Crossover Flange : A double or single studded adapter flange with a restricted area sealing means and with a top connection pressure rating above that of the lower connection. (Spec 6A)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}