Yes, spray foam insulation can be used in a shipping container. Closed-cell spray polyurethane foam is often considered because it can follow corrugations and provide insulation plus air control in limited space, but suitability depends on the complete assembly. The steel must be inspected, clean and dry; thickness and continuity must be designed; openings and future repairs must remain workable; and installation, re-entry and any required thermal or ignition protection must follow the selected product, workplace controls and locally applicable code.
Decide what the spray foam must control
Inspect the steel before it disappears
Specify product, thickness and passes
Control exposure during application and cure
Resolve fire protection and interior finish together
Plan penetrations and future repair before spraying
Accept the installation as an assembly
Quote the steel preparation and finish with the insulation
Provide shell photos, climate, intended use and target assembly performance. Require the product, preparation, minimum depth, exposure controls, protection layer, testing and repair details in writing.