A.  Disassembly of GateValves for Inspection and Repair

Caution: Before any attempt is made to disassemble the valve, verify that the valve is isolated from system pressure and secured against accidental pressurization. Follow standard tag out saftey procedures before proceeding.

1. Position the stem at mid-travel.
2. Completely remove the clampbolt from the yoke and screw it into the opposite (threaded) side of the clampbolt lug. Place a metal flat (like a fender washer) into the yoke split to stop the clampbolt. Tighten clampbolt, using it as a jacking screw, until the yoke split expands by 1/32" for a 1/2" valve and up to 1/16" for a 4" valve.
3. Loosen the yoke by applying force in a counterclockwise direction. Using a yoke wrench or pipe wrench, unscrew and carefully remove the yoke and all valve internals. Once the gate has cleared it's guides, it can slide off the stem. Be careful to insure that this does not happen inadvertently.
4. Slide the gate off them stem, then rotate the handle clockwise to unscrew the stem out of the yoke. (Note: use caution to avoid damage to bonnet or stem during disassembly.)
5. Carefully slide the bonnet from the stem by holding the stem vertically on a bench with the threaded end down and pressing down on bonnet. This process can be faciliated by using a light lubricant like WD40 on the stem.
6. Remove gland, gland wrench and spring.
7. Inspect the condition of the sealing surfaces for damage:
       *  Body      Seat, Bonnet seal
       *  Stem      Disc sealing surface, packing sealing surface, backseat lip of retainer
       *  Bonnet   Backseat nose, body seal, packing chamber surface
       *  Gate       Seating surface
           If the stem or bonnet surfaces identified above are damaged, the part should be replaced. If the body or gate sealing surfaces are damaged, please consult the factory for repair instructions.
   In general, further disassembly will not ne necessary . However, if access to the stem nut or bearings is required, proceed as follows:
8. Back off on the set screw and remove the handwheel.
9. Remove the cap screws securing the bearing cap.
10. Remove the bearing cap, stem nut and thrust bearing.

B.  REPACKING

 It is recommended that valves be repacked by replacing the bonnet with a prepacked spare. When the original bonnet is going to be used, repack it as follows.

1. Place the bonnet on a flat surface with the seal lip up.
2. Insert wooden dowel or brass rod into the stem opening and remove the lowest ring by pressing down around it's circumference. Repeat until all packing is removed. Removal of the old packing from the bonnet can be made easier by first soaking the packed bonnet in a light oil or solvent.
3. Clean the chamber wall and inspect the surface finish. If the surface is badly pitted or scored, the bonnet should be replaced.
   NOTE:  DO NOT USE A STANDARD PACKING PULLER TO REMOVE PACKING. The use of a packing puller may scratch the inside surface of the bonnet, which will result in a packing leak.
4. Replace the bonnet over the stem.
5. Add rings individually and manually depress them into the chamber using the packing gland. Be very carefull not to damage the stem with the gland while repacking.
   NOTE:  Use only dieformed flexible graphite seal rings and woven graphite wiper rings for best packing performance.

C.  Reassembly

1. Clean all parts thoroughly with clean solvent, and lubricate threads. A recommended thread lubricant is Never-Seez Pure Nickel Special.
2. If the bearing housing has been disassembled, reassemble the stem nut, bearings, bearing cap and handwheel as shown in Figure A and fill the housing with grease.
3. For a prepacked bonnet, hold the gland against the packing to prevent movement of the rings, and slide the bonnet onto the stem until the backseat position is achieved. Remove the gland.
4. Reassemble the gland wrench and spring and screw the gland onto the yoke bushing all the way up. It is important that the gland be screwed all the way on since it may otherwise prevent a proper bonnet seal.
5. Screw the stem into the stem nut until the bonnet is just short of contact with the yoke. (NOTE: Stem has left hand thread.)
6. Slide the gate onto the stem. Exercise care to prevent the gate from sliding off.
7. Align the gate groves with the guide rods and screw the yoke onto the body. Apply torque as specified in Table 2. DO NOT OVERTORQUE.
8. Return clampbolt to normal position and tighten per Table 2.
9. Screw the gland down onto the packing and apply torque as specified in Table 2.
10. Cycle the valve open and closed several times to seat the packing. Reapply proper torque to gland.