GLOBE VALVES OS & Y - FORGED - ISO 15761/API 602/B16.34
Australian Pipeline Valve - Installation, Operation and Maintenance Manual
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loosened but they will leak. Always keep the valve in the backseat position when re-tightening the
packing.
If there are indentations or pitting marks no deeper than 0.12mm (0.005”), a cast iron lapping disc with
the proper seat angle must be used with a suitable lapping compound to roughen the surface first with
the use of a new or refurbished original disc, use a fine lapping compound to final lap the disc and seat
together.
Note, For body seat damage exceeding 0.12mm (0.005”) up to a maximum (for valve a seat angle of 30°),
1mm (0.040”) can be removed by grinding with the automatic grinding machines by an APV approved
valve repairer. For major seat damage use 60 – 80 grit, diamond or micron Alumina stick on abrasive
discs, and finish with fine grit 180 and up. For minor imperfections use medium coarse 120 grit stick on
abrasive discs and finish with fine grit, 180 and up.
For the valve disc seating surface damage exceeding 0.12mm (0.005”), up to a maximum of 1mm (0.040”)
can be removed in a lathe by an APV approved valve repairer (for disc with angle 27°).
