Section 3 Methodology

3.1.1 Risk assessment requires the consideration of hazards and the likelihood of the hazards’ consequences, and the means of hazard management.

3.1.2 The specific risk-based methodology used is to be in accordance with an applicable and recognised International or National Standard or Code.

3.1.3 The methodology is subject to approval by LR. The earliest engagement with class is encouraged when riskbased techniques are to be used as part of any design submission. This should happen far earlier than normal class approval, to ensure the approach adopted is acceptable, and does not result in project delay.

3.1.4 If risk assessment is used to examine individual systems, sub-systems, or components of an installation, a clear boundary marking the limit of such systems is to be identified.

3.1.5 These boundaries are subject to approval by LR.

3.2.1 Hazards that may threaten safety or integrity of the installation are to be identified.

3.2.3 National Administration requirements may specify other hazards to be considered.

3.3.1 The identified hazards are to be screened to provide a ranking of the hazards in terms of the consequences and likelihoods. Major hazards are those hazards that pose a significant threat to the safety and integrity of the installation.

3.3.2 The major hazards identified are subject to approval by LR.

3.3.3 Frequency analysis is an examination of the likelihood of the occurrence of hazardous events. The frequencies of occurrence of major hazards are to be estimated by suitable techniques, using appropriate occurrence or failure rate data. Both the likelihood of consequences and those consequences are to be analysed.

3.3.4 Consequence analysis is to consider the effects of hazardous events on the safety and integrity of the installation. Consequence analysis provides input to calculations of risk, and design information for risk reduction measures.

3.3.5 An assessment is to be performed to evaluate the availability of the emergency systems of the installation. Emergency systems are those systems that are required to operate when a hazard occurs, to protect the safety and integrity of the installation.

3.3.6 Emergency systems are to be assessed to evaluate their vulnerability to hazards that may occur.

3.4.1 The risk is to be assessed for each of the possible failure modes identified. The risks from all the outcome events are to be considered together to assess the overall risk to the installation. This summation forms the baseline against which further risk reduction measures can be evaluated and a means of showing where the major risk contributors are in the installation.

3.4.2 The results of the risk assessment are subject to approval by LR.

3.5.1 LR’s Rules have been developed to the point where they achieve a standard of design and construction quality that ensures an acceptable level of safety and assurance of integrity of the installation. Provided that the Rules are followed throughout all the design and construction of the installation, this would ensure that the installation has an acceptable level of safety and assurance of integrity. Deviations from the Rules, using risk assessment as a method for justifying Class, must therefore demonstrate that such changes to the design and construction of an installation or its parts do not result in an unacceptable level of safety or integrity of the installation.

3.5.2 LR will require the Owner/Operator to develop risk acceptance criteria to be achieved by the design and maintained in service, to ensure the safety and integrity of the installation in line with the spirit and intent of LR’s Rules.

3.5.3 Risk acceptance criteria are subject to approval by LR.

3.6.1 Critical elements of the installation are to be identified in relation to the major hazards to safety and integrity of the installation. Critical elements provide the means to prevent, or to detect, control, mitigate and recover from, the hazards. Identification of critical elements is to be based on consequence of failure in relation to the reduction in safety and loss of integrity of the installation. Critical elements may be systems, sub-systems or components, of the installation.

3.6.2 Critical elements are subject to approval by LR.

3.7.1 For new construction, it is expected that the risk assessment will be initiated at the concept design stage. Opportunities may be identified for reducing the risks to the installation in its design. The aim is to achieve inherent safety by eliminating potential hazards. Where this is not practicable, a series of measures is to be applied which in order of preference prevent, detect, control, mitigate and allow recovery from the hazards.

3.8.1 Performance standards are to be developed for the critical elements in order that they will manage the identified hazards.

3.8.2 Performance standards are subject to approval by LR.