The action takes place outside the pressure boundary in
the valve ‘operator.’ This design will allow the valve
dimensional envelop to be the most compact.
n
n
Lazy Z or Lazy S: The lazy S design is driven by an
external coupling in which a pin is guided through the
coupling to make the lift and turn action. The plug will
rise shortly to retract the seats from the body and then
follow the path of the Lazy S tract and progress to the
open position while rising and turning at the same time.
A true benefit to the Lazy S design is a manually
operated valve will be self locking and slam proof.
n
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Lower spiral trunnion: With this design, the turning
action is driven by a spiral stem that is integral to the
lower plate. The valve plug is lifted by a linear operator
and the plug is guided through the sweeping quarter
tracking the spiral stem.
DBB and DIB
DBB plug valves are usually designed to meet the API
definitions of DBB as well as ‘double isolation and bleed’.
The original DBB systems required the use of two valves and
a spool piece. A bleed valve was used to drain a spool piece
between the two independent valves to verify a positive
seal. The DBB plug valve is an alternative to the original two
valve system with just one double seated bubble tight valve.
The upstream and downstream seals provide the same
function as the two block valves. The body cavity serves as
the spool piece allowing verification of seal integrity.
Thermal relief
When a DBB plug valve is cycled to the closed position,
process liquids will remain in the body cavity. It is
Figure 2.
Thermal relief system.
Strategically located petroleum bulk storage facility.
The only deep water platform (64’ operating draft)
on the U.S. East Coast
•
20 storage tanks 80 miles East of New York Harbor
•
The only deep-water loading/unloading platform on
the U.S. East Coast.
•
Total Storage Capacity of 5 Million Barrels
•
Easy reloading for distribution of product to U.S.,
Canada and Europe
United Riverhead Terminal, Inc.
(631) 284-2010
