Difference Between DBB vs DIB Valves

What is the difference between a Double Block and Bleed (DBB) valve and a Double Isolation and Bleed (DIB) valve consumer needs to know? Recognizing the similarities and differences between these two types of valves is important for designing, selecting, and using them in industrial systems safely.

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In this blog, consumers can explore the unique difference between dbb vs dib valve, how they are used differently, and why engineers must pay special attention when specifying one over the other.

What is DBB or Double Block and Bleed Valve

A double block and bleed valve or DBB ball valve is a kind of valve that is specifically designed to provide two inline isolation points. The two isolation points create a physical barrier between the upward and downward sections of the system, preventing any contamination or cross-contamination between the two flows. They are used in many industries, especially gas, oil, and petrochemical, and can be found as part of process plants and pipelines.

Most industrial valve company&#;s basic construction of a DBB valve consists of two separate, but connected, shutoff valves with an interconnecting bleed line between them. The first stage of the valve is a primary isolation valve which provides full closure off of the upstream side. This ensures that no upstream flow can penetrate through to the downstream side. 

The second stage is then a secondary isolation valve, which further prevents any fluid from traveling through to the downstream side by creating an additional physical barrier. The bleed line is then connected between the two valves, allowing for any pressure or moisture to be released from the system.

If you&#;re looking for a reliable butterfly valves supplier for your DBB valve needs, it&#;s important to choose one that provides absolute assurance that there is no communication between the upstream and downstream flows. This is extremely important when dealing with hazardous fluids and other volatile compounds, as they must be kept separate in order to maintain safety. 

Additionally, the bleed line acts as a pressure relief valve, allowing for any residual pressure or moisture to be released from the system.

What is DIB or Double Isolation and Bleed Valve

The Double Isolation and Bleed (DIB) valve is a specialized component used in pipeline systems. It is a two-stage valve that combines isolation and pressure relief in one, allowing for a quick shut-off of hazardous fluids. The DIB valve is commonly used in the oil and gas industry, industrial processes, and cold storage plants, as well as various nuclear power plant applications.

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The innermost stage of the DIB valve acts as the primary isolation point, completely isolating the fluid from the system on both the upstream and downstream sides.

The second stage of the industrial ball valve contains two separate venting points, ensuring that any pressure build-up downstream from the valve is safely vented to the atmosphere. This prevents any potential safety issues related to high pressure or temperature disasters which could otherwise cause significant equipment damage or injury.

Along with this double-stage protection, DIB valves are usually constructed from special corrosion-resistant materials such as carbon steel or stainless steel to ensure long-term durability. Additionally, they have low internal volumes which remove the need for any further containment vessels or large-scale drainage systems. As a result, this type of solution is often chosen for applications in tight spaces with restricted access.

All in all, when we compare dib vs dbb valve, the Double Isolation and Bleed (DIB) Valve gives operators an effective and reliable way to quickly and safely shut off hazardous fluids in their systems, as well as to vent any excess pressure. This high-quality system offers numerous advantages for a wide range of industrial and energy applications.

DBB vs DIB Valves&#;Differences

 &#;DBB valve&#; and &#;DIB valve&#; are crucial components in the oil and gas industry as they play a vital role in controlling the flow of fluids in pipelines and process systems. They are used to isolate, divert, and regulate the flow of fluids, and they provide a reliable and efficient method of maintaining the safety and integrity of the overall system. 

Understanding the differences between SBB and DBB valves is essential for selecting the right valve for the job. Here are the key differences between the single block and bleed valve vs double block and bleed.

DBB Valve

A DBB valve is a valve that has two independent closure elements with a bleed valve between them, providing a double block and bleed configuration for isolation. Valves companies offer DBB valves because they provide enhanced safety features due to two fully-sealed chambers. However, they are larger and more complex than single valves, requiring additional space for installation.

The valve design is commonly used in the oil and gas industry for applications such as pipeline transportation, production, and refining. It helps prevent the leakage of hazardous materials and allows for the maintenance or replacement of one of the closure elements while the other is still operational.

The bleed valve between the closure elements releases any pressure buildup, ensuring that the valve can be opened and closed safely, and it can also be used to monitor the pressure between the two chambers.

DBB valves are also used in other industries where safety and isolation are critical, such as chemical processing, pharmaceuticals, and power generation. Although they are more expensive than single valves, their enhanced safety features and the ability to perform maintenance without shutting down the system make them a valuable investment for many industries.

