Tri Lok
®
Cryogenic Valve
Installation, Operation and Maintenance Manual
TRI LOK
®
CRYOGENIC TRIPLE OFFSET VALVE
| 12
10.3 Seat Replacement
Refer to parts diagrams (Pgs 7 and 9)
It is highly recommended that both the seat (B1) and seal
ring (C2) be replaced at the same time However, individual
components are not matched in pairs; and may be replaced
separately if desired
Exercise extra care when handling the seat and disc seal ring to
avoid damage to the sealing surfaces
1 Close the valve and remove the actuator Place the
valve on a flat stable surface with the body seat (B1)
facing up
2 Carefully clean the surface of the seat and remove all
foreign matter from the hex sockets of seat retaining
cap screws (B3) Use compressed air to blow out the
gap between the seat OD and the wall of the retaining
cavity in valve body (A1) Apply a suitable penetrant
into the gap between the seat OD (B1) and the body
(A1) to help in extracting the seat (B1) from the body
cavity
3 Using a wrench, remove all seat retainer set cap screws
(B3)
4 Using a hardwood or aluminum drift and a light
hammer, tap the top of the seat (B1) lightly all around
to loosen the seat in the retaining cavity
5 Using full-threaded bolts or suitable threaded rod
matched to the threads in all tapped jacking holes,
begin jacking the seat (B1) evenly out from the
retaining cavity Tap the seat lightly with the drift as
necessary to keep it in alignment with the walls of the
retaining cavity in the body (A1) Remove the seat (B1)
from the body (A1)
6 Using non-abrasive tools, carefully clean any
remnants of old gasket and foreign matter within the
retaining cavity Blow out all threaded holes and gasket
grooves with compressed air
7 Remove the seal ring retainer cap screws (C5) from seal
ring retainer (C4) Remove disc seal ring retainer (C4)
If the old seal ring (C2) is to be reinstalled, extract it
carefully Wipe the seal ring (C2) clean, removing all
remnants of old gasket and foreign matter Place the
old seal ring (C2) aside for reinstallation
8 Using soft tools and a suitable wire brush, carefully
clean any remnants of old gasket and foreign matter
from the face of the disc (C1) Blow out all threaded
holes and the gasket groove with compressed air
9 Place a new disc gasket (C3) into the groove on the
disc face (C1) Place the seal ring alignment pin (C7)
into the disc Place the seal ring (C2) onto the disc
such that the notch is aligned Place the seal retainer
(C4) over the seal ring Apply PTFE Thread Lubricant
to the seal ring retainer cap screws (C5) Install all
disc seal ring retainer cap screws (C5) The seal ring
retainer cap screws (C5) should be fully threaded into
the disc (C1), but remain only finger-tight at this time
Open the valve to approximately 20°
10 Place the seat gasket (B2) into the groove of the seat
(B1) Insert the seat (B1) into the body (A1) making
sure the alignment dimples in the seat (B1) and the
retaining cavity in the body (A1) match Apply PTFE
Thread Lubricant to seat retaining cap screws (B3) and
install the screws (B3) finger-tight
11 Verify that all four alignment marks match (body, seat,
seal ring and seal ring retainer) and then tighten the
seat retainer cap screws (B3) evenly and firmly using a
cross bolting technique to the torque specified in Table
3 (Pg 15)
12 Reinstall actuation device and test the valve
13 Using a suitable actuator, close and open the valve 2-3
times, only closing the valve to the point where the
seal ring engages with the seat Check each time that
the disc seal ring makes full contact without torquing
into the seat Attention should be paid in the closing
stroke that the seat does not scratch the seal ring This
will allow the seal ring and seat to be properly aligned
14 Close the valve Tighten at least four screws in the
seal ring retainer to prevent the seal ring from further
movement Open the valve approximately five degrees
Tighten all seal ring retainer screws (C5) using a cross
bolting technique, to the torque specified in Table 3
(Pg 15)