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. 23, 1994
Filed:
Jul. 20, 1993
William L Carbaugh, Humble, TX (US);
Douglas W Carlson, Kingwood, TX (US);
Hydril Company, Houston, TX (US);
Abstract
A safety sub is disclosed for retaining drilling fluid in the kelly or equivalent and other components of the mud system located above the drill string when pressure drops in the drill string, such as when the circulation pump is turned off in adding a new joint to the drill string. The safety sub includes a pressurized elastomeric cartridge having three or more depressions surrounding a central bore. When internal drilling pressure drops, the external pre-charge pressure closes the elastomeric material by creating a cusp opposite each depression, the cusps closing together. The metallic end pieces of the cartridge and parallel round connecting rods between these inserts are bonded to the elastomeric material during the molding process. Thus, the cusps are precisely formed between the rod locations, resist tearing loose from the rods and the metallic end pieces even after many operations and the material becomes fatigued, and the end pieces do not translate longitudinally during the closing operation to further extend elastomer wear. Having at least three depression/cusp sections also causes the material to undergo less angle of buckling than with an elastomeric cartridge having only a twin buckling mode.