GLOBE VALVES OS & Y - FORGED - ISO 15761/API 602/B16.34
Australian Pipeline Valve - Installation, Operation and Maintenance Manual
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Leaks can also develop from failure to close the valve tightly, resulting in high-velocity flow through a
small opening. Trim materials such as F51/CR13 (410) and especially Stellite are corrosion and erosion-
resistant, but grooves, pit marks or other surface irregularities may still form on the mating surfaces.
Valves which leak should be repaired as quickly as possible to prevent greater damage caused by high
velocity. Leakage through seats and disc cannot be verified when valve is in service. However, when leaks
are identified, immediate action is necessary. Any delay can permanently damage the seat or disc seal
surfaces.
To repair or replace disc or seats, the valve must be removed from the line then use the following
procedure:
• Make sure that the valve is not under pressure before unscrewing bonnet nuts.
• Remove bonnet, being careful not to damage the gasket. (Refer Section 4.3)
• Remove bonnet when disc is in half open position.
• Lift up bonnet until disc is disconnected from guides.
If seat surfaces show signs of seizing, pitting, grooves or other defects not deeper that 1.0mm (1/16”) it is
possible to repair seating surfaces to its original condition by relapping the surface with line grain
abrasive paste, creating a perfect tightness once again.
Defects having a depth exceeding .8mm (1/32”) cannot be repaired by lapping, in this case, parts must be
replaced, or re-metallised or reground by an approved APV approved professional valve reconditioning
service centre. Refer Section 4.7 below.
It is recommended that the face of the disc be blued to check for contact of seating surface after final
lapping. For re-assembly of valves use the procedure outlined under Section 4.7.
4.7 DISC & SEAT REPAIR
FIGURE 8
FORGED GLOBE VALVES OPTIONAL SEATING/DISC TYPES
Disc
Washer
Replaceable
Disc Ring
Screw
Body
Seat
Overlay
Stem
Body
Disc
Gasket
Body
Disc
Body
Seat
Elastomeric or Plastic Seat Insert
Needle Point Metering Plug
Flow Control Nozzle
Example only, refer to as-built drawing.
These valves are available with either threaded-in seat rings or an integral seat, both of which may be
repaired (threaded in seats shall be replaced) while the valve is in line.
Globe valves require a guide fixture (refer to APV approved repairer) to maintain alignment during the
