Lock Screws (Tie-Down Screws) : A series of threaded pins extending through the wall of a casing head or tubing head flange used to lock down hangers or energize seals. (Spec 6A)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}