Patents by Inventor Robert Hallerstrom

Robert Hallerstrom has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5183299
    Abstract: A conduit and method of making a conduit for an underground conduit system, where the conduits are protected from ultra-violet rays, the conduit system being able to transport and insulate a variety of materials including, but not limited to, fluids and wires. The assembled conduits being able to be located underground to support the weight of the soil without crushing the insulating layer and thus destroying the insulating qualities of the insulating layer. The assembled conduits coact to protect the interior of the conduit system from moisture located radially outward of the conduit system.
    Type: Grant
    Filed: October 24, 1991
    Date of Patent: February 2, 1993
    Inventors: Robert Hallerstrom, Kirby Durgin, Wesley Benjamin