Failure Investigation of a Multi-hopper Steel Silo

• Published in: Journal of failure analysis and prevention Vol. 22; no. 1; pp. 209 - 221
• Main Authors: Ranjan Debbarma, Swarup, Das, Debashis, Kumar, Abhishek, Bouri, Dayamay, Banerjee, Sumanta, Chatterjee, Sumanta, Kumar, Raju
• Format: Journal Article
• Language: English
• Published: Materials Park Springer Nature B.V 01.02.2022
• Subjects: Chemical analysis; Discharge; Failure analysis; Failure investigations; Field tests; Finite element method; Fluid penetrant testing; Hoppers; Steel plates; Steel structures; Stiffeners; Thickness measurement; Vibration analysis; Vibration measurement; Wagons
• ISSN: 1547-7029; 1864-1245
• DOI: 10.1007/s11668-022-01333-9

The paper is based on a case study and the technique used to resolve the problem of recurring failure of a steel silo that discharged coal through multiple bottom hoppers at a wagon loading station. The coal storage silo had four hoppers and discharge doors with a capacity of 850 tons. After a few years of its operation, various sign of damage such as cracks appeared in the hopper structure of the silo. Critical observations were made to understand the pattern of the cracks, the nature of rotation of the hoppers, and the sagging of the central bottom portion of the silo. The observations facilitated understanding the technical reasons of the root cause of failure. In situ tests like dye penetrant testing, thickness measurement of steel plates, vibration measurement of structures, and chemical analysis of the steel in the silos were carried out. A finite element-based model of a silo was developed, and analysis revealed the deficiency in the design of the structure which confirmed the findings of the critical observations. The addition of stiffeners at one-third height of the hopper will significantly reduce the stress concentrations which led to failure. The analysis also reveals that the replacement of multiple hoppers with a single hopper at the center of the silo bottom is a potential long-term solution.