Yes, if you offer or transport in commerce more than 3,000 L (792 gallons, as printed in the rule) of Division 2.1 propane in one packaging. U.S. DOT (PHMSA) requires a written security plan under 49 CFR 172.800 and 172.802.
Who has to have one?
The rule covers offering the propane for transportation as well as transporting it in commerce. The quantity is measured in a single packaging. A cargo tank on a bobtail or transport is one example; portable tanks and tank cars also count. Check the actual quantity offered or transported, not just the tank's rated capacity.
Does it have to be in writing?
Yes. Keep the plan on paper or on file where the people who run it can get to it.
How often do we look at it?
At least once a year. Look again when your trucks, routes or people change.
What next?
Read our answer on what goes in a 49 CFR 172.800 security plan. Your own adviser should confirm how the rule, including any exceptions, applies to the materials you offer or transport.
We help with safety manual writing, review and revision; see propane safety help.