Title: Subsea master valve apparatus

Abstract: A control valve apparatus adapted to be positioned within a subsea blowout preventer stack for controlling the flow of fluid from an offshore well includes a ball valve element provided with the capability of cutting coil tubing typically employed in well workover and completion operations. The ball element has a cutting edge that coacts with the valve seat to shear the tubing, and a relief slot that receives the tubing during cutting to prevent the tubing from being placed in double shear. Hydraulically operable means is provided to assist in closure of the ball valve element and consequent cutting of tubing extending into the well, in case of emergency.

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Inventors: McGill, Howard L. (Houston, TX, US)
Randermann, Jr., Ervin (Beasley, TX, US)
Musik, Olgierd J. (Houston, TX, US)

Application Number: 669128
Filing Date: 1976-03-22
Publication_date: 1977-03-01
Assignee: Schlumberger Technology Corporation (New York, NY)
Primary Class(es): 166/55.1 166/298, 166/319, 251/58
Other Classes:
US Patent Ref:

2969838	Jan, 1961	Wilde	166/55.
3233860	Feb, 1966	Dollison et al.	251/58.
3561526	Feb, 1971	William, Jr. et al.	166/55.
3766978	Oct, 1973	Orund et al.	166/55.
3786865	Jan, 1974	Tausch et al.	251/58.
3946806	Mar, 1976	Meynier	166/55.

Other Refs:
Primary Examiner: Leppink, James A.
Assistant Examiner:
Attorney: Moseley; David L., Sherman; William R., Moore; Stewart F.