Application of Fracture Mechanics Parameters to Spherical Storage Tank Integrity Assessment

Abstract

Fracture mechanics parameters have been applied to assess pressure vessel integrity. The pressure vessel analysed here was the ammonia spherical tank (volume of 1800 m3, outer diameter 15.12 m, thickness 30 mm) where different cracks in the longitudinal and transverse butt joints were found. The finite element method was used to calculate stress and strain state and to analyse cracks and their influence on spherical storage tank integrity. Toward this end, the stress intensity factors were analytically determined, and compared with the fracture toughness to find out the critical pressure using Failure Assessment Diagram (FAD) in combination with net stress vs. critical stress.

Keywords

• failure assessment diagram
• finite element method
• spherical storage tank
• stress intensity factor
• structure integrity