JPH10267188A - Corrosion prevention method of pipe at pipe support part and corrosion prevention method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a progress of corrosion of a contact part of a pipe such as carbon steel pipe and a pipe support member such as a bracket by providing an anticorrosive late between the pie and the pipe support member and bonding the pipe with the anticorrosive plate by adhesive. SOLUTION: A corrosion prevention pipe consists of a pipe 1, a U-shaped metal fitting for fixing a pipe 2, an anticorrsive plate 3, a pipe support member 4 such as a bracket, and an adhesive layer 5. As a material of the anticorrosive plate, there is no particular restriction so far as it has the rigidity. As an example, stainless steel or fiber reinforced plastic such as fiber glass reinforced plastic or carbon fiber reinforced plastic may be used. Polyester adhesive, epoxy adhesive, and acrylic adhesive are preferable as adhesive. In particular, acrylic adhesive is preferable, and two-liquid type modified acrylic adhesive is most preferable. This is because it excels in the bonding property of an existing painted pipe with the anticorrosive plate and enables easy construction without removing a painted film of the pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anticorrosion method and an anticorrosion method for a contact portion between a pipe and a pipe support member, and more particularly to an anticorrosion method and an anticorrosion method having excellent durability.

[0002]

2. Description of the Related Art Conventionally, a pipe support surface of a pipe support member such as a bracket is often disposed horizontally to support a load of the pipe, and a pipe and a pipe near a contact point between the pipe and the pipe support member are often provided. Rainwater and dust that have penetrated into the gap with the support member stay and form a local battery. Corrosion in the vicinity of the contact point is unavoidable, and pipe repair work is required.

[0003] As a simple method of preventing corrosion of the contact portion between a carbon steel pipe and a pipe support member such as a bracket, a method of coating the pipe with anticorrosion tape or a method of welding a patch plate to the pipe and increasing the thickness of the pipe to prevent corrosion. Method. But,
The former method using anticorrosion tape causes peeling of the anticorrosion tape due to friction with the bracket due to the expansion and contraction of the pipe, and the latter method of welding the patch plate to the pipe involves the production of hazardous materials with restricted use of fire. It is difficult to implement in factories, chemical factories or factories where fire prevention measures are complicated.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and prevents the corrosion of a contact portion between a pipe such as a carbon steel pipe and a pipe support member such as a bracket, thereby improving durability. It is an object of the present invention to provide a simple and economical method for preventing corrosion of piping in a piping support portion, and a method for preventing corrosion of piping.

[0005]

According to a first aspect of the present invention, an anticorrosion plate is interposed between a pipe and the pipe support member, and the pipe and the anticorrosion plate are bonded with an adhesive. It is a method of preventing corrosion of piping in the part. In the first invention, in the plate thickness cross-sectional shape of the anticorrosion plate, an adhesion surface of the anticorrosion plate to the pipe has an arc shape that is a part of a circle, and the arc is substantially the same as the outer periphery of the pipe. It is preferable that the adhesive surface of the anticorrosion plate is bonded to the outer peripheral surface of the pipe with an adhesive.

In the first invention, it is preferable that the adhesive is an adhesive selected from a polyester-based adhesive, an epoxy-based adhesive, and an acrylic-based adhesive. Is more preferably an acrylic adhesive. Further, in the first invention, it is preferable that the material of the anticorrosion plate is stainless steel or fiber reinforced plastic.

A second invention is a method for preventing corrosion of a pipe in a pipe support portion in which an anticorrosion plate is interposed between the pipe and a support member of the pipe, and the outer peripheral surface of the pipe and the surface of the anticorrosion plate are bonded with an adhesive. In the thickness cross-sectional shape of the anticorrosion plate, the bonding surface of the anticorrosion plate to the pipe has an arc shape that is a part of a circle,
After applying the adhesive to the adhesive surface of the anticorrosion plate having the same radius of curvature d as the outer circumference of the pipe, after inserting the anticorrosion plate into the gap between the pipe and the pipe support member provided in advance, 0.5mm between pipe and top of U-shaped pipe fixing bracket
A method for preventing corrosion of piping in a piping support portion, wherein the above-described gap is provided and the piping is fixed by a U-shaped piping fixing bracket.

