JPH0422585A - Piping joining device - Google Patents

Abstract

PURPOSE:To improve repair efficiency by fitting a shape memory alloy sleeve pipe joint which is reduced on the diameter by heating on the piping damaged part periphery. CONSTITUTION:The shape memory alloy sleeve pipe joint 12 which is reduced on the diameter by heating is fitted on the damaged part 10a periphery of piping 10. A high-frequency heating means to heat this sleeve pipe joint 12 to the diameter reducing temperature is provided to heat it by a heating coil 9. Consequently, the sleeve pipe joint 12 is reduced on the diameter and fixed watertightly on the piping damaged part l0a periphery and the cut peripheries of piping are joined. This is utilized effectively for repairing when a stainless steel pipe in the water is damaged due to fatigue failure, etc., in a nuclear power plant, etc.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a pipe joining device suitable for nuclear power plants, etc., and particularly relates to a sleeve pipe joint made of a heat-reduced shape memory alloy. This invention relates to a pipe joining device with improved heating means.

(Prior art) If stainless steel pipes, etc. in a radiation atmosphere or underwater in a nuclear power plant etc. are damaged due to fatigue fracture or stress corrosion cracking, the damaged part of the pipe must be repaired immediately by remote control. Must be.

For example, in the unlikely event that piping such as a built-in jet pump measurement pipe breaks in a boiling water reactor, it would be necessary to repair it by remote control because the environment is high radiation and underwater. be.

Therefore, the following methods have been proposed as such repair methods.

That is, first, both ends of the broken portion of the pipe are removed by electric discharge cutting, and sleeve pipe joints made of a heat-reduced shape memory alloy are fitted around the outer periphery of both cut ends.

Next, the diameter of the sleeve joint is reduced by heating the sleeve joint with steam or a heater.
Watertightly fix to the outer layer of the broken pipe and join around the cut pipe.

(Problems to be Solved by the Invention) However, when a sleeve pipe joint is heated in water approximately 20 m below the water surface using such a steam heating method, there are the following problems.

That is, since the steam pipe through which the heating steam passes is submerged in water, the heating steam passing through the steam pipe is cooled in the water and condenses into water, making it impossible to raise the temperature of the sleeve pipe joint to a predetermined temperature. For this reason, the sleeve pipe joint does not shrink in diameter.
Difficult to secure to piping.

Therefore, methods such as making the steam pipe into a double pipe or wrapping it with a heat insulating material are considered, but in the former case, the rigidity and weight increase and the operability of the device deteriorates.

Further, in the latter method of wrapping the heat insulating material, there is a problem that the heat insulating material may contaminate the reactor water, which violates management regulations for CI ions, S ions, etc.

On the other hand, in the heater heating method, even if the heater is configured to cover the outer periphery of the sleeve pipe joint, the heater heats the reactor water at the same time as the piping, so the higher the heating temperature of the heater, the higher the temperature of the furnace of about 30°C. Water convection becomes faster, and the cooling effect becomes more effective. For this reason, there is a problem in that the sleeve pipe joint is easily heated to a predetermined temperature and reduced in diameter, making it difficult to fix it to the pipe.

In addition, in order to remotely control these devices, it is necessary to configure the heater to cover the outer periphery of the sleeve pipe joint, but a gap inevitably occurs between the heater and the sleeve joint, and reactor water floods into this gap. However, there is a problem in that it is difficult to raise the temperature of the surface of the sleeve pipe joint to a predetermined temperature.

Further, as other conventional methods, the following method can be considered.

In other words, by heating the sleeve joint to 808C to 100C using the conventional method described above, the diameter of the sleeve joint is slightly reduced, and the sleeve joint is loosely temporarily fixed around the outer periphery of the damaged pipe. .

Next, when reactor water is heated to, for example, 286°C due to reactor operation, this reactor water heats the sleeve pipe joint to the deformation (diameter reduction) end point (Af point), causing the sleeve pipe joint to shrink. diameter and fix it around the outer periphery of the damaged pipe.

However, this method cannot be adopted because it goes against the strict quality requirements of nuclear reactors, which require confirming the joint performance of the sleeve pipe joint in advance before starting reactor operation.

Therefore, the present invention was made in consideration of the above circumstances, and its purpose is to provide a pipe joining device that can easily heat a sleeve pipe joint made of a heat-reduced shape memory alloy to a diameter-reducing temperature in water by remote control. It is about providing.

[Structure of the invention]

(Means for Solving the Problems) The present invention was made by focusing on the electrical conductivity of a sleeve pipe joint made of a heat-reduced shape memory alloy that is fitted around the outer periphery of a damaged part of a pipe. It is composed of

In other words, the present invention provides a sleeve pipe joint made of a shape memory alloy that is fitted around the outer periphery of a damaged part of a pipe via a seal, contracted in diameter by heating, and fixed watertightly to the outer periphery of the damaged part, at a temperature at which the diameter contracted. It is characterized by having a heating means for performing high frequency induction heating.

(Function) When a high frequency current is passed through the conductive sleeve pipe joint by the heating means, an eddy current is generated in the sleeve pipe joint, which generates heat and is heated by high frequency induction.

For this purpose, heat is generated from inside the sleeve fitting, so it is easily heated to the diameter reduction temperature, and as a result, the sleeve fitting shrinks in diameter and is fixed watertight to the outer periphery of the broken part of the pipe via a seal. , this damaged part is covered and repaired with a sleeve pipe joint.

Therefore, according to the present invention, it is possible to easily heat the sleeve pipe joint to its diameter reduction temperature and repair the damaged portion of the pipe.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 and 2.

