Page 576 - Marine Structural Design

552 Part V Risk Assessment

Import/export systems such as risers, flowlines and offloading systems
catastrophic - resulting in major oil spill or fire due to the leakage of oil and gas
critical - leading to moderate oil spill and downtime of above 6 months
severe - ruptures in the pipe require repair and replacement and downtime of 1 to 6
months
minor - repair or replacement of the riser, flowline and offloading systems that cause
shut-down of less than one month.
For generic methodologies for risk-based inspection, reference is made to AF'I RP 580 (MI,
2002). This newly developed RP contains the following Sections:
Introduction to risk-based inspection
Screen and boundary identification
Data and information collection for RBI assessment
Identifylng deterioration mechanisms and failure modes
Assessing likelihood of failure
Assessing consequences of failures
Assessing risk
Risk management with inspection activities
Other risk mitigation activities
Reassessment and updating RBI assessment
Roles, responsibilities, training and qualification
RBI documentation and record keeping
The formulation for probability and risk-based inspection has been given in Part IV Chapter
28. The effectiveness of inspection depends on the degradation mechanism and rate,
inspection scope/frequency and detection capability as well as the usefulness of the mitigation.
For FPSO, the biggest benefit from the use of risk-based inspection is perhaps the reduced loss
of production.

30.7 Environmental Impact Assessment
In many situations, an environmental impact assessment must be conducted prior to the
execution of an offshore field development. The results of the environmental impact
assessment may be used to minimize the environmental impact from development and
operation of the oil/gas field. The scope of an environmental impact assessment may depend
on the geographical regions and the characteristics of the field, and may for example include
the following:
Investigate distribution, population size and biology of key species of fish, birds and
mammals
Evaluate food webs and tropical interactions, energy transfer in the ecosystem,
Assess environmental toxins in sediments, benthic organisms and fish