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US 4,129,152 AGranted
Double wall helical pipe and strip configuration for forming same
AssigneePacific Roller Die Co., Inc.
InventorPaul K. Davis
Life of this patent
Estimating the term…
Abstract
Double wall helical pipe formed from a single metal strip, pipe forming method and configuration of strip for forming such pipe. A metal strip is formed with pipe seam elements and curled into overlapped helical convolutions, and the seam elements are secured together to provide a helical pipe seam. One or both pipe walls may be corrugated.
Claims9
A configuration of strip for forming double wall helical seam pipe by curling a single workpiece, comprising in uniform cross-section:
- a. a right angle flange formed along one side edge portion of said strip and projecting to a side of the plane of said strip and defining a first pipe seam element;
- b. a U-shaped portion formed along the side edge portion opposite said one side edge portion and projecting to the same side of the plane of said strip as said flange for defining a second pipe seam element;
- c. a U-shaped portion formed longitudinally of said strip midway between and to the same side of the plane of said strip as said first and second seam elements and defining a third seam element;
- d. said third seam element being proportional for receipt of said first seam element and said second seam element being proportioned for receipt of said third seam element;
- and
- e. strip portions respectively extending between said first seam element and said third seam element and between said second seam element and said third seam element.
3 more elements
Double wall helical seam pipe formed from a single elongated strip having parallel side edges, comprising:
- a. first and second pipe seam elements respectively at the opposite side edge portions of said strip;
- b. a third pipe seam element longitudinally in said strip midway between said first and second seam elements;
- c. an inner wall formed of helical convolutions of the portion of said strip between said first and third seam elements;
- d. an outer wall formed of helical convolutions of the portion of said strip between said second and third seam elements;
- and
- e. a helical pipe seam formed of said first, second and third seam elements in interconnected relationship with said third seam element between said first and second seam elements.
3 more elements
Dependencies are inferred from the claim text.