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Audit of fatigue analyses and inspection planning - Petrojarl 1

The Petroleum Safety Authority Norway (PSA) has carried out an audit of Teekay Petrojarl Production AS (Teekay) related to fatigue analyses and analyses of reliability-based inspection planning of supporting structures and maritime systems on the Petrojarl 1 facility.

The audit was carried out on 4 June as well as 27 and 28 September 2010 at the premises of Det Norske Veritas AS (DnV) at Høvik.

The background for the audit is that the Petroleum Safety Authority stipulated as a condition for issuing the Acknowledgement of Compliance for Petrojarl 1 that new, updated fatigue analyses must be prepared for the facility. The condition was set with a basis in the fact that, over the years, several cracks have formed in the hull. The condition read:
”If Petrojarl 1 is to undergo classification inspection at sea, the facility must be documented in accordance with DnV-OS-C102 Appendix A. The fatigue analyses must be in accordance with DnV-OS-C101 Section 6 A205 Table A1 and DnV-RP-C203.”

The PSA has followed up the work on the new analyses through status meetings, and has now carried out an audit to achieve a more detailed review of the analyses. This was done by asking questions regarding how the analyses were carried out and by making a few spot checks of the analyses.

The purpose of the audit was to ensure that the documentation of the fatigue analyses was in accordance with the condition and the regulations for this type of analyses. The PSA carried out spot checks of documentation related to analyses of loads, load impacts, fatigue capacity and the use of reliability methods.

The performed analyses are comprehensive and complicated. In such analyses, a significant amount must be done correctly or in a conservative manner. The PSA's impression was that the number of faults was minor. Neither did we identify any breaches of the condition or of regulatory provisions.

Still, the PSA has a few suggestions for improvement items related to the use of checklists, tolerance requirements during construction and as a basis for the analyses, wave loads on the bilge keel and turret, analyses of risk-based inspections and control of the use of software versions.

Improvement items
The audit identified improvement items in the following areas:

  • Checklists
  • Tolerance requirements during construction and as a basis for the analyses
  • Wave loads on the bilge keel and turret
  • Analyses of risk-based inspection (RBI)
  • Control of the use of software versions