Underwater Safety Valve (USV) 2 : An automatic valve assembly (installed at an underwater wellhead location) which will close upon loss of power supply. (RP 14C)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}