A Double Block and Bleed (DBB) valve is a combination of two isolation valves placed back-to-back and a third bleed valve in the center cavity.
API 6D defines this valve as a “single valve with two seating surfaces that, in the closed position, provides a seal against pressure from both ends of the valves with a means of vending/bleeding the cavity between the seating surfaces.”
These valves are used to segregate two pressure sources and to bleed, vent or introduce pressurized media in the void between the two sealing elements. They can be found in many different industries and applications, such as gas and liquid pipelines, production, processing, instrumentation and more, and are used for the following:
- Detection of valve leakage while maintaining sealing with the second valve
- Maintenance, repair or replacement of equipment while the process is still running
- Double blocking the flow of hazardous materials (for example, in industrial burners)
- Mounting of instrumentation
- Isolating the process of an unwanted feed
- Isolation of vents and drains
- Measuring of pressure without shutting off the line
- Purging instruments or pipe sections.
Note that the term DBB valve should not be confused with the term Double Isolation and Bleed (DIB) valve, which is defined by API 6D 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. The note adds that this feature can be provided in one or in both directions.”
Habonim’s casted valve benefits now available for DBB valves with short lead times
Habonim offers an enhanced and comprehensive DBB valve offering that comprises two in-line floating ball vales and one bleed valve (can be a floating ball valve or a needle valve). These valves offer three major benefits:
Casted valve body for design flexibility and optimal cost-efficiency
There are many advantages to using casted-ready valve components. Cast valve designs offer flexibility as it enables us to create valves from different materials and with complex shapes, patterns and sizes, as well as different configurations to suit specific requirements that are utilizing stocked parts of our standard offering. For example, our casts are made so that actuators can be easily connected in any line configuration. In addition, casting is a more cost-effective solution as it eliminates material waste, can be used to reproduce valve series with more complex or large parts, reduce the amount of labor required for forging valves and machining costs, and makes it easier and less time-consuming to make replacement valves when required.
Equipped with Total HERMETIXTM for highest level of integrity
Our DBB valves are equipped with the Total HermetiX integrity package, which includes a double-body sealing for body-to-ends and for body-to-bonnet superior atmospheric sealing, the patented HermetiX™ steam sealing with zero fugitive emission sealing capability, which is tested and certified to ISO 15848-1 and API641 standards with up to 500,000 maintenance-free cycles life span. In addition, its fully fire-safe tested and certified design meets API 607 and ISO 10497 standards.
Based on Habonim’s proven standard parts and existing valve series for proven reliability and performance
Our DBB valves are based on the following existing and proven series, which means higher reliability, availability and cost-efficiency:
DBB cast design based on the 47 3-piece series
This Double Block and Bleed (DBB) valve is based on our 47 3-piece series for a size range of 1/4”- 2 1/2” (DN8-DN65) and Class 600 pressure rating with a variety of optional end connection styles. It incorporates two main isolation valves and one bleed valve in a single body construction, and offers the lowest possible number of potential leakage points with a reduced overall system size and weight, and the integrity of the Total HERMETIXTM package.
DBB cast design based on the 73 flanged series
This Double Block and Bleed (DBB) valve is based on our 73 flanged series for a size range of 3”- 8” (DN80-DN200) and Class 150 pressure rating. It incorporates two main isolation flanged valves and one bleed valve with a variety of optional end connections in a single body construction, and offers the lowest possible number of potential leakage points with a reduced overall system size and weight, and the integrity of the Total HERMETIXTM package.
Completes our extensive Double Block and Bleed (DBB) valve range
This unique casted Double Block and Bleed valve offering completes our already-comprehensive offering of trunnion mounted ball valves, BAR-made valves, “wafer” style valves, special alloy, and custom-made valves – all of which are now available in DBB designs that answer the diverse range of industrial requirements for cryogenic, high-pressure, high-temperature, and other applications.