Inflatable heating device for in-situ repair of conduit and method for repairing conduit
View Patent ↗The apparatus of the present invention is generally characterized by a heating/inflation module having pressurizable interior and an attached heat curable pre-preg. In particular, an elastomeric, seamless composite is provided that includes a heating element disposed within a thermoset resin matrix. The composite adapted to maintain a consistent temperature profile and an internal air pressure. A first end piece is attached to a first end of the composite and has an air port for communication with a compressed air source, a vacuum port for communication with a vacuum supply source and at least one electrical cable port for communication with a power supply source. A second end piece attached to a second end of the composite. The apparatus further includes a pre-preg removably attached to an outer surface of the composite. The pre-preg includes a structural fiber matrix supporting a heat curable resin. The composite is constructed by applying a liquid silicone matrix to at least one layer of braided or wound and/or tape fibers, wherein a portion of the fibers are electrically conductive. The layer of braided fibers is introduced into a mold, and a removable, expandable inner bladder is then loaded into the mold. The inner bladder is inflated to conform the layer of braided fibers to an interior surface of the mold. An electric current is caused to flow to the conductive fibers to cure the silicone matrix into a stable, elastomeric state. The composite is removed from the mold. A method for repairing a damaged section of a conduit is also disclosed.
1. An apparatus for curing a pre-preg repair material supporting a heat curable resin for in-situ repair of a conduit, comprising:
an elastomeric composite having a first end and a second end, wherein the composite includes a non-ferrous heating element comprising electrically conductive fibers comprised of carbon fibers, graphite fibers, carbon filaments or graphite filaments and disposed within a thermoset resin matrix wherein the electrically conductive fibers are braided or arranged helically;
a first end piece fixedly attached to the first end of the composite and having an air port for communication with a compressed air source, a vacuum port for communication with a vacuum supply source and at least one electrical cable port to convey electric current to the non-ferrous heating element from a power supply source; and
a second end piece fixedly attached to the second end of the composite, wherein the composite, the first end piece, and the second end piece form a generally hollow inflation chamber.
2. The apparatus of claim 1 wherein the thermoset resin is selected from the group consisting of fluorocarbon and fluorosilicone.
3. The apparatus of claim 1 wherein the heating element includes a plurality of braided fibers comprising temperature tolerant fiber braids and electrically conductive fiber braids.
4. The apparatus of claim 3 wherein the braided fibers interact to define a braid angle measure at +/−45 degrees.
5. The apparatus of claim 3 wherein the electrically conductive fiber braids are carbon filaments.
6. An apparatus for curing a pre-preg repair material supporting a heat curable resin for in-situ repair of a conduit, comprising:
an elastomeric composite having a first end and a second end, wherein the composite includes a non-ferrous heating element comprised of a plurality of filament wound carbon fibers, filament wound graphite fibers, filament wound carbon filaments or filament wound graphite filaments and disposed within a thermoset resin matrix;
a first end piece fixedly attached to the first end of the composite and having an air port for communication with a compressed air source, a vacuum port for communication with a vacuum supply source and at least one electrical cable port to convey electric current to the non-ferrous heating element from a power supply source; and
a second end piece fixedly attached to the second end of the composite, wherein the composite, the first end piece, and the second end piece form a generally hollow inflation chamber.
7. The apparatus of claim 6 wherein the wound fibers interact to define an angle measure at +/−45 degrees.
8. A method for repairing a damaged section of a conduit comprising the steps of:
providing an elastomeric composite having a first and second end, wherein the composite includes a non-ferrous electrically conductive heating element comprising electrically conductive fibers comprising carbon fibers, graphite fibers, carbon filaments or graphite filaments and disposed within a thermoset resin matrix wherein the electrically conductive fibers are braided or arranged helically;
fixedly attaching a first and second end piece respectively to the first and second ends of the composite, wherein the first end piece, the second end piece, and the composite form a heating/inflation module;
removably attaching a pre-preg to an outer surface of the composite, wherein the pre-preg includes a structural fiber matrix supporting a heat curable resin;
positioning the module with the attached pre-preg into the conduit at a damaged location;
inflating the module to a predetermined internal air pressure to expand the composite and press the pre-preg against an inside surface of the conduit;
curing the resin of the pre-preg by causing an electrical current to flow in the heating element to resistively heat the module to a predetermined temperature; and
deflating the module and removing it from the conduit.
9. A system for in-situ repair of a conduit, comprising:
an apparatus including an elastomeric composite having a first end and a second end, wherein the composite includes a non-ferrous heating element comprising electrically conductive fibers comprising carbon fibers, graphite fibers, carbon filaments or graphite filaments and disposed within a thermoset resin matrix wherein the electrically conductive fibers are braided or arranged helically;
a first end piece fixedly attached to the first end of the composite and having an air port for communication with a compressed air source, a vacuum port for communication with a vacuum supply source and at least one electrical cable port to convey electric current to the non-ferrous heating element from a power supply source;
a second end piece fixedly attached to the second end of the composite, wherein the composite, the first end piece, and the second end piece form an inflation chamber; and,
a pre-preg removably attached to an outer surface of the composite of the apparatus, the pre-preg including a structural fiber matrix supporting a heat curable resin.