What is Double Block and Bleed Valves? Why use a Double Block and Bleed valve? Double Block and Bleed valves have evolved to replace the process of bolting together individual valves to provide dual isolation. This new assembly provides great savings in weight, space and installation times especially in instrument or instrument cage isolation.
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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. 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 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. A bleed valve is used to drain the spool and verify seal integrity. 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.
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. 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. 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.
What is Double Block and Bleed Valves ?
Committed to Quality. Committed to Customer Satisfaction. Our commitment to quality has allowed us to build strong relationships with customers. We design, manufacture and deliver innovative and high quality valves, which are used worldwide in critical applications. Our design and manufacturing process adheres to the most stringent quality standards of safety and efficiency, which has earned us the ISO certification. Our quality control process is designed to ensure that all our products meet the international standards. We offer an extensive portfolio of instrumentation valve, which help our customers meet the changing industrial requirements.
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IN Type - Maximum Pressure 6,psi 10,psi available as an option. Maximum Temperature C C available as an option. Heavy duty Firesafe versions are available. ID Type - Maximum Pressure 6,psi 10,psi available as an option.