JPH03209086A - Covered tube and tube outer surface covering method - Google Patents

Abstract

PURPOSE:To prevent breakdown due to breakage and/or electric erosion even when damage is caused to covering materials by filling a support material of electrical insulating property between a tube and a covering material, forming the covering material which covers the outer surface of the metal tube of titan and titan alloy, and sufficiently raising heat resisting temperature of covering materials. CONSTITUTION:Corrosion preventive coating is applied to the outer surface of an inner tube 1 made of metal, for transportation of high temperature fluid, the inner tube 1 is covered with a heat insulating material of calcium silicate and others, an outer tube 4 made of metal is covered with a coating material 5 and a supporting material 8 and a space 6 is formed with a spacer 7 between the heat insulating material 3 and the outer tube 4. The gap between the outer tube 4 and the covering material 5 is closed with a lid 14, the supporting material 8 is supplied between the outer tube 2 and the covering material 5 with an injector 9 and air is extracted from a discharging cylinder 14a of another lid 14. Consequently, it is excellent in heat transport property, corrosion resistance, heat resistance and strength, low in cost and suitable for burying and weld-connection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cladding tube in which the outer surface of a metal tube is coated for corrosion protection, and a method for coating the outer surface of a tube.

[Conventional technology]

Conventionally, the outer surface of a metal tube has been covered only with a coating material made of a polymeric material such as polyethylene, polypropylene, or epoxy resin.

[Problem to be solved by the invention]

However, the heat resistance temperature of the polymer material is about 110° C. or lower, and the long-term durability is about 80° C. or lower, so there is room for improvement in the following points (a) to (2).

(b) In order to keep the temperature of the sheathing material below 80°C and sufficiently prevent deterioration of the sheathing material over a long period of time, the temperature of the fluid transported in the pipe must be kept quite low, and the heat generated by the fluid must be kept quite low. Transportation capacity will be reduced.

(0) In order to increase the heat transport ability of the fluid while maintaining long-term durability, the heat insulating layer inside the pipe must be made thicker, which increases cost.

(c) When burying cladding pipes, there is a risk that the cladding material will deteriorate due to high temperature groundwater.

(2) When connecting cladding tubes by welding, the cladding material deteriorates due to welding heat.

Moreover, once pinholes or fine cracks occur in the polymeric material, corrosion occurs in the pipe, and the sheathing material is likely to peel off due to rust, causing rapid damage to the sheathing material.

The purpose of the present invention is to make the heat-resistant temperature of the sheathing material sufficiently high, to sufficiently prevent corrosion of the pipe even if pinholes or small cracks occur in the sheathing material, and to make the mechanical strength of the sheathing material sufficiently high. The purpose is to sufficiently prevent destruction and destruction due to electrolytic corrosion, and to suppress an increase in cost required for the covering material.

[Means to solve the problem]

The characteristic structure of the cladding tube according to the present invention is that the cladding material covering the outer surface of the metal tube is made of titanium or a titanium alloy, and an electrically insulating support material is filled between the tube and the cladding material. In particular, its functions and effects are as follows.

[For production]

By using titanium or a titanium alloy as the coating material, the heat resistance temperature at which the coating material can maintain long-term durability can be increased to approximately 200°C, which is sufficiently higher than the approximately 80°C of the prior art described above.

Therefore, the temperature of the fluid transported within the pipe can be made sufficiently high without increasing the cost due to insulation for protecting the covering material, and the heat transporting ability of the fluid can be sufficiently improved.

In addition, even if the cladding pipe is buried, there is almost no risk of the cladding material deteriorating due to high-temperature groundwater, and
Since deterioration of the sheathing material due to welded connection of the sheathing tubes can be sufficiently prevented, corrosion of the tubes hardly occurs, and corrosion protection of the tubes can be achieved in a highly reliable state over a long period of time.

Furthermore, since an electrically insulating support material is filled between the metal tube and a coating material made of titanium or titanium alloy, there is no possibility of electrolytic corrosion caused by the electrical connection between the tube and the coating material made of different metals. In addition, the support material can sufficiently prevent deformation and destruction of the sheathing material due to external forces, and even if the sheathing material is made thin, the long-term durability of the sheathing material can be sufficiently ensured.

By forming titanium or titanium alloy into a thin plate shape, preferably 1 mm or less, the cost required for the coating material can be significantly lower than when using precious metals such as gold, platinum, tantalum, etc. It can be made into something that is almost the same as the technologically advanced polymer materials.

〔Effect of the invention〕

As a result, it has become possible to provide a cladding tube that is superior in all aspects of heat transport capacity, corrosion resistance, heat resistance, and strength, is low in cost, is suitable for burial and welding, and is more convenient overall.

When the covering material is made thin as described in claim 2, the cost required for the covering material can be sufficiently reduced, and parts with complicated shapes such as bent portions and joints of pipes can be easily covered.

When the supporting material is provided with heat insulating properties as described in claim 3, or when the inner tube coated with a heat insulating material is installed inside the tube as described in claim 4, the coated tube becomes more convenient for transporting high-temperature fluids. is obtained.

If the tube is covered with the coating material and then filled with the support material as described in claim 5, the tube coating process can be easily carried out especially in the repair of piping.

〔Example〕

Next, examples will be shown.

