What Are Double Block And Bleed Valves And Requirments?

Why DBB valves are so important and how to keep them functioning effectively?

It looks like the three valves are packaged in one valve body, but they are all independent valves.Functionally, they can realize the two-end stage and middle relief functions.

A double block and bleed valve (DBB valve for short) are one of the most widely-used safety valves on the market, as it combines two separate blocks and bleeds systems into one compact package, making it suitable for space-constrained applications.

Double block and bleed valves are commonly installed to control media flow in an upstream and downstream direction. Once locked into place, two block valves provide positive isolation, with the latter serving to depressurize excess media pressure if required. Let’s take a detailed view of the valves.

Types of Double Block and Bleed Valve

DBB double block and bleed valve 

Single valve with two seating surfaces in the closed position provides a seal against pressure from both ends of the valve. With a means of venting/bleeding the cavity between the seating surfaces.

DIB double isolation and bleed valve 

Single valve with two seating surfaces. In the closed position, each seating surface provides a seal against pressure from a single source, with means to vent/bleed the cavity between the seating surfaces.

K.3 Double Block and Bleed (DBB)

The ability of the valve or valves to segregate two pressure sources and to bleed/vent pressure in the void between the two sealing elements (blocks) is what is referred to as DBB. The pipework/pipeline where the two valves are used or in the valve body between the two seats when the valve has the DBB feature is where the bleed is.

K.4 Double Isolation and Bleed (DIB)

The DIB feature of the valve or valves is the ability to provide two sealing elements to a single pressure source, and to bleed/vent between the two sealing elements. Note that some documents dealing with isolation of equipment may refer to this feature as double block and bleed.

Valve seats are SPE and DPE. SPE is a one-way sealing valve seat, and DPE is a two-way sealing valve seat. In the API ball valve, the two valve seats of the ball valve are designed into different combinations and are divided into three structures, DBB, DIB-1, DIB-2. The DBB structure means that the two valve seats are all SPE valve seats, and DIB-1 is an SPE Seat, a DPE seat. DIB-2 has both DPE valve seats. DIB-1 also has two structures, one is for discharge before the valve and the other is for discharge after the valve.

Standards for Double Block and Bleed Valves

There are several standards and guidelines that some of the industrial valve company apply to DBB ball valve,which ensure that they are designed and manufactured to meet specific safety and performance requirements. Here are some of the most commonly referenced standards:

API 6D: This standard, developed by the American Petroleum Institute (API), provides specifications for pipeline valves, including double block and bleed valves, intended for use in the oil and gas industry.

ANSI/ASME B16.34: This standard, developed by the ASME, provides specifications for valves, including double block and bleed valves, intended for use in various industries.

ISO 10497: This standard, developed by the International Organization for Standardization (ISO), provides testing requirements for fire-safe valves, including double block and bleed valves.

MSS SP-61: This standard, developed by the Manufacturers Standardization Society (MSS), provides specifications for pressure testing of steel valves, including double block and bleed valves.

NACE MR0175/ISO 15156: This standard, developed by the National Association of Corrosion Engineers or NACE, and ISO, provides requirements for materials and equipment used in sour gas environments, including double block and bleed valves.

Compliance with these standards is important to ensure that double block and bleed valves meet the necessary safety and performance requirements for specific applications. When choosing a double block and bleed valve, it is critical to ensure that the valve meets the relevant industry and application standards and guidelines.

Applications of double block and bleed valves

Double block and bleed (DBB) valves are used in a wide range of applications where it is necessary to isolate two separate pressure sources and provide a redundant seal between them. Some common applications of DBB valves include:

Oil and gas industry

Chemical industry

Power generation

Pharmaceutical industry

Water treatment

China Industrial Valve Manufacturer

Double Block and Bleed (DBB) ball valves are an essential component of piping systems. Not only do they provide a safe, reliable and efficient means to block, bleed and monitor pressure in a system, their wide range of applications makes them diverse and cost-effective for various industries. Consumers have learned what is double block and bleed valves are all about.

When selecting DBB ball valves, factors like size, temperature, media, pressure and installation should be considered to ensure the most appropriate valve is chosen for the job. Furthermore, adhering to ball valve industry standards is critical to ensuring the safety and quality of piping systems. Consider contacting WKT for every double block and bleed ball valves needs.