What is cavity relief in ball valve?
What is cavity relief in ball valve?
Cavity Relief of Floating Ball Valves When closing the valve, the media gets trapped in the cavity. The pressure relief hole must connect the valve body cavity to the high-pressure side of the ball when it’s closed per Shell MESC SPE 77/170 specifications. We use this design for Process to Instrument Valves.
What is body cavity in a valve?
1) Body cavity (pocket) inside the valve unit are completely filled with fluid (incompressible fluid) 2) Heated due to an increase in the external or fluid temperature.
What is SPE and DPE?
In API 6D we have two different types of valve seats called as Single Piston Effect (SPE) and Double Piston Effect (DPE) seats. Using these two kinds of valve seats, we can come up with two different functions from the ball valves commonly called Double Block and Bleed (DBB) and Double Isolation and Bleed (DIB).
What is the function of ball valve?
A ball valve is a flow control device which uses a hollow, perforated and pivoting ball to control liquid flowing through it. It is open when the ball’s hole is in line with the flow inlet and closed when it is pivoted 90-degrees by the valve handle, blocking the flow.
What is body cavity relief?
Body Cavity Relief (Pressure Equalisation) Ball valves are double seated valves which incorporate a cavity between the seats. The body cavity will get pressurized only when the seats are damaged. Cavity relief provision required only for trunnion mounted ball valves.
What is a vented ball valve?
Vented Ball Valves for Sodium Hypochlorite The vent is designed as a hole through the side of the ball. When turned to the closed position, the hole allows any liquid or gas in the ball to flow freely in and out of the ball.
What is a DIB 1 valve?
DIB-1 Explained DIB-1 ball valves have DPE seats both upstream and downstream to provide a seal in both directions. For the DIB-1 configuration, over pressurization of the cavity is avoided by the use of an external relief valve.
What is the difference between DIB and DBB?
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.
What are the advantages of a ball valve?
Compared to other types of valves, ball valves are simple and require less maintenance. Because the ball valve stem rotates without axial movement, the packing seal on the valve stem does not easily wear or fail. Ball valves are easy to disassemble and repair, and worn parts can be easily replaced.
Where is the ball valve?
It is attached directly to the operating handle of the valve, which is usually located above or to the side of the device, often on the outside of a pipe assembly. By rotating the handle, typically one-quarter turn through 90 degrees, the ball is physically turned on its axis within the port.
When would you use a vented ball valve?
Most typically, one finds a vented ball valve employed on services where thermal expansion of the subject medium represents a critical concern such as in cryogenic applications, refrigeration systems, or processes involving substances like liquid nitrogen or liquid oxygen.
Can a ball valve fail?
Common Ball Valve Failures One of the most common types of ball valve failures involves a buildup of dirt and sediment within the valve, making it difficult to open and close. The use of solvent cement glue can also clog up the ball, causing it to stick to the inside of the valve and resist turning.
What is SBB valve?
SBB Ball Valves (Single block &bleed) Single block & bleed valves are recommended for low pressure classes ensuring long-lasting seal. Floating type valves are more often required, however it is possible to supply the Trunnion version valve, too. Main applications in the petrochemical field: Cryogenic service.
When would you use a DBB valve?
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.
What are the disadvantages of a ball valve?
Disadvantages of ball valves They are not suitable for slurry type applications due to cavities around the ball and seats. Slurries or other thick liquids tend to solidify or clog inside of the cavities, greatly increasing the operating torque of the valve and in some cases rendering the valve inoperable.
Which of the following is a disadvantage of ball valve?
The main disadvantages of these valves are as follows: The position of the valve handle is rotated, Could not be used for throttling, and. These valves with drive mechanism should be installed upright.
What are the types of ball valves?
There are four general body styles of ball valves: single body, split body, top entry, and welded. There are four general types of ball valves: full port, standard port, reduced port, and v port.