GB1575110A - Mobile cooling device - Google Patents

Description

(54) MOBILE COOLING DEVICE (71) We, GENERAL ELECTRIC COM PANY, a corporation organized and existing under the laws of the State of New York, United States of America, of 1 River Road, Schenectady 12345, State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particulary described in and by the following statement: - The present invention relates to a mobile device for cooling inner surfaces of pipes.

Stress corrosion cracking in weld heat affected zones of stainless steel piping in nuclear reactors has long been generally recognized as being a significant problem.

Our U.S. Patent No. 4,049,186 teaches an effective method of eliminating or substantially reducing the stress corrosion tendency in a weld constraint zone (a weld strengthened region) terminating within a primary weld heat affected zone of a butt welded stainless steel pipe joint. The method includes applying to the outside of the pipe a secondary or overlay weld which extends across the pipe joint and bridges on each side of the pipe joint beyond the axial extremities of the primary weld heat affected zone at the inner surface of the pipe. The overlay weld is preferably applied while the inner surface of the pipe is being cooled by water or other coolant.

It has now been found that inner surfaces of pipes can be effectively cooled in simple efficient manner by practice of the present invention, which provides a mobile cooling device especially suitable for cooling the inner surface of pipes during application of overlay welds. In operation, the device typically provides highly turbulent coolant flow in regions of overlay weld applications.

According to the present invention, the mobile device for cooling the inner surface of a pipe comprises: (A) an elongate semi-rigid tubular conduit adapted for connection to a source of high-pressure liquid coolant and suitable for passing the high-pressure liquid coolant axially therethrough, (B) a first semi-rigid pressure inflatable member connected to and in flow communication with the tubular conduit, (C) a second pressure inflatable member spaced from the first inflatable member, and (D) a tubular conduit section connected to and in flow communication with the first and second inflatable members, the section having a plurality of holes for outward radial flow of the liquid coolant, one of the inflatable members being expansible into sealed engagement with substantially the entire inner circumference of a portion of the pipe and the other inflatable member having spaced apart members protruding radially outwardly from the outer surface thereof, the protruding members being disposed transversely of the longitudinal axis of the device, said other inflatable member being expansible to a condition wherein the spaced apart protruding members contact a portion of the inner circumference of the pipe and define flow channels therewith.

Practice of the present invention will be made more fully apparent by referring to the following detailed description of a preferred embodiment thereof, given by way of example only, taken with the accompanying drawing wherein like numerals refer to similar elements throughout the several views.

In the drawing: FIG. 1 is a fragmentary side view illustrating the cooling device embodying the present invention as it is being advanced in partially deflated mode through a pipe to a use location therein; FIG. 2 is a side view, partially in section, showing the cooling device in an inflated mode and in-position within a pipe for cool ing a region of-the inner surface of the pipe during-an overlay welding operation; FIG. 3 is a sectional view taken on line -3-3-of FIG. 2; and FIG. 4 is a sectional view taken on line of of FIG. 2.

!Referring now to the drawing and especi ally FIG. 1, there is shown mobile cooling device 10 being advanced in the direction of arrow 12 along a tortuous path through pipe 14 containing adjacent bends 16 and 18 defining an S-shape pipe section. The pipe, which may be a type 304 stainless steel pipe in boiling water service in a nuclear reactor, contains butt weld 20 which is to receive overlay weld 22 (FIG. 2) in a welding oper ation which typically increases the temper ature of the inner surface of the pipe to 300 F. or more. In the absence of effective tooling of the inner surface of the pipe, sensitization to stress corrosion may result.

The cooling device 10 includes elongate semi-rigid tubular conduit 24 provided at an end thereof with coupling 26 for con necting the conduit to a source (not shown) of-high-pressure liquid coolant, which may be water preferably at a gauge pressure of to to 150 p.s.i. or more and preferably at a temperature of 35 to 80"F. The elongate conduit 24 is connected near an opposite end thereof to inflatable member 28 which - -is in flow communication with the elongate conduit through a port defined by neck 30 provided on the inflatable member. The cooling device further includes tubular con 'duit section 34 connected to and in flow eommunication with the inflatable mem bey 28 through a port defined by neck 32.

