BSN-3 Safety Valve
Master valve that controls well flow and can cut wireline and coiled tubing
Description
The 8-in BSN-3 safety valve is a master valve for onshore or offshore testing. It is normally run inside or below the BOP and is used to control well flow. Using balance line and nitrogen pressure, it can cut wireline and coiled tubing.
Features
- Controlled by two hydraulic lines and fitted with a chemical injection port
- Designed to close by spring force, with a nitrogen charge chamber to speed up closing; held open by maintaining control-line pressure
- Floating valve prevents nitrogen from escaping; nitrogen pressure acts directly on the operating piston
- Special ball mechanism can cut coiled tubing up to 1.5-in OD × 0.125-in wall
Operation
The valve is operated and controlled through three hydraulic lines. Pressure applied to the control line holds the ball valve open. The balance line normally needs no pressure; when cutting coiled tubing, pressure is applied to it for extra closing force. The chemical injection line is used for downhole chemical injection or other purposes and does not affect ball valve opening or closing.
The valve is usually charged with 1,000–1,500 psi nitrogen, enough to cut 7/32-in cable but not coiled tubing. Charging to a higher pressure allows coiled tubing to be cut, but raises the pressure required to hold the ball valve open.
