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LT Valve Manual - 4.0 Disassembly
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When repairing a MSI plug valve, the following basic guidelines can help you ensure a good hydrostatic test of the reassembled valve.
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Disassemble the valve completely and detach the internal parts from the adjusting nut. See Section 2.0 DISASSEMBLY PROCEDURES for detailed instructions on valve disassembly. Remove old grease and debris from valve pocket with a solvent and inspect for wear or damage such as:
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- In the adjusting nut seal bore of the pocket: Scratches could be caused by previous installation of a damaged adjusting nut. Dings can also occur during assembly. Pitting is usually caused by failure to disassemble and clean valves after they are in service. Use your fingers to feel for any surface defects which may either fail to seal against the o-ring or may even damage the o-ring during assembly.
- On the adjusting nut o-ring groove area: Check for scratches, dings, or pitting. Dings and scratches here are usually caused by careless use of sharp metal objects when trying to remove old o-rings. Feel for any raised edges that might scratch the internal seal bore of the valve body and sand or file as necessary.
- On the adjusting nut threads: Check for damaged threads, especially the lead thread. Use your fingers to check for any raised edges and carefully sand as needed. Severely damaged threads must be repaired at the factory.
- On the pocket walls: Scratches, dings, or pitting, especially in the area immediately surrounding the valve bore. Use your fingers to feel for any surface defects which may either fail to seal against the o-ring or may even damage the o-ring during assembly. Check for any sharp edges around the valve bore that can cut the insert o-rings. These can be caused by using a bar when swabbing excess grease or using a bar to carry the valve.
- On the internal threads: Check for damaged threads, especially the lead thread. Use your fingers to check for any raised edges and carefully sand as needed. Severely damaged threads must be repaired at the factory.
- On the plug seal area: Check for scratches, dings, or pitting. Dings and scratches here are usually caused by careless use of sharp metal objects when trying to remove old seals.
- On the plug outside diameter: Check plug for washout, which will render the part unusable. Hold part in a well illuminated area and inspect for slight scratches in plug. If scratches are visible use 600 grit sandpaper to remove.
- On the insert inside diameter: Check inserts for washout, which will render the parts unusable. Hold parts up to a well illuminated area and inspect for slight scratches in outer and inner diameters of inserts. If scratches are visible use 600 grit sandpaper to remove.
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