Patents by Inventor Karl Duren

Karl Duren 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).

  • Making clad seamless pipes
    Patent number: 4630351
    Abstract: Rounds are clad by weld-depositing austenitic materials on the outside and, subsequently, an axial bore is drilled, followed by extrusion or cold-pilger-rolling or both. The cladding layer and the bore diameter must follow particular rules, the ferrite content of the clad material must not exceed 50%, preferably not 10%.
    Type: Grant
    Filed: November 2, 1981
    Date of Patent: December 23, 1986
    Assignee: Mannesmann AG
    Inventors: Eckhard Kranz, Karl Duren
  • Seam welding of pipes
    Patent number: 4292492
    Abstract: Pipes are submerged - arc seam welded with a welding wire having a relatively high nickel content (about 6%), and low carbon content (<0.08%) to obtain a seam having a ductility and toughness which is still adequate for very low temperatures.
    Type: Grant
    Filed: May 6, 1977
    Date of Patent: September 29, 1981
    Assignee: Mannesmann AG
    Inventor: Karl Duren