JP2013164120A - Heat insulation material - Google Patents

Abstract

An object of the present invention is to provide a heat insulating material that is maintenance-free and can suppress corrosion on the outer surface of a metal pipe over a long period of time.
The heat insulating material is disposed in contact with the outer surface of a metal pipe 11, and a large number of the heat insulating materials are provided between the surface in contact with the outer surface of the pipe 11 and the outer surface of the pipe 11. And a main body 12 having a metal as a sacrificial anode for the pipe 11 as a main component.
[Selection] Figure 1

Description

  The present invention relates to a heat insulating material arranged in contact with an outer surface of a metal pipe.

  In various plants, such as chemical plants and energy plants, many metal pipes that circulate high-temperature fluids are laid, and in order to prevent a decrease in the temperature of the fluid, heat insulation is usually performed to cover the outer surface of the pipes. The material is being constructed. However, in such a metal pipe covered with a heat insulating material, moisture enters the heat insulating material, so that moisture enters between the outer surface of the pipe and the heat insulating material and corrodes the outer surface of the pipe. There is a problem that (CUI: Corrosion Under Insulation) occurs. In addition, when chloride ions are present in the invading water, the corrosion is further promoted.

  Since the outer surface of the pipe is covered with a heat insulating material, when it is attempted to check and check the corrosion under the heat insulating material, visual inspection becomes difficult, and it is necessary to remove the heat insulating material. In addition, when the piping to be inspected is at a high place, it is necessary to install a scaffolding, which further increases labor and cost.

  Generally, in order to prevent and suppress such corrosion under the heat insulating material without maintenance, it is effective to apply the heat insulating material after painting the outer surface of the metal pipe with paint or the like. However, the application of this paint, etc., avoids direct contact between the metal surface of the pipe and the corrosive component, but from the defective part of the paint film or the damaged part due to aging of the paint film itself, salt, moisture, etc. There is a problem that local corrosion occurs on the metal surface of the pipe.

Therefore, in order to suppress the corrosion under the heat insulating material generated from such a damaged portion, Patent Document 1 discloses a heat insulating material that preliminarily contains hydrocalumite that collects chloride ions serving as a corrosion promoting factor as an active ingredient. A method of using is disclosed.
Further, Patent Document 2 discloses a component (anode inhibitor) that forms a corrosion-resistant oxide film by oxidizing the outer surface of a metal pipe, that is, that promotes passivation (in an anode type inhibitor), or in a corrosive environment. A method of using a heat insulating material that acts with other ions coexisting in the water to form a salt that is hardly soluble or insoluble in water and that contains a precipitating component (cathode inhibitor) on the outer surface of the metal pipe. It is disclosed.

JP 2005-299822 A JP 2006-112533 A

However, although the method described in Patent Document 1 creates an environment that is unlikely to corrode due to an action such as reducing the amount of chloride potentially contained in the heat insulating material, in actuality, sea salt entering from the outside Since the influence of chlorides due to flying components such as the above is great, if the allowable amount of the components that collect chloride ions filled in the heat insulating material is exceeded, corrosion will occur.
Similarly, the method described in Patent Document 2 also has a limit in the amount of the inhibitor filled in the heat insulating material, so that the anticorrosion function is also lowered with a decrease in the inhibitor component.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat insulating material that eliminates such conventional problems, is maintenance-free, and can suppress corrosion on the outer surface of a metal pipe over a long period of time.

  The heat insulating material according to the present invention is a heat insulating material arranged in contact with the outer surface of a metal pipe, and a large number of minute spaces between the outer surface of the pipe and the surface in contact with the outer surface of the pipe And a main body containing a metal as a main component that serves as a sacrificial anode for the pipe.

