|Publication number||US3562887 A|
|Publication date||Feb 16, 1971|
|Filing date||May 8, 1968|
|Priority date||May 8, 1968|
|Publication number||US 3562887 A, US 3562887A, US-A-3562887, US3562887 A, US3562887A|
|Inventors||Berman Irwin, Schroeder Joseph W, Smith Herman P|
|Original Assignee||Foster Wheeler Corp|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (25), Classifications (11)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Feb. 6, 1971 J. w. SCHROEDER ETAL 3,562,887
EXPLOSIVE EXPANSION OF LINER SLEEVES Filed May 8, 1968 FIG] INVENTORS. JOSEPH W SCHROEDER HERMAN P SMITH IRWIN BERMAN A T TORNE Y United States Patent O EXPLOSIVE EXPANSION OF LINER SLEEVES Joseph W. Schroeder, Clark, and Herman P. Smith, Bound Brook, N..l., and Irwin Berman, Bronx, N.Y., assignors to Foster Wheeler Corporation, Livingston, N.J., a corporation of New York Filed May 8, 1968, Ser. No. 727,530 Int. Cl. B21d 53/00 US. Cl. 29--157.4 Claims ABSTRACT OF THE DISCLOSURE By use of an explosive charge together with an accompanying medium two concentric tubes may be expanded at the same time, with the inner tube or liner sleeve expanding and locking to the outer tube and the outer tube expanding into a tube hole in a tubesheet or heat transfer medium. In cases where the inner tube does not extend the full length that must be expanded in the outer tube the medium or explosive may be shaped to provide the proper force required at each section.
BACKGROUND Corrosion-erosion is a phenomenon which combines a corrosive medium with high flow rates so that the corrosive medium reaches new surface. For ferritic tubes this occurs frequently with many feedwater heaters under operating conditions. It also occurs for other materials. The occurrence generally depends upon the particular feedwater treatment and rate of flow.
Since it is difficult and expensive to change these conditions for many heaters various methods of lining the initial portion of the tubes with corrosion resistant material have been tried.
The methods which have been tried include tube into tubesheet expansion and then electrochemical plating, or electrochemical plating of tubes and subsequent tube into tubesheet expansion. In either case, this allows corrosion resistant material which has poor heat conduction to be used at the point of maximum corrosion.
Electrochemical plating has the possibility that corrosive elements can be washed into other parts of the boiler system, and cause damage.
Tubes have been mechanically expanded, and kinetically expanded into tubesheets. In either case, subsequent mechanical expansion of an insert is very difficult. Sleeve inserts must be designed with a feather edge on the trailing side so as to reduce turbulence. This feather edge requires special equipment for the mechanical expansion to the tube. The result, even if special equipment is used, is questionable. In addition, mechanical cold work would probably damage the insert surface.
In mechanical expansion of a tube into tubesheet, a space is left near the weld of the tube to the face of the tubesheet. This is done because in mechanical expansion, the direct compression of the tube on the tubesheet surface causes tube elongation. If an insert is then mechanically rolled into the tube, it will close up this gap and put an axial load on the 'weld. In addition, it will put an axial load on the previously rolled portion and possibly open the seal.
Kinetic expansion of inserts into both previously kinetically and mechanically rolled tubes is excellent for rework and can be so carried out as not to close the gap near the weld. It does however, for a new heater, require two steps, namely, expansion of the tube into tubesheet, and expansion of insert into tube.
SUMMARY The main object of the present invention is to provide 3,562,887 Patented Feb. 16, 1971 corrosion erosion resistant surface at inlet end of feedwater heater tube. Accordingly a corrosive resistant liner sleeve shorter than the thickness of the tube sheet is inserted in a tube within the tube sheet. An insert having a central portion with grains of explosive distributed therealong and excluded in a force transmitting annular portion of polyethylene or the like, is inserted in the liner sleeve. The sleeve preferably tapered toward the inner end thereof to form a thin edge. The explosive is detonated, and the liner sleeve is expanded and locked inside the tube, and the tube is simultaneously expanded and locked inside the tube sheet hole. In the drawings:
FIG. 1 is a section through a tube sheet longitudinally of a tube therein, illustrating the method and apparatus for explosive expansion of a liner sleeve into the tube and tube sheet, according to the preferred embodiment of the present invention;
FIG. 2 is a transverse section through the structure shown in FIG. 1;
FIG. 3 is a view similar to FIG. 1, showing a modification; and
FIG. 4 is a transverse section through the structure shown in FIG. 3.
