0 maintenance instructions (continued) – Flowserve 800 Split-Wedge Gate Valve User Manual

Page 13

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9.0 MAINTENANCE INSTRUCTIONS (Continued)

9.3

Lapping Procedure

After the valve has been disassembled, a visual inspection of the seating surfaces of the discs (004) and seat rings

(013) can be made to determine if lapping is necessary to remove any minor scratches on these parts prior to

assembling the valve. Adhere to the following procedure:

(a)

The disc should be lapped on a flat, grooved lapping plate or, if available, a lapping machine can be used.

A “medium” grade lapping compound should be used for the first and successive applications and a ‘fine”

grade compound similar to “Clover A Grit No. 280” should be used for the final lapping process.

(b)

If it is necessary to lap the face of the seat ring, a standard lapping plate can be used of approximately the

same diameter as the disc.

9.4

Troubleshooting

A.

EXCESSIVE HANDWHEEL (136) EFFORT OR BINDING

Excessive tee handle 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 (Paragraph 7.3) should be checked at regular intervals of six months. To evenly tighten the

gland stud nuts, they should be loosened and retightened in an alternating fashion.

B.

LEAKAGE BETWEEN THE DISC (004) AND SEAT RING (013)

Leakage between the disc (004) and seat ring (013) could be an indication that foreign matter is 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, SINCE THIS COULD 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 Paragraph 9.3).

C.

LEAKAGE AROUND STEM (025) AND THROUGH THE STUFFING BOX

Worn packing (110, 112). Replace the packing following the instructions set forth in Paragraph 9.2.

800-lb. Split-Wedge Gate Valves FCD ADENIM0002-00

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