KR910007127B1 - Tubular member stretching device and method - Google Patents

Abstract

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Description

Tubular member stretching device and method

1 is a cross-sectional view of the propellant action device shown as a tubular member to be expanded in a steam generator tube according to the present invention.

FIG. 2 is a cross sectional view similar to FIG. 1 showing the device immediately after the propellant is ignited.

FIG. 3 is a cross sectional view similar to FIG. 2 showing the apparatus after draining the stretch gas to withdraw the apparatus from the prolonged exhausted and drawn tube.

* Explanation of symbols for main parts of the drawings

10 device 12: tubular member

14 steam generator 16 cap 1

18: 2nd cap 20: center circumference (or coupling rod)

22: bladder 24: space

26: ignition port 28: bore

30: rod 32: electric wire

34: igniter 36: blind bore

38: flange 40: separation ring

42, 44: sleeve extension

FIELD OF THE INVENTION The present invention generally relates to repairing, installing or otherwise handling a tube by tubular members, and more particularly to a new and advantageous apparatus and method for radially stretching tubes.

When installing and repairing pipes, it is sometimes advantageous to model them by handling pipes or tubular members in the pipes.

In nuclear steam generators, known repair procedures show that the tubular members are arranged inside the steam generator and extend to their ends. The weld is configured to seal and fix the tubular member in the steam generator tube.

Conventional methods for accomplishing the above have used a hydraulic stretching machine to stretch the tubular member of the joint before welding.

This process has proved to be too slow and cumbersome, limiting the number of tubes that can be repaired within a given time. This method is particularly unfavorable for nuclear steam generators, and long-term repairs increase radiation exposure to the repairer.

Hydraulic pipe drawing methods and apparatus are described in US Patent Application No. 4, 195390.

An inflatable bladder is placed between the caps at each end connected to a coupling rod located within the bladder. Hydraulic pressure is supplied in to inflate the bladder and surrounds the tubular member. However, the above-mentioned hydraulic softening is slower, especially in an environment where radiation is emitted. In addition, an external pressure source is required and additional time is required to operate the device of this type.

Faster techniques using propellants or explosives are known. For example, U.S. Patent Application No. 3,287,947 discloses a tube stretching technique that uses explosives to stretch the tube ends outward. U.S. Patent Application No. 3,876,233 also discloses an automatic pipe coupling device that allows the use of a propellant to move and couple the two parts, respectively.

The present invention provides a method and apparatus for rapid stretching of a tubular member. All installations can be done immediately outside the repair area, so that the invention is particularly suitable for minimizing exposure in a radiation emitting environment.

Accordingly, an object of the present invention is to provide a method and a device for rapidly stretching a tubular member, and having a second end cap with a space from the first end cap and the first end cap, and a support for firmly connecting the caps at both ends to each other. And an expandable bladder connected between the cap and the cap and extending around the rod to form an enclosed space, igniting the propellant or explosive filling the space and the propellant to extend the bladder outwardly. An ignition means connected to the propellant. The bladder and the caps at both ends are located in the tubular member so that the propellant can be ignited for rapid stretching of the tubular member for the desired purpose. The propellant mechanism can thus be used to stretch the tube in the steam generator tube of a nuclear fuel steam generator.

The present invention may also be usefully used to stretch tubes in other constructs such as tube sheets, support plates and headers. The device can also be used to draw tubular plugs or to make special tubular shapes.

It is still another object of the present invention to provide a method and apparatus for rapidly stretching a tube because of its simple design, compact structure, economical in manufacturing, and simple tool.

Various unusual features of the invention are particularly well pointed out in the claims appended hereto at the conclusion of this specification.

In order to more clearly understand the operational advantages of the present invention, the special objects obtained by using the present invention, and the like, reference is made to the accompanying drawings and drawings for explaining the embodiments in which the embodiments of the present invention are shown.

In particular in the drawings, the device 10 provided in the present invention shows the rapid stretching of a tubular member to be repaired in a steam generator tube of a nuclear fuel steam generator (not shown).

The device of the present invention includes a central column or connecting rod 20 for firmly connecting the first cap 16 and the second cap 18 and the two caps to fix the space between the caps.

In the steam generator 14, which is generally vertical, the first cap 16 becomes the lower cap and the second cap 18 becomes the upper cap.

The flexible and resilient bladder 22 is connected between the cap 16 and the cap 18 and surrounds the strut 20 to form a good circular space. Propellants are provided to partially or completely fill the space.

There should be a passage through the ignition port 26 formed at one end of the support 20 to the space. The rod 30 can be assembled to press assembly or by inserting the rod 30 into the bore 28 to be fixed to the cap 16, which facilitates positioning the device in the desired position in the tube 12. .

