JPH074586A - Structure and method for moisture-proof of heat insulating structure for fluid piping or the like - Google Patents

Abstract

PURPOSE:To prevent a heat insulating structure from the intrusion of moisture, steam, etc., by forming a heat insulating layer on the outer periphery of a transferring piping, apparatus or the like and permitting the heat insulating layer to maintain pressure a little higher than the atmospheric pressure to enclose gas such as nitrogen gas, dry air, therein. CONSTITUTION:A heat insulating layer 2 of hard polyurethane foam, etc., is formed integrally on the outer periphery of low temperature fluid transferring piping 1. A moisture preventing layer 3 serving also as a pressure holding layer is formed on the outer periphery of the heat insulating layer 2. A pressurizing piping 4 is mounted in the heat insulating layer 2 and a plurality of gas jet ports 41 are disposed to maintain the pressurizing gas such as nitrogen gas, dry air so that such pressurizing gas from the gas jet ports 41 maintains the interior of the heat insulating layer 2 at pressure only a little higher than the external pressure of the moisture preventing layer 3. An opening and closing valve 51 is mounted on the intermediate part of an introducing pipe 5 to extend through the moisture preventing layer 3 and heat insulating layer 2 and be connected to the pressurizing piping 4. The proximal end of the introducing pipe 5 is connected to a pressure maintaining device for pressure-feeding nitrogen gas, dry air, etc., for giving pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture-proof method for effectively preventing moisture, water vapor and the like from entering a heat insulating structure provided on pipes for transferring low temperature fluids such as LPG and LNG, and equipment.

[0002]

2. Description of the Related Art When a pipe or a device for transferring a low temperature fluid such as LNG or LPG is provided with a heat insulating structure, its moisture proof performance is maintained by a moisture proof layer formed on the surface of the heat insulating structure.

Materials for forming these moisture-proof layers include
It is common to use a mastic, a butyl tape, a film obtained by laminating a polyester film on an aluminum thin film, or the like.

[0004]

However, these moisture-proof layers are not suitable for long-term moisture permeability of the material itself used for the moisture-proof layer, structural defects in the connection portion formed, or pins generated in the moisture-proof layer. It is difficult to fully exert the moisture-proof effect due to holes, etc., and it often causes problems such as deterioration of heat insulation performance caused by moisture and water vapor entering the heat insulation layer and corrosion of pipes caused by these. It has drawbacks.

Further, it has been pointed out that it is difficult to accurately inspect the moisture-proof performance because the only means for inspecting the moisture-proof layer for defects, etc., is visual visual inspection.

[0006]

It is an object of the present invention to solve these problems, and to apply a gas pressure from the outside to a heat insulating structure provided on pipes for transferring fluid, devices and their various accessories such as valves and flanges. By applying this, the internal pressure of the heat insulating structure is constantly maintained at a pressure higher than the external pressure, and this internal pressure (pressurization) prevents the ingress of moisture, water vapor, etc. to effectively protect the moisture-proof layer from moisture. It is intended to provide a novel method for preventing moisture in a heat insulating structure formed in a fluid pipe or the like configured to exert the effect.

Another object of the present invention is to provide a moisture-proof layer whose properties are deteriorated due to defective construction, aging, etc.
Moisture protection of the heat insulation structure formed on the fluid piping, etc. configured so that the function of the moisture prevention layer due to the maintenance of pressurization to the heat insulation structure part, the state of deterioration of the moisture prevention performance and the deteriorated part can be easily and accurately inspected visually. It is intended to provide a method.

[0008]

The present invention provides a heat insulating structure in which a heat insulating layer is formed on the outer circumference of a pipe for transferring a low temperature fluid and equipment, and a moistureproof layer is formed on the outer circumference of the heat insulating layer, and the heat insulating layer is formed at a pressure higher than atmospheric pressure. The essential point of the invention is a method for preventing moisture from a heat insulating structure such as fluid piping, which is characterized in that a gas such as nitrogen gas or dry air is sealed while maintaining a slightly higher pressure.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

Reference numeral 1 is a pipe for transferring a low-temperature fluid, and a heat insulating layer 2 such as hard polyurethane foam is integrally formed on the outer periphery thereof.

