- System design error
DEFINITION: system not properly designed for the operative boundary conditions and/or for the use of hydrogen. it covers inadequacies in desin risk assessment and in design of preventive and mitigating safety measures.
EXAMPLES: Inadequate mechanical integrity measures; corrosion-related loss of integrity; inadequate design of pressure relief valves, venting components; lack of attention to risk of hydrogen accumulation; Inappropriate material choices; unwanted hydrogen generation; Inadequate process hazards analysis; Inadequate operating procedures.
- Manufacturing error
DEFINITION: Although the correct component was selected and implemented, it didn’t work properly due to a manufacturing error.
NOTE: this cause term was made in HIAD 2.1 of two components: materials and manufacturing causes. With the creation of a set of descriptors related to the INITIATING CAUSE, which gives the possibility to account for material failures, this class is now limited to manufacturing errors.
EXAMPLES: badly executed welds, gaskets and seals not respecting the quality claimed.
- Installation & maintenance error
DEFINITION: although the correct component was designed, selected and implemented, it didn’t work properly due to improper installation or maintenance. It covers preventive and corrective maintenance (repair).
EXAMPLES: wrong consumables replacement after maintenance; components erroneously installed (one-way valves placed in the wrong direction; bolts with wrong dimension, not properly sitting in the flange).
- Individual factors
DEFINITION: factors related to the personal situation of the operator, leading to operator error.
EXAMPLES: inadequate skill and competence levels; individual medical problems; mistakes, etc.
- Job factors
DEFINITION: factors related to the quality of the working conditions, leading to mishaps.
EXAMPLES: lack of instructions (example, when purging), badly given or written instructions; over-arduous works, such as too high workload; too noisy and unpleasant working conditions; constant disturbances and interruptions, etc.
- Management factors
DEFINITION: factors related to the on-site organisation and management, leading to operator errors or material failures.
EXAMPLES: poor work planning; leading to high work pressure; lack of safety systems and barriers; failure to learn from previous incidents; inadequate management of changes, management too biased to one-way communications; lack of co-ordination and clear definition of responsibilities; poor management of health and safety; poor safety culture.
- Environment
DEFINITION: abnormal (i.e. unexpected, out-of-design) natural phenomena such lightning, earthquake, flooding or abnormally high or low temperatures, contributing od directly causing the incident
EXAMPLES: all type of Natech hazards or 'force majeure'.
NOTE: environment factors which are normally considered in design, such local typical wind forces, rainfalls and temperature excursion do not fall under this definition. For example, galvanic corrosion of underground pipe is part of the technical risk assessment and is considered in the design, therefore does not belong to this category.
- Unknown
To be selected when none of the other terms can be identified with certainty as root cause.
EXAMPLE: if several causes are plausible, but there is no elements to select one above the others.
