CAPITULO V CONCLUSIONES Y RECOMENDACIONES
Ecuación 19 Diámetro del tanque
13.3.1 General
13.3.1.1 The provisions of this subsection apply to wind turbines, support structures and cables for which periodical inspections are chosen as the approach to in-service inspection.
13.3.1.2 The manufacturer's service manual for the wind turbines shall be consulted for its specification of requirements for inspections of the wind turbines and their support structures.
13.3.2 Interval between inspections of wind turbines
The interval between inspections above water should not exceed one year. Requirements in the wind turbine service manual shall be followed.
13.3.3 Scope for inspection of wind turbines
13.3.3.1 The following items shall be covered by the inspection: — blades
— gear boxes — lifting appliances — fatigue cracks
— dents and deformation(s) — bolt pre-tension
— status on outstanding issues from previous periodical inspections of wind turbines.
13.3.3.2 Inspections as required in the wind turbine service manual come in addition to the inspection implied by [13.3.3.1].
13.3.4 Interval between inspections of structural systems above water
The interval between inspections above water should not exceed one year. Requirements in the wind turbine service manual shall be followed.
13.3.5 Scope for inspection of structural systems above water
13.3.5.1 The following items shall be covered by the inspection: — tower structures
— transition pieces — grouted connections — lifting appliances — access platforms — upper part of J-tubes — upper part of ladders — upper part of fenders — heli-hoist platforms
— corrosion protection systems — marine growth
— fatigue cracks — dents
— deformation(s) — bolt pre-tension
— status on outstanding issues from previous periodical inspections above water.
13.3.5.2 Inspection for fatigue cracks at least every year as required by the lists in [13.3.3.1] and [13.3.5.1]
may be waived depending on which design philosophy has been used for the structural detail in question: When the fatigue design of the structural detail has been carried out by use of safety factors corresponding to an assumption of no access for inspection according to Sec.7 Table 7-15, then there is no need to inspect for fatigue cracks and inspection for fatigue cracks may be waived. When smaller safety factors have been used for the fatigue design, inspections need to be carried out. The inspection interval depends on the structural detail in question and the inspection method and may be determined based on the magnitude of the safety factor applied in design. In general, the smaller the safety factor, the shorter is the interval between consecutive inspections.
Guidance note:
Provided a reliable inspection, such as an inspection by eddy current or a magnetic particle inspection, is carried out after a good cleaning of the hot spot area, the interval between consecutive inspections can be calculated from the safety level expressed in terms of the design fatigue factor DFF as follows:
Inspection interval = Calculated fatigue life · DFF/3.0. This implies the following requirements to inspection:
DFF = 3.0 No check for fatigue cracks is needed, corresponding to an assumption of no access to the structural detail.
DFF = 2.0 Checks for fatigue cracks needed every 13 years if the calculated fatigue life is 20 years. This will result in the same safety level as that achieved for DFF = 3.0 without inspections.
DFF = 1.0 Checks for fatigue cracks needed every 7 years if the calculated fatigue life is 20 years. This will result in the same safety level as that achieved for DFF = 3.0 without inspections.
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13.3.5.3 Guidance for inspection of grouted connections is given in [13.4.1.4].
13.3.5.4 Inspections as required in the wind turbine service manual come in addition to the inspection implied by [13.3.2].
13.3.6 Interval between inspections of structures below water
The interval between inspections below water should not exceed five years. Guidance note:
Five-year inspection intervals are common; however, more frequent inspections during the first few years after installation are recommended.
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13.3.7 Scope for inspection of structures below water
13.3.7.1 The following items shall be covered by the inspection: — support structures
— lower part of J-tubes — lower part of ladders — lower part of fenders
— marine growth — fatigue cracks
— scour and scour protection — damages and dents — deformations — debris
— status on outstanding issues from previous periodical inspections below water. Visual inspections may be carried out by a remotely operated vehicle (ROV).
13.3.7.2 Inspection for fatigue cracks at least every five years as required by the list in [13.3.1.1] may be waived depending on which design philosophy has been used for the structural detail in question: When the fatigue design of the structural detail has been carried out by use of safety factors corresponding to an assumption of no access for inspection according to Sec.7 Table 7-15, then there is no need to inspect for fatigue cracks and inspection for fatigue cracks may be waived. When smaller safety factors have been used for the fatigue design, inspections need to be carried out. The inspection interval depends on the structural detail in question and the inspection method and may be determined based on the magnitude of the safety factor applied in design. In general, the smaller the safety factor, the shorter is the interval between consecutive inspections.
Guidance note:
Provided a reliable inspection, such as an inspection by eddy current or a magnetic particle inspection, is carried out after a good cleaning of the hot spot area, the interval between consecutive inspections can be calculated from the safety level expressed in terms of the material factor γm as follows:
Inspection interval = Calculated fatigue life · γm5/1.255. This implies the following requirements to inspection:
γm = 1.25 No check for fatigue cracks is needed, corresponding to an assumption of no access to the structural detail. γm = 1.15 Checks for fatigue cracks needed every 13 years if the calculated fatigue life is 20 years. This will result
in the same safety level as that achieved for γm = 1.25 without inspections.
γm = 1.0 Checks for fatigue cracks needed every 7 years if the calculated fatigue life is 20 years. This will result in the same safety level as that achieved for γm = 1.25 without inspections.
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13.3.7.3 The protection potential shall be measured and fulfil minimum requirements. 13.3.7.4 If deemed critical, steel wall thickness shall be measured.
13.3.8 Interval between inspections of submerged power cables
The interval between inspections of submerged power cables should not exceed five years. A risk assessment can be carried out for determination of the appropriate inspection interval, such that export cables will be inspected frequently and array cables less frequently. Further, subsea cables buried in very stable seabed may not need as much monitoring as subsea cables buried in less stable sediments or in areas with significant tide.
13.3.9 Scope for inspection of submerged power cables
13.3.9.1 Array cables between the wind turbines and the transformer station as well as export cables to the shore shall be inspected, unless they are buried.
13.3.9.2 To the extent that submerged power cables are to be buried, it shall be ensured that the cables are buried to design depth.