Chapter 24 of NFPA 30 covers "storage tank buildings". Is this chapter intended to apply to indoor fuel tanks for oil burners or for engines for equipment like fire pumps or emergency power generators?
No, Chapter 24 does not apply to either of these situations. In the first case, Chapter 7 of NFPA 31 governs; in the second case, Chapter 6 of NFPA 37 governs. Having said this, in both cases, the respective standards defer to NFPA 30, if the fuel tanks are buried or are located outside aboveground.