Porytetrafluoroethylene armed flax filter is used in chemical industry and medicine to filter the strong corrosive fluids having maximum temperature of 250°C and is made up of two metal rings completely coveres by a compact polytetrafluoroethylene coating, the rings being situated at the ends of the filter, containing in between a porous flax/tube made of grains oi polytetrafluoroethylene and a number of metal bars completely covered by a compact polytetrafluoroethylene coating.