Spherical　storage　tanks　are　widely　used　for　various　types　of　liquids,　including　hazardous　contents,　thus　requiring　suitable　and　careful　design　for　seismic　actions.　On　this　topic,　a　significant　case　study　is　described　in　this　paper,　dealing　with　the　dynamic　analysis　of　a　spherical　storage　tank　containing　butane.　The　analyses　are　based　on　a　detailed　finite　element　(FE)　model;　moreover,　a　simplified　single-degree-of-freedom　idealization　is　also　set　up　and　used　for　verification　of　the　FE　results.　Particular　attention　is　paid　to　the　influence　of　sloshing　effects　and　of　the　soil–structure　interaction　for　which　no　special　provisions　are　contained　in　technical　codes　for　this　reference　case.　Sloshing　effects　are　investigated　according　to　the　current　literature　state　of　the　art.　An　efficient　methodology　based　on　an　“impulsive–convective”　decomposition　of　the　container-fluid　motion　is　adopted　for　the　calculation　of　the　seismic　force.　With　regard　to　the　second　point,　considering　that　the　tank　is　founded　on　piles,　soil–structure　interaction　is　taken　into　account　by　computing　the　dynamic　impedances.　Comparison　between　seismic　action　effects,　obtained　with　and　without　consideration　of　sloshing　and　soil–structure　interaction,　shows　a　rather　important　influence　of　these　parameters　on　the　final　results.　Sloshing　effects　and　soil–structure　interaction　can　produce,　for　the　case　at　hand,　beneficial　effects.　For　soil–structure　interaction,　this　depends　on　the　increase　of　the　fundamental　period　and　of　the　effective　damping　of　the　overall　system,　which　leads　to　reduced　design　spectral　values.　©　2018,　The　Author(s).