Reliability Assessment of a Full-ocean-depth Pressure-retaining Sediment Sampler Using Fault Tree Analysis

Abstract

Seabed sediment samples are vital to the study of marine geology, microbial communities, and the history of life on earth, and pressure-retaining samplers are fundamental to obtaining sediment samples while maintaining in situ conditions. Due to the harsh environment, with extremely high pressures, low temperatures, and no light, samplers can easily fail as structural components are stressed beyond their limits. Therefore, it is essential to develop a pressure-retaining sampler with high reliability. In this paper, a sediment sampler that we developed was used as the research object. A fault tree model of the sampler was established using the fault tree analysis method, and the failure rate, reliability, and importance index of each component in the sampler were calculated under different working conditions. The results showed that the sampler’s O-ring seals were the component most likely to fail, with failure rates as high as 29.86. Furthermore, as operational time increased, the reliability of the sampler gradually decreased. Under ultra-high pressure, the reliability index decreased from 90.97 % after running for 1000 hours to 35.30 % after running for 11000 hours. These new discoveries have provided important insight for increasing the robustness of the design and establishing maintenance priorities for samplers to ensure high reliability.

Keywords

• deep-sea sampler
• pressure-retaining
• reliability
• fault tree model
• failure rates