NORSOK Z-008

The assignment of a criticality ranking (typically A, B, or C) to each equipment item based on the consequences of its failure across safety, environmental, production, and maintenance cost dimensions. Criticality classification determines the level of engineering attention, inspection rigor, maintenance strategy, and spare parts investment appropriate for each asset.

Maintenance performed at predetermined intervals or according to prescribed criteria to reduce the probability of failure or functional degradation. Preventive maintenance includes time-based activities (replacement, overhaul, calibration at fixed intervals), usage-based activities (at fixed operating hours or cycles), and condition-based activities (when monitored parameters indicate intervention is needed). The goal is to prevent failures that would otherwise occur.

The process of monitoring a parameter of condition in equipment (vibration, temperature, pressure, flow, oil quality, acoustic emission, electrical properties) to identify significant changes indicative of a developing failure. Condition monitoring is the technical enabler of predictive maintenance, detecting degradation at the P point on the P-F curve to allow planned intervention before functional failure.

A methodology that uses risk assessment to prioritize and plan inspection activities for pressurized and other equipment. RBI combines Probability of Failure (driven by damage mechanisms and equipment condition) with Consequence of Failure (driven by process hazards and safety impact) to rank equipment by risk and allocate inspection resources where they will have the greatest impact on risk reduction.