# US 8,783,735 B2 · Conductance on hydraulic fittings using a soft metal interlayer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,783,735 B2 - Document ID: US8783735B2 - Status: Granted - Kind: B2 - Application number: 13/279,973 - Filed: 2011-10-24 - Published: 2013-04-25 - Granted: 2014-07-22 - Earliest claimed: 2011-10-24 - Assignees: The Boeing Company - Applicants: Eddie Kwon; Michael E. Rorabaugh; Benjamin A. Johnson; James P. Irwin; Robert E. Fisher - Inventors: Eddie Kwon; Michael E. Rorabaugh; Benjamin A. Johnson; James P. Irwin; Robert E. Fisher - Web page: https://patentgrep.com/patent/US8783735B2 ## CPC - B64D 37/32: Safety measures not otherwise provided for, e.g. preventing explosive conditions - B64D 45/02: Lightning protectors; Static dischargers - F16L 13/146: {by an axially moveable sleeve} - F16L 25/01: specially adapted for realising electrical conduction between the two pipe ends of the joint or between parts thereof - Y10T 29/49826: Assembling or joining - Y10T 29/49913: by constricting outer annulus - Y10T 29/49927: Hollow body is axially joined cup or tube - Y10T 29/49934: by axially applying force - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - F16L: PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A method for improving conductance on hydraulic fittings by incorporating a soft metal interlayer between the fitting and a hydraulic tube, wherein the soft metal interlayer is located in an area where the fitting engages the hydraulic tube upon swaging or installation under pressure. ## Claims ### Claim 1 A method for improving electrical conductance on a hydraulic fitting in need thereof comprising: providing a hydraulic fitting having an inner surface and a hydraulic tube having an outer surface, wherein the inner surface of the fitting is adapted to extend over at least a portion of the outer surface of the tube in coaxial relationship therewith; and incorporating a soft metal interlayer between the inner surface of the fitting and the outer surface of the tube, wherein the soft metal interlayer is located in an area where the fitting engages the hydraulic tube upon swaging or installation under pressure and wherein the soft metal interlayer is about 0.001 to about 0.010 inches thick. ### Claim 2 (depends on 1) The method of claim 1 wherein said soft metal is selected from the group consisting of aluminum, copper, gallium, silver, cadmium, gold, antimony, platinum, tin, indium, rhodium, thallium, bismuth, lead, alloys thereof, and steel alloys. ### Claim 3 (depends on 1) The method of claim 1 wherein said soft metal interlayer is present on the inner surface of the fitting. ### Claim 4 (depends on 1) The method of claim 1 wherein said soft metal interlayer is present on the outer surface of the tube. ### Claim 5 (depends on 1) The method of claim 1 further comprising swaging the fitting and tube to bring the inner surface of the fitting and the outer surface of the tube into engagement and electrical contact through the soft metal interlayer. ### Claim 6 (depends on 1) The method of claim 1 wherein said swaging comprises radial swaging or axial swaging. ### Claim 7 (depends on 1) The method according to claim 1 further comprising providing a second hydraulic tube with a second outer surface, wherein the inner surface of the fitting is adapted to extend over at least a portion of the second outer surface of the second hydraulic tube in coaxial relationship therewith; incorporating a second soft metal interlayer between the inner surface of the fitting and the second outer surface of the second hydraulic tube, wherein the second soft metal interlayer is located in an area where the fitting engages the second hydraulic tube upon swaging or installation under pressure, and wherein the second soft metal interlayer is about 0.001 to about 0.010 inches thick; and wherein the hydraulic fitting joins the hydraulic tube and the second hydraulic tube in axial alignment with respect to one another to define a fluid passage. ### Claim 8 A method for providing protection against sparking as a protective feature in preventing an ignition source in a composite fuel tank in need thereof comprising: providing a composite fuel tank comprising; a carbon reinforced polymer material and a hydraulic system, wherein the hydraulic system includes a hydraulic fitting having an inner surface and a hydraulic tube having an outer surface, wherein the inner surface of the fitting is adapted to extend over at least a portion of the outer surface of the tube in coaxial relationship