Moreover, it is preferable that a main body is formed from the foam which contains the metal used as a sacrificial anode as a main component.
Or a main body can also be comprised from the aggregate | assembly of many fibrous members which contain the metal used as a sacrificial anode as a main component.
The pipe is preferably made of carbon steel or stainless steel, and the main body is preferably made of an aluminum alloy.
The aluminum alloy preferably contains 0.1 to 20% by weight of zinc, and more preferably contains 0.005 to 2% by weight of indium.
Further, the aluminum alloy preferably contains any of tin, magnesium, calcium, manganese, titanium, beryllium, strontium, cadmium, silicon, zirconium and gallium.

A heat insulating material covering the outer surface of the main body can be further provided.
In this case, the heat insulating material is preferably any one of foamed plastics such as glass wool, rock wool and polystyrene foam.

  Moreover, you may further provide the water-permeable sheet which covers the outer surface of a main body.

  According to this invention, maintenance-free and corrosion on the outer surface of a metal pipe can be suppressed over a long period of time.

It is sectional drawing which shows the structure of the piping covered with the heat insulating material which concerns on Embodiment 1 of this invention. It is a figure for demonstrating the mechanism of corrosion. It is a figure for demonstrating the anti-corrosion effect | action using the sacrificial anode by the heat insulating material which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure of the piping covered with the heat insulating material which concerns on the modification of Embodiment 1 of this invention. It is sectional drawing which shows the structure of piping covered with the heat insulating material which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the structure of piping covered with the heat insulating material which concerns on Embodiment 3 of this invention. It is sectional drawing which shows the structure of the piping covered with the heat insulating material which concerns on Embodiment 4 of this invention.

  Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

Embodiment 1
In FIG. 1, the structure of the piping covered with the heat insulating material which concerns on Embodiment 1 of this invention is shown. This heat insulating material is divided into a shape along the pipe 11, for example, a half-divided cylindrical shape, and is arranged in contact with the outer surface of the metal pipe 11.
In addition, the heat insulating material has a concave and convex shape for creating a large number of micro spaces between the outer surface of the pipe 11 and a metal that serves as a sacrificial anode for the pipe 11 on the surface in contact with the outer surface of the pipe 11. It is formed so as to include a main body 12 included as a main component.

  The main body 12 includes a metal that becomes a sacrificial anode for the pipe 11 as a main component, and among these, the metal is preferably a foam.

  When the pipe 11 is made of general carbon steel or stainless steel, the metal serving as the sacrificial anode is preferably an aluminum alloy. In particular, since the foamed aluminum alloy can be molded into a free shape by the mold material, the main body 12 can be installed along the pipe 11. Further, when the foamed aluminum alloy is used for the pipe 11, since it has a large number of bubbles, rainwater or the like easily enters the main body 12 from the outside, but the moisture corrodes chloride or the like in the main body 12. After the components are diluted, they can be discharged from the main body 12 to the outside. In addition, the thermal conductivity of a molded product made of a foamed aluminum alloy is as low as about 1/1000 that of a bulk aluminum alloy, and is excellent in the heat insulation and heat insulation effect, so that it can be used alone as a heat insulation material.

Moreover, it is preferable that an aluminum alloy contains 0.1-20 weight% of zinc. In the case of aluminum alone, a dense oxide film is formed on the surface, so that the sacrificial anode effect cannot be obtained efficiently. However, by adding a predetermined amount of zinc, aluminum can be activated and the potential can be lowered.
Moreover, it is preferable that an aluminum alloy contains 0.005 to 2 weight% of indium with the said zinc. Furthermore, by adding a predetermined amount of indium, it is possible to suppress adhesion of corrosion products to the surface of the metal serving as the sacrificial anode and to impart uniform solubility.
Moreover, in order to improve current efficiency, in place of zinc and indium, or in addition to zinc, or in addition to zinc and indium, aluminum alloys include tin, magnesium, calcium, manganese, titanium, and beryllium. , Strontium, cadmium, silicon, zirconium and gallium are preferably included.

Since the heat insulating material of Embodiment 1 is formed in this way, it is maintenance-free and can suppress corrosion on the outer surface of the metal pipe over a long period of time.
As described above, the corrosion under the heat insulating material occurs when moisture enters between the outer surface of the pipe and the heat insulating material. In general, corrosion is a combination of an anode reaction (oxidation reaction) in which atoms in a metal material dissolve as cations in moisture (aqueous electrolyte solution) and a cathode reaction (reduction reaction) in which an oxidant receives electrons. It is a phenomenon that occurs at the same time.

