The term “double block-and-bleed (DBB)” carries a lot of misconception when it’s used to describe valve functionality. Every valve buyer and manufacturer seems to have a different idea of what the term means for valve selection, which can result in misguided specifications or the wrong choice of valve type. In the oil and gas industry, some of this confusion stems from the fact there are two credible sources that define the term differently. Another point of confusion comes because many people using the term double block-and-bleed really want a valve with double isolation-and-bleed (DIB) capabilities. However, the differences in definitions and terminologies involved are important when it comes to determining which valve capability is needed for what type of system.