JP2004205020A - Regenerative working method for steel pipe by stainless steel plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent water and the other carried fluid from leaking due to the corrosion of a steel pipe. <P>SOLUTION: In this regenerative working method for a steel pipe 11, the inner surface of the existing steel pipe 11 is covered while forming a tubular stainless steel wound pipe 13 of a specified length by winding a stainless steel plate, and the joint 16 of the stainless steel wound pipe 13 is sealed by an annular body 17 to increase the strength of the steel pipe 11 without actually reducing the cross section of the steel pipe 11. To prevent the stainless steel wound pipe 13 from coming into contact with the inner surface of the steel pipe 11, a plastic sleeve 12 is disposed between the inner surface of the steel pipe 11 and the stainless steel wound pipe 13 to electrically insulate the steel pipe 11 from the stainless steel wound pipe 13. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention covers the inner surface of an existing steel pipe while forming a tubular wound pipe having a predetermined length by winding a stainless steel plate, and seals a seam of the stainless steel wound pipe with an annular body, thereby obtaining a cross-sectional area of the steel pipe. The present invention relates to a method for rehabilitating steel pipes that increases the strength without substantially narrowing the steel pipe.
[0002]
[Prior art]
When the pipeline for water supply and the like is made of steel pipes, it is necessary to pay attention to the progress of the aging corrosion deterioration. There are various causes of corrosion, such as deterioration of water quality, environmental pollution, problems with the material itself, etc., but it is best to check the degree of progress in advance and take countermeasures before it becomes important to extend the life. In order to rehabilitate such water distribution pipes, for example, as in the invention of JP-A-2002-122287, rehabilitation is performed by pressing a reinforcing plate made of a stainless steel material against the inner wall surface of the pipe to form a reinforcing cylinder. There is a construction method.
[0003]
This method mainly targets buried pipes installed underground, and is premised on the practice of precast concrete pipes called PC pipes. On the other hand, there is no problem in implementing the above method for steel pipes, but the problem of electrochemical reaction caused by the contact of stainless steel pipe with the dissimilar metal on the inner wall surface of the existing steel pipe is taken into consideration. Must.
[0004]
Although there are various types of electrochemical reactions, it should be noted that macrocells occur in dissimilar metal contact systems such as steel and stainless steel contacts. Moreover, the amount of existing steel pipes is enormous, and it can be said that there is no other stainless metal material that can be used for reinforcement or repair, except for stainless steel plates.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above point, and an object thereof is to prevent leakage of water or other transport fluid due to corrosion of a steel pipe. Another object of the present invention is to provide a rehabilitation method having significance as an inner surface coating of a steel pipe.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention covers the inner surface of an existing steel pipe while winding a stainless steel plate to form a tubular stainless steel pipe having a predetermined length, and forms a seam of the stainless steel pipe in an annular shape. In order to prevent the stainless steel tube from coming into contact with the inner surface of the steel pipe, as a rehabilitation method for the steel pipe that increases the strength without substantially narrowing the cross-sectional area of the steel pipe, In this method, a plastic sleeve is arranged between the winding tube and the winding tube to create an electrically insulated state.
[0007]
By coating the inner surface of the existing steel tube while forming the stainless steel tube, a reinforcing structure having a form in which the stainless steel tube is attached to the inner surface of the steel tube is completed. As a result, the pressure acting from the outside (external pressure) is taken over by the steel pipe, and the pressure acting from the inside (internal pressure) is taken over by the stainless steel tube, so that a remarkable improvement in strength can be achieved. The cross-sectional area decreases only very slightly.
[0008]
In addition, in the case of an existing steel pipe, not only the already installed steel pipe but also all the existing steel pipes even before installation are included. Therefore, the latter includes a case where a new pipeline is installed while applying the method of the present invention. In this case, it means a method of reinforcing a steel pipe.