DIB Valve

While on the other side, the DIB valve uses a single direct injection seal for isolation. This results in a more economical and simpler design compared to the DBB valve. Additionally, the DIB valve is smaller in size, making it easier to install in tight spaces. When selecting between these two valve types, it&#;s important to consider factors such as space limitations, level of security needed, and budget constraints.

The main difference between single block and bleed valve vs double block and bleed valves is the number of closure elements they have. A DBB valve has two closure elements and a bleed valve, while a DIB valve has three closure elements and a bleed valve. DIB valves provide an extra level of isolation, making them more suitable for applications where fluid leakage can have severe consequences.

When selecting between these two valve types, it&#;s important to consider factors such as space limitations, level of security needed, and budget constraints. It&#;s also important to research and compare the specific features and benefits offered by each valve company to ensure that the selected valve will meet the required specifications and provide optimal performance.

Conclusion

It is critical to fully comprehend the distinctions of DBB vs DIB valve in order to select the appropriate solution for any specific application. DBB valves are ideal for situations where double isolation is necessary in order to prevent any fluid leakage. On the other hand, DIB valves are designed with an extra level of protection, making them suitable for use in high-risk applications.

Choosing the right valve type is essential in order to ensure that your system operates safely and effectively. Dombor is one of the leading industrial valves supplier worldwide, offering a range of valves to suit different needs like double block and bleed ball valve. These valves are designed to be durable, reliable and safe. 

Dombor&#;s reputation for quality products is well-respected in the industry, as evidenced by their commitment to achieving ISO certification and ensuring that all their products meet the highest standards of safety and reliability.

All products from Dombor undergo stringent testing before leaving the warehouse, with a certificate of compliance provided at delivery. Check their website for more information about the different valves. 

The definitions of double block and bleed (DBB) and double isolation and bleed (DIB) differ between sources in the oil and gas industry. Differences in definitions and terms are important when it comes to which valve capability to use in what type of system. Because DBB and DIB have become such generic terms in the industry, it is important to take into consideration the application, media, and various environmental challenges when choosing the appropriate solution and valve type.

DBB definitions

There are two entities in the United States that define DBB&#;API and OSHA. According to API, a DBB valve is 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 venting/bleeding the cavity between the seating surfaces." API also notes in this definition that this valve does not provide positive double isolation when only one side is under pressure.

In contrast, OSHA describes DBB as "the closure of a line, duct, or pipe by closing and locking or tagging two inline valves and by opening and locking or tagging a drain or vent valve in the line between the two closed valves."

API's DBB definition does not achieve the same level of isolation as OSHA's. API allows DBB valves to be one single valve with two unidirectional seats, while the OSHA standard can only be achieved with two separate valves with a method to bleed pressure in between. There are some valves that utilize a twin-valve design. By combining two valves into one body, a twin-valve design reduces weight and potential leaks paths while meeting the OSHA requirements for double block and bleed.

Valve associations usually choose to follow either API's or OSHA's definition, but some have created their own handbook with their own definitions for industry terms. For example, the British Valve and Actuator Association (BVAA) defines DBB as "a manifold that combines one or more isolation valves, usually ball valves, and one or more bleed/vent, usually a needle-style global valve, into one assembly for interface with other components (e.g., pressure measurement transmitters, pressure gauges, and switches)."

The double block and bleed system requires the use of two valves and a spool piece. A bleed valve is used to drain the spool and verify seal integrity.

The double block and bleed system requires the use of two valves and a spool piece. A bleed valve is used to drain the spool and verify seal integrity.

DIB definition

API defines DIB as a &#;single valve with two seating surfaces, each of which, in the closed position, provides a seal against pressure from a single source, with a means of venting/bleeding the cavity between the seating surfaces.&#; This feature can be provided in one direction or in both directions.

The difference between API&#;s DBB and DIB definitions is that a double block and bleed valve seals against pressures from both sides of the valve while a double isolation-and-bleed valve provides an additional seal against pressure from only one side. It is important to use a DIB valve instead of a DBB valve in applications that require an additional pressure barrier that seals separately of the main pressure barrier. This is important to fulfill certain operational safety requirements or according to the nature of the service, such as low tolerance for leakage or the cleanliness of the fluid.

