If yo want them to be filled with argon, they need to be pressure rated for at least 2200psi.
Also, they would have to be fully purged. the only problem is finding someone to fill them.
They sell oxygen acetylene tanks also.
I have 4 tanks here that I am bringing to the dump. (2) 40cf and (2) 80cf that were for Oxy acet. I cant find anyone to fill them. Free. they are going to the dump on friday.