Reply #9: the Katyusha is very unreliable and the the idea political nonsense

[tocqueville]

they shot 5 at a US ship recently at short range and managed to hit a warehouse...

Of course you could cause damage, you could be lucky... but on a BIG refinery it's likely that you'd cause local damage nothing more. The flammable tanks are separated from each other with security areas. The burning parts of the distillery can be shut off from fuel. The area is constructed to PREVENT Fire.

If you want to blow it you use air means (stealth) or commandos with semtex. But that's too risky.

Besides blowing off a refinery is meaningless for the West. Iran is already threatening to only use its production internally (stop export) because such a measure would have the oil prices skyrocketing...