Second pressure inflatable member 36, which is spaced from the first inflatable member 28, is connected to and in flow communication with tubular conduit sec tion 34 at an end thereof through a port defined by neck 38. The various connec tions described above may be made by any suitable securing means, e.g. mechanical clamps or strong adhesives. Alternatively, the device or- any portion of adjoining ele ments thereof may be of one-piece con struction.

'The cooling -device may be pushed or pulled through - the pipe-while the inflatable members are in deflated modes, has shown in FIG. 1, until the- axially medial portion of the tubular conduit section 34 of the de- vice reaches a location to be cooled, for example the- pipe region bridging butt weld 20, as illustrated in FIG. 2. -The semi-rigid construction of the elongate conduit 24 and thewinflatàble member 28 provides a good balance of sufficient flexibility for the -device to be moved along a tortuous path and sufficient rigidity- or stiffness such that the device does not loop over on itself. Tubular conduit section 34 may also be of semi rigid construction.

The device preferably further includes means for detecting the presence of the device at a preselected location within a pipe. For service in non-magnetic pipe, an effective detection means - includes one or more magnets on the device, as illustrated by magnets 40, 41, 42 and 43 embedded in inflatable member 28 on a circumference thereof perpendicular to axis A-A. A com pass or other magnet detection means can be held near the outer surface of the pipe at a preselected distance from butt weld 20, e.g. at line 44 in FIG. 2. When the com pass needle is deflected to a direction point ing perpendicularly toward the pipe, the presence of the magnets in the plane of the needle is indicated. The device may thus be precisely positioned within the pipe.

After the device is axially positioned in the pipe, the coupling can be attached to a source of high-pressure water or other liquid coolant, which is then permitted to flow through the conduit 24 to fill the in flatable members 28 and 36 and the con necting conduit section 34. Upon con tinuing the flow, the high-pressure liquid coolant 44 expands the inflatable members to inflated modes illustrated in Fig. 2. As shown in FIG. 2 and FIG. 4, inflatable member 28 is expanded into sealed engage ment with substantially the entire inner cir cumference of a portion of the pipe 14, releasably securing the device to the pipe.

Inflatable member 36 is provided with a plurality of spaced -apart members, illus trated by lugs 469 47, 48, 49, 50 and 51 (FIG. 2 and FIG. 3), -which protrude radi ally outwardly from the outer surface of the inflatable member. The lugs are dis posed transversely of longitudinal axis. A-A of the cooling device, that is at least a por tion of each lug is on the maximum surface circumference of the inflated member 36 taken perpendicular to the axis. Inflatable member 36 is expanded by the high pres sure liquid - coolant - therein to an extent such that the spaced apart lugs contact a portion of the inner circumference of pipe 14 and define therewith flow channels -52, 53, 54, 55, 56 and 57.

Tubular conduit --section 34sis provided with a plurality of holes 58 through lhe -annular-wall thereof. .-The' boles are.-prefer- ably arranged in uniform - manner axially along. and .about the circumference of the conduit section, as illustrated . in -FIG. 2.

Jets of high pressure liquid coolant are emitted -generally radially outwardly through the - holes - and - form a highly turbu lent coolant bath which typically substanti ally fills the interior zone !of the pipe - ex tending from inflatable member 28 to in flatable member 36. While maintaining the flow of coolant into the bath, overlay weld 22 may be applied. The inner surface of the pipe in contact with the turbulent cooling bath is effectively held at a low temperature, with heat from the welding operation being carried away by the coolant which is discharged through the flow channels 52, 53, 54, 55, 56 and 57. The highly turbulent coolant bath substantially prevents formation of vapor pockets adjacent the pipe wall being cooled.

The inflatable members are preferably expandable to substantially symmetrical configurations about axis A-A of the device, as illustrated in FIGS. 2-4. Such symmetry results in positioning the axis of the tubular conduit section 34 along the axis of the pipe and effects more uniform cooling of the pipe.

After a cooling operation is completed, the device may be separated from the source of liquid coolant, allowed to drain and deflate, and then removed from the pipe.

The various elements of the device may be formed of any suitable materials. The inflatable members may be formed, for example, of elastomeric material such as rubber. The holes 58 may be of any suitable diameter, e.g. from 0.05 inch or less to 0 10 inch or more and preferably about 007 inch. The radial thickness of the lugs may be, for example, about 1/32 to about Q inch, preferably about Çw inch.

