Marwin Valve KC Series Trunnion Valves - Manual (Page 2)

Operation
For Side/Top Entry Ball Valves
1. Marwin ball valves are designed as quarter turn
valves, which means from fully open to fully closed,
operation of the valve stem just needs to turn 90°.
Unless otherwise specified the valve closes by
rotating the stem in the clockwise direction.
2. Marwin ball valves provide DBB (Double block
& bleed) functionality in either fully open or fully
closed position. This means the body cavity pres-
sure venting and fluid/sampling is available when
pressure is maintained in the pipeline.
3. The DBB function allows drain or flush of the valve
body cavity, while preventing downstream leakage
to insure safety of downstream activities.
To perform a DBB action:
First turn the valve in fully open or fully closed position
using an appropriate wrench (Hex head) to turn the
release part of the Drain plug. Caution: For safety the
exhaust ports should never be positioned toward any
personnel
. Continue draining/venting until body cavity
pressure reaches atmospheric pressure. The fluid sam-
pling can be performed during the venting period.
Emergency Seat/Stem sealant injection:
Marwin ball valves are equipped with Seat/Stem sealant
injection plugs which allow performing a sealant injec-
tion if there is a leak during normal operation.
To perform a sealant injection:
To the seat:
normally the seat injection should be done
to the upstream seat. Remove the protective cover of
the sealant plug and inject the sealant with appropriate
injection gun while monitoring from the downstream side
to see if the leakage has been stopped. (This can be
monitored by the DBB function mentioned above).
To the stem:
Release the gland and simply remove the protective
cover of the sealant plug and inject the sealant with ap-
propriate injection gun while monitoring from the gland.
If the leakage stopped, tighten the gland again.
Body drain and flush:
The Marwin ball valves are equipped with two fittings in
the body cavity. The vent fitting used in DBB above and
a drain fitting on the bottom of the valve.
-2-
Gland
Gland Packing
Stem
Spring
Seat
Ball
Gasket
Body Cap
Body
BLOCK BLOCK
BLEED
Grease-sealant
Grease-jet valve
Grease sealant
O-Ring
Ball
Seat
Spring
O-Ring