Double Block And Bleed Valve

Introduction

The Habonim double block and breed valve series presents an optimal design solution and guarantees isolation on critical applications and service when an emergency shut-down (ESD) valve is a necessity.

The Dual-Safe unit incorporates two main isolation valves and one bleed valve in a single body construction.

This special construction offers the lowest possible number of potential leakage points from a process connection and reduces the overall valve envelope size and weight by integrating valves, piping, and fittings into one compact design.

Technical summary
Size range	1/4" - 8" (DN8 - DN200
Design	Single Body Construction (SBC) with reduced number of body seals
Pressure range	ANSI Class 150 to 2500
Temperature range	-200 °C to +260 °C ( -328 °F to 500 °F)
Materials	Carbon Steel, Stainless Steel ,Alloy C22, Duplex, Super Duplex, 254SMO and more
End connections	Threaded, welded, flanged and more
Operation	Manual, actuated and coupled actuation

Prevention of explosions in fuel, oil and natural gas furnaces

Furnace explosions are caused by the ignition of an accumulated combustible mixture within the boiler furnace enclosure.

• An interruption of the fuel or air supply or ignition energy to the burners, sufficient to result in momentary loss of flames, followed by restoration and delayed reigniting of an accumulation

• Repeated unsuccessful attempts to light off without appropriate purging can result in an accumulation of an explosive mixture

• Fuel leakage into an idle furnace and the ignition of the accumulation by a spark or other source of ignition

Explosions, including "furnace puffs", are the result of improper equipment design, improper procedures by operating personnel or control system malfunctions.

How Dual-Safe Works

The two main isolation valves are operated by one actuator with a coupled mechanical link system that ensures they rotate together. The bleed valve is actuated separately.

This unit presents a simple concept that will assure zero flow to the furnace and maximum operational safety.

Standard Operation

In a standard application, the primary line valves are set to the "fail to close" position, and the bleed valve is set to the "fail to open" position. During normal operation, the primary line valves are open; the bleed valve is closed, and gas flows to the furnace.

Shutting down

When shutting down the system, the isolation valves are closed, while the bleed valve is switched to its open position.

A pipeline connected to the bleed valve releases the trapped pressure between the two isolation valves out into the atmosphere. Any trace of leakage detected between the isolation valves triggers a sensor on the bleed line and sets off an alarm in the control room.

Dual-Safe Advantage

• Minimizes the risk of furnace explosion.

• Increases system reliability.

• Saves space and reduces weight.

• Reduces installation time.

• Streamlines maintenance operations.

• Reduces number of items in repair kits.

• Rugged construction.

• Bubble tight shutoff on all three valves.

• Coupled operating mechanism reduces the number of actuators on the main line

• Tongue and groove design for all body seals Variety of end connections (welded, threaded, flanged)