A presentation 19.4 in the MainTech Conference 2017, focused among other aspects, on the importance of maintenance backlog for major accident risk. Two messages were presented:

• For offshore installations, HC leaks are mainly due to failures occurring during manual intervention on normally pressurized systems, degradation accounts for about 25% of the leaks, and reduced maintenance is not a significant factor.
• For onshore petroleum facilities, the contribution from degradation is significantly higher contribution (some uncertainty, because the data basis is much smaller).

As an example for onshore petroleum plants, consider the gas leak on Mongstad 25.10.2016, where the Statoil investigation report confirms that corrosion protection preventive program was lagging far behind the plan.

For the offshore facilities the point was made that indirect effects on work practices due to change of framework conditions are likely to be more dominating, compared to effects of reduced maintenance. The data basis in this case comes from comparison with helicopter pilots, for offshore and onshore transportation. The point was made:

• It is naive not to consider that significant changes of framework conditions are expected to have significant influence on safe working practices offshore.

The presentation is due to appear soon from the conference site.