Leading or Front Flank (Stab Flank) : The flank of the pipe thread facing the near end of pipe. The flank of the coupling thread forcing the open end of the coupling. (RP 5B1)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}