Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby ICRARD Stavanger September 12, Walter Bobby

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby Canada  Additional information on the website ICRARD

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby  Safety  Environmental Criteria Issues Discussion

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby HELP! Issues

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby  SIL used Application of IEC and IEC IEC – Part 6 Reliability of a SIL loop is a function of the components reliability and test period of the components component failure rates are constant over the life of the system Reliabilities of valves normally dormant (shut down valves, blow down valves) are dependent on test frequency of the valve. Therefore, their failure rates are not constant Issues Safety

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby  SIL used (Contd.) Is there a need to review the application of IEC and IEC for valves normally dormant (shut down valves, blow down valves)? The reliability of such valves are dependent on the frequency of testing. How should IEC and IEC be applied for components whose failure rates are dependent on testing frequency? Issues Safety (Contd.)

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby  A QRA is done to verify that the target level of safety is achieved. API RP 14C defines the emergency shut down valve as part of a primary system Should the reliability (frequency of failure) of the emergency shut down valve be verified on an ongoing basis? How does the frequency of failure of the emergency shut down valve influence the QRA? Issues Safety (Contd.)

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby  Target reliability for subsea systems Failure of subsea systems affects safety For people marginally For the environment significantly Repair of subsea systems may affect safety For people significantly For the environment marginally  Should the target reliability for subsea systems be the same as for a manned installation? Issues Safety (Contd.)

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby  Concept of safety envelope Risks associated with repair is normally not included in QRA Sometimes the risk associated with repair is comparable or more than during normal operation Repairs increase project duration and hence the duration of exposure to risk Issues Safety (Contd.)

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby  Concept of safety envelope (Contd.) For some hazards such as noise and thermal radiation, acceptable levels are a function of time of exposure to the hazard, e.g., less than 1 hour for level of sound of 105 dB Should criteria be established for the integral of risk and time of exposure? Issues Safety (contd.)

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby  Accelerated fatigue noticed on the Grand Banks  Semi-submersibles are designed for 100 year environmental criteria A lesser return period for beam seas is used if it produces higher stresses  Grand Banks experiences cross seas Issues Environmental Criteria

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby  Should additional load combinations be included in design for cross seas? Issues Environmental Criteria (Contd.)

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby  Rare environmental events. CSA S471 states Specified loads based on frequent environmental processes shall have an annual probability of exceedance, PE, not greater than 10-2 Note: For practical reasons, a probability of exceedance, PE, of 10-2 per annum is generally used to choose a process of defined magnitude rather than, as would ideally be the case, to choose a load resulting from processes of different magnitudes that occur with different probabilities. specified loads based on rare environmental events shall have an annual probability of exceedance, PE, within the range of 10-4 to 10-3 Issues Environmental Criteria (Contd.)

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby  Iceberg considered both as frequent environmental processes and as rare environmental process Iceberg loads generated based on probability distribution of shape, mass, velocity, eccentricity etc. 500 year and one in values were determined Issues Environmental Criteria (Contd.)

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby  It is possible for an iceberg to be in the vicinity of the installation that could cause loads in excess of the 500 year load value How can this be captured in the design criteria? Issues Environmental Criteria (Contd.)

Canada-Newfoundland and Labrador Offshore Petroleum Board Presenter : Walter Bobby Thank You