06276450 is referenced by 114 patents and cites 5 patents.

Apparatus and method for rapid replacement of upper inside blowout preventers (IBOP) on a top drive system (TDS) utilizes a hydraulic pressure booster to increase the operating pressure of a pipe handler/torque wrench, an air amplifier to increase the air pressure to a main shaft brake of the TDS in order to provide torque back-up, a rotary table back-up structure (RTBS) for providing a torque back-up for removing the upper IBOP, and a drive ring for preventing relative rotation between the RTBS and upper IBOP. The saver sub and lower IBOP are first broken out, or loosened, with the pipe handler/torque wrench. The upper IBOP is then broken out by placing the RTBS over the rotary table with the rotary table and the TDS main shaft locked. The modified TDS and pipe handler/torque wrench are then used together with the RTBS and drive ring in order to rapidly and safely replace the upper IBOP.

Title
Apparatus and method for rapid replacement of upper blowout preventers
Application Number
9/364747
Publication Number
6276450 (B1)
Application Date
July 30, 1999
Publication Date
August 21, 2001
Inventor
Padmasiri Daya Seneviratne
Fullerton
CA, US
Agent
Christie Parker & Hale
US
Assignee
Varco International
CA, US
IPC
E21B 19/00
View Original Source