it's just not well known outside of production fabrication shops.
Technically oxygen and fuel tanks should be stored no less than 20 feet from each other, or with a fire barrier between the two areas which meets certain specs. They are also not to be stored in enclosed areas.
"Oxygen cylinders in storage shall be separated from fuel-gas cylinders or combustible materials (especially oil or grease), a minimum distance of 20 feet (6.1 m) or by a noncombustible barrier at least 5 feet (1.5 m) high having a fire-resistance rating of at least one-half hour." -http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9854
There is some sort of waiver for tanks "in use or expected to be in use". It's not well defined though.