The ignition means is provided with the electric conductor 32 and the igniter 34, and is provided through the bore in bore 28 and the ignition hole 26 which are located in the center of the rod 32, the rod 30. Two known ignition means may be provided, which may or may not require a mechanical passage through the ignition port 26 to the space 24.

The end of the strut 20, including the ignition port 26, is sandwiched in the bore 28, and the opposite side is sandwiched in the blind bore 36 of the cap 18.

In order to properly support and fix the bladder 22, the space 24 must be narrow, except for the ignition hole 26, the support 20 has a flange 38, or both ends of the bladder 22. It should be wrapped by a separation ring 40 that can withstand the pressure exerted by the inner surface of the adjacent bladder 22. Cap 16 and cap 18 are provided with sleeve extensions 42 and 43, respectively, to support the outer surface of the end of the bladder.

In operating the device in the position shown in FIG. 1, by igniting the propellant, the propellant rides at a high speed, abundant gas is generated to generate a high pressure, thereby rapidly expanding the bladder 22, FIG. As shown in the drawing, the surrounding tubular member is stretched.

Once the propellant has been consumed, the gas can be discharged through the ignition or breaking portion of the bladder shown in FIG. 3 and then the device 10 can be removed. The tubular member 12 is elongated in the steam generator 14 in a rapid, safe manner with minimal radiation exposure. Compared with the conventional hydraulic tube drawing method, the present invention provides a method and apparatus capable of stretching a tubular site within 10 to 15 milliseconds, while the hydraulic method requires about 5 minutes. The present invention is particularly important when a large number of steam generators have to be repaired in an environment to which radiation exposure is to be made.

Another advantage is that it can be cleaned up. Although this is not a common problem with hydraulic stretching techniques, it can be a problem with stretching techniques that require lubricants, generate unnecessary or generate hazardous waste. All of the propellant used in the present invention remains in the bladder 22, the generated gas can be discharged to one outside of the draw zone. Thus, there is no contamination of the pipe which causes problems in the next welding, and there is no contamination of the pipe which deteriorates the quality of the pipe by remaining unnecessary by-products on the pipe or the surface of the pipe.

The added advantage of the present invention over the prior art is that there is little need for an auxiliary device, and in a very simple form it only requires a power supply connected to the ignition conductor, and unlike the hydraulic method, the present invention provides a pump, a water supply device and a pipe. No device, pressure recorder, or electronic controller is required.

Unlike roller-type expanders, the present invention does not damage the pipe surface, thereby eliminating the corrosion problem resulting from the damage.

In repairing a nuclear fuel steam generator, the present invention may use any type of heat exchanger and may be used for any type of material. The apparatus and method can also be used regardless of the diameter of the tube and can be stretched to the desired length. For example, the bladder may be made of polyurethane, or a similarly resilient material. Propellant charges are used with smoke-free guns with the required combustion rate.

Lead-free chemistry that can be used in the present invention may be provided with commercially available HI-SKOR or Dupont de Nemours Co 700-X, Hercules Incorporated HERCULES 2400.

Although embodiments of the present invention, which apply the principles of the present invention, have been illustrated and described in detail, the present invention may be practiced in other ways without departing from the principles of the present invention.

Claims (6)

An apparatus for radially stretching a tubular member, comprising: a second end cap isolated from a first end cap and a first end cap, a strut securely connected to connect the caps to each other between the caps, and connected between the caps; An expandable bladder spread around the strut to form a space between the caps, a propellant filled in the space, and an ignition connected to the propellant to ignite the propellant to generate a gas and radially expand the bladder A tubular member drawing apparatus comprising a means. The tubular member drawing apparatus according to claim 1, wherein the space is annular and extends around the post. The tubular member drawing apparatus according to claim 1, wherein the first cap includes a bore extending through the cap and the post is fixed in the bore and comprises an ignition port connecting the bore and the space. 2. The support of claim 1 wherein the strut comprises flange means disposed in a space adjacent the cap, the cap having a sleeve portion surrounding the flange means, and an end of the bladder connected between the sleeve and the flange means. Tubular member stretching apparatus, characterized in that. The rod of claim 1, further comprising a placement rod firmly fixed to the first cap, the rod having a longitudinal bore in the rod, the ignition means having a pair of conductors extending through the longitudinal bore, Is provided with an ignition port connecting the bore of the first cap and the space in the support, and a pair of conductive wires extending through the ignition port and the igniter connected to the ignition lead, and the like. . A method of radially stretching a tubular member, the method comprising: providing a device having a cap secured to a space end by a support, with an expandable bladder connected between the caps at the perimeter of the support to form a space; Propellant is rapidly burned by ignition to generate a large amount of gas, and placing the device on the tubular member igniting propellant to extend the bladder from a portion of the tubular member The tubular member stretching method.

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