Method for installing tubes in tube sheets

Claim 1

A method of installing a tube within a surrounding structure to form a tight leakproof joint between said tube and said structure, said method comprising the steps of: inserting said tube in a bore in said structure from a first side of said structure; inserting a draw bar in said tube, said drawbar being encircled by compressible inner and outer expanders; compressing said expanders axially and expanding said expanders radially, thereby initially expanding an outer region of said tube corresponding to said outer expander and adjacent said first side and an inner region of said tube corresponding to said inner expander axially spaced from said outer region, leaving an unexpanded land between said inner and outer regions; removing said draw bar and said expanders from said tube; inserting a hydraulic swaging mandrel in said tube, said mandrel having two axially separated seals defining a pressure zone between them; positioning said mandrel so that said seals are located on opposite sides of said inner region within unexpanded portions of said tube, one of said unexpanded portions being said land; and

Claim 2

A method of installing a tube within a surrounding structure to form a tight leakproof joint between said tube and said structure, said method comprising the steps of: inserting said tube in a bore in said structure from a first side of said structure; inserting a draw bar in said tube, said drawbar being encircled by compressible inner and outer expanders; compressing said expanders axially and expanding said expanders radially, thereby initially expanding an outer region of said tube corresponding to said outer expander and adjacent said first side and an inner region of said tube corresponding to said inner expander axially spaced from said outer region, leaving an unexpanded land between said inner and outer regions; removing said draw bar and said expanders from said tube; inserting a hydraulic swaging mandrel in said tube, said mandrel having two axially separated seals defining a pressure zone between them; positioning said mandrel so that said seals are located on opposite sides of said inner region within unexpanded portions of said tube, one of said unexpanded portions being said land; and

Claim 8

A method of installing a tube within a surrounding structure to form a tight leak-proof joint between said tube and said structure, said method comprising the steps of: inserting said tube in a bore in said structure; inserting a draw bar within said tube, said draw bar being encircled by axially compressible outer and inner expanders axially separated by an incompressible spacer; compressing said expanders axially and expanding said expanders radially by pulling said draw bar and thereby initially expanding said tube radially in the regions of said expanders while leaving said tube substantially unexpanded and thus forming a land in the region of said spacer; removing said draw bar, said expanders and said spacer from said tube; inserting a hydraulic swaging mandrel in said tube, said mandrel having two axially separated seals defining a pressure zone between them; positioning said mandrel so that one of said seals engages said land, the other of said seals being positioned on the opposite side of the region that corresponds to said inner expander, said tube being unexpanded and of equal diameter at said two seals; and supplying pressurized fluid through said mandrel to an annular space between said mandrel and said tube corresponding to said pressure zone and thereby expanding said tube radially throughout said pressure zone, the axial forces acting on said mandrel and attributable to said fluid being balanced.

Claim 9

A method of installing a tube within a surrounding structure to form a tight leak-proof joint between said tube and said structure, said method comprising the steps of: inserting said tube in a bore in said structure; inserting a draw bar within said tube, said draw bar being encircled by axially compressible outer and inner expanders axially separated by an incompressible spacer; compressing said expanders axially and expanding said expanders radially by pulling said draw bar and thereby initially expanding said tube radially in the regions of said expanders while leaving said tube substantially unexpanded and thus forming a land in the region of said spacer; removing said draw bar, said expanders and said spacer from said tube; inserting a hydraulic swaging mandrel in said tube, said mandrel having two axially separated seals defining a pressure zone between them; positioning said mandrel so that one of said seals engages said land, the other of said seals being positioned on the opposite side of the region that corresponds to said inner expander, said tube being unexpanded and of equal diameter at said two seals; and supplying pressurized fluid through said mandrel to an annular space between said mandrel and said tube corresponding to said pressure zone and thereby expanding said tube radially throughout said pressure zone, the axial forces acting on said mandrel and attributable to said fluid being balanced.

Claim 17

A method of installing a tube within a tube sheet to form a leak-proof joint between said tube and said tube sheet, said method comprising the steps of: inserting said tube in a bore in said tube sheet and positioning said tube so that it projects out of said tube sheet; inserting a draw bar within said tube, said draw bar being encircled by axially compressible outer and inner expanders axially separated by an incompressible spacer, said draw bar further having an anti-extrusion ring thereon adjacent said outer expander; positioning said draw bar so that a stop thereon contacts said tube sheet and restrains said draw bar against axial movement toward said tube sheet; compressing said expanders axially and expanding said expanders radially by pulling said draw bar and thereby initially expanding said tube radially in the regions of said expanders while leaving said tube substantially unexpanded and thus forming a land in the region of said spacer, said region corresponding to said outer expander extending outside said tube causing a corresponding portion of said tube to be flared radially outwardly while said anti-extrusion ring slides axially on said draw bar, thereby inhibiting extrusion of said outer expander; removing said draw bar, said expanders and said spacer from said tube; inserting a swaging mandrel so that one of said seals engages said land, the other of said seals being positioned on the opposite side of the region that corresponds to said inner expander, said tube being unexpanded and of equal diameter at said two seals; and supplying fluid, at a pressure exceeding the pressure applied to said tube by said expanders, through said mandrel to an annular space between said mandrel and said tube corresponding to said pressure zone and thereby expanding said tube radially throughout said pressure zone, the axial forces acting on said mandrel and attributable to said fluid being balanced.

Claim 18

A method of installing a tube within a tube sheet to form a leak-proof joint between said tube and said tube sheet, said method comprising the steps of: inserting said tube in a bore in said tube sheet and positioning said tube so that it projects out of said tube sheet; inserting a draw bar within said tube, said draw bar being encircled by axially compressible outer and inner expanders axially separated by an incompressible spacer, said draw bar further having an anti-extrusion ring thereon adjacent said outer expander; positioning said draw bar so that a stop thereon contacts said tube sheet and restrains said draw bar against axial movement toward said tube sheet; compressing said expanders axially and expanding said expanders radially by pulling said draw bar and thereby initially expanding said tube radially in the regions of said expanders while leaving said tube substantially unexpanded and thus forming a land in the region of said spacer, said region corresponding to said outer expander extending outside said tube causing a corresponding portion of said tube to be flared radially outwardly while said anti-extrusion ring slides axially on said draw bar, thereby inhibiting extrusion of said outer expander; removing said draw bar, said expanders and said spacer from said tube; inserting a swaging mandrel so that one of said seals engages said land, the other of said seals being positioned on the opposite side of the region that corresponds to said inner expander, said tube being unexpanded and of equal diameter at said two seals; and supplying fluid, at a pressure exceeding the pressure applied to said tube by said expanders, through said mandrel to an annular space between said mandrel and said tube corresponding to said pressure zone and thereby expanding said tube radially throughout said pressure zone, the axial forces acting on said mandrel and attributable to said fluid being balanced.