JPH09327834A - Method and device for covering steel material to be covered with covering agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the oxidation of a steel pipe die to the residual air at the covering part of materials to be covered from developing by a method wherein a thermosetting covering agent is charged in an enclosed gap made between the outer peripheral surface of steel pipes to be covered and the inner surfaces of split molds, which are installed on the region aiming at covering with the covering material of the steel pipes to be covered and then cured. SOLUTION: A split mold 13 having a vent hole 12 is installed so as to cover the butt-weld of steel pipes to be covered Pa and Pb and its peripheral part. Next, a thermosetting covering agent PU is prepared by mixing a urethane resin solution and a hardener with a mixing device so as to be supplied through the covering agent supplying hole of the splid mold 13 into an enclosed gap A, which is formed between the inner surface of the split mold and the outer surface of the steel pipes to be covered Pa and Pb. Next, after the covering agent PU is confirmed to be fully filled in the enclosed gap A by means of a vent hole 12, the covering agent PU is cured and hardened for a predetermined period of time, the covering agent PU covers the weld WP and its peripheral part. Then, after the elapse of the predetermined curing time, the split mold 13 is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for coating a coated steel material such as coated steel pipe, coated steel, coated steel bar, coated steel wire, etc., which is required to have high corrosion resistance, with a thermosetting coating agent. is there.

[0002]

2. Description of the Related Art As is well known, steel materials, such as steel pipes, are widely used for transporting gas, water, oil, etc., and in marine structures. To enhance their corrosion resistance, urethane resins and epoxy resins are used. It is often used as a coated steel pipe by coating a resin such as a resin or a polyester resin.

This coated steel pipe is often used by connecting a plurality of pipes, and in this case, butt welding is generally used for the connection. When the welded portion is coated with the coating agent, the coating agent impedes the weldability during welding and the strength of the welded portion cannot be secured. In the vicinity of the weld,
The coating material disappears due to welding heat, and the function as a coating material is lost. For this reason, when using by welding and joining, the coating is not applied to the welded portion and its peripheral portion, or the coating is removed in advance and the coating is recoated after welding.

Conventionally, as a method of coating a welded portion of a coated steel pipe and its peripheral portion, a heat-shrinkable tube generally composed of two layers of a polyethylene layer and an adhesive layer has been used, which is burner-heated to be heat-shrinked and bonded. -A coating method for coating is known.

In this coating method, as shown in FIG. 4, at the joint wp between the coated steel pipes Pa and Pb to be welded and the peripheral portion thereof, the coating film c is not formed on the steel pipe P, or the coating film is removed before welding. I am trying to do this 2
Before the covered steel pipes Pa and Pb of the book are butted, a heat-shrinkable tube tb composed of two layers of a polyethylene resin ps and an adhesive ss is inserted into one of the coated steel pipes and then butt welded.

After the welding, the welded portion wp and its peripheral portion are brushed to remove the deposits, and the heat-shrinkable tube tb is positioned so as to cover the welded portion wp and its peripheral portion, and the heat-shrinkable tube tb. The adhesive ss on the inner surface of the tube tb is melted by the burner heating from the outer surface of the tube tb, and the tube is thermally shrunk to bond the adhesive ss to the welded portions wp of the coated steel pipes Pa and Pb and their peripheral portions. It is intended to be covered.

However, in this coating method, since the welded portion wp is not flat, as shown in FIG. 5, a gap ao is formed at the stepped portion between the welded portion wp and the coating c of the coated steel pipe.
It is unavoidable that air remains after the coating, and the oxidation of the steel pipe P grows in the air residual portion, and the durability of the steel pipe deteriorates. Further, it is necessary to uniformly heat the heat-shrinkable tube tb with a burner in order to uniformly heat-shrink the tube, and it requires a skilled worker in the construction technique and a long time for heating.

