I've changed many outage valves on all kinds of LPG tanks. Cleaning and checking them is not too bad but purging them with nitrogen is a pain. They have to be purged and all attachments leak tested prior to filling. (unless you are doing it yourself and no certification is required on the tank)
Put it all back together and fill it with dry nitrogen (to 200 PSI) and test it with soapy water to find any leaks. Drain reseal and repeat. When no leaks are present you drain it and fill with fuel, and retest.
I have "More" full propane tanks then I could use in twenty years. About 16 or 18 full tanks.
This is becoming a "Bear Bait" barrel. They will not crush these like the crush the 55 gal. steel drums. That is why drill many holes for the bait to fall out of.