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Statistical Verification of FMEDA Predicted Failure Rates

Statistical Verification of FMEDATM Predicted Failure Rates Using OREDA Gate Valve Field Failure Data

In this paper the total failure rates predicted by Calibrated Failure Modes Effects and Diagnostic Analysis (Calibrated FMEDA) for a specific gate valve (Manufacturer X/Model Y) under specific conditions are statistically verified against the 70% confidence interval for the total failure rate computed from the Offshore and Onshore Reliability Data (OREDA) project field failure data (FFD) for the same gate valve under the same conditions. The detailed valve data provided by OREDA for this study clearly documents 60 gate valves from Manufacturer X/Model Y at a single installation, in a single system, all normally opened, with the same environmental exposure, with the same preventative maintenance, and in the same severe service with a total operating time exceeding 1,000,000 hours. This paper explains the motivation behind this project, summarizes the work performed, describes the findings, and presents the main conclusions. The paper also provides all necessary details required to ensure that the computations are transparent and reproducible while preserving the proprietary nature of certain data.

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