JPS60244378A - Method for inner surface lining of steel pipe - Google Patents

Abstract

PURPOSE:To form a thick resin mortar cured coating layer, by a method wherein a fluid curable resin solution is supplied to the inner surface of a steel pipe rotating at a low speed and a rotary speed is subsequently increased while a filler is supplied and this operation is repeated before the curable resin solution is cured at last. CONSTITUTION:A horizontally arranged steel pipe is rotated around the center axis thereof at a low speed and a fluid curable resin solution is supplied into the steel pipe to form the thin film comprising the resin solution to the inner surface thereof. Next, the rotary speed of the steel pipe is increased and a fine filler is supplied into the steel pipe to be scattered on the thin resin solution layer and centrifugal force of about 1.5-12.5G is applied to form the resin mortar layer in which the resin solution and the filler are compounded uniformly. This operation is repeated and the curable resin solution in the resin mortar layer is cured at last.

Description

[Detailed description of the invention] (Summary of the invention, industrial application field) This invention supplies a fluid hardening resin liquid, which is a component of resin mortar, to the inner surface of a steel pipe rotating at a low speed. , then increase the rotational speed of the steel pipe to add the filler (
The inner surface of the steel pipe is sequentially coated with the resin liquid and filler, and the resin liquid and filler on the inner surface of the steel pipe are coated with the high centrifugal force caused by the high speed rotation of the steel pipe. At the same time, a thin layer (lining layer) of this resin mortar composition is formed by forcibly accelerating the blending with the resin mortar composition on the inner surface of the steel pipe, and finally, this resin mortar layer is hardened. The present invention relates to a method of lining the inner surface of a steel pipe with a cured resin mortar coating layer by curing a resin liquid.

The steel pipe with a hardened resin mortar coating layer on the inner surface obtained by the lining method of this invention has excellent corrosion resistance and protective coating properties, and is useful as a material for construction and civil engineering. It becomes the basic material.

(Prior Art) Various methods of coating the inner surface of steel pipes with various coating materials, lining materials, etc. have been proposed in order to prevent corrosion.For example, (1) heating powdered thermoplastic resin; (2) Spraying or coating a thermosetting resin liquid, etc. by applying it uniformly to the surface of the steel pipe using electrostatic coating or fluid dipping to form a molten coating film; Methods have already been proposed in which a thin film of resin liquid is formed using a method of coating, and then the thin film of resin liquid is cured for coating, and some of these methods have been put into practice.

(Problems to be Solved by the Invention) Method +1 above involves a fairly complicated process such as preheating the steel pipe, forming an adhesive layer, and forming a coating layer using powdered thermoplastic resin. For steel pipes having a coating layer made of powdered thermoplastic resin, the anticorrosion liquid TfiN may not necessarily be sufficient in terms of physical properties such as heat resistance, abrasion resistance, and hardness depending on the purpose of the anticorrosion coated steel pipe. There wasn't.

In addition, the coating method using a thermosetting resin liquid according to method (2) above still does not provide satisfactory physical properties such as abrasion resistance and impact resistance. When spraying or coating the inner surface of a steel pipe, the resin liquid often drips downward before being thermoset, resulting in the formation of an uneven coating layer. This method has the disadvantage that it is difficult to form a uniform coating layer or a thick coating layer. In addition, if the curing speed of the thermosetting resin is increased to prevent the above-mentioned dripping, the storage stability of the resin liquid deteriorates, and the coating operation must be shortened, making it difficult to form a uniform coating layer. This makes things extremely difficult.

On the other hand, high viscosity resin mortar, in which a high proportion of fillers such as aggregates are blended into a curable resin liquid, is used in the construction and construction fields for its chemical resistance, heat resistance, abrasion resistance, hardness, and impact resistance. Because it forms a hardened layer with excellent physical properties such as hardness, it is generally used to form flat floor surfaces in buildings, etc.
In addition, some methods have been used to coat the surfaces of other flat materials, but due to the high viscosity of the resin mortar, the coating work is mostly done manually, similar to general cement mortar. This is done by a painting method that uses a trowel, etc., and it requires skill to form an anti-corrosion coating layer on the inner surface of the steel pipe, and lining is applied to the inside of the steel pipe whose diameter is too small for people to enter. However, there were no known industrially efficient methods for coating the inner surfaces of steel pipes.