As shown in FIGS. 1 and 2, a tube sheet 10 has a base receiving a tube 12 of carbon steel or other material subject to corrosion. Generally the tube is inserted within the tube sheet with a clearance of .006 inch, plus or minus. One end of the tube 12 is welded as at 14 to one surface of the tube sheet.
A liner sleeve 16 of corrosion resistant material such as stainless steel, is inserted inside the tube 12. This liner sleeve 16 is shorter than the thickness of tube sheet 10, and is tapered in thickness toward the inner end thereof to form a thin edge 18. The outer end to the sleeve 16 is preferably flanged outward as at 20, forming a stop to gauge the distance the end 18 extends into the tube 18.
For generating the explosive force an insert 22 has an external diameter by which it can be inserted into the liner sleeve 16, and a length so that when it is positioned within the tube 12, the insert 22 is at least substantially coextensive with the area of overlap between the liner sleeve 16 and the tube 12. In essence, the insert 22 comprises a central axial portion 24 which contains a predetermined number of grains of explosive, generally from 25 grains per foot to 40 grains per foot, uniformly disposed along the insert axis. For a detonating fuse, a known material can be used, consisting of grains of explosive embedded in a fiber or plastic body.
Encompassing the axial portion 24 is an annular tubular force transmitting portion 26 which occupies the space between the center portion and tube inside surface. In practice, the annular force transmitting portion 26 is extruded and is then cut to desired insert length. The center portion 22 is then inserted into the force transmitting portion 26.
A preferred transmitting medium for the force transmitting portion 26 is polyethylene, or another thermoplastic hardenable resin having essentially the same properties as polyethylene. Some examples of suitable mediums other than polyethylene are polyvinyl acetate, polyvinyl butyrals, polystyrene, nylon, Teflon, polyester resins, Delrin, Lexon, polypropylene and Tygon. These materials have essentially the same flexibility, formability, resiliency, density, and at least about as high a melting point as polyethylene.
The force transmitting portion 26 has a flange 28 at the outer end thereof, to gauge the extent of the insert 22 into the hole of tube sheet 10. In the form of the invention shown in FIGS. 3 and 4 the tube 12 is not welded to the tube sheet 10, because the expansion of the tube into the hole of the tube sheet 10 is adequate for some low pressure installations. Also, the inner end of the force transmitting portion 26 is shaped as at 30 for variation of the forming power to suit work.
What is claimed is:
1. Apparatus for simultaneously expanding a liner sleeve within a tube in turn within a tube sheet,
said liner sleeve extending inward from one end of said tube end for a length materially shorter than the thickness of the tube sheet, said apparatus comprising an insert comprising a central axial portion including a predetermined number of grains of explosive uniformly dispersed along the axis of the insert;
an annular tubular force transmitting portion encompassing the center portion;
the annular portion being formed to make a close fit with the inside of said liner sleeve; and
means to position the insert within the tube whereby length dimension thereof is coextensive with a major portion of the area of overlap between the liner sleeve and the tube.
2. Apparatus for expanding a liner sleeve within a tube in turn within a tube sheet as claimed in claim 1, in which the tube extends through the tube sheet and one end thereof is adjacent to one surface of the tube sheet, said insert includes a length dimension approximately equal to the thickness of the tube sheet, and said annular portion being a thermoplastic hardenable resin of the class consisting of polyethylene and resins having essentially the same qualities.
3. Apparatus for expanding a liner sleeve within a tube in turn within a tube sheet as claimed in claim 1, in which the thickness of the liner sleeve is tapered toward the inner end thereof to form a thin edge.
4. A method of expanding a liner sleeve within a tube inturn within a tube sheet comprising the steps of positioning the tube within a tube sheet hole to define an area of overlap between the tube sheet and tube; positioning the liner Within the tube to define a smaller area of overlap between the liner and tube, positioning a cylindrical explosive insert within the liner wherein the insert is coextensive with the major portion of both overlaps;
the explosive insert including a central axial portion comprising a predetermined number of grains of explosive uniformly disposed along the axis of the insert, and an annular tubular force transmitting portion between the center portion and the tube inside surface;
the insert outside surface defining a close fit with the inside surface of the liner; the annular portion being a thermoplastic hardenable resin of the class consisting of polyethylene and resins having essentially the same qualities; and
detonating said explosive insert such that said liner and tube are simultaneously expanded within said tube sheet hole.
5. A method as claimed in claim 4 in which said tube is welded to said tube sheet prior to the positioning of the liner therein.
