Gage and Test Port Connections : Holes drilled and tapped into API Spec 6A equipment through which internal pressure may be measured or through which pressure may be applied to test the sealing mechanisms. (Spec 6A)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}