FIG. 2 is a perspective view showing the overall configuration of an embodiment of the present invention, and in the figure, the pipe joining device 1 has a length of, for example, 20 m.
A bar-shaped handle 2a is provided at the upper end of the operating pole 2, which has an elongated circular tubular shape exceeding .

The operation ball 2 has a crank-shaped bent part formed in its axially intermediate part, and a waterproof cylindrical underwater step-up transformer 3 is coaxially provided at its lower end.

The underwater step-up transformer 3 is connected to a high frequency power supply panel 5 via a power cable 4 passing through the operation ball 2, and an operation box 6 is electrically connected to this high frequency power supply panel 5. By operating the operation box 6, For example, high frequency power of 53 KW at a frequency of 21 KHz is applied from the high frequency power supply panel 5 to the underwater step-up transformer 3 for about 140 seconds per energization.

A U-shaped heating coil 9 is fixed to the bottom of the underwater step-up transformer 3 via a support 7 and a support arm 8.

As shown in FIG. 1, the heating coil 9 is configured such that a pipe 10 made of stainless steel or the like is housed in the U-shaped space from the side of its U-shaped opening. Electric insulators 11a and llb, which are integrated on the left and right sides in the figure and are sandwiched in the radial direction, are fixed to the inner circumferential surface of the heating coil 9.

For example, the plumber 0 cuts the damaged part 10a by electrical discharge machining (not shown) and divides it into two parts in the vertical direction, and the outer periphery of the pipe 10 before and after the damaged part 10a has a short axis heat-reduced shape memory. A sleeve pipe joint 12 made of alloy is fitted onto the outside through a cylindrical grooved seal 13 .

The sleeve pipe joint 12 is made of, for example, a Ni-CrNb heat-shrinkable shape memory alloy, and has a transformation point (As point) at which it starts shrinking (diameter reduction) and a point at which it ends shrinking (As point).
Af point) is set at 160°C, and at the stiff Af point, the diameter of the sleeve pipe joint 12 is reduced and the damaged part 10a of the pipe 10 is
It is firmly fixed to the outer periphery.

Next, the operation of this embodiment will be explained.

First, by operating the handle 2a of the operating ball 2, the position and direction of the heating coil 9, which is located below the water surface, for example, at a depth of more than about 20 meters, is adjusted as appropriate to prevent damage to the plumber 0 as shown in FIG. The heating coil 9 is fitted around the outer periphery of the sleeve pipe joint 12 which is fitted on the outer periphery of the section 10 in a watertight manner.

Next, the operation box 6 is operated to cause the high frequency power panel 5 to output high frequency power of 53 KW at a frequency of, for example, 21 KHz for 140 seconds per energization.

This high-frequency power is applied to the underwater step-up transformer 3 via the power cable 4, where it is boosted in pressure, and then applied to the heating coil 9.

For this purpose, a high frequency magnetic field is applied from the high frequency heating coil to the sleeve pipe joint 12, where eddy currents are generated and heat is generated from within, resulting in high frequency induction heating.

Since this sleeve pipe joint 12 is submerged in water, it is cooled and the outer surface only rises by about 110 to 120 degrees Celsius, but since induction heating generates heat from inside, the temperature inside it reaches the transformation end point (Af). 300-400℃, far exceeding
The temperature is raised to

For this purpose, the sleeve fitting 12 has a diameter of, for example, 0.5 mm.
The diameter is reduced by about 0.9 mm and is firmly and watertightly fixed to the outer peripheral surface of the damaged portion 10a of the pipe 10 via the grooved seal 13. With this, the plumber.

The damaged part 10a is covered with the sleeve pipe joint 12,
Then, they are joined and repaired.

By the way, the sleeve pipe joint 12 is made of 50%Ni-35%
The joint performance when constructed from a heat-reduced shape memory alloy of Ti-15%Nb and fixed around the damaged part 10a of a stainless steel plumber 0 is pressure resistance... test pressure is 73
The pull-out strength without leakage in kg/cm is 2460 kgf, and the sleeve pipe joint 12 is the damaged part 10a of the pipe 10.
This shows that it is extremely firmly fixed to the outer periphery of the

〔Effect of the invention〕

As explained above, the present invention applies high-frequency induction heating to a sleeve pipe joint made of a heat-reduced shape memory alloy that is fitted around the outer periphery of a damaged part of a pipe, so that the sleeve pipe joint that is underwater can be contracted by remote control. It can be easily heated to the diameter temperature.

For this purpose, the diameter of the sleeve pipe joint is reduced by heating.
The sleeve pipe joint can be firmly fixed to the outer periphery of the damaged part of the piping, and the outer periphery of the damaged part can be covered with the sleeve pipe joint.

In other words, according to the present invention, a damaged portion of a pipe can be repaired extremely easily by remote control.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a main part of an embodiment of a pipe joining device according to the present invention, and FIG. 2 is a partially cutaway perspective view showing the entire embodiment of the present invention having the main parts shown in FIG. be. 1... Piping joining device, 2... Operation pole, 3...
Underwater step-up transformer, 9... Heating coil, 10... Piping, 10a... Damaged part. Applicant's agent Hisashi Hatano 1yJ

Claims (1)

[Claims] A sleeve pipe joint made of a shape memory alloy that is fitted around the outer periphery of the damaged part of the pipe via a seal, contracted in diameter by heating, and fixed watertightly to the outer periphery of the damaged part, is heated by high-frequency induction heating to the diameter reduction temperature. A pipe joining device characterized by having a means.