Further, it is necessary to insert a heat-shrinkable tube into one of the coated steel pipes in advance before welding work, and since it is exposed to the outdoor environment until the construction is completed, the adhesive surface on the inner surface is It is not uncommon for dust, water, etc. to adhere to and remain on the surface, impairing the adhesiveness of this adhesive. There is a problem that complicated construction is required to prevent the occurrence of such an inconvenient phenomenon, resulting in an increase in construction cost.

[0009]

SUMMARY OF THE INVENTION The present invention provides a coated steel pipe,
On the outer surface of coated steel materials such as coated shaped steel, coated steel bars, coated steel wires (including coated stainless steel materials and referred to as “coated steel materials”), a main agent and a curing agent made of a resin such as urethane resin, epoxy resin, polyester resin, etc. When coating a thermosetting coating agent mixed with, there is no fear of oxidation of the steel pipe due to air residue, decrease in adhesiveness, no increase in construction cost, and a simple method for coating the coating material on the coated steel material and A coating device is provided.

[0010]

Means for Solving the Problems The first invention of the present invention is:
In the coating agent coating target area on the outer surface of the coated steel material, a split die having a gas vent is attached, and a sealed gap corresponding to the coating thickness is formed between the outer surface of the coated steel material and the split die inner surface, and in this sealed gap, A coating agent for coated steel, characterized by supplying and curing a thermosetting coating agent obtained by mixing a curing agent with a main agent made of a resin liquid such as urethane resin, epoxy resin, polyester resin, etc. Is a coating method.

According to a second aspect of the present invention, a split mold having a gas vent and a coating agent supply port and having a heating device is mounted in the coating target area on the outer surface of the coated steel material, and the split mold is provided between the outer surface and the inner surface of the split mold. Form a closed gap corresponding to the coating thickness, and in this closed gap,
A thermosetting coating material prepared by mixing a curing agent with a base resin consisting of a resin liquid such as urethane resin, epoxy resin, polyester resin, etc., to a coated steel material characterized by curing and curing while heating. The coating method of the coating agent.

The third invention and the fourth invention are positioned as a coating material coating apparatus for carrying out the first invention or the second invention, and the third invention is a moving carriage,
A storage tank for the main agent and the curing agent, a supply pump, a mixing device, a split mold having a gas vent and a coating material supply port, and a supply pipe connecting the split mold and the mixing device, A fourth invention is characterized in that, in the third invention, a heating device is attached to the split mold.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a thermosetting coating is prepared by mixing a coating material, for example, a coating steel pipe, with a main agent composed of urethane resin, epoxy resin, polyester resin, etc. and a curing agent on the outer peripheral surface thereof. When coating the agent, a split mold is attached to the coating target area of the coated steel pipe, and a sealing gap corresponding to the coating thickness is formed between the split mold inner surface and the outer peripheral surface of the coated steel pipe. , The outer peripheral surface of the coated steel pipe is coated by supplying and curing the above-mentioned thermosetting coating agent, and there is a fear of oxidation of the steel tube due to residual air in the coating portion of the coating agent, deterioration of adhesion, and construction. It is possible to realize the coating of the coating agent easily and accurately without concern about cost increase. By heating during the curing, the curing time can be shortened and the coating time can be shortened.

The present invention can be widely applied as a method for coating the outer surface of a coated steel material with a thermosetting coating material, but it can be used for coating a joint portion of a coated steel material or repairing a coating agent peeling portion (coating damaged portion). It is more suitable as a coating method of a coating agent in a relatively narrow range.

In the case of covering the joint, not only when the joint is obtained by butt welding, but also when the coated steel material is joined in a T-shape or when joined in an inclined manner, Can be applied. In this case, the shape and structure of the split mold to be mounted may be taken into consideration depending on the shapes of the joint portion and its peripheral portion.

The split mold is for forming a gap corresponding to the coating thickness of the thermosetting coating agent between the outer surface of the coated steel material and the inner surface of the split mold. The split mold is composed of an upper mold and a lower mold. By fitting and locking the mold on the outer surface of the coated steel material, the thermosetting coating agent supplied in a liquid state can be cured in the closed gap to coat the coated steel pipe with the thermosetting coating agent.

