General

Spent sulfuric acid, generated by refinery alkylation units (spent acid), may differ from fresh sulfuric acid (fresh acid) in several ways. The most notable differences between alkylation unit fresh acid and spent acid are the acid concentration, water content, possible contaminants from the alkylation process, temperature of the spent acid entering the tank from the alkylation unit, and the presence of dissolved hydrocarbons and hydrogen. These differences must be taken into consideration when developing inspection strategies, setting inspection intervals, conducting an external inspection, and/or internally inspecting a tank that is in spent sulfuric acid service. This standard was developed to address these differences between fresh acid and spent sulfuric acid as they may have an impact on the integrity of spent sulfuric acid storage tanks.

NACE Standard RP0294 shall be followed for all aspects of spent sulfuric acid storage not covered by this standard.

This standard presents additions to and deviations from NACE Standard RP0294 that apply to alkylation unit spent sulfuric acid storage.

HF alkylation unit spent acid is not within the scope of this standard.