[0008] In the second invention, the adhesive is preferably an adhesive selected from a polyester-based adhesive, an epoxy-based adhesive, and an acrylic-based adhesive. More preferably, it is an acrylic adhesive. In the second aspect, the material of the anticorrosion plate is preferably stainless steel or fiber reinforced plastic.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The present inventors have conducted extensive research to reduce repair work associated with corrosion of the contact portion between the pipe and the bracket,
A simple and economical anticorrosion method and anticorrosion method have been developed to prevent the progress of corrosion at the contact portions between pipes such as carbon steel pipes and pipe support members.

[0010] Basic conditions for preventing corrosion at a contact portion between a pipe and a pipe support member such as a bracket include:
It is required to block corrosion accelerating substances such as rainwater, to prevent the anticorrosion member provided at the contact part from being easily damaged, to be simple and economical to construct, and to use fire in chemical factories handling organic chemical substances. Not required construction method is required.

As a method for satisfying the above-mentioned conditions, the present inventors provide a pipe support in which an anticorrosion plate made of a rigid material is interposed at a contact portion between a pipe and a pipe support member, and the anticorrosion plate is bonded to the pipe with an adhesive. We came up with a method of anticorrosion of piping in pipes and anticorrosion method. Further, in this case, in the plate thickness cross-sectional shape of the anticorrosion plate, the adhesion surface of the anticorrosion plate to the pipe has an arc shape that is a part of a circle, and the arc has substantially the same radius of curvature d as the outer circumference of the pipe.
By using an anticorrosion plate having the above, the anticorrosion plate is adhered to the outer peripheral surface of the pipe with an adhesive, so that the thermal expansion and contraction in the longitudinal direction of the pipe due to the temperature change in summer to winter and the temperature change in a short period of time. It has been found that an anticorrosion method and an anticorrosion method having no problem can be achieved.

FIG. 1 shows a cross-sectional view (a) and a side view (b) of a corrosion protection pipe according to the present invention. In FIG. 1, 1 is a pipe, 2 is a U-shaped pipe fixing bracket, 3 is an anticorrosion plate (hereinafter also referred to as a pad), 4 is a pipe supporting member such as a bracket, 5
Indicates an adhesive layer. Further, FIG. 2 shows specifications such as dimensions of each member in a pipe cross section (a) and pipe longitudinal directions (b) and (c) according to the present invention.

In FIG. 2, 1a is a pipe outer periphery, 4a and 4b are pipe support points (locations at which the pipe support members are provided), D is an outer diameter of the pipe, and d is an adhesive surface of the anticorrosion prevention plate 3 to the pipe outer circumference 1a. The radius of curvature of a circular arc, t is the thickness of the anticorrosion plate 3, and θ is two straight lines X ₁ and X ₂ connecting both ends of the anticorrosion plate in the arc direction of the anticorrosion plate and the center of the pipe. L (hereinafter referred to as the circumferential angle of the anticorrosion plate (pad)), L is the length of the pad 3 in the longitudinal direction, B is the distance between adjacent pads (hereinafter referred to as the span), and other symbols are It shows the same contents as FIG.

As described above, the pipe thermally expands and contracts in the longitudinal direction of the pipe due to a change in temperature. On the other hand, a pipe support member such as a bracket (hereinafter, the pipe support member is collectively referred to as a bracket) is connected to a pipe such as an angle. When the anticorrosion method shown in FIG. 1 is adopted, the adhesive layer 5 of FIG. 1 may be separated from the pipe 1 due to a change in temperature.

In this case, intrusion and stagnation of rainwater, dust and the like into the concave gap generated between the anticorrosion plate 3 and the pipe 1 cannot be avoided, and conversely, corrosion of the pipe is promoted. For this reason, the present inventors compared the adhesive strength between the pad and the pipe and the frictional force between the pad and the bracket, as described below. This is because when the pipe thermally expands and contracts in the longitudinal direction, if the adhesive strength τ between the pipe and the pad is sufficiently large with respect to the frictional force P between the pad and the bracket, peeling of the pad from the pipe is prevented. Because I thought.

