Bit of a strange question really. There is a lot of LPG stored and distributed around the place - the ones I know are nearly 100% Propane, with maybe a small percentage of other components such as Butane, Pentane, etc. But that doesn't make the liquid or gaseous form significantly more safe or less safe.
That's not to say that there haven't been some monumentous explosions (BLEVEs), but provided you don't have leaks and ignition sources, and have all the safety controls and procedures in place, then sure it is safe to store and distribute propane.
Within the US most propane is transported between ht refineries and gas processors to major cities via underground product pipeline. Often the pipeline product terminals have underground caverns, either excavated or leached into salt domes. These product terminals add odor when loading the transport trucks or rail cars.
A major propane or other LPG disaster occurred in Mexico City. Search the web for details.
If a propane truck leaked propane from a damaged valve and caught fire the fire would be a jet burning away from the truck until approximately empty. However a major rupture of a vessel like a propane truck could release the liquid that rapidly boils into a vapor cloud. A major explosion could occur once the cloud meets an ignition source while blended with air. Such releases could be very bad things.
In my opinion, propane is far safer than gasoline. Gasoline is among the most hazardous materials that most of use use on a regular basis. Still I see people smoking while fueling their vehicles. Hazardous materials and stupid people could be very very bad things.
It depends on the details. You might find some guidance in NFPA 30, which has building codes requirements for flammable liquids. (I assume propane is included, but haven't checked.) Anyway, it spells out how much can be stored in what kind of building, how far separated from other stuff, etc. You might also be able to get some information from the local fire department or building permit people. There is also a Uniform Fire Code, but I think it mainly refers back to NFPA 30 for tank issues.
Around here, the 7-11's and other stores have outside storage racks of propane bottles for propane exchanges, so it's obviously done. But those racks are outsiden, not inside, and there may be a reason for that.
I have API 2510 (Design and Construction of LPG Installations), and while that is definitely not applicable to your situation, I note that apart from NFPA 30, it does reference NFPA 58 - Storage and Handling of Liquified Petroleum Gases. That may be worth a look as well.
NFPA 54 is the National Fuel Gas Code. ASME B31.8 applies to gas transmission. A few CSA standards in the B149.1 series apply in Canada. FMDS0754 and FMDS0755 could apply.
We have the complete system, the plant and the distribution of the cilinders. So I understand that if we follow the standards, it is safe to handle 100% propane...
