What Are The Differences in Design between DBB Ball Valves And DIB Ball Valves?

DBB (Double Block and Bleed) ball valves and DIB (Double Isolation and Bleed) ball valves are two common types of industrial ball valves. They have significant differences in sealing principles, seat structures, and pressure relief mechanisms.

In terms of sealing principle, the DBB ball valve realizes sealing by relying on a single piston effect (SPE) seat. The medium pressure pushes the seat towards the ball. At the same time, it has an automatic pressure relief function and can release excess pressure to the downstream or upstream pipeline. While the DIB ball valve adopts a double piston effect (DPE) seat, which can independently isolate the medium pressure on both sides. Even if one seat fails, the other can still maintain sealing, with higher safety. 

In terms of seat structure, the seat design of the DBB ball valve is relatively simple and has a lower cost, but its sealing performance is weaker. The seat structure of the DIB ball valve is complex and is divided into two types: DIB-1 and DIB-2. The DIB-1 type has two seats both designed with DPE. The DIB-2 type combines SPE and DPE seats, taking into account automatic pressure relief and high safety.