That is, if the condition of the following formula (1) is satisfied, the peeling of the pad from the pipe does not occur. τ> P (1) In the above equation (1), the frictional force P between the pad and the bracket and the adhesive strength τ between the pipe and the pad are expressed by the following equation (2), respectively.
Required by (3).

Friction force between pad and bracket: P = W · μ [kg] (2) Adhesive strength between pipe and pad: τ = a · σ [kg] (3) Each symbol in (2) and (3) indicates the following. W [kg]: Load applied to bracket μ [-]: Friction coefficient between pad and bracket, μ =
0.3.

A [cm ² ]: Adhesive area of pad σ [kg / cm ² ]: Adhesive strength per unit area of pad Next, for a water pipe having a pipe diameter of 100 A, the specifications of FIG. Then, the above equations (1), (2) and (3) were estimated. Pad longitudinal dimension: L = 20 cm Pad circumferential angle: θ = 60 ° Piping outer diameter: D = 11.43 cm Span: B = 7.5 m (Self weight + liquid weight) per pipe unit length: H = 20.89kg / m
(Liquid density γ = 1) Length of circular arc in section of pad (: length in circumferential direction of pad): C = πD × (1/6) = 6 cm Adhesive area of pad: a = 20 × 6 = 120 cm ² Load applied to bracket per span: W = H
・ B = 20.89 × 7.5 = 157kg Therefore, from the above formula (2), the frictional force between the pad and the bracket: P = W ・ μ = 157 × 0.
3 = 47.1 kg Next, based on the measurement results of the adhesive strength (tensile shear strength) shown in Examples (Reference Examples 1 and 2) described later, the adhesive strength σ per unit area of the pad was set to 30 kg / cm ^2. , The formula (3)
As a result, the following results were obtained.

Adhesion strength between pipe and pad: τ = a · σ = 12
0 × 30 = 3,600 kg or more From the results obtained, τ≫P, τ / P = 76 (times). According to the present invention, the bonding of FIG. Agent layer 5 is piping 1
It is presumed that the possibility that the anticorrosion function of the anticorrosion plate of the present invention is impaired is low, and the present invention has been achieved.

Hereinafter, anticorrosion plates, adhesives, construction methods and the like preferably used in the present invention will be described. The present invention is preferably used as a method for preventing corrosion of pipes such as carbon steel pipes and alloy steel pipes in a pipe support portion, and as a corrosion prevention method. More preferably used.

The material of the anticorrosion plate used in the present invention is not particularly limited as long as it has rigidity. However, as shown in Examples described later, from the viewpoint of durability, stainless steel or fiber is used. More preferably, it is a reinforced plastic. Examples of the fiber reinforced plastic include glass fiber reinforced plastic and carbon fiber reinforced plastic.

The adhesive used in the present invention is preferably a polyester-based adhesive, an epoxy-based adhesive or an acrylic-based adhesive, more preferably an acrylic-based adhesive, and particularly preferably a two-pack type modified adhesive. Acrylic adhesives are preferred. This is because the present invention is more preferably applied as an anticorrosion method for existing pipes, in which case the existing pipes are often coated, and the above adhesive, more preferably an acrylic adhesive, particularly a two-part type By using the modified acrylic adhesive of the above, the adhesion between the painted existing pipe and the anticorrosion plate is excellent, and at the time of construction, the pipe near the peeling / corrosion part where the existing pipe and the bracket are in contact. This is because the construction can be easily performed without removing the coating film.

As a preferable construction method according to the present invention, the following method is exemplified. Lift the pipe corresponding to the bracket by several tens of mm, and remove the rust from the pipe with a metal spatula or wire brush. In this case, if necessary, the paint on the pipe is removed by the same method as described above. According to the present invention, the polyester-based adhesive described above,
By using an epoxy adhesive, an acrylic adhesive, more preferably an acrylic adhesive, especially a two-part modified acrylic adhesive, it is not necessary to completely remove the paint, and the floating paint is removed. Sufficient adhesive strength can be obtained even with this degree.

