2 Definitions
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1455 – Guidelines for the Approval of Alternatives and Equivalents as Provided for in Various IMO Instruments – (24 June 2013) - Annex – Guidelines for the Approval of Alternatives and Equivalents as Provided for in Various IMO Instruments - 2 Definitions

2 Definitions

 For the purposes of these Guidelines, the following definitions apply:

  2.1 ALARP (As Low As Reasonably Practicable) refers to a level of risk for which further investment of resources for risk reduction is not justified. When risk is reduced to ALARP, it is acceptable.

  2.2 ALARP area refers to risks neither negligibly low nor intolerably high where a cost-benefit analysis is used to identify cost-effective risk control options.

  2.3 Approval means that the Administration issues an approval certificate as proof of verification of compliance with the regulations, standards, rules, etc. which are aimed at ensuring safety against hazards to the ship, personnel, passengers and cargo, and against hazards to the environment.

  • Note: For approval of alternative oil tanker designs according to MARPOL, regulation I/19(5), it is noted that the MEPC is the Approval Authority for the preliminary approval (referred to as approval in principle in MARPOL) of the concept design.

  2.4 Design casualty scenario means a set of conditions that defines the development and severity of a casualty within and through ship space(s) or systems and describes specific factors relevant to a casualty of concern.

  2.5 Design team is a team established by the owner, builder or designer, which may include, as the alternative design and arrangements demand, a representative of the owner, builder or designer and expert(s) having the necessary knowledge and experience for the specific evaluation at hand. Other members may include marine surveyors, ship operators, safety engineers, equipment manufacturers, human factor experts, naval architects and marine engineers.

  2.6 Failure mode is the observed mechanism or manner in which a failure can occur.

  2.7 FME(C)A. Failure Mode, Effect (and Criticality) Analysis.

  2.8 Preliminary design is a design developed for the design preview and the first analysis phase. The preliminary design is a high-level design taking into account the general arrangement, major systems, components, etc.

  2.9 HazId. Hazard identification, a process to find, list and characterize hazards.

  2.10 HazOp. Hazard and operability study.

  2.11 Novel/new technology or design. A new technology is a technology that has no documented track record in a given field of application, i.e. there is no documentation that can provide confidence in the technology from practical operations, with respect to the ability of the technology to meet specified functional requirements. This implies that a new technology is either:

  • .1 a technology that has no track record in a known field;

  • .2 a proven technology in a new environment; or

  • .3 a technology that has no track record in a new environment.

  2.12 Preliminary approval/approval of preliminary design is the process by which the Administration issues a statement that a proposed concept design complies with the intent of the rules, regulations and/or appropriate criteria set by the Administration – even though the design may not be fully evolved. The preliminary approval is subject to a list of conditions that are addressed in the final design stage.

  2.13 Proven technology has a documented track record in the field for a defined environment.

  2.14 Risk is a measure of the likelihood that an undesirable event will occur together with a measure of the resulting consequence within a specified time, i.e. a combination of the frequency and the severity of the consequence (this can be either a quantitative or qualitative measure).

  2.15 Risk analysis is the science of risks, their probability and consequence.

  2.16 Risk assessment is an integrated array of analytical techniques, e.g. reliability, availability and maintainability engineering, statistics, decision theory, systems engineering, human behaviour, etc. that can successfully integrate diverse aspects of design and operation in order to assess risk.

  2.17 Risk evaluation criteria are formally recognized objective criteria defining the acceptable risk.

  2.18 Risk-based design is a design where the design process has been supported by a risk assessment or the design basis has resulted from a risk assessment. That is, it is a structured and systematic methodology aimed at ensuring safety performance and cost-effectiveness by using risk analysis and cost-benefit assessment.

  2.19 Risk control measure is a means of controlling a single element or risk; typically, risk control is achieved by reducing either the consequences or the frequencies; sometimes it could be a combination of the two.

  2.20 Risk control option (RCO) is a combination of risk control measures.

  2.21 Safety is the absence of unacceptable levels of risk to life, limb and health (from non-wilful acts).

  2.22 Safety critical. Containing an element of risk. Necessary to prevent a hazard.

  2.23 Final design. Elaboration of the preliminary design. The final design complies with the results of the preliminary analysis, e.g. with respect to risk control options already identified, and the requirements of the Administration. The final design is developed on the basis of the statement by the Administration.

  2.24 Submitter is an entity seeking approval of an alternative design and/or equivalent from the Administration, responsible for communicating with the administration for the submission and follow-up of the approval process.


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