For example, when corrosion occurs due to water droplets (neutral) on an iron plate as shown in FIG. 2, two reactions occur as follows.
First, on the iron plate in the center of the water droplet having a relatively thick water droplet and a low oxygen concentration, an anode reaction (oxidation reaction) such as the following formula (1) occurs, and the iron atom Fe leaves an electron e ⁻ on the iron plate, Dissolves in the form of ferrous ions Fe ²⁺ and diffuses into the water droplets.
Fe → Fe ²⁺ + 2e ⁻ (1)
On the other hand, in a place where the oxygen concentration in the water droplet is high, a cathode reaction (reduction reaction) as in the following formula (2) occurs, and water H ₂ O, oxygen O _2, and electrons e ⁻ supplied from the iron dissolving part react. This produces the hydroxide ion OH ⁻ .
_{H 2 O + O 2/2} + 2e - → 2OH - (2)

However, as shown in FIG. 3, in the first embodiment, the main body 12 made of the foamed aluminum alloy has a large number of surfaces between the outer surface of the pipe 11 and the surface in contact with the outer surface of the pipe 11 made of steel. It has a concavo-convex shape for creating a minute space, and has as its main component a metal that serves as a sacrificial anode for the pipe 11, that is, a base metal that has a lower potential than the steel pipe 11 that is subject to corrosion protection. Yes.
Therefore, when moisture enters between the outer surface of the pipe 11 and the main body 12, a potential difference is generated between the materials, an anodic reaction occurs on the main body 12 side, and a cathodic reaction occurs on the outer surface of the pipe 11. More specifically, the corrosion reaction is applied to the heat insulating material (main body 12), and the electrons e ⁻ are supplied to the metal of the pipe 11, so that no corrosion occurs on the outer surface of the pipe 11.

  The heat insulating material (main body 12) of the first embodiment is manufactured, for example, by compression molding a metal powder that becomes a sacrificial anode and a foaming agent and then solidifying by sintering. Further, as shown in FIG. 1, the piping may be sandwiched between a plurality of foamed aluminum alloy molded products 12 a and 12 b that are divided and molded into a shape along the piping 11, and may be installed by a fixing jig that can be welded or detached. In addition, the manufacturing method and installation method of a heat insulating material are not limited to the said method, if it can contact and arrange | position to the outer surface of piping.

In the heat insulating material according to the first embodiment, the main body 12 is installed so as to cover the entire pipe 11, but as shown in FIG. 4, only the lower part of the pipe 11 in which moisture including corrosive components easily accumulates. The main body 13 may be installed.
Thus, if it is a heat insulating material which covers only the lower part of the piping where corrosion under the heat insulating material is likely to be a problem, it can be installed at a lower cost than covering the entire piping. In addition, even when the upper portion of the pipe 11 is close to other members and there is no space for placing the heat insulating material, the occurrence of corrosion is effectively prevented by covering only the lower portion of the pipe 11 with the heat insulating material. be able to.

Embodiment 2
The heat insulating material according to the first embodiment covers the pipe 11 with the main body 12 composed of the half cylinder shapes 12a and 12b divided and molded into a shape that fits the pipe 11, but the present invention is limited to the shape. Instead, a heat insulating material having a wool-like main body 14 as shown in FIG. 5 may be used. The main body 14 is composed of an aggregate of fibrous members containing a metal that becomes a sacrificial anode as a main component.

