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0 0 <br /> 42 API RECOMMENDED PRACTICE 1646 <br /> cathodic protection). Cathodic protection can also be achieved by passing low levels of electrical charge through specially <br /> designed and installed anodes(active or"impressed current"cathodic protection). <br /> 14.6.3 Dielectric Fittings <br /> Bungs or holes in the tops of many steel tanks where various components are attached have special fittings to prevent the compo- <br /> Dents from coming into electrical contact with the UST.This allows the tank's corrosion protection system to work properly. <br /> 14.6.4 Other Corrosion Considerations <br /> 14.6.4.1 Electrical Shorts <br /> Care shall be taken when working around steel USTs to assure that no electrical conduits or other metal components touch the <br /> outside of the tank.This may cause the cathodic protection system to become inoperable. <br /> 14.6.4.2 Dissimilar Metal Corrosion <br /> Some metals may corrode merely by being in contact with other metals having different chemical compositions.An example of <br /> this is steel and copper.Care should be taken to avoid this type of corrosion of parts used in the construction and repair of UST <br /> systems. <br /> 14.7 LIFTING AND SETTING STORAGE TANKS <br /> Please see API Safe Work Practice for Lifting and Hoisting. USTs shall only be lifted or hoisted by using their lifting lugs as <br /> attachment points for a properly designed hoisting sling.If control lines are needed,they shall be in place before the lift begins. <br /> 14.8 ATMOSPHERIC HAZARDS OF GASOLINE VAPORS <br /> Gasoline presents three common atmospheric hazards; <br /> 14.8.1 Explosive/Flammable <br /> Workers shall not enter or remain in an area where an explosive/flammable atmosphere over 10%of the Lower Explosive Limit <br /> (LEL)is present <br /> 14.8.2 Oxygen Depleted Atmosphere <br /> 14.8.3 Workers may not enter or remain in an area where there is less than 19.5%or more than 23.5%oxygen in the atmo- <br /> sphcre <br /> 14.8.4 Toxic Substances <br /> Workers may not enter or remain in an area where levels of toxic substances such as benzene or hydrogen sulfide are greater than <br /> allowed by federal,state or local requirements. <br /> Each of these types of hazards are readily detected by air testing meters <br /> 14.8.5 Buildup of Vapor <br /> Care shall be taken when working around the following components,as gasoline vapors may buildup in these areas: <br /> • Sumps and man ways. <br /> • Inside electrical conduits.All conduits at a petroleum/convenience site should be sealed at each end to prevent vapors from <br /> being transmitted. <br /> • In and around fill pipes and vapor connections. <br /> • Around vent stacks. <br /> Anywhere residual gasoline liquid may accumulate. <br /> 14.9 RETURNING FUEL TO STORAGE TANKS <br /> To minimize a static charge concern,petroleum products from maintenance operations(e.g. pump calibration)shall not be dis- <br /> pensed into,nor carried in a plastic container.All fuel shall be dispensed into and carried back to the UST in a metal container. <br /> While dispensing fuel the metal container shall be in contact with the pavement or ground at all times.When returning petroleum <br />