JPH1128539A - Hydraulic tube expander - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expand heat transfer tube without a clearance generated between the tube and tube plate. SOLUTION: By expanding the heat transfer tube 22 located upper than the vicinity of upper surface of tube plate 21 with a cylindrical ring 31 with slits 33, a bordering part 42 upon expanded part of heat transfer tube 22 is formed at a position apart from the upper surface of tube plate 22, and thus getting rid of very small clearance between the heat transfer tube 22 and the hole of tube plate 21 the heat transfer tube 22 is expanded without a clearance generated between the tube and tube plate 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic expansion tool used for joining a heat transfer tube of a PWR steam generator to a tube sheet, for example.

[0002]

2. Description of the Related Art For example, when a heat transfer tube of a PWR steam generator is brought into close contact with a tube sheet, a hydraulic expansion tool is used. FIG.
A conventional hydraulic expansion tool will be described with reference to FIG. FIG. 4 shows a cross section of a conventional hydraulic expansion tool in a state before expansion, and FIG. 5 shows a cross section of a conventional hydraulic expansion tool in a state after expansion.

[0003] As shown in the figure, a mandrel 3 is disposed on the inner periphery of a heat transfer tube 2 which is in close contact with a tube sheet 1. 4 are provided. A urethane rubber 5 and an O-ring 6 are provided inside the locking portion 4, respectively.
The ring 6 is compressed in the axial direction by the hydraulic pressure supplied from the outside and is locked to the locking portion 4, and the diameter thereof is increased, so that water tightness with the inner peripheral surface of the heat transfer tube 2 is ensured. Mandrel 3
A pressurizing hole 7 is formed in the axial center portion, and the pressurizing hole 7 opens between the upper and lower urethane rubbers 5 and the O-ring 6. The liquid pressure is supplied through the pressurizing hole 7. Further, a temporary expanded portion 8 is formed at a lower end portion of the heat transfer tube 2.

[0004] At the beginning of the tube expansion process, in order to position the heat transfer tube 2, as shown in FIG. 4, the vicinity of the lower end portion of the heat transfer tube 2 is temporarily fixed to the tube sheet 1 by a temporary expansion portion 8. After the heat transfer tube 2 is temporarily fixed, the mandrel 3 is set so that the urethane rubber 5 and the O-ring 6 are located in the base tube portion at the upper end and the temporary expanded portion 7 at the lower end of the heat transfer tube 2. In this state, as shown in FIG. 5, a hydraulic pressure P is applied through the pressurizing hole 7 of the mandrel 3 to expand the heat transfer tube 2 to the tube sheet 1 and to closely join the tube.

[0005]

In a conventional pipe expanding tool,
When a high pressure is applied while the sealing portion composed of the urethane rubber 5 and the O-ring 6 is outside the tube sheet 1, the reaction force due to the pressurization cannot be received only by the heat transfer tube 2, and the outer diameter of the heat transfer tube 2 is reduced. Large deformation will occur. Therefore, it is necessary to position the urethane rubber 5 and the O-ring 6 for sealing inside the tube sheet 1. Therefore, in the pipe expansion using the conventional pipe expansion tool, as shown in FIG. 5, the pipe expansion boundary portion 9 always occurs near the upper surface 10 of the tube sheet 1, and the heat transfer pipe 2 and the hole of the tube sheet 1 A minute gap 11 is generated between them.
Therefore, during a long operation period of the plant, it becomes a factor of causing corrosion cracking from the outer surface of the heat transfer tube 2.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pipe expanding tool capable of expanding a pipe to be processed without generating a gap between the pipe and a pipe sheet.

[0007]

To achieve the above object, the present invention comprises a main body which is inserted into a pipe to be processed and has locking portions at both axial ends, and a locking portion at both ends. A seal member that is arranged inside and is compressed in the axial direction by the hydraulic pressure supplied from the outside, is locked in the locking portion, and expands the diameter to ensure watertightness with the inner peripheral surface of the pipe to be processed. A hydraulic expansion tool that expands the pipe to be processed between the seal members by applying a hydraulic pressure to the inside of the pipe to be processed between the seal members and tightly joins the pipe to the tube sheet; A cylindrical ring having conical tapered surfaces formed at both ends thereof and having a slit extending in the axial direction and formed at both ends of the cylindrical ring. Conical taper with a tapered surface on the end face opposite to the conical tapered surface Characterized in that comprising the ring.

