Factory Seal : A factory seal is a seal provided in an explosion-proof device during manufacture for the purpose of eliminating external, field-installed "conduit seals" for that device. (RP 14F)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}