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 remotely. In fact, some operations such as pig launching or receiving can be effected in semi-automatic mode using push button controls (i.e. from a remote station).
Maintenance procedures, however, invariably involve human intervention and can interrupt automated processes creating ‘abnormal’ working conditions. 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 may fall subject to operator error. Distributed Control Systems, (DCS) cannot effectively regulate such (maintenance) procedures. The SFC ‘Coded Card Key Interlock System’ can!