[0008]

FIG. 1 shows a cross section of a pipe expanding tool according to an embodiment of the present invention. The left half in the drawing shows a state before expansion, and the right half in the figure shows a state after expansion. It is. FIG. 2 shows a partially enlarged state of the cylindrical ring, and FIG. 3 shows a view taken along line III-III in FIG.

As shown in FIG. 1, a mandrel 23 as a main body is inserted into the inner periphery of a heat transfer tube 22 as a pipe to be welded which is tightly joined to a tube sheet 21, and locking portions 24 are provided at both ends of the mandrel 23. Is provided. A urethane rubber 25 and an O-ring 26 as a sealing member
Are provided respectively. The urethane rubber 25 and the O-ring 26 are compressed in the axial direction by the hydraulic pressure supplied from the outside and are locked on the locking portion 24, and the water-tightness between the inner circumferential surface of the heat transfer tube 22 is increased by increasing the diameter. Is secured.

A pressure hole 27 is formed in the axial center portion of the mandrel 23. The pressure hole 27 is formed between the upper and lower urethane rubbers 25 and O.
It is open between the rings 26. The liquid pressure is supplied through the pressurizing hole 27. Further, a temporary expanded portion 28 is formed at a lower end portion of the heat transfer tube 22.

A cylindrical ring 31 is disposed between the upper locking portion 24 and the urethane rubber 25. At both ends of the cylindrical ring 31, a conical tapered surface 32 having a short axial dimension on the inner peripheral side. Are formed. As shown in FIGS. 1 to 3,
A slit 33 is formed in the cylindrical ring 31 so as to extend in the axial direction. A plurality of slits 33 are formed in the circumferential direction of the cylindrical ring 31, and upper and lower slits 33 are formed by changing the phase in the circumferential direction. .

A cylindrical urethane rubber material 40 is provided on the outer peripheral surface of the cylindrical ring 31. The urethane rubber material 40 serves as a buffer between the inner peripheral surface of the heat transfer tube 22 and a contact mark on the heat transfer tube 22. It does not stick.

A first conical taper ring 34 is disposed between the cylindrical ring 31 and the upper locking portion 24. Opposing tapered surfaces 35 are formed. First
The other end surface (upper surface) of the conical taper ring 34 is
4. A second conical taper ring 36 is disposed between the cylindrical ring 31 and the urethane rubber 25, and one end surface (upper surface) of the second conical taper ring 36 has a tapered surface facing the conical tapered surface 32. 37 are formed. The other end face (lower face) of the second conical taper ring 36 faces the urethane rubber 25.

The cylindrical ring 31 is provided with an axial thrust force of the mandrel 23 generated by pressure at the time of hydraulic expansion, and
An elastic structure in which the outer diameter is increased by a combination of the first conical taper ring 34 and the second conical taper ring 36 provided at both ends is provided.

As shown in the right half of FIG. 1, by applying a hydraulic pressure P through a pressure hole 27 of the mandrel 23, an axial thrust force of the mandrel 23 acts on the O-ring 26 and the urethane rubber 25. This load acts on the first conical tapering 34 and the second conical tapering 36. Further, a load acts on the conical tapered surfaces 32 at both ends of the cylindrical ring 31 via the tapered surfaces 35 and 37 of the first conical taper ring 34 and the second conical taper ring 36, so that the slit 33 is expanded and the cylindrical shape is formed. The ring 31 is expanded in diameter, and the heat transfer tube 22 is expanded.

When the expansion is completed (when the pressure returns to 0)
As shown in the left half of FIG.
The first conical taper ring 34 and the second conical taper ring 36 that have pressed the shaft in the axial direction return to their original positions, and the diameter of the cylindrical ring 31 is restored to the initial size.

First, in order to position the heat transfer tube 22, as shown in the left half of FIG. 1, the vicinity of the lower end of the heat transfer tube 22 is temporarily fixed to the tube sheet 21 by the temporary expansion portion 28. After the heat transfer tube 22 is temporarily fixed, the tube ring 22 is set so that about half of the length of the cylindrical ring 31 is located in the tube sheet 21 so that the tube sheet 22 can bear the load for expanding the heat transfer tube 21. To

In this state, as shown in the right half of FIG.
The hydraulic pressure P is applied through the pressurizing hole 27 of the mandrel 23 to apply an axial thrust force of the mandrel 23 to the O-ring 26 and the urethane rubber 25. The load acting on the urethane rubber 25 acts on the first conical taper ring 34 and the second conical taper ring 36, and further via the tapered surfaces 35 and 37 of the first and second conical taper rings 34 and 36. It acts on the conical tapered surfaces 32 at both ends of the cylindrical ring 31.

