API Bull 2TD:2006 pdf download

API Bull 2TD:2006 pdf download.Guidelines for Tie-downs on Offshore Production Facilities for Hurricane Season.
– Verify that equipment is fail safe (tie-down force will he maintained in the event of equipment failure).
• For welded tie-downs:
– Verify that plans. weld size, welding procedures. and inspection procedures are adequate.
• Verify that welded components of tie-downs have been properly inspected.
• Determine if there is a preferred well position for stowing the rig. If so, verify that this is clearly defined in the platform hurricane evacuation procedures.
• Verify that proper tie-down procedures are part of the Platform evacuation procedures and that proper tie-down is verified in i,rriting by the Offshore Installation Manager (OIM) or his designate prior to evacuation.
• Verify that other procedures such as setting down of all drill pipe. handling of setback load, emptying of tanks, etc. are clearly defined in the evacuation procedures and have been considered in engineering of the tie-down procedures.
• Verify that all required tie-down tools, equipment. and labr including all required spares will be available as required prior to evacuation. Any new components should be prefabricated for quickness and ease of connection.
• Verify that hurricane evacuation procedures allow time for proper tie-down prior to evacuation.
• Where feasible, an engineered, welded stop should be installed at the end of skid beams to prevent skid packages from skidding of I the end of the beams. Welds should be of structural quality and properly inspected. Stops should be sized to withstand shear associated with wind and platform tilt (on floating structures) in combination with a lower bound friction assumption.
• Verify that all rig packages are properly tied down based on risk appropriate environmental and dynamic loads.
• After each hurricane evacuation, the tie-downs should be visually inspected prior to returning the rig to normal service. Any damage found should be evaluated to determine if any design or procedural modifications are required. Inspection results should be documented. Damage that is repeatedly discovered indicates a need for design and/or procedure change, and should result in more frequent inspections until such inspections indicate that the cause(s) of the fault(s) has been resolved.
The above recommendations are considered the minimum required, and any additional inspections or modifications required to prevent movement or failure of’ rig package tie-downs during design storm conditions should be completed as soon as possible.
1.4 INTERMEDIATE-TERM RECOMMENDATIONS
The following items should be considered for implementation by the platform operator andlor rig owner in the intermediate-term time frame:
• Review design calculations of all tie-downs with updated site-specific environmental and dynamic loads and document results. Analysis and results should be approved by an engineer experienced and qualified in offshore structures. Clamps should be assessed for all appropriate well positions. Special care should be given to calculations that show either no predicted uplift or only a small uplift when compared to the gravity reaction. In such cases, there niay effectively he no reserve against slightly higher wind forces.
• Review fabrication and material records to assure that all tie-down systems are properly documented. Consider replacement of tic-downs if proper documentation is not available. Otherwise. make an assessment based on conservative assumptions of material and weld properties.
• Review derrick or mast and substructure design based on site-specific environmental and dynamic loads and document results. Analysis and results should be approved by an engineer experienced and qualified in this area.
2 Permanent Equipment and Facilities
2.1 BACKGROUND
Permanent equipment. quarters, and helidecks also suffered severe damage due to tie-down failure during the recent Gulf of Mexico hurricanes. This resulted in a significant amount of damage as well as lost and/or deferred production. Recent experience shows that enhancements to current industry practice can improve tie-down performance during hurricanes.
2.2 PHILOSOPHY/DESIGN CONDITIONS
Tie-downs of permanent equipment and facilities to the platform are critical structural components and should have the same, or higher, level of design, quality assurance, maintenance, and documentation as other critical structural components.