After the rust or the paint is further removed, the surface of the pipe is finished using sandpaper, and an adhesive is applied to the surface of the anticorrosion plate that has been cut into a predetermined size and is bonded to the outer periphery of the pipe.
The anticorrosion plate after application is bonded to the outer peripheral surface of the pipe at a location facing the bracket. After bonding the anticorrosion plate, lower the pipe, and between the pipe and the top of the U-shaped pipe fixing bracket, preferably 0.5m
The pipe is fixed with a U-shaped pipe fixing bracket with a gap of at least m, more preferably at least 1 mm.

This is to prevent the adhesive layer from peeling off due to stress applied to the adhesive layer due to thermal expansion and contraction of the pipe due to a change in temperature. In order to fix the piping, it is preferable that the gap is 2.5 mm or less. According to the present invention, by applying the present invention to horizontal piping,
Since the adhesive layer between the pipe and the anticorrosion plate is press-bonded by the weight of the pipe, better adhesive strength can be obtained.

The pipe diameter under the condition that the adhesive strength is 30 kg / cm ² ,
The preferred specifications of the longitudinal dimension L of the anticorrosion plate, the circumferential angle θ of the anticorrosion plate, and the thickness t of the anticorrosion plate are SUS, FRP
Table 4 (SUS anticorrosion board) and Table 5
(SUS anticorrosion board), Table 6 (FRP anticorrosion board), and Table 7 (FRP anticorrosion board). In the present invention, the total length in the longitudinal direction of the anticorrosion plate shown in Tables 4 and 6 (dimensions:
L) It is preferable that the adhesive is applied over the entire angle θ in the circumferential direction of the anticorrosion plate.

Further, in the present invention, as described above, in the thickness cross-sectional shape of the anticorrosion plate, the bonding surface of the anticorrosion plate to the pipe has an arc shape that is a part of a circle, and the arc corresponds to the outer periphery of the pipe. It is preferable that the adhesive surface of the anticorrosion plate has substantially the same radius of curvature d and that the adhesive surface of the anticorrosion plate is bonded to the outer peripheral surface of the pipe with an adhesive. a)
It is preferable that the following formula (4) is satisfied.

(1/2) · D ≧ d ≧ (1/2) · D-2 [unit: mm] (4) The radius of curvature d of the arc is the upper and lower limits of the above equation (4). If it does not, sufficient adhesive strength cannot be obtained in either case,
Not preferred. According to the anticorrosion method of the present invention described above, according to the anticorrosion method, as shown in Examples below, the adhesive layer between the carbon steel pipe and the anticorrosion plate, the longitudinal direction of the pipe with the temperature change. Since it has adhesive strength enough to withstand the frictional force between the anticorrosion plate and bracket due to thermal expansion and contraction, rainwater into the gap between the pipe and the anticorrosion plate due to peeling of the adhesive layer,
The intrusion and accumulation of dust did not occur, and the corrosion of the pipe at the pipe support could be completely prevented.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. (Reference Example 1) First, assuming an existing painted pipe as a main target pipe when applying the present invention, as a basic experiment, a painted test material (a test material as a pipe) and an unpainted sample pipe were used. The adhesive strength with a test material (a test material as an anticorrosion plate) was examined.

The test was conducted under the following conditions and the method shown in FIG. [Test material:] Test material as anticorrosion board; SUS304 or FRP (glass fiber reinforced plastic) Test material as piping; SS400 Painted product (paint; phthalic acid paint) [Adhesive:] Polyester adhesive , Epoxy adhesive, two-pack type modified acrylic adhesive [Test method:] Tensile shear strength test Test method: As shown in FIG. 3, tensile shear in which the above two types of test materials were bonded with an adhesive The test was performed by applying a tensile load to the strength test piece and measuring the breaking load.

