Design of a subsea pressure housing for ambient noise measurement system in the Arctic region

Abstract

This paper presents the design and development of a subsea pressure housing which is cylinder and made of austenitic stainless steel with a grade of 316L material, to withstand an external hydrostatic pressure of 10 bar in the Arctic environment. The material is selected based on its characteristics like formability, strength, corrosion resistance, durability and properties to withstand extreme temperatures. The design of the pressure housing is planned to accommodate electronic subsystems like data acquisition system, power controller, solid state memory and a power pack. The cylinder considered here is a thin cylinder with the dimensions of 330mm as diameter and 700 mm as length. The estimated wall thickness is 4mm. In this work, the pressure housing has been designed using American Society of Mechanical Engineers (ASME) boiler and pressure vessel code- Section VIII. The design dimensions have been verified with Indian Standard (IS) code 2825 -1969. In order to verify the design, the pressure housing is assumed as axi-symmetric and finite element analysis with ANSYS software has been studied with an external pressure of 10bar and the results are found satisfactory. The pressure housing forms the main component of an independent ambient noise measurement mooring system in the Arctic region. In India, under Ocean Acoustics programme of National Institute of Ocean Technology (NIOT), an indigenous ambient noise measurement mooring system has been developed and deployed in the Kongsfjorden, Arctic region at an ocean depth of 100m during July 2018 near IndARC mooring system installed by Ocean Observation System (OOS) program of NIOT. The designed subsea pressure housing has successfully completed its operation for one year withstanding the rated pressure, temperature and harsh environment prevailing in the Arctic region. The schematic of subsea pressure housing is shown in the below Fig. 1. The system was retrieved successfully during July 2019. The purpose of the ambient noise measurement system is to record time series ocean ambient noise data in the Arctic region for studying the dynamics of the sea ice cover and biological and anthropogenic noise sources.