Oil and gas

NorMoor JIP – on safe mooring-line design

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Siril Okkenhaug

Siril Okkenhaug

Principal Engineer

Speak with our expert and download report for NorMoor JIP - phase 2

Register your interest Download Summary report

Challenge

There is a need to establish a consistent design analysis procedure for time-domain mooring calculations. Why?

  • Mooring standards are interpreted and applied in different ways.
  • The inherent reliability implied by the safety format is not known.

Solution

Analysis methodology and calibrated safety factors for mooring lines in ULS (intact), ALS (damaged) and FLS (fatigue) as a function of the target probability of failure. Calibration based on time-domain analyses for a range of environments and mooring systems: Haltenbanken, GOM and Brazilian environments

  • Small and large MODUs, turret and spread moored FPSOs and large production semis
  • Chain and wire systems and polyester systems
  • Water depths: 150, 350 and 1,500 m

Benefits

We have shown that the results and deliveries from Phases 1 and 2 (ULS and ALS) can give the industry more cost-effective mooring systems without jeopardizing the safety level:

  • The reliability levels implicit in existing standards are documented
  • Today’s safety factors can be reduced for time-domain analyses
  • Safety factors and analysis methodology are interlinked - detailed guidance will be given for both the time domain and frequency domain

For FLS: We believe there is a further potential for cost optimization by improving the FLS code check through Phase 3.

Contact us:

Siril Okkenhaug

Siril Okkenhaug

Principal Engineer

Speak with our expert and download report for NorMoor JIP - phase 2

Register your interest Download Summary report

Summary and recommendations from phase I and II, ULS and ALS

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Download reports for the NorMoor JIP - phase I

Summary and recommendations for the ultimate limit state

ULS reliability for a polyester moored semi-submersible in Gulf of Mexico hurricanes

ULS reliability of mooring lines for a semi-submersible in Gulf of Mexico Hurricanes

ULS reliability for a polyester moored semi-submersible at Haltenbanken

Test data and a probabilistic model for polyester rope strength

Reliability analysis of the ULS for conventional mooring systems at Haltenbanken

Metocean model for hurricane conditions in the Gulf of Mexico

Metocean model for Haltenbanken

Initial design of mooring systems at Haltenbanken

Distributions of mooring line tensions from Haltenbanken NorMoor

Download reports for the NorMoor JIP - phase II

ALS - Damaged Condition with one Line Failure - Reliability of Mooring Lines in the Gulf of Mexico

Summary and Recommendations from Phase I and II, ULS and ALS

Mooring line tension and reliability analysis in ULS and ALS for Brazilian waters

Metocean storm model for offshore Brazil

Metocean directional joint distribution model with windsea and swell for offshore Brazil

Empirical Frequency of Mooring Line Failures

Design of test cases for Brazilian waters

Calibration of Safety Factors for Frequency Domain Analyses

ALS pilot reliability study

ALS – One Line Failure -Calibration of Safety Factors for Moorings at Haltenbanken

ALS – Distribution of mooring line tensions from Haltenbanken