Captive key interlocks are one of the most powerful, yet underutilized, safeguards in the process industries. Captive key systems function by preventing a physical action, such as opening a valve, unless an engineered key has been inserted into the valve’s topworks. Once the valve is moved, the key cannot be removed until the valve has been completely cycled. This physical interlocking enforces a specific sequence of operations and prevents valve misalignment, improper opening, and other potentially catastrophic operational errors. These interlocks are simple and effective. Essentially, they can only fail if they are installed incorrectly or physically tampered with, making their PFD dramatically lower than other active safeguarding measures.
This webinar will begin with a description and explanation of operation using a typical application by Ginny Vance of Sofis. Subsequently, Ed Marszal of Kenexis will demonstrate how to account for the use of captive key interlocks in LOPA by presenting a LOPA scenario for the typical oil and gas application of Pig Launcher valve sequencing.