Number of tests: 3 Note that 10 in FIGS. 3A and 3B is a plan view and a cross-sectional view of a tensile shear strength test piece, respectively. Also, in FIG.
11 is a test material as the above-mentioned anticorrosion plate, 12 is a test material as the above-mentioned piping, 13 is an adhesive layer, and ₁₁ is each test material 1
The length of 1 and 12 (= 100 mm), l ₂ is the length of the adhesive surface in the length direction of the test material (= 25 mm), and l ₃ is the width of each test material 11 and 12 (=
50 mm) and F indicates a tensile load.

Table 1 shows the test results. From the test results shown in Table 1, even in the case of a pre-painted pipe, a tensile shear strength of ²⁰ to 55 kg / cm ² was obtained by using the above-mentioned adhesive, and from the above-mentioned estimation results, the method of the present invention was used. In this case, it was found that the possibility of peeling of the adhesive layer due to thermal expansion and contraction in the longitudinal direction of the pipe due to a change in temperature was low.

[0033]

[Table 1]

(Reference Example 2) In Reference Example 1, a paint of a test material (SS400 painted product) as a pipe was prepared using the two-pack type modified acrylic adhesive having the best adhesive strength. The adhesive strength was examined in the same manner as in Reference Example 1, except that each of the urethane-based, epoxy-based, polyester-based, and silicone resin-based paints was used. In this case, for comparison, the SS400 coated product coated with a phthalic acid paint was tested again.

Table 2 shows the test results. From the test results shown in Table 2, the two-pack type modified acrylic adhesive shows good adhesive strength to any of the test materials (SS400 painted products) as pipes coated with the various paints described above. I understood that.

[0036]

[Table 2]

(Example) Based on the results of the above basic experiment,
The method of the present invention was applied to a carbon steel pipe having a pipe diameter of 100A. In this embodiment, a pad made of SUS304 (d = 56.8 mm, θ = 90 °, L = 200 mm) as an anticorrosion plate and FRP
(Glass fiber reinforced plastic) pad (d = 56.8
mm, θ = 60 °, L = 200 mm 2), and the same two-part modified acrylic adhesive as in Reference Examples 1 and 2 showing the best adhesive strength was used as the adhesive.

The construction method was as follows. [1] Lifting and retaining pipes individually: Using a combination of a crane truck and a chain block, gradually lift and retain pipes by about 20 mm. [2] Pipe pad contact surface Keren: Use a metal spatula to remove paint and rust on the pipe, and finish it with sandpaper.

[3] Processing pad alignment, pad gap measurement,
Pad fine correction: Align the pad cut in advance to a length of 200 mm with the piping, measure whether the gap for the adhesive application is even, and fine-correct the pad shape. [4] Adhesive preparation, adhesive brush application: After mixing two components of the two-component type modified acrylic adhesive, apply the obtained paint to the pipe bonding surface of the pad using a brush.

[5] Pad attachment: Check the position of the pad in the circumferential and longitudinal directions, and attach it to the pipe. [6] Pad crimping: Gradually lower the piping by chain block operation and crimp the pads. [7] U-bolt installation: The U-bolt is provided with a gap of 1 mm between the top of the U-bolt and the pipe, and fastened with a double nut.

[8] After construction, confirm the tendency with time and measure the dimensions: Two months after construction (winter), four months (spring) and eight months (summer), the situation is checked and the dimensions are measured twice. Table 3 shows the results obtained by performing the above construction method and confirming the tendency and measuring the dimensions four months after the construction (spring) and eight months after the construction (summer). As shown in Table 3, no effect on the anticorrosion plate is observed even in the summer after 8 months from the construction, and according to the present invention, it is possible to cope with the frictional force caused by the expansion and contraction of the pipe length due to the temperature change including the summer. It was proved that an excellent anticorrosion method and anticorrosion method could be achieved.

