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This presentation explores the Swiss approach to risk assessment on pipelines, focusing on new pipelines. It covers the legal context, stakeholders, assessment steps, risk criteria, experience, and future considerations.
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Risk Prevention Division Risk Assessment on Pipelines:the Swiss Approach 8 March 2006
Layout of the presentation(focus is on new pipelines) • The legal context • The stakeholders • Step 1 of assessment: max. possible damage • Step 2 of assessment: FN-curves calculation • Risk criteria • Experience so far • A look at the future
The legal context:Ordinance relating to Pipelines, LPE • OrP applies to hydrocarbon pipelines (pressure > 5 bar) • OrP requires state-of-the-art safety technology (“safety in the pipe”) • Control entrusted to the Federal Pipeline Inspectorate • For new pipelines: procedure in two steps for the risk assessment • Protection against catastrophes is a requirement of the Law on the Protection of the Environment (LPE)
The stakeholders • „Owner“ of the gas pipeline, who bears the responsibility for the safety of the pipeline • Federal Office for Energy (SFOE) lead authority, decides after consultation, concerning risk and other aspects, with: • Federal Office for the Environment (FOEN) • Federal Pipeline Inspectorate • Cantonal authorities • Third Parties • Public
First step of the risk assessment • Owner has to carry out in a summary report an assessment of the maximum damage that may be caused to the public or the environment • Assessment rough, conservative • Carried out according to a standardised methodology, jointly developed by the main stakeholders • Summary report is part of the environmental impact assessment and as such available to third parties and the public
Estimation of the maximum possible damage to the public (worst case) • Scenario assumed: Full bore rupture of a pipeline, followed by a "fireball" • Number of fatalities is considered • Parameters: pressure, pipeline diameter→ maximum lethality distance (MLD), number of persons usually within MLD • Sheltering effects of houses, etc., usually neglected
Profile: fatalities (worst case) • Drawn up over the entire length of the project • Simplifications lead to conservative results • On this basis, the authority evaluates whether a serious damage to the public (10 fatalities or more) is possible
Second step of the procedure • For those sections of the pipeline for which the maximum damage exceeds a given level, the authorities require a risk study • Requires a quantification of the risk to the public, to be displayed as a cumulative frequency distribution • Quantification carried out according to a standardised methodology, jointly developed by the main stakeholders • Risk criteria are used for final decision
Parameters used in the risk study • Pipeline operating pressure and diameter • Wall thickness • Steel grade • Depth of cover • Presence or not of concrete slab covering • Number of persons outdoors or in buildings that do not provide adequate protection from heat radiation • Number of persons in buildings that do provide adequate protection from heat radiation
Calculation of the FN-curve • A pipeline length of 300 m is used as a reference length for the risk study • The consequences and the probability of the different scenarios are calculated every 10 m. • The results of these calculations are then summed up in the FN-curve
Main additional safety measures • Optimisation of pipeline route • Greater wall thickness • Better steel grade • Greater depth of cover • Addition of concrete slab covering All these measures are subject to a number of constraints
Experience so far • The procedure described in this presentation has been applied on several hundred kilometres of new gas pipelines in Switzerland over the last years • The use of a common basis for risk assessment has led in most cases to a fair approval process and to a comparatively high acceptance of new natural gas pipeline projects • Risk is only one aspect among others
A question for the future • Population density along existing, and possibly old, pipelines significantly increased in the past and will increase also in the future • The risk is increasing accordingly • Safety measures for existing pipelines are particularly costly • Question for the future: How are we going to handle fairly these cases • Land Use Planning ? • Safety measures on the pipe ? • Safety measures for development along he existing pipelines ?
Principles to be taken into account • The safety of the public cannot be compromised • A solution can be arrived at only by involving all stakeholders in an adequate manner • All the possibilities mentioned in the previous slide should play a role • There is no need to rush for an all-encompassing solution now • Adequate priorities and deadlines will have to be set