JPH09317953A - Piping structure for reducing thermal stress - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a structure, and also prevent occurrence of failure due to reduction of thermal stress so as to improve reliability, in a piping structure such as a filling pipe for gas in a gas turbine, through which fluid or gas having a high temperature is led to flow and passed. SOLUTION: An inner pipe 2 having a space 3 except for its both ends is inserted in the inside of an outer pipe 1 arranged in a position where fluid or gas having a high temperature is led to flow and passed through, thereby a double structural piping is formed. One end side 4 of the inner pipe 2 is fixed to the inner diametral side of the outer pipe 1 by sealed welding, while the other end side 5 of the inner pipe 2 is freely formed so as to be slid on the inner diametral side of the outer pipe 1. Heat of operating fluid led to flow in the inner pipe 2 may not be transmitted to the outer pipe 1, therefore thermal stress is reduced. Also, only each one end of the inner and outer side pipes is fixed, and each other end thereof is free in an axial direction, therefore thermal stress may not be generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piping structure applied to a portion that causes thermal stress in a gas turbine machine or the like and a portion to which the piping structure is applied.

[0002]

2. Description of the Related Art Pipes applied to the inside of a gas turbine or the like are exposed to a high-temperature working fluid, and the temperature of the pipe is equal to the temperature of the working fluid.

Therefore, when the pipe is simply fixed to the rigid, it is directly subjected to thermal stress.

Therefore, conventionally, in order to temporarily reduce the thermal stress of the pipe, a method of forming a large loop in the pipe to give bending deformation to escape and a method of absorbing the deformation with a bellows or the like have been adopted.

[0005]

Among the conventional methods as described above, the former method of forming a large loop in the pipe is used when a high temperature fluid or gas such as steam is put in the gas turbine. Has a problem that the piping cannot be looped because the inside is compact.

In the latter method of absorbing deformation by means of a bellows or the like, since the expansion joint such as a bellows has a thin wall structure, a stress corrosion cracking (S
CC) occurs, and a problem that cannot withstand long-term operation occurs.

It is an object of the present invention to provide a new piping structure for reducing the thermal stress, which solves the problems of the prior art.

[0008]

As a structure for achieving the above-mentioned object, a piping structure for reducing thermal stress of the present invention is
In a pipe that allows a high-temperature fluid or gas to pass through, insert a second pipe into the pipe with a gap other than at both ends to form a double-structured pipe consisting of an inner and outer pipe, and shield one end of the inner pipe. It is characterized in that it is fixed to the inner diameter side of the outer pipe by welding, and the other end side of the inner pipe has a free structure that can slide on the inner diameter side of the outer pipe.

Further, it is effective to apply the double structure pipe having the above structure to a portion which causes a thermal stress such as an injection pipe for steam or the like in a gas turbine machine.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a double pipe structure according to the present invention.

In the figure, reference numeral 1 denotes an outer pipe arranged at a portion through which a fluid or gas having a high temperature flows, and an inner pipe 2 is inserted inside the pipe 1 with a gap 3 provided at both ends. Form a double structure pipe.

One end side 4 of the inner pipe 2 is fixed to the inner diameter side of the outer pipe 1 by shield welding. 6 indicates a welded portion.

The other end 5 of the inner pipe 2 has a free structure which can slide on the inner diameter side of the outer pipe 1 in the pipe axial direction.

Then, as shown by the arrow, the working fluid or gas having a high temperature flows from the fixed end 4 side to the sliding end 5 side.

According to the present invention, since the inner pipe is exposed to the working fluid by adopting such a double structure pipe, the temperature becomes the temperature of the working fluid, but the outer pipe does not flow.

Therefore, the heat of the working fluid flowing through the inner pipe 2 is not transmitted to the outer pipe 1, and the temperature becomes the same as the surrounding temperature.

This reduces thermal stress.

Further, since the inner tube and the outer tube are fixed at one end and the other end is free in the axial direction, thermal stress does not occur.

[0020]

As described above, according to the piping structure for reducing thermal stress according to the present invention, a pipe with reduced thermal stress can be attached to a place where the inside is compact and narrow, such as inside a gas turbine. As a result, it is possible to simplify the piping structure of the gas turbine and the like, and at the same time, prevent failures and accidents and improve reliability.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of a double piping structure according to the present invention.

[Explanation of symbols]

 1 Outer pipe 2 Inner pipe 3 Gap 4 Inner pipe end (fixed side) 5 Inner pipe end (sliding side) 6 Weld

Claims (2)

[Claims] 1. A pipe having a high temperature, such as a fluid or a gas, which is passed through the pipe, wherein a gap is provided in the pipe other than the both ends to insert another pipe into a double-structured pipe including an inner pipe and an inner pipe. A pipe structure for reducing thermal stress, characterized in that one end side of is fixed to the inner diameter side of the outer pipe by shield welding and the other end side of the inner pipe is a free structure that can slide on the inner diameter side of the outer pipe. 2. The piping structure according to claim 1, wherein the double-structured pipe is applied to a site where thermal stress is generated, such as an injection pipe for steam in a gas turbine machine.