References Cited UNITED STATES PATENTS 3,113,518 12/1963 Doan 102 24 3,140,537 7/1964 Popoff 29 -421X 3,153,848 10/1964 Glyman et al. 29421 3,364,562 1/1968 Armstrong 29-421X 3,402,870 9/1968 Carlson et al 2283 3,409,969 11/1968 Simons et al. 2283X 3,411,198 11/1968 Berman et al. 29421 3,426,681 2/1969 Oliver 102-24 JOHN F. CAMPBELL, Primary Examiner D. C. REILEY, Assistant Examiner US. Cl. X.R.
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3724062 *||Mar 18, 1971||Apr 3, 1973||Westinghouse Electric Corp||Explosively welded plug for leaky tubes of a heat exchanger and method of using the same|
|US3781966 *||Dec 4, 1972||Jan 1, 1974||Whittaker Corp||Method of explosively expanding sleeves in eroded tubes|
|US3785291 *||May 16, 1972||Jan 15, 1974||Siemens Ag||Device for closing off defective heat exchanger tubes|
|US3868131 *||Nov 30, 1973||Feb 25, 1975||Ultra Centrifuge Nederland Nv||Methods and device for welding a metal pipe to a metal body by means of an explosive charge|
|US3962767 *||Aug 13, 1974||Jun 15, 1976||Westinghouse Electric Corporation||Method for repairing a heat exchanger tube|
|US3977068 *||Jul 14, 1975||Aug 31, 1976||Balcke-Durr Aktiengesellschaft||Device and method for expansion-swaging tubes into the bores of a tube plate|
|US3993001 *||Aug 18, 1975||Nov 23, 1976||Tetra Plastics, Inc.||Explosive expansion means for attaching tubes to tube sheets|
|US4003513 *||Aug 25, 1975||Jan 18, 1977||International Research & Development Company Limited||Explosive welding|
|US4026583 *||Apr 28, 1975||May 31, 1977||Hydril Company||Stainless steel liner in oil well pipe|
|US4028789 *||Mar 29, 1976||Jun 14, 1977||Westinghouse Electric Corporation||Method of installing a sleeve in one end of a tube|
|US4055291 *||Jan 21, 1977||Oct 25, 1977||Diamond Shamrock Corporation||Explosion bonding of bipolar electrode backplates|
|US4205422 *||Jun 7, 1978||Jun 3, 1980||Yorkshire Imperial Metals Limited||Tube repairs|
|US4210167 *||Jun 20, 1978||Jul 1, 1980||Herion-Werke Ag||Emission-free valve|
|US4446891 *||Nov 4, 1981||May 8, 1984||Gebelius Sven Runo Vilhelm||Method for repairing and/or reinforcing a pipe system, and a device for utilization of the method|
|US4592577 *||Sep 30, 1982||Jun 3, 1986||The Babcock & Wilcox Company||Sleeve type repair of degraded nuclear steam generator tubes|
|US4640192 *||Nov 19, 1985||Feb 3, 1987||Nash Henry G||Means for securing tubes to a tube sheet|
|US4685205 *||Aug 26, 1985||Aug 11, 1987||Foster Wheeler Development Corporation||Apparatus for forming an explosively expanded tube-tube sheet joint including a barrier tube|
|US4783890 *||Mar 27, 1986||Nov 15, 1988||Framatome||Method of repairing a steam generator tube by means of lining|
|US4867369 *||Nov 4, 1987||Sep 19, 1989||Exploweld Ab||Method pertaining to the explosion welding of very thin metal layers|
|US5038994 *||Apr 14, 1989||Aug 13, 1991||The Babcock & Wilcox Company||Apparatus for explosively welding a sleeve into a heat exchanger tube|
|US5368075 *||Jun 20, 1991||Nov 29, 1994||Abb Reaktor Gmbh||Metallic sleeve for bridging a leakage point on a pipe|
|US5787933 *||Feb 17, 1995||Aug 4, 1998||Abb Reaktor Gmbh||Method of obtaining a leakproof connection between a tube and a sleeve|
|US20050086187 *||Sep 28, 2004||Apr 21, 2005||Xfi Corporation||Apparatus and methods for a computer-aided decision-making system|
|US20070175634 *||Aug 20, 2004||Aug 2, 2007||Wardlaw Louis J||Apparatus and method for repairing failure spots on subterranean well tubulars using shock waves|
|WO1982001489A1 *||Nov 4, 1981||May 13, 1982||Sven R Gebelius||Method for repairing and/or reinforcing a pipe system,and a device for utilization of the method|
|U.S. Classification||29/890.44, 29/421.1, 228/107|
|International Classification||B21D39/04, F28F9/16, F28F19/00, F28F9/04|
|Cooperative Classification||B21D39/042, F28F19/002|
|European Classification||B21D39/04B, F28F19/00B|