Scope and field of application This publication describes those procedures and precautions which are considered good practice for gas freeing@ entry into@ cleaning and exist from no portable atmospheric and pressurized petroleum storage tanks. This publication does not apply to refrigerated storage. Purpose The purpose of this publication is to set forth those practices which@ by general consensus@ are considered necessary for the safety and health of personnel@ and the prevention of property damage. It is recognized that circumstances will determine the specific application of the procedures described. The practices herein are intended as a guide for personnel engaged in these activities.