Would you please advice; is there any general repair procedure that we can use for different kind of relief valve defects , beside if there is something concerning welding & coating limitation.Advice from our workshops most skilled and experienced instrument mechanics:...Clean everything carefully, taking as little as possible apart. Inspect visually. If no apparant cause for failure is found: put together again and see if it is working properly now....Will work for more than 60% of all apparantly mechanical undamaged instruments and for instance pilot operated valves exposed to fluid for some periode.Specific Repair Procedures are documented in PRV Manufacturer's Maintenance Manuals, which in many cases are available on their websites: (See website info below) Specific Critical Dimensions (Inspection Points and Acceptance Criteria, Tolerances) include: Spring Range needs to be verified correct. Overall Spring Free Height is critical. Spring Squareness is important. Spring Footprint needs to be checked. Uneven Spring Coil Spacing is unacceptable. Check Stem/Spindle Runout (Concentricity). Look for wear or galling. Check Guide & Disc Holder Clearance for minimum/maximum dimensions (overall clearance). Check Surface Finish. (Replace if worn or galled). Check Nozzle Overall Height (Replace if under minimum). Check Nozzle Bore Diameter (Critical to Flow Capacity). This info is available in NB-18.

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