Reference numeral 3 is a moisture-proof layer formed also on the outer periphery of the heat insulating layer 2, which also serves as a pressure holding layer, and is formed by using a butyl tape, a mastic or a film obtained by laminating a polyester tape on an aluminum thin film.

Reference numeral 4 is a pressurizing pipe mounted in the heat insulating layer 2, and a large number of gas ejection ports 41 ... 41 are bored to arrange a pipe body, and nitrogen gas and dry air supplied from the gas ejection ports 41 ... 41 are provided. The pressure inside the heat insulating layer 2 is maintained to be slightly higher than the external pressure (atmospheric pressure) of the moisture barrier layer 3 by the pressurized gas such as.

Reference numeral 5 denotes a pressurizing gas introduction pipe having an opening / closing valve 51 attached to an intermediate portion thereof, and a tip portion thereof penetrates the moisture-proof layer 3 and the heat insulating layer 2 and is connected to the pressurizing pipe 4.

The base end portion of the pressurizing gas introduction pipe 5 is connected to a pressurizing pressure maintaining device (not shown) for pumping nitrogen gas or dry air for pressurizing.

[0015]

According to the present invention, as described above, nitrogen gas, dry air, etc. are enclosed in the heat insulating layer 2 covered with the moisture proof layer 3 at a pressure slightly higher than the atmospheric pressure. There is an advantage that moisture, water vapor, etc. do not enter from the outside, and problems such as deterioration of heat insulation performance and corrosion of fluid pipes and equipment caused by the entry of water can be completely solved.

Further, according to the method of the present invention, the pressure inside the heat insulating structure is set to be slightly higher than the pressure outside (atmospheric pressure), so that the moisture proof performance can be easily confirmed at the time of construction, and the defective portion Existence can be accurately grasped and repaired.

Furthermore, if a minute defect occurs in the moisture-proof layer due to a change with time or the like, the defect portion can be grasped very easily by grasping the change in the pressure holding performance, and the maintenance can be accurately carried out.

Especially when the pipes and equipment for transferring low-temperature fluid are in operation, it is necessary to check the moisture-proof performance under strict and complicated conditions for fire prevention, but according to the method of the present invention. For example, it is possible to easily repair trouble spots, and there is a feature that it can be applied particularly effectively to working conditions that require a work floor such as scaffolding.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view with a part cut away showing a case where it is applied to a fluid conduit.

[Explanation of symbols]

 1 Pipe for transfer 2 Thermal insulation layer 3 Moisture-proof layer that also serves as pressure-holding layer 4 Pipe for pressurization 41 Gas ejection port 5 Introduction pipe for pressurized gas 51 Open / close valve

Claims (2)

[Claims] 1. A heat insulating structure in which a heat insulating layer is formed on the outer periphery of a pipe for transferring a low temperature fluid and devices, and a moisture-proof layer is formed on the outer periphery of the heat insulating layer. A pressure slightly higher than atmospheric pressure is applied to the heat insulating layer. A method for preventing moisture in a heat insulating structure such as a fluid pipe, which is characterized in that a gas such as nitrogen gas or dry air is sealed while being maintained. 2. A heat insulating layer is formed on the outer circumference of a pipe for transferring a low temperature fluid and equipment, and a moistureproof layer which also serves as a pressure holding layer is integrally formed on the outer circumference of the heat insulating layer, and a large number of heat insulating layers are formed on the heat insulating layer. Attaching a pressurizing pipe that forms a gas ejection port, and connecting a part of the pressurizing pipe to a pressurizing gas introduction pipe whose base end is connected to a pressurizing maintenance device. Moisture-proof structure of a kind of heat insulation structure.