CPC Subgroup
F28F 11/04 using pairs of obturating elements, e.g. washers, mounted upon central operating rods (F28F11/06 takes precedence)
Full Title
Arrangements for sealing leaky tubes and conduits (stopping flow from or in pipes in general F16L55/10) > using pairs of obturating elements, e.g. washers, mounted upon central operating rods (F28F11/06 takes precedence)