant metal coating. It will be shown that it is formed.

As described above, according to the method of coating the inner surface of a steel pipe with a corrosion-resistant and wear-resistant metal material, the inner surface of the steel pipe, which was difficult or impossible to implement using conventional surface treatment techniques,
In particular, it has become possible to coat the inner surfaces of long steel pipes and small-diameter steel pipes with corrosion-resistant and wear-resistant metal materials of a thickness suitable for practical use. It becomes easy to obtain pipes for this purpose and other uses, which is a great advantage in terms of industrial technology.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a tubular electric furnace that accommodates stacked tubes applied to Example 1 of the present invention, and FIG. 2 is a longitudinal cross-section of a zone heating electric furnace that accommodates stacked tubes applied to Example 2. 3 and 3 are microscopic micrographs of the covered portion of Example 1, and FIG. 9 is a microscopic micrograph of the coated portion of Example 2. L...Steel pipe, K...Thin-walled pipe, 3...Seal cap, D...Gas cylinder for pressurizing thin-walled pipe, 3...
Tubular electric furnace, 6...atmosphere adjustment chamber, ri...
Heating coil, t...Induction heating power supply device, t...Heating filter moving device, /θ...Evacuation device, /C...
Gas cylinder for atmosphere adjustment gas, l... Corrosion-resistant and wear-resistant metal material. Patent applicant: Kawasaki Steel Corporation,

Claims (1)

[Claims] 1. $4 In a method of coating the inner surface of a pipe with a metal material having corrosion resistance and/or wear resistance, a thin-walled pipe having an outer diameter slightly smaller than the inner diameter of the steel pipe is prepared, The outer surface of the thin-walled tube is coated with the desired metal material, and the coated thin-walled tube is inserted into the inside of the steel tube to expand and heat the tube to a high temperature. is bonded to the inner surface of the steel pipe by melting and/or diffusion, and if necessary, the thin-walled pipe bonded to the inner surface of the steel pipe is bonded to the inner surface of the steel pipe by at least one of mechanical means and chemical means.
A method of coating the inner surface of a steel pipe with a corrosion-resistant and wear-resistant metal material, the method comprising: removing a corrosion-resistant and wear-resistant metal material by two means; 2. In the method according to claim 1, after inserting the thin-walled tube coated with the metal material into the inside of the steel tube to form a stacked tube, while pressurizing the inner surface of the thin-walled tube with gas, A method for coating the inner surface of a steel pipe with a corrosion-resistant and wear-resistant metal material, the method comprising heating the stacked pipes at a high temperature and then cooling them. 3. The method according to claim 1 or 2, characterized in that the layered tubes are subjected to zone heating, and the zone heating is performed continuously and sequentially over the entire length of the layered tubes. A method of coating the inner surface with a corrosion-resistant and wear-resistant metal material. 4. In the method according to any one of claims 1 to 3, the mechanical means for removing the thin-walled pipe joined to the inner surface of the steel pipe includes at least one selected from polishing, grinding, and other methods. The chemical means to remove the thin-walled pipe bonded to the inner surface of the steel pipe is washing. A method of coating the inner surface of a steel pipe with a corrosion-resistant and wear-resistant pure metal material, which is at least one method selected from chemical polishing and other methods.