What is Double Block & Bleed Valves
The greater activity in the offshore area of the power industry has led to further factors that have to be taken into thought when designing piping systems. Space in these new places is forever at a best and the design of piping structures and their linked parts must therefore be compact. There are structural restrictions that are also very vital, such as keeping the structure as light as easy. And there are obvious advantages from making parts lighter and smaller. Construction site job is also extremely costly and any drop in installation manpower is also valuable.
The above isolation has led to the alteration of the patterns of the control device parts to incorporate savings in weight, space, and labor costs where easy, while still retaining the real work of the valve. The biggest savings are to be seen in the decrease of leak to environment because the possible leak points are decreased matched to the old design. Process separation philosophy has become more hard as safety problems have to be deal with and the need for DBB isolation has become more generally used. Double block and bleed isolation needs two in line isolation control devices and bleed control device, used to vent or drain trapped liquid between the 2 closure components.
Double block and bleed control devices change existing traditional methods employed by pipeline engineers to produce a double block and bleed pattern in the pipeline. Conventionally, in order to get a DBB system, engineers would install 2 standard isolation control devices and a separate facility for bleeding the cavity in between.
Area is generally at a premium in the refinery atmosphere, and this approach needing a further control device unit to be installed as well as T-injection to permit the cavity to be bled more than doubles the area needed matched with a single control device system. This rise in size can generally make the installation unfeasible, mainly where multiple control devices along the line are to be upgraded.
Double block and bleed main works
Tool double block and bleed for chemical sampling & injection
Double block and bleed control devices for chemical sampling & injection need a further instant tubing onto the bore of the control device inlet projection face. This quill go into the procedure flow and chemicals can be introduced via the valve.
Incorporated in the control device design a further check valve is needed for this application in order to stop reverse flow and procedure fluid infecting the chemical source. For sampling the reverse is applied.
Tool double block and bleed for force connections.
DBB valves for force connections are commonly used to isolate instrumentation such as force indicators and lever gauges.
In-line DBB for process isolation
Double block and bleed valves for isolation process are placed in the initial process stream.
There are a couple different styles of DBB valves. One style, like this one from J-Flow controls, has 2 freely seating valves inside, with a drain or bleed valve. This pattern is known as a DIB or double isolation and bleed.