[0009]
In the method of rehabilitating or reinforcing the steel pipe, the present invention arranges a plastic sleeve between the inner surface of the steel pipe and the stainless steel pipe in order to prevent the stainless steel pipe from coming into contact with the inner surface of the steel pipe. The plastic sleeve keeps the steel tube and the stainless steel tube electrically insulated. This has the same significance as coating the inner surface of the steel pipe.
[0010]
As the plastic material that can be used for the sleeve, there can be mentioned several types based on a material having good insulating properties. For example, polyethylene, vinyl chloride, polyamide-based materials and the like are suitable, and silicone resin-based and polytetrafluoroethylene are effective in terms of heat resistance. These or other plastic materials are desirably placed at the destination in sheet or film form. Because it is supplied in liquid form, the working environment can be kept better than when a coating film is formed on the inner surface of the steel pipe or the outer surface of the stainless steel sheet, and the workability is good. This is because it is advantageous also in strength and is excellent in electric insulation.
[0011]
Since the stainless steel sheet is carried into a steel pipe, unfolded into a tubular shape, and the ends are welded, heat resistance is required at the welding location. Therefore, when using a plastic sleeve that does not have heat resistance, a sheet or tape-like member having fire insulating properties is interposed between the stainless steel tube and the plastic sleeve at the welded part of the stainless steel tube. Dress. As the heat-resistant and heat-insulating member, for example, a member made of glass fiber or the like, or a material obtained by combining glass fiber, mica, asbestos, and the like with another material can be used. The thickness of the sheet or tape-shaped member having fire-resistant and heat-insulating properties can be reduced by wetting the member.
[0012]
Other configurations, for example, a method of welding a stainless steel tube and sealing the adjacent end of a stainless steel tube having a predetermined length by using an annular body are described in the conventional method described above (Japanese Patent Application Laid-Open No. 2002-122287). No.). That is, an annular body made of a resilient material such as rubber is disposed over both adjacent ends of the stainless steel tube, and the annular body is pressed outwardly against the stainless steel tube newly covering the inner surface of the steel tube. As described above, a mounting method using a fixing plate can be adopted.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the illustrated embodiments. FIG. 1 shows an existing steel pipe 11 in which the rehabilitation method of the present invention is applied, and a ductile pipe is assumed as the steel pipe 11. A sleeve 12 made of polyethylene is disposed on the entire inner surface of the steel pipe 11.
[0014]
Next, a step of coating the inner surface of the existing steel pipe 11 is performed while forming a wound pipe 13 having a predetermined length L by winding a stainless steel plate. The stainless steel sheet is carried into the steel pipe according to the method disclosed in the invention of JP-A-2002-122287, for example, rolled and carried into the steel pipe from a manhole or the like. The stainless steel plate has a dimension equal to or greater than the perimeter of the inner surface of the steel pipe 11, and while bending this into a cylindrical shape, using a tool for pushing and spreading the inner surface of the steel pipe covered with the sleeve arranged in the previous step. By pressing, the overlapping edges of the stainless steel plates are joined by welding in a direction parallel to the axis of the steel pipe 11. The weld is indicated by reference numeral 14 in FIG.
[0015]
FIG. 3 further shows a refractory and insulating member 15 made of glass fiber with a non-heat-resistant polyethylene sleeve 12 interposed for protection from the heat of welding. The member 15 is provided between the outer surface near the end of the stainless steel plate and the inner surface of the sleeve 12 covering the inner surface of the steel pipe so as to back the welded portion 14. Since the welded portion 14 is provided over the length L which is a fixed size of the stainless steel wound tube 13, the fire-resistant and heat-insulating member 15 must also cover this length. The member 15 may be a tape-like member that has been previously attached to the back surface (outer surface) of the stainless steel plate.