As a result, the slit 35 is expanded, the diameter of the cylindrical ring 31 is expanded, and the heat transfer tube 22 is expanded to the tube sheet 21 and closely joined. At the time of expanding the tube, the heat transfer tube 22 deviating from the upper surface of the tube sheet 21 is formed into a cylindrical ring 3 having a plurality of slits 33 formed in the axial direction so that rigidity in the circumferential direction is reduced.
Since the diameter of the heat transfer tube 1 is expanded, the tube is forcibly expanded without exerting an excessive expansion force, and the expansion boundary 42 of the heat transfer tube 22 is provided outside the tube sheet 21.

The expanded boundary portion 42 of the heat transfer tube 22 is located 20 mm from the upper end surface of the tube sheet 21 in consideration of the amount of deposits such as sludge.
A position of about mm is appropriate.

The heat transfer tube 22 is expanded by using the above-described tube expansion tool to expand the heat transfer tube 22 above the vicinity of the upper surface of the tube sheet 21 with the cylindrical ring 31 having the slit 33 formed therein.
Can be formed at a position away from the upper surface of the tube sheet 21. Therefore, the heat transfer tube 22 can be expanded without generating a gap between the heat transfer tube 22 and the pipe expansion boundary portion 42 where chemical concentration on the secondary side of the heat transfer tube 22 can be avoided. Become.

Therefore, there is no minute clearance between the heat transfer tube 22 and the hole of the tube plate 21, so that chemical concentration of the liquid can be avoided even during a long-term plant operation, and the outer surface of the heat transfer tube 22 can be prevented. Can prevent corrosion cracking.

[0023]

According to the present invention, there is provided a pipe expanding tool which is inserted into a pipe to be processed and provided with locking portions at both ends in an axial direction, and which is disposed inside the locking portions at both ends and supplied from outside. A sealing member that secures watertightness between the inner peripheral surface of the pipe to be processed by being compressed in the axial direction by the hydraulic pressure and locking to the locking portion to increase the diameter; A hydraulic expansion tool that expands a pipe to be processed between seal members by applying a liquid pressure to the inside of the pipe to be bonded and adheres tightly to a pipe sheet.
A cylindrical ring having a conical tapered surface having a short axial dimension on the inner peripheral side formed between the sealing member and the locking portion and having slits extending in the axial direction at both ends and a cylindrical ring; And a conical taper ring having a tapered surface facing the conical tapered surface at both end portions of the tube plate, so that the pipe to be processed above the vicinity of the upper surface of the tube sheet is expanded with a cylindrical ring having slits formed. Thus, the pipe expansion boundary portion of the pipe to be processed can be formed at a position away from the upper surface of the pipe sheet. As a result, it is possible to expand the pipe to be processed without generating a gap between the pipe and the pipe sheet.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pipe expanding tool according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view of a cylindrical ring.

FIG. 3 is a view taken along line III-III in FIG. 2;

FIG. 4 is a cross-sectional view of a conventional hydraulic expansion tool in a state before expansion.

FIG. 5 is a sectional view of a conventional hydraulic expansion tool in a state after expansion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Tube sheet 22 Heat transfer tube 23 Mandrel 24 Locking part 25 Urethane rubber 26 O-ring 27 Pressurization hole 28 Temporary expansion part 31 Cylindrical ring 32 Conical taper surface 33 Slit 34 First conical taper ring 35, 37 Taper surface 36 2 Conical taper surface 40 Urethane rubber material 42 Expansion boundary

Claims (1)

[Claims] 1. A main body which is inserted into a pipe to be processed and has locking portions at both ends in an axial direction, and is axially compressed by a hydraulic pressure which is disposed inside the locking portions at both ends and is supplied from the outside. A sealing member that secures water tightness between the inner peripheral surface of the pipe to be processed and the diameter of the pipe to be expanded by being locked to the locking portion. In a hydraulic expansion tool that expands a pipe to be processed between seal members and tightly joins it to a tube sheet by adding a seal, a conical portion having a short axial dimension on the inner peripheral side disposed between the seal member and the locking portion is provided. Tapered surface formed at both ends and formed with a slit extending in the axial direction, and a conical tapered ring disposed at both end portions of the cylindrical ring and having a tapered surface opposed to the conical tapered surface at the end surface. A hydraulic expansion tool characterized by the following.