Tubing Couplings 2 : May be called tubing collars. Tubular steel with internal threads into which are made up the ends of tubing joints, to form a continuous flow string. (WT)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}