WHAT WE CLAIM IS:- 1. A mobile device for cooling the inner surface of a pipe, comprising: (A) an elongate semi-rigid tubular conduit adapted for connection to a source of high-pressure liquid coolant and suitable for passing said high-pressure liquid coolant axially therethrough, (B) a first semi-rigid pressure inflatable member connected to and in flow communication with said tubular conduit, (C) a second pressure inflatable member spaced from said first inflatable member, and (D) a tubular conduit section connected to and in flow communication with said first and second inflatable members, said section having a plurality of holes for outward radial flow of said liquid coolant, one of said inflatable members being expansible into sealed engagement with substantially the entire inner circumference of a portion of the pipe and the other inflatable member having spaced apart members protruding radially outwardly from the outer surface thereof, said protruding members being disposed transversely of the longitudinal axis of the device, said other inflatable member being expansible to a condition wherein said spaced apart protruding members contact a portion of the inner circumference of the pipe and define flow channels therewith.

2. A mobile device according to Claim 1, further including means for detecting the presence of the device at a preselected location within a pipe.

3. A mobile device according to Claim 2, wherein said detecting means includes a magnet disposed on the device.

4. A mobile device according to any one of Claims 1 to 3, wherein said first inflatable member is expansible into sealed engagement with substantially the entire inner circumference of a portion of the pipe.

5. A mobile device according to any one of the preceding claims, wherein said first and second inflatable members are expandable to axially symmetrical configurations.

6. A mobile device for cooling the inner surface of a pipe, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. flatable member 36. While maintaining the flow of coolant into the bath, overlay weld 22 may be applied. The inner surface of the pipe in contact with the turbulent cooling bath is effectively held at a low temperature, with heat from the welding operation being carried away by the coolant which is discharged through the flow channels 52, 53, 54, 55, 56 and 57. The highly turbulent coolant bath substantially prevents formation of vapor pockets adjacent the pipe wall being cooled. The inflatable members are preferably expandable to substantially symmetrical configurations about axis A-A of the device, as illustrated in FIGS. 2-4. Such symmetry results in positioning the axis of the tubular conduit section 34 along the axis of the pipe and effects more uniform cooling of the pipe. After a cooling operation is completed, the device may be separated from the source of liquid coolant, allowed to drain and deflate, and then removed from the pipe. The various elements of the device may be formed of any suitable materials. The inflatable members may be formed, for example, of elastomeric material such as rubber. The holes 58 may be of any suitable diameter, e.g. from 0.05 inch or less to 0 10 inch or more and preferably about 007 inch. The radial thickness of the lugs may be, for example, about 1/32 to about Q inch, preferably about Çw inch. WHAT WE CLAIM IS:-

1. A mobile device for cooling the inner surface of a pipe, comprising: (A) an elongate semi-rigid tubular conduit adapted for connection to a source of high-pressure liquid coolant and suitable for passing said high-pressure liquid coolant axially therethrough, (B) a first semi-rigid pressure inflatable member connected to and in flow communication with said tubular conduit, (C) a second pressure inflatable member spaced from said first inflatable member, and (D) a tubular conduit section connected to and in flow communication with said first and second inflatable members, said section having a plurality of holes for outward radial flow of said liquid coolant, one of said inflatable members being expansible into sealed engagement with substantially the entire inner circumference of a portion of the pipe and the other inflatable member having spaced apart members protruding radially outwardly from the outer surface thereof, said protruding members being disposed transversely of the longitudinal axis of the device, said other inflatable member being expansible to a condition wherein said spaced apart protruding members contact a portion of the inner circumference of the pipe and define flow channels therewith.

2. A mobile device according to Claim 1, further including means for detecting the presence of the device at a preselected location within a pipe.

3. A mobile device according to Claim 2, wherein said detecting means includes a magnet disposed on the device.

4. A mobile device according to any one of Claims 1 to 3, wherein said first inflatable member is expansible into sealed engagement with substantially the entire inner circumference of a portion of the pipe.

5. A mobile device according to any one of the preceding claims, wherein said first and second inflatable members are expandable to axially symmetrical configurations.

6. A mobile device for cooling the inner surface of a pipe, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.