Atteris performed an assessment of the periodic survey data for the Angostura flowlines and pipelines.
Atteris reassessed allowable span lengths for all flowlines and pipelines to level 2 – consideration of fatigue. Periodic survey data was reviewed, and some specific spans that were either interacting or unacceptable based on level 2 analysis were analysed to level 3 – full FEA analysis to determine natural frequencies and mode shapes. Based on the results of the span analysis and assessment of the survey results, the span rectification scope was defined specifying correction method, location of placement, required height, etc for each location. Rectification methods considered included, gravel bags, mattresses, and grout bag supports, with the method defined for each span dependant on soil conditions and span configuration. In some locations where survey data was inconclusive a number of options were proposed. Atteris supported the offshore execution of the span correction with additional input as required.
