SAFETY AND ENVIRONMENTAL RISK AND RELIBIALITY MODELING PROCESS


159


Table 4


Consequence risk acceptability criteria for maritime industry. Quantification


Current failure that can result to death failure, performance of mission


Failure leading to degradation beyond accountable limit and causing hazard


Controllable failure leading to degradation beyond acceptable limit


Nuisance failure that do not degrade system overall performance beyond acceptable limit


Serenity catastrophic critical major minor


Occurrence Detection 1


2 3 4 7 4 6 8


RPN 10


7 5 2


analysis. FMEA is probably the most com- monly used for qualitative analysis and is also the least complex. FMEA has been employed in the following areas:


i. The aerospace industry during the Apollo missions in the 1960s. ii. The US Navy in 1974 developed a tool which discussed the proper use of the tech- nique.


Today, FMEA is universally used by many dif- ferent industries. There are three main types of FMEA in use today:


i. System FMEA: concept stage design sys- tem and sub-system analysis. ii. Design FMEA: product design analysis before release to manufacturers. iii. Process FMEA: manufacturing assembly process analysis.


Analyzing FMEA involves:


i. Listing key process steps in firm column for the highest ranked items risk matrix. ii. Listing the potential failure mode for each process step: how the process input could go wrong.


iii. Listing the effects of the failure mode: what does the failure mode mean to stake- holders. iv Rating severity of the effect : 1 being not


.


severe at all and 10 being extremely severe.


v. Identifying the causes of the failure mode


effect and rank the effects in the occur- rence column: the scoring denotes how likely this cause will occur. Score of 1 means it is highly unlikely to ever occur and 10 means we expect it to happen all the time. vi. Identifying the controls in place to detect the issue and rank its effectiveness in the detec- tion column: 1 would mean there are excel- lent controls and 10 would mean there are no controls or extremely weak controls.


It is strongly recommended that Serenity, Oc- currence and Detection (SOD)for weak control should be noted. SOD numbers is multiplied and the value is stored in RPN (risk priority number) column. This is the key number that will be used to identify where the team should focus first. If, for example, there is case with severity of 10 (very severe), occurrence of 10 (happens all the time), and detection of 10 (can- not detect it) RPN is 1000. This indicates a seri-


Journal of Marine Environmental Engineering


145-173 pp MB_37(Kader)2.indd 159


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