Differences of DIB and DBB

With a DBB valve, there are usually two unidirectional self-relieving seats. These seats do not rely on an outside mechanism to relieve pressure. In contrast, a DIB valve utilizes one or two bidirectional seats. The valve provides double isolation from pressure at both ends of the valve but cannot relieve body cavity pressure past the seats. DIB valves require an external relief system to relieve pressure buildup.

Both valves can provide isolation in both the upstream and downstream directions, even in high-pressure or high-temperature situations. Isolation is important in cases where leakage through a valve could have major consequences. Once the fluid is isolated, the bleed mechanism can drain the area between the two valves or two seating surfaces. This is important for maintenance and integrity check situations where leakage can be monitored.

Benefits

Both DBB and DIB valves save space, reduce the need for costly multivalve systems, and provide zero-leakage capabilities from upstream to downstream. The valves also enable integrity check of seat seals.

Applications

DBB and DIB valves are used in applications where critical isolation is needed to ensure that leakage does not occur. Both valves can be used in a variety of applications and markets, such as LNG, petrochemical, transmission and storage, natural gas industrial processes, mainline and manifold valves in liquid pipelines, and refined products transmission lines.

Another application in which DBB and DIB valves are used is the meter calibration market. Every closed valve in the meter system must seal drop tight. Even a small leak will cause errors in the meter calibration, and the incorrect meter factor will persist until the next proving operation, costing significant sums. Choosing the correct API-verified DBB or DIB valve can help ensure correct calibration almost every time.

Cameron offers a wide range of DBB or DIB valve types and options to fit specific needs. For example, in liquid service near waterways or municipalities, double expanding gate valves with DBB capabilities, such as the Cameron WKM Pow-R-Seal double expanding gate valve, are preferred for critical isolation because they provide a tight mechanical seal simultaneously upstream and downstream, which is normally unaffected by pressure variations or vibrations.

The mechanical wedge action of a double block and bleed plug valve, such as the Cameron GENERAL Twin Seal double block and bleed plug valve, firmly compresses both the upstream and the downstream seals against the valve body, requiring no help from the line pressure to effect a positive seal. Double block and bleed plug valves, which are used often in the transmission and storage markets, provide consistent and provable zero leakage of various fluids.

 

Valve Type

Sealing Arrangement

Block and Bleed

Double Block and Bleed

Double Isolation and Bleed

OSHA Double Block and Bleed

Two block valves with bleed between

Any valves with bidirectional sealing

Yes

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Yes

Yes

Yes

Slab gate, through-conduit gate, or both

Pressure energized; downstream sealing only; fixed seats&#;

No&#;

No

No

No

Slab gate, through-conduit gate, or both (DIB-1)

Pressure energized; upstream and downstream sealing&#;

Yes

Yes§

Yes§

No

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Wireline Pressure Control Equipment

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Trunnion-mounted ball valve 

Self-relieving upstream sealing and pressure-energized seats&#;

Yes

&#;&#;

No&#;&#;

No

Trunnion-mounted ball valve (DIB-1)

Upstream and downstream sealing; pressure energized (e.g., two bidirectional sealing seats)&#;

Yes

&#;&#;

§§

No

Trunnion-mounted ball valve (DIB-2) 

Upstream and downstream sealing; pressure energized (e.g., one bidirectional and one unidirectional sealing seat)&#;

Yes

&#;&#;

Only if the bidirectional seat is on the downstream side§§

 

No

Floating ball valve 

Pressure energized

No&#;

No

No

No

Plug

Pressure-energized downstream sealing&#;

No&#;

No

No

No

Expanding plug (DIB-1) 

Mechanically energized

Yes

Yes

Yes

No

Expanding gate (DIB-1) 

Mechanically energized

Yes

Yes§

Yes§

No

&#; Upstream and downstream refer to pressure source and open-end equipment, respectively, and do not refer to flow direction
&#; Not possible to bleed from valve body, but bleed may be in downstream pipework or pipeline
§ Depending on detailed design of the valve, some valves can have preferred sealing direction, specified sequence of operation, or both
&#;&#; Depending on detailed design
&#;&#; Downstream seat can provide a second barrier at pressures below the cavity relieving pressure but will not provide a high-pressure barrier
§§ Depending on detailed design and ability to achieve testing per API Spec 6D Section D13

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