Further, since the method of the present invention does not use fire, it can be said that it is an excellent method as a simple anticorrosion method for existing piping in a chemical factory that handles organic chemical substances subject to fire restriction. Note that, in the above-described examples, as the adhesive, the test results using the two-pack type modified acrylic adhesive showing the best adhesive strength in the aforementioned reference example 1 were described. Epoxy adhesives are also preferably used, and the type of the adhesive is not limited as long as the object of the present invention is not impaired.

[0043]

[Table 3]

[0044]

[Table 4]

[0045]

[Table 5]

[0046]

[Table 6]

[0047]

[Table 7]

[0048]

As described above, according to the present invention, it is possible to connect a pipe such as a carbon steel pipe and a pipe support member such as a bracket without causing a problem associated with the expansion and contraction of the pipe due to a change in temperature including summertime. It has become possible to provide a simple and economical method of preventing corrosion of a pipe in a pipe support part which prevents the progress of corrosion of a contact part.

Furthermore, since the method of the present invention does not use fire, it can be said that it is an excellent method as a simple anticorrosion method for existing piping in a chemical factory that handles organic chemical substances subject to fire restriction.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a corrosion protection installation pipe according to the present invention (a).
And a side view (b).

FIG. 2 is an explanatory view showing specifications such as dimensions of each member in a pipe section (a) and pipe longitudinal directions (b) and (c) according to the present invention.

FIG. 3 is an explanatory view showing a tensile shear strength test test method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pipe 1a Pipe outer periphery 2 U-shaped pipe fixing bracket 3 Corrosion protection plate (pad) 4 Pipe support members 4a, 4b Pipe support points (: locations where pipe support members are provided) 5, 13 Adhesive layer 11 Serving as anticorrosion plate Test material 12 Test material as piping B Distance between adjacent pads (span) D Outer diameter of piping d Curvature radius of arc of anticorrosion plate F Tensile load L Length of pad in longitudinal direction t Thickness of anticorrosion plate θ Anticorrosion Circumferential angle of board (pad)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiyuki Matsuki 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Inside the Chiba Works of Kawasaki Steel Corporation (72) Inventor Fumiyoshi Yoshida 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba (72) Inventor Hiroshi Nakajima 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside (72) Inventor Takanori Sonoda 910 Large-sized Shindoji Temple, Kokura-minami-ku, Kokura-minami-ku, Kitakyushu-shi, Fukuoka Maruei Kako Co., Ltd. Inside the company (72) Inventor Taishi Teraoka

Claims (5)

[Claims] 1. A method for preventing corrosion of a pipe in a pipe support part, wherein an anticorrosion plate is interposed between a pipe and the pipe support member, and the pipe and the anticorrosion plate are bonded with an adhesive. 2. In the thickness cross-sectional shape of the anticorrosion plate, an adhesion surface of the anticorrosion plate to the pipe has an arc shape that is a part of a circle, and the arc has a curvature radius substantially equal to the outer circumference of the pipe. 2. The method according to claim 1, wherein d is provided, and wherein the adhesive surface of the anticorrosion plate is bonded to an outer peripheral surface of the pipe with an adhesive. 3. The adhesive according to claim 1, wherein the adhesive is a polyester-based adhesive,
3. The method according to claim 1, wherein the adhesive is selected from an epoxy adhesive and an acrylic adhesive. 4. The method according to claim 1, wherein the material of the anticorrosion plate is stainless steel or fiber reinforced plastic. 5. An anticorrosion method for a pipe in a pipe support portion in which an anticorrosion plate is interposed between a pipe and a support member of the pipe and an outer peripheral surface of the pipe and a surface of the anticorrosion plate are bonded with an adhesive. In the thickness cross-sectional shape of the plate, the adhesion surface of the anticorrosion plate to the pipe has an arc shape that is a part of a circle, and the arc has the same radius of curvature d as the outer circumference of the pipe. After the adhesive is applied to the bonding surface, the anticorrosion plate is inserted into the gap between the pipe and the pipe support member provided in advance, and the gap between the pipe and the top of the U-shaped pipe fixing bracket is 0.5 mm or more. Wherein the pipe is fixed by a U-shaped pipe fixing metal fitting.