Title: Method of assembly of a dual-walled pipe

Abstract: A method for assembling two pipes into a single section of double-walled, radially-spaced, concentric pipe of sufficient strength for use in a wellbore in a permafrost zone in the earth is disclosed. Connectors having both left-hand and right-hand and internal and external threads connect corresponding internal and external threads on the pipe. Marks on the pipe ends indicate the various thread start points and, in combination with the left-hand and right-hand threads, permits proper alignment of the threads and facilitate threaded assembly of the two pipes into the double-walled section of pipe. Standard sizes of pipe may be used.

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Inventors: Perkins, Thomas K. (Dallas, TX, US)

Application Number: 537355
Filing Date: 1974-12-30
Publication_date: 1976-03-16
Assignee: Atlantic Richfield Company (Los Angeles, CA)
Primary Class(es): 29/407.1 29/445, 29/455.1, 138/109, 138/148, 285/47, 285/93, 285/123.3, 285/392
Other Classes:
US Patent Ref:

572124	Dec, 1896	McElroy	285/48.
724675	Apr, 1903	Decker	285/133.
861828	Jul, 1907	Grindrod et al.	285/175.
3778089	Dec, 1974	Fredd	285/392.
3870346	Mar, 1975	Kappeler et al.	285/47.

Other Refs: 26,890

Aug, 1912	SU

Primary Examiner: Schroeder, Werner H.
Assistant Examiner: Shedd, Wayne L.
Attorney: MacDonald; Roderick W.