[0016]
In this way, the inner surface of the steel pipe 11 is covered with the stainless steel winding pipe 13 with the plastic sleeve 12 interposed therebetween, so that the resistance to the pressure from inside and outside is greatly increased. I have. However, since a seam 16 is formed between the ends of the adjacent stainless steel winding tubes 13 and 13, the seam 16 is closed with an annular body 17 and sealed with water. The annular body 17 is formed in a ring shape having a diameter matching the inner diameter of the steel pipe 11 using rubber or a resin material that can be expected to have almost the same elasticity as this. The joint 16 is covered by fixing from the inside using the fixing plate 18 (see FIG. 4). The annular body 17 is provided with tip portions 19, 19 having bell-shaped outer surface shapes provided at both ends over the entire circumference so as to be in contact with the stainless steel winding tube 13, and a second seal portion 20 interposed therebetween to form a double seal. have. Further, a haunch portion 21 for transmitting the fixing force of the fixing plate 18 to the bell mouth portion is provided.
[0017]
The method of fixing the fixing plate 18 and the like are shown in FIGS. The illustrated fixing plate 18 divides the entire circumference into three equal parts, two parts of which are connected by a hinge part 22 so as to be foldable, and the remaining one part is a final connecting part 23. The coupling portion 23 has long holes 25, 25 through which screws 24 to be screwed into one of the two ends 18S, 18T of the fixed plate 18T are passed, and a resin 28 is injected and solidified into a gap between the long holes 25 and the screws 24. It is illustrated as using a connecting piece 27 that has a locking portion 26 that locks and locks the other 18T.
[0018]
According to the method of the present invention, since the original shape of the pipeline hardly decreases in the inner diameter and the unevenness can be suppressed in the flow direction, it is not necessary to pay attention to the change before and after the construction, particularly the decrease in the flow rate. Further, since only a thin stainless steel plate and an annular body are added, the weight increase after construction is small, and it is effective in a case of an aqueduct in which reinforcement of a substructure must be considered.
[0019]
【The invention's effect】
Since the present invention is constructed and operates as described above, it is possible to prevent the corrosion progress of the steel pipe, to prevent the leakage of water and other transport fluids, and to reduce the cross-sectional area of the steel pipe to a small extent. Therefore, there is no need to worry about a change in flow characteristics, and since the inner surface of the steel pipe can be covered with a stainless steel plate, the steel pipe has a remarkable effect such as having a meaning as a corrosion-resistant coating on the inner surface of the steel pipe.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an example of a method for rehabilitating a steel pipe using a stainless steel plate according to the present invention.
FIG. 2 is a transverse sectional view of the same.
FIG. 3 is a sectional view in the circumferential direction showing a welded portion of a stainless steel tube.
FIG. 4 is a cross-sectional view showing an annular body.
FIG. 5A is a plan view showing a hinge of a fixing plate.
(B) The same side view.
FIG. 6A is a plan view showing a connecting portion of a fixing plate.
(B) A sectional view in the same circumferential direction.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Steel pipe 12 Sleeve 13 Stainless steel winding pipe 14 Welding part 15 Fireproof and heat-insulating member 17 Annular body 18 Fixing plate

Claims (3)

While forming a tubular stainless steel tube having a predetermined length by winding a stainless steel plate, the inner surface of the existing steel tube is covered, and the seam of the stainless steel tube is sealed with an annular body to substantially reduce the cross-sectional area of the steel tube. This is a rehabilitation method for steel pipes that increases strength without narrowing.In order to prevent contact between the inner surface of the steel pipe and the stainless steel tube, a plastic sleeve is inserted between the inner surface of the steel tube and the stainless steel tube. A method for rehabilitating steel pipes using stainless steel plates, which is arranged and electrically insulated. For the purpose of protecting the plastic sleeve having no heat resistance from the heat of welding to the stainless steel tube, a sheet or tape-like member having fire resistance and heat insulation is used to weld the stainless steel tube to the stainless steel tube. 2. The method for rehabilitating a steel pipe with a stainless steel plate according to claim 1, wherein the method is performed by interposing the pipe between the sleeve and a plastic product sleeve. 3. The method for rehabilitating a steel pipe with a stainless steel sheet according to claim 2, wherein the sheet or tape-shaped member having fire-resistant and heat-insulating properties is reduced in thickness by moistening the member.

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