Definition
Kelly Cock — A kelly cock is a manually operated valve installed at the kelly to shut in pressure inside the drill string, providing well-control isolation when a kick is taken while circulating through the kelly.
Also known as: kelly cock, kelly valve, upper kelly cock, lower kelly cock
What a kelly cock is
A kelly cock is a full-opening valve fitted at the kelly to isolate the bore of the drill string. An upper kelly cock is installed between the swivel and the kelly, and a lower kelly cock (also called a drill-pipe safety valve when on the string) is fitted below the kelly. Either can be closed to shut in pressure coming up through the string.
Kelly cocks are a primary internal well-control device: if a kick enters the string while drilling, closing the kelly cock isolates the string pressure and protects the surface equipment above it.
Key points
- Full opening — the bore is unobstructed when open, so tools and fluid pass freely.
- Manual operation — turned closed with a wrench during a well-control event.
- Backup — works with the inside BOP and full-opening safety valve as string-side barriers.
Renting kelly-side pressure control
Kelly cocks and associated safety valves are essential, inspected, pressure-rated components. We rent kelly equipment and pressure control tools for well-control readiness — contact us to complete your string-side barrier package.