(Means for Solving the Problems, Functions and Effects) The inventors have developed a steel pipe that has a hardened coating layer of resin mortar on its inner surface, which has excellent physical protection performance, in order to avoid the above-mentioned problems. As a result of intensive study on the inner lining method for steel pipes 1, which can be manufactured efficiently,
First, a fluid, hardening resin liquid is applied or sprayed onto the inner surface of a steel pipe rotating at a low speed to form a thin layer of the resin liquid, and then the rotational speed of the steel pipe is increased considerably, and the inner surface of the steel pipe is A filler such as aggregate for resin mortar is sprinkled on top of the thin layer of the resin liquid, and a high centrifugal force is applied to the hardening resin liquid and filler on the inner surface of the steel pipe. By quickly forming a resin mortar layer containing a high proportion of fillers such as aggregate, and then curing the hardening resin liquid of the resin mortar layer, it is easy to form a hardened resin mortar coating layer on the inner surface of the steel pipe. He discovered that this invention could be applied to

That is, this invention supplies a fluid curable resin liquid to the inside of the steel pipe while rotating the horizontally arranged steel pipe at a low speed about its central axis as the rotation axis, thereby forming a thin layer of the resin liquid. is formed on the inner surface of the steel pipe, and then the rotational speed of the steel pipe is increased, and a fine filler is supplied into the interior of the steel pipe to scatter the filler on the thin layer of the resin liquid, and the By applying a centrifugal force of approximately 1.5 to 12.5 G to the thin layer of the resin liquid and the filler, a resin mortar layer in which the resin liquid and the filler are uniformly blended is formed. Finally, the present invention relates to a method for lining the inner surface of a steel pipe, which is characterized by curing the curable resin liquid in the resin mortar layer.

This invention is a novel method for lining the inner surface of steel pipes, which allows a hardened resin mortar coating layer with excellent physical properties to be easily formed on the inner surface of steel pipes with excellent industrial reproducibility. ) etc. is not necessary.

In particular, this invention uses a fluid curable resin liquid J that can be applied uniformly by spraying, etc. to apply a thin layer of resin liquid to a uniform thickness on the inner surface of a steel pipe rotating at a low speed. Immediately, by "increasing the rotational speed of said steel pipe", a filler (such as aggregate) is sprinkled on the thin layer of resin liquid on the inner surface of the steel pipe, and A large centrifugal force is applied to the thin layer and the filler to forcibly promote the blending of the thin layer of resin liquid and the filler, and by forming a high viscosity resin mold layer, a uniform layer is formed on the inner surface of the steel pipe. It is possible to quickly form a thick resin mortar cured coating layer, and this point is the most distinctive point of the present invention.
is important.

In a steel pipe having a hardened resin mortar coating layer formed by the lining method of the present invention on its inner surface, the corrosion-protected ff1 layer on the inner surface is formed by the original hardened resin mortar mixed with a filler such as aggregate in advance. It is a hardened layer that has excellent physical properties that are exactly the same as those previously used, such as chemical resistance, heat resistance, abrasion resistance, hardness, and impact resistance, so it has extremely high anticorrosion performance.

(Detailed Description of the Present Invention) The curable resin liquid used in the present invention has a rotational viscosity of about 0.000 at the temperature during the initial coating or spraying operation in the present invention. 0.5～
Any fluid curable resin liquid may be used as long as it has a wide range of 1000 voids, preferably 0.1 to 800 voids.

In this invention, the curable resin liquid has a viscosity of about 100 to 10
Even with high viscosity ranges such as 00 poise, especially 250 to 800 poise, the uniform thickness of the inner surface of the steel pipe is affected by the large centrifugal force due to the increased rotational speed of the steel pipe after dispersing the filler. The filler dispersed in a thin layer of resin liquid can be forcibly incorporated easily and in a short time.

Furthermore, the curable resin liquid used in this invention is designed so that when it is applied or sprayed onto the inner surface of a steel pipe to form a thin layer of resin liquid, it will not harden until the next filler is sprayed. It is preferable that the curable resin liquid has a pot life of about 10 minutes to 2 hours, particularly about 20 minutes to 1 hour. When cured,
It is preferable that the main component is a curable resin that acts as a binder for fillers (aggregates, etc.) and has the ability to bond to the inner surface of the steel pipe to be coated with sufficient adhesive force.

In this invention, the curable resin liquid may be a thermosetting resin, room temperature curable resin, etc. used in common resin mortars, as long as it has the rotational viscosity described above at the temperature during the coating or spraying operation. For example, two-component curable resins such as epoxy resins, unsaturated polyester resins, and polyurethane resins can be used as main components, and appropriate curing agents, additives, etc. can be used. Examples include uncured liquid substances contained therein.