The thermosetting coating agent used in the present invention includes:
It is suitable to use a resin liquid such as urethane resin, epoxy resin, polyester resin, etc. as the main agent, and mix it with a hardening agent, depending on the type of coating film coated on the coated steel material. A material that has a sufficient melting / adhesive strength (affinity) with respect to this coating and a sufficient melting / adhesive strength (affinity) with respect to steel materials and that hardens in a short time is selected.

It can be said that the coating film of the coated steel material and the coating material are preferably the same, but they are not necessarily the same. If the coating and the coating are not the same, it is effective to apply a primer treatment, roughening or heat treatment to the coating of the coated steel that comes into contact with the coating to strengthen the adhesive strength with the coating. is there.

The thermosetting coating material is stored in a storage tank, and is supplied from each storage tank to the inside of the split mold closed gap by a supply pump through a mixing device composed of a mixing block and a mixer. Here, the outer surface of the coated steel material is coated by curing and hardening.

At this time, by heating, the thermosetting coating material can be cured in a shorter time. As the heating means in this case, a heating device such as an electric heater, an electric heating device, an induction heating device, an electric heating device such as a band heater, which can accurately control the heating temperature that influences the adhesiveness of the coating agent, is highly suitable. To prevent the thermosetting coating agent from adhering to the inner surface of the split mold, it is desirable to carry out anti-adhesion treatment such as chrome plating, Teflon coating, or release material coating.

The present invention will be outlined below together with an example of a coating apparatus for carrying out the present invention shown in FIGS. In this example, the joined coated steel pipes Pa and Pb are to be coated, a urethane resin liquid is used as a main component, and a curing agent is mixed with this as a thermosetting coating agent.

As shown in FIGS. 1 and 2, the coating apparatus of the present invention stores a moving carriage 1, a storage tank 3 for storing the urethane resin liquid 2 mounted on the moving carriage, and a curing agent 4. The storage tank 5, the two-liquid supply pump 6 for supplying the urethane resin liquid 2 and the curing agent 4 from the two storage tanks, the two-liquid supply pipes 7a and 7b, and the urethane resin liquid 2
A mixing device 10 including a mixing block 8 for mixing the curing agent 4 and a curing agent 4, a coating agent supply port 11 and a gas vent port 1
A split mold 13 having a built-in electric heater h and a flexible coating material supply hose 1 for connecting the split mold and the mixing device 10.
4 and an on-off valve (three-way valve) 1 arranged on this supply hose
5, a cleaning pump 16 for cleaning the flow path of the thermosetting coating material pu, and a cleaning liquid storage tank 16t.

The cleaning liquid is supplied from the mixing device 10, and after cleaning the mixing device and the coating material supply hose 14, it is discharged from the discharge pipe 16o through the on-off valve (three-way valve) 15. The split die 13 includes an upper die 13a and a lower die 13b, and the upper die 13a and the lower die 13b can be locked by a locking tool 17.

As shown in FIG. 2, the split mold 13 has a gap adjusting ring 1 made of silicon rubber and having sidewalls at both ends.
8a and 18b are provided, and the joined coated steel pipe P is
When split mold 13 is attached to a and Pb, this split mold 1
A closed gap A corresponding to the coating thickness of the thermosetting coating agent pu can be formed between the outer surfaces of the coated steel pipes Pa and Pb joined to the inner surface of 3. The split mold 13 is placed on a pedestal 19 provided on the moving carriage 1, and is attached / detached to / from the coated steel pipes Pa and Pb by hand.

The thermosetting coating agent can be coated on the welded portion of the coated steel pipe by using the coating apparatus configured as described above. The coating operation is performed in the following procedure. After the field welded coated steel pipes Pa and Pb are butt-welded and joined, the joint wp and its peripheral portion are sanded to clean the surface (corrosion-proof treatment is performed as necessary).

