For ship-type floating production installations such as FPSOs, topside modules installed on deck of an installation may include but are not limited to oil/gas processing modules, gas compression modules, power generation modules, flare tower, vent stack, helideck, pipe rack, and laydown areas. Newer generations of topside structures are large in size and heavy in weight. They are important parts of the installation structures that are critical to the operation and structural integrity of ship-type installations. Thus there may be a need to perform the fatigue assessment in addition to strength evaluation of the topside structures.

As a supplement to the fatigue assessment of the topside interfaces on ship-type installations, these Guidance Notes provide the recommended procedures for performing fatigue assessment of the topside structures on ship-type installations. 

The topside structure fatigue assessment involves the evaluation of the following areas:

  • Environment wave conditions
  • Metocean data, sea state scatter diagram
  • Design load conditions
  • Finite element model local boundary conditions
  • Structural geometry
  • Structural stress range and stress concentration factor
  • Fatigue analysis methodology
  • Accumulated fatigue damage, fatigue acceptance criteria and design fatigue life

The primary features of these Guidance Notes include:

  • Design principle of hull interface structure and topside structures
  • Design loads for fatigue strength assessment
  • Loading conditions for topside structure fatigue analysis
  • Accumulated fatigue damage prediction
  • Fatigue acceptance criteria for topside structures

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ABS-fatigue-assessment

Source: ABS