Analysis of the Remaining Life Assessment of Fb-8701c Spherical Tank based on Thickness Measurement Data with Ultrasonic Testing Method

Abstract

This remaining life assessment assessed the thickness and corrosion rate characteristics of A516 Grade 70 carbon steel, a material widely used in the fabrication of pressure vessels and boilers, including spherical tanks. The material was evaluated through ultrasonic non-destructive testing, with the aim of determining the minimum thickness and corrosion rate, based on field data collected by the inspector. The data was then analyzed to determine the minimum allowable thickness and estimate the remaining life of the pressure vessel based on API 510 standard. The study results showed that all components examined were within safe limits for use, above the required thickness (actual thickness > required thickness). The calculation of the highest corrosion rate is on the Top Head Plate 7 component, which is 0.067 mm/year, so this component has the shortest remaining life, which is 54.06 years. This study also calculates the maximum allowable working pressure (MAWP) value which is a reference to ensure the safety of pressure vessels when operated. The working pressure when operated must not exceed the calculated MAWP value. The calculated MAWP value is in the range of 6.99 to 8.12 psi.