Discussion on DBB and DIB valves
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Dear sea friends, I would like to ask: do the DBB and DIB types of valves specified in API 6D apply only to ball valves? Or can all valves have this function?
DBB, Double Block & Bleed Valve – there are posts discussing it in the forum; DIB, I haven’t seen it.
In API6D version 22 from 2002, only the definition of DBB is provided, with no definition for DIB. DBB is the abbreviation for Double block and bleed, which means double shutdown and drainage. Version 23 of API6D in 2008 included definitions for both DBB and DIB. DIB is an abbreviation for Double isolation and bleed, which means double isolation and discharge. DBB and DIB are two types of seat configurations for valves, both featuring a dual-seat structure. Each seat in a DBB can resist forces in one direction; such seats are known as single-piston effect seats (self-venting seats) and can be used to drain the internal chamber. Each valve seat of DIB-1 can resist forces in two directions; it is known as a dual-piston effect valve seat, and this design requires a mechanism for releasing pressure from the intermediate chamber. DIB-2 features a DBB valve seat at the inlet side and a DIB valve seat at the other side; it is also known as a single or dual-piston effect valve seat. This design allows the pressure in the middle chamber to be released automatically through the valve seat at the inlet side.
Yeah, it’s very informative and detailed, but I wonder if DBB and DIB apply only to ball valves?
Ball valves are generally used for shut-off valves, while ball valves or needle valves are used for drain valves
It’s not specific to ball valves; anything that meets the requirements can do it, and gate valves are also capable of achieving this.
I also wondered why the standards didn’t mention it applying only to ball valves; I see, thank you so much