Studded-Flange Connections : Flanged end and outlet connections in which thread anchored studs screwed into tapped holes replace the holes for bolt studs. (Spec 6A)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}