For example, when the pipe 11 is made of carbon steel or stainless steel, the fibrous member forming the main body 14 is preferably made of an aluminum alloy.
Moreover, it is preferable that an aluminum alloy contains 0.1-20 weight% of zinc. In the case of aluminum alone, a dense oxide film is formed on the surface, so that the sacrificial anode effect cannot be obtained efficiently. However, by adding a predetermined amount of zinc, aluminum can be activated and the potential can be lowered.
Moreover, it is preferable that an aluminum alloy contains 0.005 to 2 weight% of indium with the said zinc. Further, by adding a predetermined amount of indium, it is possible to suppress adhesion of corrosion products to the surface of the fibrous member and to impart uniform solubility.
Moreover, in order to improve current efficiency, in place of zinc and indium, or in addition to zinc, or in addition to zinc and indium, aluminum alloys include tin, magnesium, calcium, manganese, titanium, and beryllium. , Strontium, cadmium, silicon, zirconium and gallium are preferably included.

The main body 14 is made by forming a large number of fibrous members into a flexible shape such as a wool shape, a cotton shape or a non-woven fabric shape.
Since the heat insulating material having such a shape is light and easy to deform, the piping 11 can be easily covered even when the space for arranging the heat insulating material is very narrow or the piping is at a high place. . In addition, since the heat insulating material can be easily installed on the outer surface of the pipe 11, it is not necessary to install a large scaffold, and the occurrence of corrosion on the outer surface of the pipe can be effectively prevented at a low cost. Can do.

  Moreover, since the main body 14 is formed in a wool shape from an aggregate of fibrous members, a large number of fibrous members containing a metal serving as a sacrificial anode as a main component are exposed as they are on the surface of the main body 14, and the uneven shape is Is formed. Therefore, as with the heat insulating material of the first embodiment, when the main body 14 is brought into contact with the outer surface of the pipe 11, a large number of minute spaces are formed between the outer surface of the pipe 11 and are maintenance-free. Corrosion on the outer surface of the metal pipe can be suppressed.

Furthermore, since the main body 14 has a wool-like shape, a large number of minute spaces are also formed inside the main body 14, and a high heat insulation and heat insulating effect is exhibited by the air entering these minute spaces.
The heat insulating material (main body 14) according to the second embodiment can be installed by, for example, winding a metal fiber made of a metal serving as a sacrificial anode into a wool shape, wrapping it around the pipe 11, and using a fixing jig. In addition, the manufacturing method and installation method of a heat insulating material are not limited to the said method, if it can contact and arrange | position to the outer surface of piping.

Embodiment 3
In FIG. 6, the structure of the piping covered with the heat insulating material which concerns on Embodiment 3 of this invention is shown. In the heat insulating material of Embodiment 3, the outer surface of the main body 12 of Embodiment 1 shown in FIG. 1 is further covered with a heat insulating material 15 made of glass wool.
In this embodiment, glass wool is used as the heat insulating material 15, but is not particularly limited as long as it is generally used. For example, foamed plastic such as polystyrene foam, rock wool, or the like is used. You can also.

Similarly to the heat insulating material of the first embodiment, the heat insulating material of the third embodiment formed in this way creates a large number of minute spaces between the outer surface of the pipe 11 and the surface in contact with the outer surface of the pipe 11. The main body 12 includes a metal 12 as a main component that serves as a sacrificial anode for the pipe 11, and is maintenance-free, so that corrosion on the outer surface of the metal pipe can be prevented over a long period of time. Can be suppressed.
Furthermore, even when the heat insulating material formed only by the main body 12 as in the first embodiment cannot obtain sufficient heat insulating performance, the heat insulating material according to the third embodiment further includes the heat insulating material 15 that covers the outer surface of the main body 12. Since it has the structure provided, the outstanding heat retention performance can be obtained. Further, it is not necessary to increase the thickness of the main body 12 in order to obtain heat retention performance, and further weight reduction can be realized.

  For example, the heat insulating material 15 can be wound around the main body 12 and installed by a tape or a fixing jig. In addition, if the installation method of the heat insulating material 15 can be arrange | positioned on the outer surface of the main body 12, it will not be limited to the said method.

  The heat insulating material of the third embodiment is one in which the outer surface of the main body 12 of the first embodiment shown in FIG. 1 is further covered with a heat insulating material 15, but is not limited to this, and the second embodiment shown in FIG. The outer surface of the main body 14 may be further covered with a heat insulating material 15.

