The following tasks should be performed for the structure removal:
- Preliminary assessment of make-safe preparation work
- Design and sizing of temporary work platforms required for flushing of risers and removal of structures
- Platform (risers, deck, jacket and piles) lift weight estimation / verification
- Development of the lift configuration and lift rigging design
- Design of grillage beam supports and other supporting structures for platform back loading and transportation
- Design of tie-down braces
- Development of off-loading procedure at an onshore facility
Furthermore, A SACS model should be developed for the platform to be removed. The strength of the platform framing and joints and the new rigging members and supports should be verified by running lift, back loading, and transportation analyses using SACS models. Joint can punching shear check should be performed based on API RP 2A guidelines for all the existing and the new tubular connections.
Members that are corroded and or damaged to the extent non-useable for structural strength should not be included in the structural analyses unless it is shown absence of this member will result in overstressing many other members and joints. Such member then should be strengthened to its full capacity by cleaning, welding plates, clamps etc. to fit the situation.
The constructability issues related to lifting and back loading of the salvaged structures and miscellaneous components should be considered in the design.
Measures to mitigate the potential hazard of dropped objects should be considered in the design and analysis.