EP0112612A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Repairing degraded tubes of steam generators
Assignee: Babcock and Wilcox Co
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Filing: 1983-09-23
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Granted: —
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Expires: 2003-09-23
Abstract
Abstract @ A sealable multimetallic sleeve (10) is used for rapidly repairing a tube (22) degraded by a detrimental chemical attack on the outside surface of the tube (22) within and in a vicinity of a tube sheet in a steam generator. The sleeve (10) is sealably inserted into the degraded tube (22), spanning the region of the degradation. The sleeve (10) includes an inner member (12) with equivalent mechanical properties of the degraded tube (22) and an outer member (14) metallurgically bonded to the inner member (12) and resistive to caustic intergranular chemical attack causing tube degradation. The sleeve (10) has an expanded portion (17) at one end for positioning in the tube (22) within the tube sheet, and a multiplicity of grooves (16) in and adjacent to the other end of the sleeve (10) and containing brazing material.
Inventors
- 👤 Paul S. Ayres
- 👤 Louis E. Stark
- 👤 Joel G. Feldstein
- 👤 Tzerong Fu
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 12:00
CPC Classifications
F; F28; F28F; F28F11/00; F28F11/02; F16; F16L; F16L55/00; F16L55/16; F16L55/179; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/4935; Y10T29/49352; Y10T29/49805; Y10T29/49806
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
161 words
A sealable sleeve for rapidly repairing a tube (22) degraded by a detrimental chemical attack on the outside surface of the tube within and in a vicinity of a tube sheet (20) in a steam generator (18) by inserting and sealing the sleeve (10) in the degraded tube (22) spanning the region of degradation, the sleeve (10) being characterised by an inner member (12) of equivalent mechanical properties to the degraded tube (22), an outer member (14) metallurgically bonded to the inner member (12) and resistive to caustic intergranular chemical attack causing tube degradation, an expanded portion (17) of the sleeve at one end of the sleeve for positioning in the tube (22) within the tube sheet (20), a multiplicity of grooves (16) formed in and adjacent to the other end of the sleeve (10), which other end extends inwardly in use into the steam generator (18) beyond the tube sheet (20), and a brazing material contained in the grooves (16).
Claim 2
Dependent Claim
161 words
A sealable sleeve for rapidly repairing a tube (22) degraded by a detrimental chemical attack on the outside surface of the tube within and in a vicinity of a tube sheet (20) in a steam generator (18) by inserting and sealing the sleeve (10) in the degraded tube (22) spanning the region of degradation, the sleeve (10) being characterised by an inner member (12) of equivalent mechanical properties to the degraded tube (22), an outer member (14) metallurgically bonded to the inner member (12) and resistive to caustic intergranular chemical attack causing tube degradation, an expanded portion (17) of the sleeve at one end of the sleeve for positioning in the tube (22) within the tube sheet (20), a multiplicity of grooves (16) formed in and adjacent to the other end of the sleeve (10), which other end extends inwardly in use into the steam generator (18) beyond the tube sheet (20), and a brazing material contained in the grooves (16).
Claim 3
Dependent Claim
36 words
A sleeve according to claim 1, wherein the inner member consists of an alloy of nickel, chromium and iron in the composition ranges by weight of 72% minimum, 14 to 17% and 6 to 10%, respectively.
Claim 4
Dependent Claim
29 words
A sleeve according to claim 1 or claim 2, wherein the outer member (14) consists of a nickel alloy with a minimum content of 99% by weight of nickel.
Claim 5
Dependent Claim
45 words
A sleeve according to claim 1, claim 2 or claim 3, wherein the inner member (12) has been subjected to a heat treatment at 718°C ± 28°C (1325°F + 50 0 F) for approximately 15 hours producing a stress relieved condition in the material thereof.
Claim 6
Dependent Claim
27 words
A sleeve according to any one of the preceding claims, wherein the braze material preferably consists of an alloy of 82% gold and 18% nickel by weight.
