A new international standard: Combining safety with dependability

Safety and dependability should be handled within the same reliability framework. However, the current international safety standards exclude the dependability from their scopes, and vice versa. ISO/TC 67/WG4 is making a new international standard, ISO 12489 “Reliability modelling and calculation of safety system”, which was drafted by experts in the major international oil companies, including the experts of Chinese Oil Company hereinto. And meanwhile, the special meetings in regard to the standard drafting were ever held in Oslo (Norway), Pau (France), Antwerp (Belgium) and Rio de Janeiro (Brazil). A safety system may be defined as a system that protects another system against incident or accident. Typical safety systems in oil and gas industry include protection systems of overpressure, overflow, over temperature, and so on. At the present, the safety system is divided into two types. Reactive safety systems are commonly used whereas preventive safety systems have just begun to be implemented in the oil and gas industry. It is purpose to solve the problem of the dependability of the safety system itself, the standard was drafted, it introduces reliability block diagrams, fault trees analysis, Markov graphs, Petri nets modelling, and Formal language modelling initially, and then, according to the above mentioned theories, the standard proposes simplified formulas which provide typical applications, including reactive/preventive topside safety system and reactive /preventive subsea safety system.