For duplex stainless steel 2205,its corresponding casting grade is 4A. There is also 2507,  and casting grade 5A.

The duplex stainless steel 2205 and 2507, are commonly used in seawater and desulfurization conditions in power plants. At present,
our company can supply Duplex stainless steel butterfly valve ranging from DN50 to DN1600, PN1 to PN100. The butterfly valve has
triple-eccentric structure and both multi-layer metal seals and soft seals are available.

The multi-layer metal seal is made of duplex stainless steel and graphite, which is a composite seal on valve disc. When sealing, the steel
sheet plays a major role and graphite is auxiliary . This composite seal is suitable for any sizes and pressures. At present, our company can
produce butterfly valves  at max pressure rating PN100/600LB.

For the valve with soft seat, it has the same structure , but the composite sealing is replaced by material PTFE, RPTFE, PPL and others.
Compared with composite sealing made of duplex stainless steel,, PTFE and RPTFE are more corrosion resistant, but not resistant to high
temperature and high pressure. Usually it is used for working temperature below 200 °C, and pressure below PN40 or 300LB.