therewith; and a soft metal interlayer is incorporated between the inner surface of the fitting and the outer surface of the tube, wherein the soft metal interlayer is located in an area where the fitting engages the hydraulic tube upon swaging or installation under pressure, and wherein the soft metal interlayer is about 0.001 to about 0.010 inches thick. ### Claim 9 (depends on 8) The method of claim 8 wherein said soft metal is selected from the group consisting of aluminum, copper, gallium, silver, cadmium, gold, antimony, platinum, tin, indium, rhodium, thallium, bismuth, lead, alloys thereof, and steel alloys. ### Claim 10 (depends on 8) The method of claim 8 wherein said soft metal interlayer is present on the inner surface of the fitting. ### Claim 11 (depends on 8) The method of claim 8 wherein said soft metal interlayer is present on the outer surface of the tube. ### Claim 12 (depends on 8) The method of claim 8 further comprising swaging the fitting and tube to bring the inner surface of the fitting and the outer surface of the tube into engagement under pressure and electrical contact through the soft metal interlayer. ### Claim 13 (depends on 8) The method of claim 8 wherein said swaging comprises radial swaging or axial swaging. ### Claim 14 (depends on 8) The method of claim 8 wherein said composite fuel tank is part of an aircraft. ### Claim 15 (depends on 8) The method of claim 8 wherein said swaging with said soft metal interlayer enhances electrical contact between the fitting and tube compared to a fitting and tube without the interlayer. ### Claim 16 (depends on 8) The method according to claim 8 wherein the hydraulic system further comprises a second hydraulic tube with a second outer surface, wherein the inner surface of the hydraulic fitting is adapted to extend over at least a portion of the second outer surface of the second hydraulic tube in coaxial relationship therewith; a second soft metal interlayer between the inner surface of the hydraulic fitting and the second outer surface of the second hydraulic tube, wherein the second soft metal interlayer is located in an area where the hydraulic fitting engages the second hydraulic tube upon swaging or installation under pressure, and wherein the second soft metal interlayer is about 0.001 to about 0.010 inches thick; and wherein the hydraulic fitting joins the hydraulic tube and the second hydraulic tube in axial alignment with respect to one another to define a fluid passage. ### Claim 17 A hydraulic system, wherein the hydraulic system comprises: a hydraulic fitting having an inner surface; and a hydraulic tube having an outer surface, wherein the inner surface of the fitting is adapted to extend over at least a portion of the outer surface of the tube in coaxial relationship therewith; and a soft metal interlayer is incorporated between the inner surface of the fitting and the at least a portion of the outer surface of the tube, and wherein the soft metal interlayer is about 0.001 to about 0.010 inches thick. ### Claim 18 (depends on 17) The hydraulic system according to claim 17 comprising a second hydraulic tube having a second outer surface, wherein the inner surface of the hydraulic fitting is adapted to extend over at least a portion of the second outer surface of the second hydraulic tube in coaxial relationship therewith; and a second soft metal interlayer is incorporated between the inner surface of the hydraulic fitting and the at least a portion of the second outer surface of the second hydraulic tube, and wherein the second soft metal interlayer is about 0.001 to about 0.010 inches thick, wherein the hydraulic fitting joins the hydraulic tube and the second hydraulic tube in axial alignment with respect to one another to define a fluid passage. ### Claim 19 (depends on 18) The hydraulic system according to claim 18 wherein the soft metal interlayer and second soft metal interlayer are located in an area where the hydraulic fitting engages the hydraulic tube and second hydraulic tube upon swaging or installation under pressure. ### Claim 20 (depends on 18) The hydraulic system according to claim 18 wherein the hydraulic fitting inner surface carries the soft metal interlayer and/or the second soft metal interlayer. ### Claim 21 (depends on 18) The hydraulic system according to claim 18 wherein the at least a portion of the outer surface of the tube carries the soft metal interlayer and/or the at least a portion of the second outer surface of the second hydraulic tube carries the second soft metal interlayer.