All the achievable external leakage factors concerning the stem & gland flange, gland flange & overall body, and physique & adapter are sealed which has a primary O-ring then a secondary graphite gasket. The seats are frequently manufactured from Teflon, but may be fabricated from other synthetic products or metals. https://s86308.mywikiparty.com/1451436/rumored_buzz_on_ss_flanges