Double Block and Bleed Valve

Double Block and Bleed Valve

Series DBB-C and DBB-F

The increased activity in the offshore sector of the energy industry has led to additional factors that have to be taken into consideration when designing piping systems. Space in these modern locations is always at a premium and the design of piping systems and their associated components must therefore be more compact. There are structural constraints that are also very important, such as keeping the structure as light as possible, and there are obvious benefits from making components smaller and lighter. Construction site job is also very expensive and any reduction in installation manpower is also beneficial. The above situation has led to the modification of the patterns of valve components to incorporate savings in space, weight, and labor costs where possible, while still retaining the original function of the valve.

The greatest savings are to be seen in the reduction of leak to atmosphere because the potential leak points are minimized compared to the conventional design. Process isolation philosophy has become more complex as safety issues have to be addressed and the requirement for double block and bleed isolation has become more commonly used. Double Block and Bleed isolation requires two in-line isolation valves and a bleed valve, used to drain or vent trapped fluid between the two closure elements

Size & Rating


20 Inch


20 Inch


20 Inch


18 Inch


16 Inch


14 Inch


Live Loaded Gland Packing

Graphite Packing are provided as standard taking care of Fire Safe Design Condition. Belleville Springs Washers are used to achieve live loading which protects Gland loosening under vibrations & shock conditions.

Antistatic Device

To ensure Electrical Continuity between the Stem and Ball and Body all Valves are provided with Antistatic device as an integral part of Floating Ball Valves.

Blow Out Proof Stem

Stem is Designed to include a collar to provide protection against Blow Outs.

Double 'D' Stem to Lever Connection

Stems are Designed to have Double 'D' Connection at the top for Lever Fixing. This feature eliminates possibility of Lever Assembly in the wrong direction as the Lever indicates the Valve Position once installed on the line.

Equalized Cavity Pressure

The Pressure equalization hole at the top of the Ball combined with Seat Design are Engineered to maintain the Pressure balance in the line & in the Body Cavity irrespective of Valve Position

Locking Device

Locking devices are provided on all Valves with both Lever Operator ad Gear Operator.

ANSI B16.5 flanged inlet connections 1/2" to 20" sizes.

Class 150 rated to class 2500 rated.

1/2"-14 to 1"-11.5 NPT (female) standard outlet (depending on bore size).

1/2" NPT (female) standard vent.

Standard materials of connection: Stainless steel ASTM A182 F316/F316L, WCB & CF8M, Carbon steel ASTM A350 LF2/A105, Duplex ASTM A182 F51.

Optional materials on request. Stainless steel ASTM A182 F316/F316L.

Carbon steel ASTM A350 LF2/A105. Duplex ASTM A182 F51.

Raised face and ring type joint flange face styles.

One-piece forged construction flange as standard. Fire safe designed (and tested) to meet BS 6755 Part 2/API 607.

304 stainless steel handles and trim as standard to reduce the risk of corrosion when required .

Designed to meet the pressure and temperature requirements of ASME/ANSI B16.34/B16.5.

Pressure boundary designs calculated to ASME VIII Div 1 and verified by testing. Heat code traceable material to EN 10204.3.1.

Bubble tight shut off.

locking and anti tamper devices for all valve types available option.

Positive lever stop. User preferred handles. Permanent affixed reference label.


Part Name




A 216 WCB, A 351 CF8 A 351 CF8M, A 351 CF3 A 351 CF3M, A 352 LCB A 217 CA 15, A 148 C95000 (AL. BRONZE) (DUPLEX) SUPER DUPLEX ALLOY 20 HAST C 276

A 105, A 350 LF2 , A 350 LF3, A 182 F6a A 182 F 304, A 182 F 316, A 182 F 316LN A 182 F 321, A 182 F 44(6% MO) A 150 C 63000 (Al. Bronze), A 182 F 51 (Duplex S.S.) INCONEL 625 (UNS N 06625) INCONEL 825 (UNS N 8825) MONEL K 400 (UNS N 04400) MONEL K 500 (UNS N 05500)


A 105, A 350 LF2 , A 350 LF3, A 182 F6a A 182 F 304, A 182 F 316, A 182 F 316LN A 182 F 321, A 182 F 44(6% MO) A 150 C 63000 (Al. Bronze), A 182 F 51 (Duplex S.S.) INCONEL 625 (UNS N 06625) INCONEL 825 (UNS N 8825) MONEL K 400 (UNS N 04400) MONEL K 500 (UNS N 05500)








A 193 GR. B7

A 193 GR. B7M

A 320 L7

A 320 L7M

A 320 L43

A 193 GR. B8

A 193 GR. B8M

A 194 GR. 2H

A 194 GR. 2HM

A 194 GR. 7 or GR.4

A 194 GR 7M

A 194 GR. 7M

A 194 GR. 8

A 194 GR. 8M

Design & Testing Standards

Design Standard:

ASME B16.34


BS -5351

ISO 17292

ISO 5211 (Mounting Pad)

End Connection Standards

Face to Face : Manufactured & Standard

Flange Dimensions : ASME B16.5, EN 1092 , JIS B 2220

Butt weld End Dimensions : ASME B16.25,

Socketweld End Dimensions : ASME B16.11

Screwed End Dimensions : ASME B 16.11

Testing Standards

Pressure Testing : API 598, API 6D, ASME/FCI 70.2, EN 12266-1, ISO 5208

Fire Testing : API 607 / API 6FA

Nace Requirements : MR 01-75

Fuggitive Emission Testing : ISO 15848-2

Technical Specifications

Bore sizes

As per API 6D.

Seat materials

TFM, PEEK, Metal

Body materials

316 Stainless Steel ASTM A182-F316/ UNS S31600 Duplex ASTM A182-F51 / UNS S31803 Super Duplex ASTM A182-F53/F55 Low Temp Carbon Steel ASTM A350 LF2 Alloy 625 UNS N06625 Alloy 825 UNS N08825

Valve configurations

Flange x screw
Flange x flange

Max. Working Temperature

360o C

Min. Working Temperature

-196o C

Max. Working Pressure

Pressure 6,250 PSI (431 bar)

Application Industries

Trunnion Ball Valve application


Trunnion Ball Valve application

Oil & gas

Trunnion Ball Valve application


Trunnion Ball Valve application

Low temperature and LNG

Global Presence of Dembla

Dembla is one of the major Manufacturer, Exporter and Supplier of Double Block and Bleed Ball Valve : Series DBB-C and DBB-F in Italy, Iraq, Korea, Germany, France, Japan, USA, Russia, Brazil, Mexico, Chile, Canada, Australia, Indonesia, Philippines, Vietnam, Austria, Africa, Turkey, Netherlands, UK and across the Entire Globe.

Our Manufacturing set up is situated at Bhiwandi, Thane - Mumbai, Maharashtra, India.