API STD 2015:2018

API Std 2015 is applicable to stationary atmospheric and low-pressure (up to and including 15 psig) aboveground petroleum storage tanks used in all sectors of the petroleum and petrochemical industry, including: crude oil and gas production; refining; petrochemicals; pipelines and terminals; bulk storage and ethanol facilities. This standard provides requirements for safely planning, coordinating, and conducting tank entry and cleaning operations, from removal from service through return to service. Specific topics covered include:
storage tank hazards (oxygen deficiency/enrichment, fires/explosions, toxic substances, stress exposures, and physical hazards);
vapor/gas freeing, degassing, and ventilating;
sludge and residue removal;
unique tanks (>200 ft diameter, double bottoms/walls, low-pressure tanks, and conservation tanks);
iron sulfide, hydrogen sulfide, lead, and hazardous waste;
control of ignition sources;
air monitoring equipment; and
floating roof hazards.
This standard does not and cannot cover every possible hazard or situation that may arise during tank cleaning operations. Site-, product-, and tank-specific hazards and situations must be addressed by employers using the appropriate principles and considerations provided for by this standard.