What is a Double Block and Bleed Valve?

Double block and bleed valves might sound like a martial arts technique, but in the world of industrial fluid systems, they play a crucial role in safety and efficiency. These valves are designed to isolate sections of a piping system, allowing for maintenance, sampling, and flow diversion. This post describes the key attributes, functions, and applications of double block and bleed valves, helping you understand how they contribute to the reliability and performance of your fluid handling operations.

Consult with our fluid handling experts at Crane Engineering to find the perfect valves and pumps for your unique needs.

What is a double block and bleed valve?

A double block and bleed valve is like having three valves in one.

API 6D defines a double block and bleed valve as a "single valve with two seating surfaces that, in the closed position, provides a seal against pressure from both ends of the valve with a means of vending/bleeding the cavity between the seating surfaces."

There are a couple different styles of double block and bleed valves. One style has two independently seating valves inside, with a bleed or drain valve. This configuration is referred to as a double isolation and bleed (DIB). The DIB valve can isolate either side of the valve (bi-directionally) to vent or bleed the cavity and isolate piping.

This trunnion style ball valve from Val-Matic provides double block and bleed in a single valve. This style can isolate piping on both sides of the valve (uni-directionally) to vent/bleed the valve cavity between the seats.

Using a single double block and bleed valve system versus 3 separate valves saves installation time, weight on the piping system, and space. It also cuts down the number of leak paths to the atmosphere, reducing the risk of hazards when transferring liquids dangerous to humans or the environment.

Which applications require a double bock and bleed valve?

Double block and bleed valves are essential components in many industries, particularly in the oil and gas sector. They are designed to ensure safety and operational efficiency by isolating sections of piping systems.

These valves are essential for various applications, such as bleeding trapped fluids from valve cavities, isolating pipelines for maintenance or repair, or redirecting fluid flow.

Beyond oil and gas, these valves find applications in various industries, including:

• Prevent product contamination
• Remove equipment from service for cleaning or repair
• Meter calibration
• Liquid service near waterways or municipalities
• Transmission and storage
• Chemical injection and sampling
• Isolate instrumentation such as pressure indicators and lever gauges
• Primary process steam

What to look for when selecting a double block and bleed valve?

As with any valve, during selection, one should consider the fluid properties, pressure, temperature. Perhaps most importantly, however, is how the valve will be used. With a number of configurations offered, consider which of these will fit your process and needs best.

If you're unsure which double block and bleed valve is right for your process, consult with a fluid handling expert at Crane Engineering to find the right solution for your unique application.

We gladly provide technical assistance to businesses in Wisconsin, Minnesota, Iowa, and upper Michigan.