Claim 7
Dependent Claim
39 words
A sleeve according to any one of the preceding claims, wherein the length of the sleeve (10) is materially greater than the thickness of a tube sheet (20) in which the sleeve is installed or intended to be installed.
Claim 8
Dependent Claim
28 words
A sleeve according to any one of the preceding claims, wherein the inner member (12) is composed of a material which duplicates that of the degraded tube (22).
Claim 9
Independent Claim
247 words
A method of installing a sealable sleeve (10) for repairing a degraded tube (22) that is vertically disposed within and in the vicinity of a tube sheet (20) in a steam generator (18), the method being characterised by cleaning the interior surface of the tube (22) above and below the degraded area, inserting an explosive device in the sleeve (10) at the elevation of multiple grooves (16) which are provided in the sleeve adjacent the upper end of the sleeve and which contain a brazing material, inserting the sleeve (10) and the explosive device in the degraded tube (22) and positioning the lower end of the sleeve flush with the lower end of the degraded tube, explosively expanding the sleeve (10) to the tube (22) above the degraded area, producing a mechanical joint between the sleeve and the tube, removing the spent explosive device and introducing a flow of an inert gas from the other end of the tube (22) undergoing repair to purge oxygen from the vicinity of the expanded sleeve (10) before and during a subsequent brazing operation, inserting an induction heater into the expanded sleeve (10) and brazing the material contained in the grooves (16) to the tube (22) and the sleeve, removing the induction heater and inserting an explosive device into the lower end of the expanded sleeve (10) slightly above the lower face of the tube sheet (20), and detonating the explosive device thereby welding the sleeve (10) to the tube (22).
Claim 10
Independent Claim
247 words
A method of installing a sealable sleeve (10) for repairing a degraded tube (22) that is vertically disposed within and in the vicinity of a tube sheet (20) in a steam generator (18), the method being characterised by cleaning the interior surface of the tube (22) above and below the degraded area, inserting an explosive device in the sleeve (10) at the elevation of multiple grooves (16) which are provided in the sleeve adjacent the upper end of the sleeve and which contain a brazing material, inserting the sleeve (10) and the explosive device in the degraded tube (22) and positioning the lower end of the sleeve flush with the lower end of the degraded tube, explosively expanding the sleeve (10) to the tube (22) above the degraded area, producing a mechanical joint between the sleeve and the tube, removing the spent explosive device and introducing a flow of an inert gas from the other end of the tube (22) undergoing repair to purge oxygen from the vicinity of the expanded sleeve (10) before and during a subsequent brazing operation, inserting an induction heater into the expanded sleeve (10) and brazing the material contained in the grooves (16) to the tube (22) and the sleeve, removing the induction heater and inserting an explosive device into the lower end of the expanded sleeve (10) slightly above the lower face of the tube sheet (20), and detonating the explosive device thereby welding the sleeve (10) to the tube (22).
Claim 11
Dependent Claim
48 words
A method according to claim 8, wherein the step of expanding the sleeve (10) to the tube (22) above the degraded area includes expanding the tube to a range of between 0.08 and 0.30 mm (3 and 12 mils) and providing self-support of the sleeve during subsequent operations.
Claim 12
Dependent Claim
62 words
A method according to claim 8 or claim 9, wherein the step of introducing a flow of an inert gas includes maintaining a flow rate of inert gas of 1.42 m 3 /h (50 ft 3 /h) for 5 minutes prior to brazing and reducing this flow rate to 0.57 m 3 /h (20 ft 3 /h) prior to the brazing operation.
Claim 13
Dependent Claim
71 words
A method according to claim 8, claim 9 or claim 10, wherein the brazing step includes heating to a brazing temperature of between 982°C and 1027°C (1800°F and 1880°F), holding this temperature for a minimum of 2 minutes, and then reducing the temperature to between 816°C and 843°C (1500°F and 1550°F) and holding this temperature for a minimum of 5 minutes to thermally treat the sleeve (10) and the tube (22).
References Cited (Backward Citations)
No citation records indexed.
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