Using valve locking devices: a review and lessons learned

摘要

This article reviews the use of valve locking devices, assessing visual locks, car seals, padlocks, single locks and interlocks. Several case histories with projects using interlocks are discussed with lessons learned being presented. Most offshore facilities have pressure safety valves, and efficient operation of the valves is critical for safe operation of the facility. The purpose of using locks on the valves is to secure their correct positions in order to ensure safe operation of the system and eliminate human error. An operator can make sure that the valve does not open mistakenly when it should be closed. There are various types of valve locking devices with different security levels such as visual seal, car seal or wire lock, padlock or chain lock, single lock, and interlock. The security level of locks increases from visual lock to interlock. Locking device selection should be done based on process and safety evaluations, and the result should be indicated on the valves in piping and instrument diagrams (P&IDs). The usage of the locks is not limited to the valves as the electrical actuators may be supplied with locking devices.