Double block and bleed main functions
The increased activity in the offshore part of the power industry has led to further factors that have to be taken into consideration when designing piping structures. Space in these new places is forever at a premium and the design of the piping structures and their linked parts must so be more compact. There are structural restraints that are also extremely vital, such as keeping the structure as light as easy, and there are obvious advantages from making parts little and lighter. Construction site job is also extremely costly and any drop in installation manpower is also valuable.
The above condition has cause to the modification of the patterns of control device parts to incorporate savings in weight, space, and labor costs where easy, while still retaining the real work of the control device. The biggest savings are to be seen in reduction of leak to environment because the possible leak dots are decreased matched to the straight design.
Process philosophy isolation has become more hard as safety problems have to be addressed and the need for double block and bleed isolation has become more generally used. DBB isolation needs two-in isolation control devices and a bleed valves, used to vent or drain trapped fluid between the 2 closure elements, this post.
DBB valves change existing traditional methods employed by pipeline engineers to produce a double block and bleed configuration in the pipeline. Conventionally, in order to get a double block and bleed system, experts would install 2 standard isolation control devices and a separate facility for bleeding the cavity in between.
Space is generally at a premium in the refinery atmosphere, and this approach needing a further valve unit to be installed as well as T-junction to permit the cavity to be bled more than doubles the area needed matched with a one valve system. This rises in size can generally make the installation unfeasible, mainly where multiple control devices along the line are to be upgraded.
Double block and bleed big functions
Tool DBB for chemical addition and sampling DBB control devices for chemical injection and sampling need a further instant tubing onto the tire of the control device inlet flange face. This quiet enters onto the process flow and chemicals can be introduced via the control device. Incorporated in the control device design a further check valve is needed for this application in order to stop reverse flow and process fluid contaminating the chemical.
Instrument DBB for force links double block and bleed control devices for force links are commonly used for isolate instrumentation such as force indicators and lever gauges. In-line DBB for process isolation DBB control devices for process isolation are placed in the initial process stream.
Valves at the end of each flowmeter assembly should be the DBB design to give for maintenance and inspection activities. The DBB valves should have 2 independent seals, either of which fully blocks the flow. The double block and bleed valve design is full port, trunnion mounted, ball control devices that give double block and bleed of the control device body without the use of the sealant.