Flowserve Noble Alloy Ball Valve IOM - Manual (Page 19)

August 22, 2002, Rev. 2 17
5 SPECIAL APPLICATIONS
5.1 2 Piece Slurry Seats - Refer to section 4.0 for photographs of 2 piece seat assembly
The 2-piece seat consists of a seat carrier and separate seat ring. The carrier provides the spring,
in the form of a bellville machined into it, and the support for the seat ring. The separate seat ring
performs the sealing against the ball and is hardened
Disassembly and assembly procedures for the 2-piece slurry seat are similar to the standard seat.
Once the body is apart, removal of the seat assembly from the body (1) and tailpiece (2) is the
same. Typically, the seats will be locked into the seat pockets by slurry buildup and are usually
damaged removing them. Soaking and scraping as much slurry from around the set assembly will
aid in removal. Care should be taken not to scratch or damage the seat pocket during seat
removal. Should removal be successful, thoroughly clean the parts and inspect them for erosion,
corrosion and scoring. Replace if damaged. Minor erosion on the waterway area of the carrier is
acceptable and the carrier can be reused as long as the sealing area where the seat ring sits is
clean and undamaged. It is recommended that the seat ring be replaced during a rebuild for good
valve performance. Nobleized seat rings cannot be repaired and must be replaced.
On assembly of the 2 piece seats, fill the spring groove in the carrier with silicone seal or graphoil,
whichever is compatible in your service, to act as an excluder to prevent slurry buildup on the
groove. Install and assemble the valve as noted in section 3.2 of the assembly instructions.
5.2 Cavity Filler - Refer to section 4.0, Figures 1 and 2 of cavity filler and location
Cavity fillers are utilized in slurry valve applications to prevent slurry from compacting around the
ball and locking up the valve. Cavity fillers are typically made from TFE or some other resilient
material and machined to fit the cavity around the ball. Cavity Fillers serve no other function
than to fill the cavity around the ball. They do not provide or aid the seats in any sealing.
To remove and replace cavity fillers, refer to sections 1.2 and 3.1 disassembly and assembly
instructions. When the valve body is first taken apart, the "A" cavity filler will be sitting on the ball.
It should lift out easily. Once the ball has been removed, the "B" cavity filler can be easily
removed. If the fillers are in good condition, they can be reused. To install, place cavity filer "B" in
the body before installing the ball. Once the ball is in place, install cavity filler "A", face down on
the ball, and assemble the valve according to the instructions in section 3.2.