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11.1.2. Diameter measurements of the tank must be taken at 11.3.6.Record the measurement at the appropriate place(as <br /> one or more locations on each tank or tank compartment. It is Measurement#1,#2,#3 or 44)on the Tank Installation Checklist. <br /> preferable to take the deflection measurement near the center 11.4. CALCULATION AND COMPARISON <br /> of a tank or compartment if possible. <br /> 11.4.1.To get the deflection measurement at anytime during <br /> 11.1.3.An initial measurement must betaken before installs- <br /> installation,take a diameter measurement and subtract it from <br /> tion of the tank begins.This first measurement is used as a Measurement#1. <br /> comparison reference for subsequent measurements in order <br /> to check proper backfill placement. 11.4.2.Compare this measurement to the applicable allowable <br /> deflection shown in TABLE 11-1. <br /> 11.1.4.Additional measurements must be taken:a)after apply- <br /> ing anchor straps(if used),b)after backfilling is brought to the <br /> top of the tank,c)after backfilling is brought to subgrade and Tank Diameter Allowable Deflection <br /> before placement of reinforced concrete or asphalt(if used). 4' 1i2^ <br /> 11.1.5.Measure the distance from the bottom edge of a tank 6' 3/4^ <br /> fitting to the bottom of the tank immediately below that fitting. 8. 1 Ila° <br /> 11.1.6. Described here are two methods using a dipstick to 10' 1 112" <br /> measure the internal diameter of the tank—one not using a 12, 1 3I4" <br /> standpipe and one using a standpipe. <br /> 11.1.6.1. Similar methods can be used,such as using a tape TABLE 11-1 <br /> measure,for example. 11.4.3.Vertical deflection in excess of this measurement indi- <br /> cates improper installation. <br /> 11.1.7.The deflection measurement can be obtained by using <br /> the same method twice or by using each method once. 12. BALLASTING TANKS (ADDING LIQUID) <br /> 11.1.8. For both methods,drive a small-headed,nonsparking ® WARNING <br /> nail(for example, brass)halfway into a wooden dipstick 1 inch - - <br /> above its base. Inert the tank and use inert gases(not air)to pressure test <br /> a tank that contains or has contained flammable or com- <br /> 11.2. DIAMETER MEASUREMENT WITHOUT bustible liquids or vapors. Failure to follow this warning <br /> A STANDPIPE could result in an explosion,and could result in death or <br /> 11.2.1. Place the dipstick into a service fitting. serious injury. <br /> 11.2.2. Measure the distance from the tank bottom to the top ® WARNING <br /> of the fitting and record this measurement. If flammable or combustible product is used as ballast,exer- <br /> 11.2.3. Pull the dipstick up until the exposed nail catches on cise special care in handling.Safeguard against sparks,fire <br /> the inside top of the tank. or product spills.Failure to follow this warning could result <br /> in a fire or an explosion,and could result in death or serious <br /> 11.2.4. Measure the distance from the tank top(inside)to the injury. <br /> top of the fitting.Subtract the distance from the nail to the <br /> base of the dipstick(1 inch)and record this measurement. ® WARNING <br /> 11.2.5.Subtract the second measurement(inside tank top to top The tank must be adequately vented to prevent the develop- <br /> of fitting)from the first measurement(tank bottom to top of fitting). ment of vacuum or pressure when filling or emptying the <br /> tank.Failure to properly vent the tank could cause tank fail- <br /> 11.2.6.Record the measurement at the appropriate place(as ure,and could result in death or serious injury. <br /> Measurement#1,#2,#3 or#4)on the Tank Installation Checklist. 12.1. GENERAL <br /> 11.3. DIAMETER MEASUREMENT WITH 12.1.1. In most anchoring systems,atank is not adequately <br /> A STANDPIPE protected against flotation until the tank is fully backfilled and <br /> 11.3.1. Place the dipstick into a service fitting with a standpipe. the top slab is in place.Therefore,during the installation <br /> 11.3.2. Measure the distance from the tank bottom to the top process,the tank should be ballasted completely after the <br /> of the standpipe and record this measurement. backfill is at least 75 percent of the way up the tank and after <br /> postinstallation testing has been successfully completed. <br /> 11.3.3. Pull the dipstick up until the nail catches on the inside 12.1.2.Only under wet-hole conditions should ballast be <br /> top of the tank. added before the backfill is 75 percent of the way up the tank. <br /> 11.3.4. Measure the distance from the tank top(inside)to the See SECTION 5.3. <br /> top of the standpipe.Subtract the distance from the nail to the 12.1.3.Care must be taken so that the use of ballast does not <br /> base of the dipstick(1 inch)and record this measurement. <br /> contaminate the product being stored.This is especially im- <br /> 11.3.5. Subtract the second measurement(inside tank top to portant for potable water,chemical and diesel exhaust fluid <br /> top of standpipe)from the first measurement(tank bottom to (DEF)tanks. <br /> top of standpipe). <br /> 19 <br />