Union 1 : A coupling device used to connect pipe without the need to rotate the pipe. The makeup is accomplished by a flanged, threaded collar on the union. (WLOP)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}