The filler used in this invention is preferably one that does not particularly accelerate the curing of the thin layer of the curable resin liquid formed on the inner surface of the steel pipe,
In addition, it has the property that it can be easily sprayed or sprayed onto a thin layer of the curable resin liquid by a known method, and that it can easily penetrate and be blended into the thin layer of the resin liquid by the aforementioned centrifugal force. , suitable shape and size, for example, aggregates such as pulverized stone powder, fine sand, silica sand, etc. for cement mortar, or thermoplastic resins, having the above-mentioned properties. , short glass fibers, glass powder, glass flakes, which are added to thermosetting resins as reinforcing agents.
Suitable examples include common inorganic fillers such as rhusium carbonate, curcum, alumina, various short metal fibers, and metal powders, as well as various inorganic colorants.

In this invention, the filler has an angle of repose of about 100 as measured by an injection method, which indicates its self-flowing property.
° or less, especially 80° or less, or about 120° or less, especially 100° or less as measured by the spatula angle, so that the thin layer of resin liquid on the inner surface of the steel pipe can easily penetrate due to the centrifugal force mentioned above. This is preferred because it is easy to do.

In addition, the above-mentioned filler has a particle diameter or short fiber diameter.
The maximum diameter of the I cross section is approximately 1/2 times or less, especially 1/4 times or less of the thickness of the resin mortar layer (finally formed layer) formed on the inner surface of the steel pipe. The particle size or the maximum cross-sectional diameter of the short fibers must be approximately 0.001 to 1000 μm.
, especially within the range of about 0.01 to 500μ,
Sufficient resin liquid permeates between the fillers, and does not form voids or bubbles between each resin mortar layer, and prevents peeling between each layer.
In order to prevent chipping, it is preferable that the short fiber filler has a length of about 2 cm or less, particularly 0.0 cm or less.
As mentioned above, it is about 1 to 10 mm.

It is preferable for the same reason.

In the lining method of the present invention, for example, the rotation speed is about 1 to
The above-mentioned fluid curable resin liquid is applied to the inner surface of a horizontally arranged steel pipe that is rotating at a low speed of about 50 r, p, m, especially about 2 to 20 r, p, m, about the central axis of the steel pipe. Using a predetermined amount, spray uniformly with air or airless spray at a temperature that does not cause curing of the curable resin liquid (at room temperature or under heating, particularly preferably at a temperature of about θ to 60°C). or by pouring a fluid resin liquid into the inside of a rotating steel pipe and spreading it uniformly over the inner surface of the steel pipe, or by depositing the resin liquid on the surface of a coating roll and rolling the roll onto the steel pipe. First, a thin layer of curable resin of uniform thickness is formed on the inner surface of the steel pipe, such as by pressing it onto the surface.

In addition, in this invention, when applying or spraying the hardening resin liquid to the inner surface of the steel pipe, if the steel pipe is rotated at an excessively high rotational speed from the beginning, a thin layer of the resin liquid with a uniform thickness may be formed. Therefore, the rotational speed of the steel pipe during formation of the thin layer of resin liquid is preferably such that a centrifugal force of about IG or less is applied to the formed thin layer. However, after a somewhat uniform thin layer of resin liquid has been formed,
It may even be preferable to increase the rotational speed of the steel tube to a fairly high speed.

In the lining method of the present invention, by pouring or spraying the curable resin liquid,
Forming a thin layer of resin liquid on the inner surface of the steel pipe is most suitable in terms of workability. The method of forming a thin layer of resin liquid using this "spray" is to form a uniform thin layer of resin liquid by moving the spray nozzle or moving the rotating steel pipe to be coated in the longitudinal direction. It is also possible to form a coating layer on a portion of the steel pipe to be coated, and is suitable for improving productivity and workability, such as scaling.

In the method for forming a thin layer of resin liquid using the spray described above,
The curable resin liquid used has a temperature of about 0.5 to 3 at the outlet of the spray nozzle during its application or spraying operation.
00 poise, especially about 1 to 200 poise,
Preferable for uniform spraying.

In the coating method of this invention, a filler (such as aggregate) is placed on a thin layer of resin liquid on the inner surface of a steel pipe that is rotated at a high speed.
For example, methods for spraying and adhering fine fillers include simply dropping and spraying fine fillers inside a rotating steel pipe from above the inner surface of the steel pipe, or
Filler is supplied to a container (cylindrical, toy-shaped, dish-shaped, tray-shaped, etc.) having a slit placed inside the steel pipe, and the container is moved or rotated to remove the filler. A constant feeding rate (approximately 0,1
- 3.0, especially at a feed rate of about 0.3 to 1.5 g/min. Examples include a method of dispersing it in the form of a mist or sandstorm together with a fluid such as air.

