Flowserve 1878 Double-Disc Gate Valve - Manual (Page 14)

14
9.0 MAINTENANCE INSTRUCTIONS (Continued)
9.4
Trouble Shooting
A. EXCESSIVE HANDWHEEL (136) EFFORT OR BINDING
Excessive handwheel effort or binding would indicate that the Stem (025)
either needs to be lubricated; or the Gland Flange (133) is too tight as a
result of the Gland Stud Nuts (234) being tightened unevenly. Lubrication
(Para. 7.3) should be checked at regular intervals of 6-months. To tighten
the Gland Stud Nuts evenly, they should be loosened and retightened in an
alternating fashion.
B. LEAKAGE BETWEEN THE DISC (004) AND SEAT (013)
This could be an indication that there is foreign matter on the seating
surfaces in which case the valve should be opened and closed ONE TIME in
an attempt to dislodge any matter that may have inadvertently lodged there.
DO NOT OPEN AND CLOSE THE VALVE MORE THAN ONCE AS THIS
MAY CAUSE PERMANENT DAMAGE TO THE SEATING SURFACES IF
THE FOREIGN MATTER IS SECURELY LODGED IN PLACE. Instead,
disassemble the valve and remove the sources of the trouble. If no foreign
matter is found, inspect the seating surfaces of the valve for signs of a
scarred or damaged seat - in which case the seating surfaces of the Disc
(004) and Seat Ring (013) should be lapped until no visible defects remain.
(Refer to Para. 9.3)
C. LEAKAGE BETWEEN THE BODY (001) AND BONNET (002)
This would be a good indication that the Gasket (100) is worn out or
damaged. Replacement of gaskets is set forth in Para. 9.1. Another source
of the trouble might be that the Bonnet Studs and Nuts are loose - if this
should be the case - tighten them securely.
D. LEAKAGE AROUND STEM (025) AND THRU THE STUFFING BOX
Worn Packing (110, 112). Replace the packing following the instructions set
forth in Para. 9.2.