Blowout Preventer Stack : The assembly of well control equipment including preventers, spools, valves, and nipples connected to the top of the casinghead. (RP 53)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}