Netherlock Safety System Closure LockNetherlocks’ Safety Systems Closure Locks are designed to ensure that correct valve operation procedures are followed when pigging operations take place. Closure locks are designed to protect against improper operation of a pigging system’s closure door, which often includes opening the closure door while pressure still remains inside the vessel, opening the main process valve while the closure door is not fully closed, and opening the closure door while a high concentration level of toxins still remains inside the vessel. The closure locks are operated using a series of keys that lock into place, and can’t be removed out of sequence. This is designed to guarantee correct valve operation procedure. – www.netherlocks.com