As shown in Figure 1, a metal inner pipe (1
) is coated with anti-rust coating (2), the inner tube (1) is covered with a heat insulating material (3) made of calcium silicate, etc., and the metal outer tube (4) is supported with the covering material (5). Covered with material (8),
There is a gap (6
) are formed by spacers (7) provided at appropriate intervals in the longitudinal direction of the pipe, forming a heat-insulating pipe for high-temperature fluid buried underground to supply high-temperature steam and hot water for district heating and cooling.

Is the covering material (5) a thin plate of titanium or titanium alloy? It is preferably formed to have a thickness of 0.1 to IM.

The support material (8) is an electrically insulating powder material that has support strength even at high temperatures, such as Sin. , TiO■, AI. 0. thermosetting resins such as metal oxides, epoxy resins, and unsaturated polyesters, preferably those with excellent heat insulation properties.

In short, the coating material is made of titanium or a titanium alloy that can withstand high temperatures of about 200°C, so that the fluid temperature in the inner tube (1) can be increased and the insulation material (3) can be made thinner.
In addition, it is possible to practically connect the heat-insulating pipes by welding, and the supporting material (8) prevents damage to the covering material (5) due to external forces and electrolytic corrosion.

To fill the support material (8) between the outer tube (4) and the covering material (5), first cover the outer surface of the outer tube (4) with the covering material (5), and then fill the space as shown in Fig. 2 (A). As shown in , close the space between the outer tube (4) and the covering material (5) with the lid (14) at one end, and insert the syringe (
9) between the outer tube (4) and the sheathing material (5).
), or as shown in Figure 2 (b), the outer tube (4
) and the covering material (5) on the lower end side with a lid (l4),
The support material (8) is supplied by the syringe (9), and the space between the outer tube (4) and the covering material (5) is closed with lids (l4) on both ends, as shown in Figure 2 (c). Then, the support material (8) is supplied from the inlet of one lid (l4) using the syringe (9), and air is vented from the exhaust pipe (14a) of the other lid (l4).

To cover the outer surface of the outer tube (4) with the sheathing material (5), a cylindrical sheathing material (5) may be used as shown in FIG. Then, a plate-shaped covering material (5) may be rolled and the overlapped portions may be welded, as shown in Fig. 3 (c).
The band-shaped sheathing material (5) may be spirally wound and the overlapped portions may be welded, or the split tube-shaped sheathing materials (5) may be welded together as shown in Figure 3 (2) and (E). In addition, if there is an overlapped part as shown in Figure 3 ([+) and (c),
A sealing agent such as epoxy resin may be injected into the overlapped portion, and the overlapped portion may be bonded with the sealant.

[Another example]

Next, another embodiment will be described.

The structure, purpose, fluid to be transported, installation form, etc. of the heat insulated pipe can be appropriately selected. For example, the heat insulating material (3) can be provided without any voids as shown in Figure 4 (A), or As shown in FIG. 4, the inner tube (1), outer tube (4), and covering material (5) are formed into a bellows shape so that they can be bent, or as shown in FIG. 4 (c), polyethylene, polypropylene Protective materials made of , polymeric materials such as epoxy resins, and other suitable materials (
10) may cover the covering material (5).

The internal structure of the tube (4) covered with the covering material (5) and the supporting material (8) can be varied as appropriate.

When the support material (8) is made of thermosetting resin, for example, as shown in FIG. etc.
The support material (8) may be cured by suitable heating means.

The support material (8) may be formed in the form of a film or a plate, and in that case, the support material (8) may be attached to the tube (4) before the covering material (5) is attached.

4 When connecting cladding pipes by welding, as shown in Figure 6, the pipes (
4) After welding them together, cover the welded part (12) with a covering material (
5a) to the covering materials (5b) and (5c) on both sides,
Fill the support material (8) through the injection port of the coating material (5a) with the syringe (9) and remove air from the exhaust port (13), and then cover the injection port and the exhaust port (13) with a suitable means. do.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of drawings]

1 to 3 show embodiments of the present invention, FIG. 1 is a partial perspective view of a cladding tube, and FIGS. 2 (a) to (c) are conceptual diagrams showing different methods of filling the support material, FIGS. 3(A) to 3(E) are partial views showing different states in which the covering material is attached. FIGS. 4A to 4C are partial views showing different embodiments of the cladding tube of the present invention. FIGS. 5 and 6 are conceptual diagrams showing different processing methods in other implementations of the present invention. (1) Inner pipe, (3) Insulation material, (4) Pipe, (5) Covering material, (8) ...Supporting material.

Claims (1)

[Claims] 1. The coating material (5) covering the outer surface of the metal tube (4) is made of titanium or a titanium alloy, and there is electrical insulation between the tube (4) and the coating material (5). A cladding tube filled with supporting material (8). 2. The cladding tube according to claim 1, wherein the cladding material (5) is in the form of a thin plate with a thickness of 1 mm or less. 3. The cladding tube according to claim 1 or 2, wherein the supporting material (8) is of a heat insulating material. 4. The pipe (4) has an inner pipe (1) coated with a heat insulating material (3).
4. The cladding tube according to claim 1, wherein the cladding tube is internally equipped with: 5. Cover the outer surface of the metal tube (4) with a coating material (5) made of titanium or titanium alloy, and then apply an electrically insulating support material (8) to the tube (4) and the coating material (5). ) A method of coating the outer surface of pipes by supplying and filling the space between the pipes.