The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 15, 1978
Filed:
Mar. 10, 1977
Fusao Koshiga, Kawasaki, JP;
Jinkichi Tanaka, Yokohama, JP;
Itaru Watanabe, Yokohama, JP;
Motoaki Suzuki, Yokohama, JP;
Toshifumi Kojima, Yokohama, JP;
Hiroyoshi Matsubara, Fukuyama, JP;
Tatsumi Osuka, Fukuyama, JP;
Kenji Takeshige, Fukuyama, JP;
Takashi Nagamine, Fukuyama, JP;
Osamu Hirano, Fukuyama, JP;
Nippon Kokan Kabushiki Kaisha, Tokyo, JP;
Abstract
After longitudinally seam-welding a pipe-blank for welded steel pipe from the inside along a groove by the arc welding process which comprises using direct electric current supplied to a consumable electrode through a cable as the welding current, the polarity of said consumable electrode applied for said longitudinal seam-welding is switched over to the opposite polarity, an arc from said consumable electrode is ignited again on a tab plate attached to the end of said pipe-blank on the completion side of said longitudinal seam-welding to cause a direct electric current for eliminating magnetism to flow through said cable in the opposite direction to that of said direct electric current for welding, thereby eliminating residual magnetism in said pipe-blank produced by said direct electric current for welding flowing through said cable introduced into said pipe-blank during said longitudinal seam-welding.