In the above-mentioned spraying of the filler, the amount of filler supplied onto the resin liquid on the inner surface of the steel pipe is the amount of filler that can form a resin mortar layer with a preferred composition ratio, that is, 1 to the volume of the resin liquid. It is preferable to increase the volume by ~10 times (volume), but excess filler may be supplied, and the excess filler not retained in the thin layer of resin liquid is recovered from the inner surface of the wi-tube by an appropriate method. be able to.

In the lining method of this invention, as described above, fine filler (such as aggregate) is spread and adhered onto the thin layer of resin liquid on the inner surface of the steel pipe at increased rotational speed.
Initially, the resin liquid layer and the filler layer appear to be joined in a layered manner. When the inner diameter of the steel pipe is approximately 400 m/s, the circumferential speed of the steel pipe is approximately 1.6 to 5.0 m/sec, particularly 2.0 to 4.9 m/sec.
A large centrifugal force (approximately 1.0 m/sec) is applied.
(5 to 12.5 G, preferably 2.0 to 12.0 G) D. Therefore, for a short period of time, for example about 0.01 to 10 minutes, especially 0.1 to 5 minutes, the filler forms a thin layer of resin liquid. The resin liquid forcibly infiltrates or permeates into the filler, or the resin liquid fills between the fillers without any gaps, and the final rotational viscosity is about 500 poise or more, especially 1000 poise or more at room temperature. The result is a highly viscous or substantially non-flowing resin mortar layer that is uniform throughout. Therefore, the time for the above-mentioned homogenization after the filler has been sprayed,
In other words, the time required for the curable resin liquid to ooze out onto the upper surface of the filler layer and cover the surface is extremely shortened. This effect occurs when the centrifugal force mentioned above is 1.5
If it is less than G, it will be difficult to perform, and if the centrifugal force is less than 12.
If it exceeds 5 G, the difference in specific gravity between the resin liquid and the filler causes unevenness in their dispersion, making it difficult to form a uniform resin mortar layer.

In this invention, the composition ratio of the resin mortar layer is such that the volume of the filler is 1 to the volume of the hardening resin liquid.
It is preferable that the capacity be ~io times as large, particularly 1.5 to 8 times as large.

In addition, in this invention, by making the volume of the blended filler smaller than the amount of resin liquid, the resin liquid layer that oozes out onto the surface of the filler layer has a smooth surface layer. Therefore, for such purposes, it is appropriate to reduce the volume of the filler blended to about 1 to 5 times that of the resin liquid.

In this invention, the thickness of the resin mortar layer is approximately 10
A thickness of about 0 to j000μ, particularly about 200 to 1000μ, is suitable for forming a coating layer with a uniform thickness without voids or bubbles, or from the viewpoint of workability.

In this invention, when supplying the filler to the thin layer of resin liquid formed on the inner surface of the steel pipe, the rotational speed of the steel pipe can be increased all at once to a high circumferential speed. It is preferable to increase the circumferential speed. That is, when the filler is sprinkled on the thin layer of thermosetting resin liquid on the inner surface of the steel pipe, for example, when the inner diameter of the steel pipe is about 400 mm, at the first stage of filler supply: By setting the circumferential speed of the steel pipe to about 2.0 to 3.0 m/sec so that the centrifugal force is 2.0 to 4.6 G,
The penetration of the resin liquid into a thin layer is promoted to form a uniformly blended resin mortar layer, and after this, centrifugal force is further applied to
．． The circumferential speed of the steel pipe was adjusted to about 3 to make it 0 to 12.5 G.
．． By increasing the speed to about 0 to 5 m/sec, the resin mortar layer can be sufficiently compacted, and the resin liquid can be sufficiently oozed out onto the surface of the resin mortar layer to form a thin, smooth resin layer on the surface. It is preferable to form.

In the lining method of the present invention, the operations of forming a thin layer of the curable resin liquid, scattering (or spraying) the filler, and forming the resin mortar layer described above are basically carried out in one step each.
By repeating this process twice, a thick resin mortar layer (with a thickness of 2 to 10 fi, especially about 3 to 6 fi) is formed on the whole.If you want to obtain an even thicker resin mortar layer, repeat the above process twice. At the end, the hardening resin contained inside the thick resin mortar layer is hardened by heating or at room temperature to form a thick hardened resin mortar coating layer on the inner surface of the steel pipe. .

