This specification covers material@ design@ fabrication@ erection@ and testing requirements for vertical@ cylindrical@ above-ground@ closed and open-top@ welded steel storage tanks in various sizes and capacities@ for internal pressures approximating atmospheric pressures but in no case exceeding the weight of the roof plates. This specification is designed to provide the oil industry with tanks of adequate safety and reasonable economy@ for use in the storage of petroleum and its products and those other liquid products commonly handled and stored by the various branches of the industry. It does not present@ nor is it contemplated to establish@ a fixed series of allowable tank sizes; but rather it is intended to permit the selection by the purchaser of whatever size of tank may be required to best meet his particular needs. Appendix A to this specification presents for ready reference design data relating to tanks which may be built under this specification. The data presented therein are for convenience and are not mandatory. Nothing contained in this specification is to be construed as granting any right@ by implication or otherwise@ for manufacture@ sale@ or use in connection with any method@ apparatus@ or product covered by letters patent@ nor as insuring anyone against liability for infringement of letters patent. Compliance. The manufacturer is responsible for complying with all of the provisions of this specification. The purchaser may make any investigation necessary to satisfy himself of compliance by the manufacturer@ and may reject any material that does not comply with this specification. It is urged that the purchaser avail himself of this right and furnish his own inspection independently of any supervisory inspection furnished by the manufacturer@ and that the purchaser inspector follow closely all of the details of field construction and testing herein specified@ which affect the integrity and safety of the completed structure.