Reliability analysis of subsea manifold system using FMECA and FFTA

Area of Science:

• Ocean Engineering
• Reliability Engineering
• Risk Management

Background:

• Subsea manifold systems are critical for marine resource exploitation safety.
• Reliability technology is essential for ensuring the safe operation of these complex systems.

Purpose of the Study:

• To introduce and apply a combined FMECA-FFTA method for comprehensive reliability analysis of subsea manifold systems.
• To identify and quantify failure modes to enhance system safety and operational integrity.

Main Methods:

• Qualitative analysis using Failure Modes, Effects and Criticality Analysis (FMECA) to identify failure modes, causes, and hazards.
• Quantitative analysis using Fuzzy Fault Tree Analysis (FFTA) to build a fault tree model and determine minimal cut sets.
• Incorporation of fuzzy set theory to improve accuracy in handling uncertainty during quantitative reliability analysis.

Main Results:

• Identification of key failure modes in subsea manifold systems, categorized by risk level.
• External leakage identified as a high-risk mode.
• Fail to close/lock on demand (medium-high risk) and leakage of critical location/plugged (medium risk) are also significant.

Conclusions:

• The FMECA-FFTA method provides a robust framework for both qualitative and quantitative reliability assessment of subsea manifold systems.
• Effective preventive protection and regular testing are recommended for identified high, medium-high, and medium-risk failure modes to ensure system safety.