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DBBV - Double Block and Bleed Valves

Control Seal has developed the  Double Block and Bleed dual expanding Plug Valve (DBBV) due to market demand for a non friction Double tight shut-off valve. Reduced space and little to no maintenance requirements were met. The Control Seal DBBV gives 100% bubble tight sealing both up and down stream.

Size: 1” ~ 42” (DN25 ~ DN1050) (up to unlimited based on approvals)

Bore: Reduced or Full (Full is piggable)

Pressure: 150# ~ 2500# (PN20 ~ PN420)

Temperature range: -196°C ~ 250°C

Connections: Wide choice on request

Materials: Wide choice on request

Dual expanding Double Block and Bleed plug Valve


The Control Seal Double Block and Bleed Dual Expanding Plug Valve or DBBV in short has been developed for replacement of two in-line valves with a drain and or bleed valve. Many different valves ( gate valves i.e.) and valve combinations have been used for blocking and bleeding, sampling or draining. Traditional solutions can result in loss of product, frequent maintenance and even failure.

One instead of two valves

The Control Seal DBBV has two seated surfaces (slips). When the valve is in closed position each individual seal is fully isolating, not allowing any leakage from downstream, upstream nor from the body cavity. A thermal relief vents / bleeds the body cavity when overpressure occurs so the downstream pipeline is fully isolated from upstream pressure without there being pressure balancing necessary. 

Compared to other types of DBB valves, Double Block and Bleed plug Valve has the DIB - Double Isolation and Bleed function.

The following benefits arise from using single valve solution:

Space + weight requirement reduction

Shorter drain times

One actuator instead of two


DBBV has the following characteristics:

100% TIGHT SHUT OFF, therefore zero leakage.

MECHANICALLY ENERGIZED SEALING without springs or other weak parts required to obtain sealing.

FRICTION-FREE OPENING AND CLOSING, no contact between slip seals and seating area during rotation.   

NON LUBRICATED SEALING, media specific soft seal material.

DUAL EXPANDING, proven zero leakage both up and downstream.

THE SELF-LOCKING OPERATING MECHANISM on all Control Seal valves secures the closing member from rotating due to in-line forces. As a result there is no danger of line slam or shock.



Metering skids

Tank farms




Filling lines

Control Seal design


Control Seal has a unique design of its products, short lead time, competetive pricing and excellent after-sales support.


Main competetive advantage of Control Seal design is a unique rotating mechanism, see benefits of the design below:

Smaller envelopedue to no stem guiding groove and no stem guides as in conventional design.

Fast opening and closing due to a very strong rotating mechanism.

The valve is maintenance friendly as the rotating mechanism is inside the valve. Furthermore, stemguides and gland packings are outside pressurized area and can be adjusted while the valve is in service. All valves are executed with a back seat.

Less moving parts lead to long durability and less spare parts needed.

No stem guiding groove and stem guides as in conventional design.


The Control Seal valves have been FIRE SAFE tested by independent laboratories and have passed BS 6755 part 2, API 6FA and ISO 10497 third party wittnessed tests succesfully.

Slip overhaul in case of system contamination is possible by bottom or top entry while the valve is in-line. No special tools are required. 

All Control Seal valves are delivered with sealing specifically chosen for customer application and media in cooperation with leading experts in the field.



The functions of the bleed system: Proving tight shut off; Pressure relief inside the body cavity

The following options are available (and more on request):

Automatic body bleed (ABB)




Manual Bleed Valve (MBV)

with Gauge (MBV-G)


Thermal Relief Upstream (TRU)

with Gauge (TRU-G)


Manual Bleed and Thermal Relief (MBTR)

with Gauge (MBTR-G)




API 6D, ASME B16.34

Face to Face dimensions

API 6D, ASME B16.10, B16.47


ASME B16.5, B16.25

Fire Safe

ISO 10497, API 6FA, BS 6755

Fugitive Emission

ISO 15848, TÜV, Shell MESC SPE 77-312


API 598, API6D, ISO 5208




ISO 5210




dbbv principle open

1. Open

Valve fully open.
Seatings slips are protected from flow path.

dbbv principle closing

2. Rotating

Plug is rotating.
There is no contact between body and seating slips.

 dbbv principle bleeding

3. Expanding

Plug/slips have rotated 90°, plug starts expanding slips.
Slips only move perpendicular to body seats.
Plug/slip assembly is kept centered in body by top and bottom bushings.

 dbbv principle closed

4. Double Block and Bleed

Valve seated.
Resilient seals have been compressed. Resilient seals
cannot be damaged by operator over-torque. Double
block and bleed function can be tested by opening the bleed valve.

 dbbv principle bleeding

5. Start to open

Valve starts opening. Plug moving up, retracting slips from the body seats. Strong dovetail and stems retract the slips.
Plug is kept centered in body by top and bottom bushings.

 dbbv principle bleeding

6. Slips retracted

Slips have been retracted prior to rotation.

(Further working as fig. 1 and 2 in reversed order)