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:
May. 19, 1992
Filed:
Jun. 01, 1988
Stanley T Low, Tucson, AZ (US);
Pedro F Lara, Dallas, TX (US);
David L Foreman, Tucson, AZ (US);
Steven G Petermann, Plano, TX (US);
Atlantic Richfield Company, Los Angeles, CA (US);
Abstract
A weld detection system for a pipeline survey pig includes a plurality of weld sensor units mounted spaced apart circumferentially on fore and aft pig support members and arranged in close proximity to the pipe wall. The sensor units comprise permanent magnet members for generating a magnetic flux field around a wire coil which is modified upon passing a girth weld or other magnetic anomaly in the pipe to produce a voltage signal which is conditioned by an amplifier and filter circuit to a signal suitable for input to a digital activation circuit. The digital activation circuit receives conditioned signals from opposed pairs of sensor units on the support members to distinguish transverse girth welds from spiral or longitudinal welds. The digital activation circuit includes circuit elements for timing the sensor output signals of the fore and aft detector arrays for measuring the velocity of the survey pig through the pipe. Each sensor unit comprises a high intensity permanent magnet disposed on a compact wire coil and support spool and arranged so that the flux field extends through the pipe wall during normal operation of the system. The output signal from the sensor units is capable of being conditioned for use in determining changes in pipe wall thickness and changes in axial strain on a pipe section of known length.