Embodiment 4
In FIG. 7, the structure of the piping covered with the heat insulating material which concerns on Embodiment 4 of this invention is shown. The heat insulating material of the fourth embodiment is obtained by further covering the outer surface of the main body 12 of the first embodiment shown in FIG.

Similarly to the heat insulating material of the first embodiment, the heat insulating material of the fourth embodiment formed in this way creates a large number of minute spaces between the outer surface of the pipe 11 and the surface in contact with the outer surface of the pipe 11. The main body 12 includes a metal 12 as a main component that serves as a sacrificial anode for the pipe 11, and is maintenance-free, so that corrosion on the outer surface of the metal pipe can be prevented over a long period of time. Can be suppressed.
Furthermore, since the water permeable sheet 16 that covers the outer surface of the main body 12 is further provided, the amount of water permeating from the outside into the main body 12 can be controlled to a value corresponding to the water permeable sheet 16. Therefore, even if the metal used as the sacrificial anode for forming the main body 12 is a foam, the water that has entered through the pores does not cause a problem that the outer surface of the pipe to be kept warm is cooled. The occurrence of corrosion on the outer surface of the steel can be effectively prevented.

  For example, the water-permeable sheet 16 can be wound around the main body 12 and installed by a fixing jig. In addition, if the installation method of the water-permeable sheet 16 can be arrange | positioned on the outer surface of the main body 12, it will not be limited to the said method.

  The heat insulating material of the fourth embodiment is one in which the outer surface of the main body 12 of the first embodiment shown in FIG. 1 is further covered with a water permeable sheet 16, but is not limited to this, and the embodiment shown in FIG. The outer surface of the main body 14 may be further covered with a water permeable sheet 16.

In addition, the characteristics of pipes that are susceptible to corrosion under heat insulation materials are as follows: (1) The surface temperature of the pipes is 60 to 80 degrees, (2) Moisture containing corrosive components tends to accumulate in the lower part of the pipes, (3) For example, the pipe is installed in the coastal area where a lot of chloride ions exist.
Even if it is such piping, if the heat insulating material in any one of Embodiments 1 to 4 above is appropriately selected according to the heat retaining properties and work efficiency required for each piping, the durability thereof is eliminated. The period can be greatly improved.

11 piping, 12, 13, 14 body, 12a, 12b foamed aluminum alloy molded product, 15 heat insulating material, 16 water permeable sheet.

Claims (10)

A heat insulating material placed in contact with the outer surface of a metal pipe,
A surface that contacts the outer surface of the pipe has a concavo-convex shape for creating a large number of minute spaces between the outer surface of the pipe and a main body containing a metal that serves as a sacrificial anode for the pipe as a main component. A heat insulating material characterized by that.   The heat insulating material according to claim 1, wherein the main body is formed of a foam including a metal that is the sacrificial anode as a main component.   The heat insulating material according to claim 1, wherein the main body is made of an aggregate of a large number of fibrous members containing a metal as a main component as the sacrificial anode. The piping is made of carbon steel or stainless steel,
The heat insulating material according to claim 2 or 3, wherein the main body is made of an aluminum alloy.   The heat insulating material according to claim 4, wherein the aluminum alloy contains 0.1 to 20% by weight of zinc.   The heat insulating material according to claim 5, wherein the aluminum alloy further contains 0.005 to 2 wt% of indium.   The heat insulating material according to any one of claims 4 to 6, wherein the aluminum alloy includes any one of tin, magnesium, calcium, manganese, titanium, beryllium, strontium, cadmium, silicon, zirconium, and gallium.   The heat insulating material in any one of Claims 1-7 further equipped with the heat insulating material which covers the outer surface of the said main body.   The heat insulating material according to claim 8, wherein the heat insulating material is any one of foamed plastics such as glass wool, rock wool, and polystyrene foam.   The heat insulating material according to any one of claims 1 to 7, further comprising a water-permeable sheet that covers an outer surface of the main body.

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