You can consult the Chlorine Institute's Pamphlet #163, "Hydrochloric Acid Storage and Piping Systems" for tank design details.
This appears to be the "authority" on the issue.
The pamphlet states that 15,000 gallons and above, use rubber lined steel tank, otherwise, if smaller, FRP can be used, as long as there is negligible risk of a forklift puncturing the tank, etc. ie: low traffic area... etc
Good luck//