Patents by Inventor Burl B. Ohnstad

Burl B. Ohnstad 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).

  • Method for sealing joints in plastic lined pipes
    Patent number: 4054473
    Abstract: The thermoplastic lining at a joint between adjacent lined pipe sections is sealed by means of a preformed elongated flat strip of thermoplastic material having resistance heater elements in spaced parallel relation along either side of the strip. The strip is placed circumferentially around the inside of the joint with the width of the strip bridging the joint and with the heater elements in contact with the respective liners on either side of the joint. Pressure is applied radially outwardly against the strip to urge the strip against the liners, and electric current is then passed through the heater elements to fuse the strip to the respective liners and seal off the joint.
    Type: Grant
    Filed: November 26, 1975
    Date of Patent: October 18, 1977
    Assignee: Ameron, Inc.
    Inventor: Burl B. Ohnstad