An Integrated Multi-Criteria Decision Framework for Reliability Evaluation of Subsea Distribution Units

Abstract

Subsea Distribution Units are critical components of subsea production control systems, responsible for the distribution of hydraulic power, electrical energy, chemical injection, and communication signals to subsea assets. Failures in SDUs can result in significant production downtime, safety risks, and costly offshore interventions, particularly in deep and ultra- deepwater environments. This study presents an integrated reliability evaluation framework combining Failure Mode, Effects and Criticality Analysis , Fuzzy Technique for Order Preference by Similarity to Ideal Solution (Fuzzy TOPSIS), and the Preference Ranking Organization Method for Enrichment of Evaluations (PROMETHEE II). Using expert-elicited field data validated with OREDA (2015), critical SDU failure modes were identified, prioritized, and ranked. Results indicate that electrical power and signal distribution components account for approximately 59.3% of critical failures, while hydraulic control and chemical injection subsystems contribute about 33.3%. Strong convergence between Fuzzy TOPSIS and PROMETHEE rankings validates the robustness of the proposed framework. The integrated approach improves decision-making under uncertainty and supports enhanced reliability- centered maintenance and design optimization for subsea distribution systems.

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