Fully lined butterfly valves from Sure Seal are offered in the range of 2” to 24” with mechanical shaft sealing technology. A molecular blend of PTFE and PFA (ProTef), creating less creep, cold flow and permeability is used for the lining of the valves. The PFA/ProTef disc/liner combination ensures good corrosion resistance. The one piece disc stem has a 3 mm thick precision moulded PFA locked inliner, encapsulating the wetted surface of the 316 stainless steel core. This elimi-nates permeation and delamination. Viton elastomer backup rings are fitted to give a bubble tight shutt-off at minimum operating torque.
Fully lined ball valves with full port design are available in the range of 1” to 6”. Unique is the live loaded stem sealing with inverted gland flange. This enables direct mounting of an actuator and still being able to adjust the gland packing. The separate lined ball and stem allows the ball to float, hence avoiding leakage under high pressure situation.
The primary seal of the valve is a soft joint between the body halves. In addition to this seal there is a metal-to-metal body joint that prevents possible leakage from temperature changes or line stresses. Both valves can be operated at temperatures from -40 °C to +230 °C and are available in Ansi and DIN standards.