scope:

This standard provides safety practices for preparing, emptying, isolating, ventilating, atmospheric testing, cleaning, entry, hot work, and recommissioning activities in, on, and around atmospheric and low-pressure (up to and including 15 psig) aboveground storage tanks that have contained flammable, combustible, or toxic materials. This standard directs the user from decommissioning (removal from service) through recommissioning (return to service). This standard applies to stationary tanks used in all sectors of the petroleum and petrochemical industry, including crude oil and gas production, refineries, petrochemical plants, and terminals.

Appendixes which provide additional guidance on specific aspects of tank preparation, emptying, isolation, ventilation, atmospheric testing, cleaning, entry, hot work, and recommissioning activities are included as follows:

Appendix A--Description of Petroleum Storage Tank Hazards

Appendix B--Vapor Freeing the Tank

Appendix C--Control of Ignition Sources

Appendix D--Tank Cleaning Precautions and Procedures for Specific Tank Designs and Products

Appendix E--Planning Checklist

Appendix F--Oxygen and Flammable Vapor Analyzers

All appendixes are offered as guidance and do not form a part of this standard.

This standard does not apply to the following types of tanks or vessels:

a. Pressure vessels exceeding 15 psig.

b. Cryogenic or refrigerated tanks.

c. Vessels maintained under a vacuum.

d. Process vessels.

e. Underground storage tanks.