What is double block and bleed valve?
Double block and bleed (DBB) is the practice of shutting in a section of pipe on both sides of the valve rather than just one. It means you close the ball valves to block both the upstream and downstream sides of your working area, and then bleed any pressure that remains in the piping and valve.
What type of valve is a general twin seal?
The Twin Seal valve is a non-lubricated, resilient seal, plug- type valve which has a mechanical means of freeing the plug before it is rotated from the closed to the open position.
What is a general valve?
General Valve is the original manufacturer of the General Twin Seal valve and is the leading provider of double block and bleed valves for the petroleum industry. Products & Technology.
What is the purpose of a block and bleed valve?
The purpose of the block and bleed manifold is to isolate or block the flow of fluid in the system so the fluid from upstream of the manifold does not reach other components of the system that are downstream. Then they bleed off or vent the remaining fluid from the system on the downstream side of the manifold.
Where are double block and bleed valves used?
Double block and bleed valves are most commonly used in the oil and gas industry, but can also be helpful in many other industries. It’s typically used where bleeding the valve cavity is required, where piping needs isolation for maintenance, or for any of these other scenarios: Prevent product contamination.
Is double block and bleed positive isolation?
A double block and bleed is often used for a more positive isolation of a process fluid from other equipment. It normally consists of two block valves (Valves 1 and 2 in the pictures) and a bleed valve (Valve 3) to a safe location, consistent with local environmental regulations.
What is API 6D?
The API 6D is the specification for Pipeline Valves. It is the primary standard based on the ISO 14313 that specifies the requirements of valves and offers suggestions for the design, manufacture, inspecting, and notation of check, ball, plug, and gate valves in pipework systems.
What is the purpose of a bleed valve?
A double block and bleed system is widely used in the process industries. It uses two closed block valves with a bleed valve between them. The bleed valve can be used to check for leakage through the root isolation valve and/or to route leakage to a safe containment system.
Is double block and bleed required?
Double Block & Bleed shall be typically applied when work on high pressure steam, high temperature hot water, highly injurious gas or chemical piping, or medium voltage (over 600V) systems, or equipment that requires a direct or indirect exposure of the employee to any part of these systems or equipment that normally …
Why use a double block and bleed system to isolate a vessel vs just one isolation valve?
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.
Which is twin seal double block and bleed plug valve?
ThE PRoVAbLE ZERo-LEAkAGE DoUbLE bLoCk-AND-bLEED PLUG VALVE wiTh RETRACTiNG SEALS Contamination is avoided in multi-product manifolds.
How does a general valve twin seal valve work?
The double block-and-bleed (DBB) Cameron GENERAL VALVE Twin Seal plug valve reduces this constant wear by using two seating slips mounted independently on a tapered plug by dovetails, which mechanically retract from the seating surface prior to rotating. This provides a bubble-tight verifiable dual seal without seal abrasion.
Why do you need a general twin seal plug?
GENERAL VALVE Twin Seal plug valves for helping avoid contamination in multiproduct manifolds. In meter block service, the differential pressure across each closed valve is very low� No assistance is required from the line pressure to energize or compress floating seals to make them hold tight� The seals typically rely on
How is a bleed valve used in a seal system?
The body (serving as a spool piece) bleed verifies seal integrity. The double block-and-bleed system (as shown above) required the use of two valves and a spool piece. A bleed valve was used to drain the spool and verify seal integrity.