Examples are shown below.

Example 1 100 parts by weight of curable epoxy resin (Epicor 828, manufactured by Yuka Shell Co., Ltd.), 50 parts by weight of room temperature curing agent (BOOI, manufactured by Yuka Shell Co., Ltd., Ebome), room temperature curable resin liquid (25° Rotational viscosity at C: 52 poise, pot life at 25°C: 25 minutes) A 1°5 pupil is arranged horizontally and rotates at a low circumferential speed of 1 m/sec or less with its central axis as the rotation axis. The resin liquid is supplied into the inside of a steel pipe (inner diameter 400fi, length 1m), the openings at both ends are closed, a thin layer of resin liquid is formed on the inner surface of the steel pipe, and the rotational speed of the steel pipe is further increased to 2m at the circumferential speed. /second, and the film thickness is about 70 mm after rotating for 1 minute.
A thin layer of resin liquid of 0 μm was formed and immediately supplied as a filler to a container (toy-shaped) having a slit with a width of about 2 mm and a length of about 20 cm installed inside the steel pipe. 6 kg of standard sand (aggregate; Toyo No. 5),
0.7 from Surin + of the container while vibrating the container.
Standard sand was sprinkled in a band shape for about 10 seconds at a supply rate of g/- minutes on the inner surface of a steel pipe rotating at a circumferential speed of 2゜m for 7 seconds (centrifugal force 2.0G). A thin layer of resin liquid was applied to the inner surface of a rotating steel pipe, and then the circumferential speed of the steel pipe was further increased to 3 m/s (centrifugal force 4.6 G).
After spinning for a minute and the resin liquid oozes out on the surface of the resin mortar layer, the surface is finished by lightly sliding it with a trowel to create a highly viscous, substantially non-flowing, uniform resin. After confirming that mortar N (thickness about 3 fi, resin liquid 1 volume, filler 4 volume) was formed, the rotation of the steel pipe was stopped. Thereafter, the steel pipe with the resin mortar layer formed on the inner surface is cured for about two weeks to harden the resin liquid of the resin mortar layer, and the inner surface of the steel pipe is coated with a hardened resin mortar coating layer (anticorrosion coating layer) of 3 fl thick. ) was formed.

The steel pipe having the anti-corrosion coating layer on the inner surface thus obtained has an adhesion force of the resin mortar hardened coating layer to the steel pipe of 70 kg/cd, a compressive strength of the hardened coating layer of 850 kg/ctd, The impact strength of the cured coating layer is 8. Q kg -rn, and it was a resin mold hardened coating layer with excellent long-term corrosion resistance.

Example 2 Unsaturated polyester (phthalic anhydride 2
．． 5 mol, fumaric acid 4.0 mol, adipic acid 3.5 mol, and 1,6-hexanediol 10.3 mol) solution) 100 parts by weight, liquid rubber (B.F. Manufactured by Gutdrich, Hiker CTBM)
A curable resin liquid (rotational viscosity at 25°C; A resin mold hardening coating layer (anticorrosion coating layer) with a thickness of 2.5 mm was formed on the inner surface of the steel pipe by performing the same operation as in Example 1, except that a pot life of 25°C (30 minutes) was used. did.

The steel pipe having the anti-corrosion coating layer thus obtained has an adhesive strength of the resin mortar hardened coating layer to the steel pipe of 1.
00 kg/a (and the compressive strength of the cured coating layer is 7
00 kglcsa, and the impact strength of the cured coating layer was 11.0 kg-m, indicating that the resin mortar cured coating layer had excellent long-term corrosion resistance.

Claims (1)

[Claims] While rotating a horizontally arranged steel pipe at a low speed about its center axis, a fluid hardening resin liquid is supplied into the steel pipe, and a thin layer of the resin liquid is applied to the inner surface of the steel pipe. and then increasing the rotational speed of the steel pipe and supplying a fine filler into the inside of the steel pipe to scatter the filler on the thin layer of the resin liquid, thereby forming a thin layer of the resin liquid. By applying a centrifugal force of approximately 1.5 to 12.5 G to the filler, a resin mortar layer in which the resin liquid and the filler are uniformly blended is formed, and finally, this A method for lining the inner surface of steel pipes, which is characterized by curing a curable resin liquid in a resin mortar layer.