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:
Nov. 15, 1994
Filed:
Mar. 15, 1994
Douglas W Carlson, Kingwood, TX (US);
Stephen P Simons, 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 with an elastomeric closure having an asymmetrical wall thickness, preferably achieved by the removal of a chord of material from its external circumference. When internal drilling pressure drops, the external pre-charge pressure closes the elastomeric material by inwardly collapsing the thinner wall portion of the closure. The metallic end pieces of the cartridge are bonded to the elastomeric material during the molding process.