Page 28: of Offshore Engineer Magazine (Nov/Dec 2014)

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ASSET INTEGRITY MANAGEMENT but the practicalities of large-scale renewal but the practicalities of large-scale renewal of structural steel while the FPSO was on of structural steel while the FPSO was on station created major restrictions for the station created major restrictions for the repairs. Gaugings taken during the survey repairs. Gaugings taken during the survey were suf? cient to develop a good picture of were suf? cient to develop a good picture of the extent and location of corrosion. the extent and location of corrosion.

As part of the team’s evaluation, the girder was divided into zones across its girder was divided into zones across its width, and a thickness was assigned to width, and a thickness was assigned to each zone. New section properties were each zone. New section properties were calculated, and as a result, the team deter-calculated, and as a result, the team deter- mined that the section properties could mined that the section properties could be augmented by additional stiffening as be augmented by additional stiffening as an alternative to the conventional cutout-an alternative to the conventional cutout-

ABS Group’s life extension program work ? ow illustrates how life extension risks are and-renew approach. The dimensions of managed. A systematic approach to data evaluation, survey, and analysis is adopted the repair steel were selected to allow the leading to the development of mitigation plans and facility upgrades.

pieces to pass through the tank hatch and to

Putting the process to work be moved into place without the use of power equipment – only

The focus of a life extension study is to demonstrate that chain falls were required.

careful reevaluation of the design and informed assessments These few examples illustrate how in-depth understanding of of expected future damage, including fatigue and corrosion, structures and novel approaches can be applied to asset service contribute to successful life extension. life.

In many cases the studies are carried out at the end of the

Experience leads to solutions original design life, but this is not always the case. One study

While design life is not an exact calculation and involves performed by ABS Group evaluated a deepwater non-ship- uncertainties, assumptions, and conservatism, software tools shaped ? oating production installation that had been in service are becoming more sophisticated, and engineers can bet- for less than half its design life. A routine periodic inspection of ter model a structure’s behavior to determine recommended the ballast and void tank structure revealed conditions ranging actions. from coating breakdown and blistering to total coating failure

Owners that want to extend the operational life of offshore and associated corrosion. With life extension in mind, the asset assets have access to a number of creative mitigation solutions owner addressed these issues by cleaning and eliminating cor- that can be carried out by experienced teams with the knowl- rosion sources, such as water ingress and humidity and correct edge to rehabilitate aging offshore units. The bene? ts of these treatment of ballast water. programs are substantial and can minimize the loss of produc-

Another example shows how careful and comprehensive tion that would normally result from removing the critical measurement, combined with the knowledge of structural infrastructure from the ? eld for a prolonged repair program.