reliability assessment of offshore jacket structures in niger delta

For the Stand–by parallel, the system is fully redundant. Any one of A or B orcombination A and B in working condition will make the system success. All componentsmust fail for the system to fail.The failure of Stand-by Parallel can be represented in Boolean Logic as:F = A ∩ B(9)The probability of the system failure is given by either:P = P . P(10)RSSAB{( 1 − R )( . − R )}= 1 −1(11)AB2.1.4 Jacket Group Bracing Reliability (Active Parallel)The reliability estimation for group bracing “A” for a jacket structures is illustrated inFigure 4 whose bracing member arrangement is in active parallel mode and can berepresented by Equation (9).R = −[(P + P + P + P −P.P.P.P)](12)AM.A. Salau, D.E. Esezobor, M. F. Omotoso/Petroleum & Coal 53 (4) 291-301, 2011 2941a b c d. a b c dwhere: R A is reliability of bracing group “A” and P a , P b , P c , P d are the failure probabilitiesof each bracing members or member thickness corrosion loss. The reliability of otherbracing groups B, C, D, E, and F will be also estimated according to the formula inEquation (12).L 4L 1L 3L 2(+) 4.0MWLbdacGroup A: Consist of allthe diagonal bracingsbetween Level (+) 4.0mand (-) 7.0mGroup B: Consistof all the horizontalbracings in Level(-) 7.0mEL (-) 7.0Group C: Consist of allthe diagonal & verticalbracings between Level(-) 7.0m and (-) 18.3mEL (-) 18.3Group D: Consistof all the horizontalbracings in Level(-) 18.3mGroup E: Consist of allthe diagonal & verticalbracings between Level(-) 18.3m and (-) 32.0mAEL (-) 32.01BGroup F: Consistof all the horizontalbracings in Level(-) 32.0m2Figure 4 Jacket Structure Diagram showing Bracing Member Groups and Support Legs