IMO
2/19
4
IMO-R26 EN
6.
DETAILED INSPECTION OF VALVE
COMPONENTS
6.1
Ball
Visually inspect the spherical surface for surface damage
in the sealing and wiping zones. These zones are shown in
Figure 1
.
Zones on ball:
1. Sealing Zone- where the seat sits on the ball in the
closed position.
2. Wiping Zone- path of the seat contact as the ball is
rotated between open and shut.
3. Non-Working Zone- area that is never in contact with
the seats.
Visually inspect the stem drive slot in the ball for damage.
Marking of surfaces is acceptable. Material which has been
raised up or deformed is not acceptable and considered
damage. Any other damage in the non-working zone is
acceptable.
6.2
Stem
Sealing and functional surfaces are shown in
Figure 2
.
Visually inspect stem for galling. No galling is allowed.
Visually inspect packing or stem seal area and thrust bearing
area sealing surfaces. No damage is allowed in these areas.
If stem has threads, visually inspect the threads and gage
threads for damage. No thread damage is allowed.
Damage on threads may not be repaired.
Figure 1: Typical Ball Sealing Area
WIPING ZONE
SEALING ZONE
NON-WORKING ZONE
SEALING ZONE
WIPING ZONE
Figure 2: Typical Stem Sealing and Functional Areas
LEGEND: Seal Surface (Solid Line) Functional Surface
