DBB Or DIB – Which Should Be Used When?

In recent years, a number of people have misused the term ‘double block and bleed’ when referring to DBB

or DIB. This has led to a number of misconceptions but these can be cleared if we take the definitions drafted by API and OSHA into account.

Definitions of DBB/DIB according to OSHA and API

Both of these entities have their own separate definitions for double block and bleed and double isolation and bleed. API believes that it refers to a single valve that comprises of two seating surfaces which are close to each other and which seal pressure from either valve ends. It also provides a means for bleeding the cavity that is located between the surfaces. API also states that the valve does not offer positive double isolation when only one side of the valve is pressurized.

OSHA on the other hand, believes that DBB refers to the closure of a line, pipe or a single duct which is made possible due to the locking or tagging or two in-line valves. It can also come about by locking, tagging or draining the line between two locked valves.

Some people are also of the opinion that double block and bleed is different from double isolation and bleed. The former offers double isolation blockades from pressure sources with a ‘bleed’ cavity.

Whether you are looking for DIB or DBB valves you can find what you are looking for at SEALEXCEL. The company has a range of valves that it offers at competitive pricing and for a range of industries.