This is your first tank design, correct ?
Selection of the correct design code depends on the operating pressure/temperature of the liquid contained as well as the fire protection and state statutes and laws regarding the tank design.
The design code permits only certain types of materials of construction and defines acceptable welding, fabrication, resting and inspection methods.
A competent engineer responsible for the tank design typically defines all of these things in a purchasing specification that is reviewed by and agreed to with the client.
API-650, AP-620, ASME-VIII, etc. etc and other codes are commonly specified in the purchasing specification
The term "AN Melt tank" is meaningless to the tank fabricator....
MJCronin
Sr. Process Engineer