Foundation Systems for Storage Tanks in Hydrocarbon Complexes: Critical Considerations and Case Studies-Paper

Paper

Pdf Summary

The paper examines foundation selection for storage tanks in refineries and petrochemical complexes, emphasizing that tank flexibility and settlement tolerance do not eliminate the need for thorough geotechnical investigation. Foundation choices should reflect tank size and roof type, soil strength and compressibility, groundwater, geological hazards, construction constraints, cost, and allowable total and differential settlement.<br /><br />Common systems include sand pads, ring walls, ground-improved shallow foundations, and piles. Sand pads require well-compacted granular material, adequate drainage, corrosion protection, and uniform support. Ground improvement is appropriate when untreated soils would produce excessive settlement; piles are preferable where weak or organic soils are deep, highly variable, or unsuitable for treatment.<br /><br />Two case studies demonstrate these principles. At a Nigerian refinery, three floating-roof tanks encountered loose sands, clay, and, beneath one tank, thick organic soil. Stone columns reduced predicted settlement for a large tank, while dynamic compaction improved saturated silty sand beneath another. A trial showed stone columns were ineffective in the thick organic soil, so the third tank was supported on piles. Hydrotests confirmed settlements within permissible limits. The study also found dynamic compaction effective to depths of about 10–12 m in the tested silty sand.<br /><br />At an Indian refinery, four tanks were founded on sand pads after heterogeneous construction fill was excavated and replaced with compacted sand-gravel fill; stone ring walls supported the shells. This approach was considered suitable where replacement depths are relatively shallow and groundwater is deeper.<br /><br />Overall, the case studies show that foundation systems must be selected through site-specific soil assessment and evaluation of treatment feasibility. Hydrotest results support the effectiveness of appropriate ground improvement and soil replacement, while highlighting that no single foundation method suits every ground condition.

Keywords

foundation selection

storage tanks

geotechnical investigation

ground improvement

settlement tolerance

stone columns

dynamic compaction

piles

sand pads

refinery foundations