As a general principle it may be said that operations which are safe when performed correctly can have catastrophic consequences when performed incorrectly. The Oil & Gas and Chemical processing industries generally have a disciplined approach to design and operating practice - usually governed by well recognised international standards and enforced by regulatory authorities and certification bodies. While good practice begins with good design - both are ultimately hostage to the 'Human Factor'.
Modern process plants are highly automated and regulated by distributed software management systems which are simply monitored by 'Production' personnel - often remote from the physical location of the plant itself. Indeed, some operations such as pig launching or receiving procedures can
be effected in semi-automatic mode using push button controls (again often from a remote station).
Maintenance procedures however invariably involve human intervention and interrupt automated processes creating 'abnormal' conditions for the duration of the work. Loading or unloading of pig traps, changeover of pressure relief valves, turbine servicing (requiring suspension of CO2 Fire Deluge), coupling or uncoupling of hoses for loading or discharge of tanker cargoes all involve human intervention and are hostage to the possibility of operator error. Distributed control systems (DCS) cannot effectively regulate such (maintenance) procedures - the SFC ‘Coded Card Key Interlock System' can!
The obligation to adopt best practice is a fundamental of safety management - mechanical key safety interlocking is a technology that has evolved to offer sophisticated technical solutions to complex and hazardous process applications and which increasingly is being adopted by major OpCo's worldwide for protection of their people, their assets and their surrounding environment' SFC 'Visual Alert' Key Cabinets provide an effective and infallible management control system against unauthorised or inadvertent operation of interlocked valves or associated process equipment by keeping the coded keys which initiate the operation of critical valves under secure supervisory control.