The split mold 13 placed on the mount 19 of the movable carriage 1 is mounted so as to cover the butt welded portion wp of the coated steel pipes Pa and Pb and the peripheral portion thereof. Urethane resin liquid 2 from storage tank 3, storage tank 5
From the hardened material 4 to the two-liquid supply pipe 7 by the liquid coating pump 6.
The mixture is fed via a and 7b to a mixing device 10 including a mixing block 8 and a mixer 9, where the urethane resin liquid 2 and the curing agent 4 are mixed to form a thermosetting coating material pu.

The on-off valve (three-way valve) 15 is opened, and the thermosetting coating material pu obtained by mixing in the mixing device 10 is passed through the coating material supply hose 14 and the coating material supply port 11 of the split mold 13.
And is supplied into a gap A formed between the inner surface of the split mold and the outer surfaces of the coated steel pipes Pa and Pb.

After confirming that the thermosetting coating material pu is sufficiently filled in the closed space A through the gas vent port 12, the on-off valve 15 is closed and cured by curing for a predetermined time. The thermosetting coating material pu is coated on the butt welding portion wp of the coated steel pipes Pa and Pb and its peripheral portion. During this curing, the heating device h heats the thermosetting coating pu and the coated steel pipe to accelerate the curing of the thermosetting coating and shorten the curing time.

The cleaning pump 16 is operated, and the thermosetting coating material pu is supplied with the cleaning liquid from the cleaning liquid storage tank 16t.
To prepare for the next coating operation of the coated steel pipe. After a predetermined curing time has elapsed, the split mold 13 is removed from the coated steel pipe and returned to the mount 19 of the movable carriage 1. In this way, the butt welded portion wp of the coated steel pipes Pa and Pb
The thermosetting coating material pu can be coated with a predetermined thickness on the and its peripheral portion.

The present invention is not limited to the contents of the above example. For example, the object to be coated is not limited to the coated steel pipe, and can be applied to the coated steel, coated steel bar and the like. In addition, in order to accelerate curing during curing of the thermosetting coating agent, the split mold 13 was provided with an electric heating machine h as a heating device, but this heating device may be an induction heating device, a hot air heating device, a device, or the like. However, it is not essential that the split mold be built in, and they may be arranged independently.

[0031]

EXAMPLE Using a coating apparatus and a coating method for a coated steel pipe as shown in FIGS. 1 and 2, a two-component curing type urethane is applied to a butt welding joint between the coated steel pipes Pa and Pb having a urethane resin coating. A coating experiment was conducted using an elastomer as the coating agent pu. The experimental conditions and experimental results will be described below.

[Experimental conditions] (Steel pipe to be coated) Material: General structural steel, outer diameter: 200 mm, thickness: 5.8
mm Coating material: Urethane resin, coating thickness: 3 mm (Covering conditions) Coating material: Two-component curing type urethane elastomer (mixing ratio main agent 3 / curing agent 1) Coating width: 300 mm, coating thickness: 2.5 mm or more (Split mold conditions) Split mold gap: 3 mm, curing time: 2 hours

As shown in FIG. 3, the coating condition of the welded portion and the peripheral portion of the coated steel pipe obtained by this experiment had a good appearance, and no defects that impair the coating properties were observed. In addition, the coating formed on the welded portion and its peripheral portion was also inspected and evaluated for the coating thickness, adhesive strength, presence / absence of air entrainment, and the like.

As a result, the coating thickness is 2.6 to 2.9 mm.
There was no problem. Also, the adhesive force is 60-80kg
/ Cm ² showed a sufficient adhesive force. Regarding the presence / absence of air entrapment, no residual air was observed in the vicinity of the welded portion and also in the stepped portion overlapping the coating c of the coated steel pipe.

