Flowserve McCANNA CryoSeal Ball Valves - Manual (Page 7)

7
McCANNA CryoSeal ® Ball Valves FCD MMENIM2007-01-AQ – 04/15
flowserve.com
3.3 Bonnet Gasket Bolting Re-tightening
3.3.1 Bonnet gasket leakage must be stopped immediately to avoid damage to the valve body/
bonnet joint surfaces, and contamination of the surrounding area. Tighten bonnet bolting to the
torque values specified (in Table 3) following the sequence shown in Figure 6. Also, If leakage
continues, remove valve bonnet and replace bonnet gasket (see Disassembly/ Reassembly
sections).
3.3.2 Valves which become difficult to operate or stuck, or show excessive seat (through valve)
leakage, should be disassembled and inspected for internal damage from corrosion or wear,
and repaired as necessary (see Disassembly/Reassembly sections).
3.4 Correcting Through Leakage – Soft Seated Valves
The wedge seat design permits soft-seated valves to be self-adjusting for seat wear, and thereby extend
service life. In many instances where through-leakage is discovered, it may be corrected by simply
cycling the valve open to closed several times, to allow the seats to “snug down” into the wedge. Soft
seats are also more prone to damage from particles or abrasives in the flow stream. When through
leakage cannot be reduced or eliminated by cycling, the valve should be taken out of service and disas-
sembled for inspection and possible replacement of seats (see Disassembly/ Reassembly sections).
3.5 Other Specially Prepared Valves
Some valves with special preparation such as for Oxygen, Chlorine, Vacuum or other special services
may have special maintenance instructions. See any special instructions which were supplied with the
valve shipment.
NOTE: These instructions may also be obtained from your McCANNA distributor.