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API Bull 2TD-2006 pdf free download

API Bull 2TD-2006 pdf free download.Guidelines for Tie-downs on Offshore Production Facilities for Hurricane Season.
1 Drilling and Workover Drilling Units 1.1 BACKGROUND The oil and gas industry has experienced rig failures and movement of rig components during recent hurricanes in the Gulf of Mexico. Some, if not all, of the failures are attributable to the tie-down components. Occurrences on both fixed and floating plat- forms have resulted in significant platform 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. 1.2 PHILOSOPHY 1.2.1 Applicability This document addresses situations where failure of a drilling or workover rig would result in significant damage to the platform or adjacent infrastructure. Generally, this would include any facility designated as having a high or medium consequence of fail- ure as defined by API RP2A. In other situations, a risk-based operational decision process should be followed. Situations that might allow deviation from the recommendations below include drilling operations in the non-hurricane season or the use of light-weight workover masts on shallow water platforms. 1.2.2 Design Conditions Drilling rig tie-downs to the platform and between drilling components are critical structural components and should have the same, or higher, level of design, material traceability, quality assurance, maintenance, and documentation as other critical struc- tural components. Primary rig and substructure tie-downs should be designed or assessed for location-specific loading conditions (environmental and dynamic) consistent with those utilized in the facility structural design and should be approved by an engineer experienced and qualified in offshore structural engineering.
1.3 SHORT-TERM RECOMMENDATIONS The following items should be considered for implementation as appropriate by the platform operator and/or rig owner in the short-term timeframe: • Visually inspect all tie-downs to confirm that they are in good condition and are constructed per the design drawings. • Verify that all tie-downs can be properly installed and that no obstructions exist that might prevent installation (e.g. stiffen- ers on plate girders). • For bolted tie-downs: – Verify by visual inspection that the bolts are in good physical condition. – Verify that bolts meet the required material specifications and the specifications are suitable for this application. Note: ASTM 325 or 490 high strength bolts are not recommended, since retorquing of these bolts is not permitted per AISC specifica- tions. – Verify that the number of bolt torquing cycles does not exceed the design allowable. – Verify required bolt torque is defined and required equipment/tools are available to achieve the required torque. – New bolts should be installed if the above items cannot be verified. • For mechanical/hydraulic tie-downs: – Verify that the tie-down system is in good working condition. – Verify that operating personnel are familiar with the operating procedures of the equipment.
• 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 hur- ricane evacuation procedures. • Verify that proper tie-down procedures are part of the platform evacuation procedures and that proper tie-down is verified in writing 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 labor 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 skid- ding off the end of the beams. Welds should be of structural quality and properly inspected. Stops should be sized to with- stand 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.

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