[0035]

INDUSTRIAL APPLICABILITY In the present invention, a thermosetting coating agent obtained by coating a coated steel material, for example, a coated steel pipe with an urethane-based, epoxy-based, or polyester-based resin liquid as a main ingredient and mixing it with a curing agent. At the time of coating, a split mold is attached to the coating target area of the coated steel pipe, and a sealing gap corresponding to the coating thickness is formed between the split mold inner surface and the outer peripheral surface of the coated steel pipe. The outer peripheral surface of the coated steel pipe is coated by supplying and curing the thermosetting coating agent.

As a result, the coating of the coating material can be easily and accurately realized without fear of oxidation of the steel pipe due to residual air in the coating portion of the coating material, deterioration of adhesiveness, and increase in construction cost. By heating during the curing, the curing time can be shortened and the coating time can be shortened.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view conceptual diagram showing a structural example of a coating apparatus used for carrying out the present invention.

FIG. 2 is a partially cutaway sectional side view conceptual diagram showing an example of attachment to the split type coated steel pipe in FIG.

FIG. 3 is a partially cutaway sectional side view conceptual diagram showing a coating agent coating state of a coated steel pipe obtained by an example of the present invention.

FIG. 4 is a partially cutaway sectional side view conceptual view showing an example of a conventional coating method for coating a coated steel pipe.

FIG. 5 is a partially cutaway side view conceptual diagram showing a coating agent coating state of a coated steel pipe obtained by a conventional example.

[Explanation of symbols]

 A, ao Sealing gap c Coating h Electric heater P Steel pipe Pa, Pb Coated steel pipe pu Thermosetting coating wp Welded part 1 Moving carriage 2 Urethane resin liquid 3 Storage tank 4 Curing agent 5 Storage tank 6 Two-liquid supply pump 7a, 7b Two-liquid supply pipe 8 Mixing block 9 Mixer 10 Mixing device 11 Coating agent supply port 12 Gas vent port 13 Split mold 13a Upper mold 13b Lower mold 14 Coating agent supply hose 15 Open / close valve (3 way valve) 16 Cleaning pump 16t Cleaning liquid storage tank 17 Locking tool 18a, 18b Gap adjusting ring 19 Stand

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kotaro Yoshida 2-6-3 Otemachi, Chiyoda-ku, Tokyo Within Nippon Steel Corporation (72) Inventor Yoshitaka Kusano 1 Kimitsu, Kimitsu-shi Kimitsu Inside the factory (72) Inventor Toyoo Ando Kimitsu No. 1 Kimitsu City Kimitsu Co., Ltd. Kimitsu factory Inside (72) Inventor Masahiro Endo Kimitsu City No. 1 Kimitsu City Kimitsu Co., Ltd. Kimitsu factory

Claims (4)

[Claims] 1. A split mold having a gas vent is attached to a coating agent coating target area on the outer surface of the coated steel material, and a closed gap corresponding to the coating thickness is formed between the outer surface of the coated steel material and the split mold inner surface. A coating characterized by supplying and curing and curing a thermosetting coating agent, which is a mixture of a main agent made of a resin liquid such as urethane resin, epoxy resin, polyester resin, and a curing agent, in the closed space. A method for coating a steel material with a coating agent. 2. A split mold having a gas vent and a coating supply port and equipped with a heating device is attached to a coating material coating target area on the outer surface of the coated steel material, and the coating thickness is equivalent to between the outer surface and the inner surface of the split die. A thermosetting coating agent, which is a mixture of a main agent made of a resin liquid such as urethane resin, epoxy resin, polyester resin, and a curing agent, is supplied into the closed gap and heated. A method for coating a coated steel material with a coating agent, which is characterized by curing and hardening. 3. A mobile trolley, a storage tank for a main agent made of a resin liquid and a curing agent, a supply pump, a mixing device, a split mold having a gas vent and a coating material supply port, and this split mold and a mixing device. An apparatus for coating a coating material on a coated steel material, comprising: a supply pipe for connecting the above. 4. The coating device for coating a coating steel material according to claim 3, wherein the split mold is provided with a heating device.