Improving the Safety of Marine Pipelines (1994) / Chapter Skim
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3 Risk Analysis: Hazards and Zonation
3 Risk Analysis: Hazards and Zonation
Pages 33-44
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From page 33... ...
This analysis can provide information fundamental to the formulation of risk management strategies tor Industry, as well as the federal and state government agencies that have jurisdiction over the enforcement of pipeline safety regulations. The use of risk analysis results for risk management purposes permits identification of high-risk situations and assessment of their evolutions caused, for example, by variations in vessel traffic or by shoreline erosion.
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From page 34... ...
This chapter outlines a risk analysis approach designed to compute the initial risk and the risk reduction benefits of safety measures. It also contains a set of safety goals for the management of marine pipelines.
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From page 35... ...
The use of risk analysis models based on zonation has proved useful in other cases to set priorities in risk management. For example, a risk-based zonation of the United States supports the seismic provisions of building codes (Applied Technology Council, 1982; Federal Emergency Management Agency, 1986; International Conference of Building Officials, 1982~.
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From page 36... ...
Another recent example, is the development, for NASA, of a risk analysis model of the heat shield of the space shuttle designed to compute the risk-criticality of the black tiles and to set priorities in maintenance operations (Pate-Cornell and Fischbeck, 1993a, 1993b)
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From page 37... ...
Systems for isolating platforms from pipelines in case of serious platform emergencies have proven to be important safety features that should be located in such a way that they can be easily maintained and quickly or automatically activated in case of emergency. Decision Criteria and Relevant Outcomes The chosen outputs of the risk analysis model depend on the structure of the decision criteria (the maximum acceptable individual risk, the cost-benefit criterion when applicable, etc.~.
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From page 38... ...
, and possibly the types of vessels if there are significant differences in drafts; · the water depth indexed by 1~1, 2, or 31; and · the number of platforms. Figure 3-1 shows an example of such a min-zone partition for a hypothetical region.2 A harbor is shown, to illustrate variation in vessel traffic density.
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From page 39... ...
These five types of initiating events can be considered mutually exclusive. Their probabilities are defined for each min-zone as functions of the information shown in Figure 3-1: water depth and the densities of vessel traffic and pipelines.
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From page 40... ...
Uncertainties about such future variables can only be described by expert opinions. DATA SETS AND BIASES As reported in Chapter 2, there are several data sets containing records of past pipeline failures, accidents, and oil spills.
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From page 41... ...
As is almost always the case in risk analysis, the data needed for the computations outlined in this chapter and in Appendix E come from three sources: . statistics from past reported incidents; · physical models (involving vessel drafts, water depth, vessel speeds, corrosion mechanisms, etch; and · expert opinions (subjective assessments of probabilities based on experience)
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From page 42... ...
Investing more resources to reduce low risks thus becomes counterproductive beyond a certain level of costs, even if one restricts the objectives to issues of individual safety and welfare. This maximum expense per capita to eliminate a low individual risk (divided by the risk magnitude)
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From page 43... ...
The risk analysis model allows computing the risk-reduction benefits by comparing the expected values of the losses with and without the proposed measures. When the options involve a continuous range (e.g., in determining the appropriate depth of burial of pipelines in shallow waters)
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From page 44... ...
To place marine pipeline safety priorities on a firm basis, it is necessary that data be gathered in a consistent format by the responsible agencies, stored in a central data base, and used in a risk analysis model based on the zonation approach presented in this chapter. REFERENCES Applied Technology Council.
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