Advantages of Metal to Metal Seated Type Triple Offset Butterfly Valve
As we know there are two seat sealing type for triple offset butterfly valve: the one is normal laminated seat sealing, the seat sealing ring is made of 2 or more metal sheets laminated with non-metal sheets. The seat sealing ring be fixed to disc by retainer ring through screws. For limitation of chemical and merchanic properties of non-metal sheet of seat ring, this kind of butterfly valve can be only used in general situation ( non-high temperature and non-high pressure, non-corrosive service ).
When the pipe pressure or temperature become higher, and disc is in half and full opening position, the high speed flow shall impact the non-metal sheet of seat ring, which cause non-metal sheet damaged; or corrosive service go through pipe line, the non-metal sheet be damaged , too. These cause valve leakage.
The second type triple offset butterfly valve is metal to metal seated type. These type valve have advantages which normal triple offset butterfly valve do not have :
1. The seat ring is made of metal , without any non-metal sheets. No matter the high speed flow impact the disc, or corrosive service, the seat ring shall not be damaged . valve get longer using life.
2. The seat ring is completely metal ring, which can work in high temperature ( even higher than 650 degree C ) high pressure and corrosive service.
Generally seat sealing of metal to metal seat triple offset butterfly valve :
Body seat integral faced STL, WC, etc.
Disc seat ring stainless steel 304, 316, Ni alloy steel, etc.
Zhejiang Zhengfeng Valve.