Safety interlocking devices -1,600 of them to be exact - have been installed at the Shell Eastern Petroleum (Pte) Ltd. ethylene cracker complex in Pular Ular, Singapore. The main applications for the interlocks from Netherlocks B.V. are for the decoking process and for isolation valves for pressure safety valves.
Netherlocks, based in Alphen aan den Rijn, The Netherlands, manufactures interlocks that use a linear key transfer system so that processes only can be carried out in the correct order, ensuring that each task has been completed safely before the next can be started.
Safely completing the previous step in the process sequence releases a unique key that then unlocks the next step. Only when a mistake is made will the operator be prevented from proceeding by a key that does not fit or by a valve locked in position. This simple principle can be propagated to more complex procedures, but in every case, it physically ensures that safety protocols and work orders are followed exactly, leaving no room for human error.