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Recommended Practices for Installation of Underground Liquid Storage Systems <br /> 4o P Q D P a D C •D. o D o 6o D D D O Q P <br /> a G G a C � o G p a <br /> paving <br /> D c7 p. p V p D p D <br /> e, D D p D � D � a o, o D o e• �' D p e, n C p e. <br /> . . . . . . . . . . . . . . . . . . . <br /> Shear <br /> is . . . . . p section;' ' ' '. . . . . . . <br /> . . . . . ' • . . .Ma . . . . D a a' ' ' ' ' '. . . �i <br /> S r <br /> r G O C <br /> >7 . . . c <br /> •��;icHc G p 6 c � D p i <br /> f 6 -4—i� — cam= Er <br /> s P c o c 0 <br /> .'. . . . <br /> wnl .'. . . . . . . . . . . . - - - •.�"•td�.�-•'moi b. 4 G O o G <br /> All dimensions in inches <br /> sc_s_ n a :,r._ . Kh'Ei. .,4»c <br /> S 1 <br /> 1 <br /> Figure 26.Trench dimensions.Pipe trenches must allow <br /> adequate clearance and cover to protect piping and coatings <br /> from physical damage.Backfilling and compaction <br /> requirements are the same as for tank excavations. Two-inch <br /> pipe is illustrated For other sizes, use twice the pipe diameter Figure 27.Emergency shutoff valve. In case of fire or collision, <br /> between pipes. the emergency shutoff valve stops the flow of fuel. Install the <br /> shear section level with the top of the dispenser islands. Do <br /> 1. Inspect all piping materials prior to installation not obstruct moving parts. Securely anchor the valve. <br /> to detect damage caused by shipping and han- <br /> dling and to confirm compliance with specifica- bottom. Measure this distance for each pipe and <br /> tions.Handle piping carefully at the jobsite, and tank carefully. Also, verify the length of sub- <br /> place it carefully into position. mensible pumps,and monitor and gauge probes <br /> 2. Provide adequate clearance between piping and before installing. <br /> trench walls,electrical conduit,monitoring wells, 9• Do not remove dielectric bushings.Take care to <br /> utilities, nearby structures, and other system avoid cross-threading. <br /> components. 10.Install pumps,check valves,impact valves,flex- <br /> 3. If crossing of lines is unavoidable, provide ible connectors, overfill devices, gauges, moni- <br /> adequate clearance to prevent contact. Consult toring systems,and other system components in <br /> manufacturer's instructions for the minimum accordance with manufacturers' recommenda- <br /> clearance required for the type of piping being tions. <br /> installed. 11. Ensure that the submersible pump and attached <br /> 4. Avoid damage to piping materials or coatings piping are free to move with the tank and are <br /> during handling, installation,testing,and back- separated from the traffic slab with a street box to <br /> filling. prevent damage from settlement. <br /> s <br /> 5. Keep pipe;as well as fitting interiors and threads, 12. Use extractor fitting.. at tank connections to <br /> free from dirt, corrosion, moisture, and debris. facilitate future testing_ <br /> 6. Exercise care to accurately measure and cut pipe 9.6 Piping Requirements:Metallic Piping.The mini- <br /> to avoid the failure that can occur when pipe mum standard for metallic product piping should be at least <br /> fittings are installed under stress. Schedule 40 factory-wrappedlcoated black steel pipe,with <br /> 7. Use a pipe sealant (dope or cement) that is comparable malleable iron or steel screw-type fittings and <br /> compatible with the piping materials and the extra-heavy couplings.The following constitute elements <br /> product being handled on tapered thread joints. of good practices for metallic piping systems. <br /> Wrap ribbon dope with the threads to avoid 1. Protect all piping from physical damage with <br /> bunching during tightening. Follow the nonconductive material at any point where it <br /> manufacturer's preparation and application in- passes through pavement and structures. <br /> structions, giving proper attention to tempera- 2. Inspect pipe-cutting dies frequently and replace <br /> ture and moisture condition limitations. when worn. Threaded metallic piping depends <br /> 8. Avoid damage to the tank bottom. Cut suction on a liquid-tight,metal-to-metal seal to prevent <br /> and fill lines to allow for at least 4 inches and no leaks. Dull dies may extrude or tear threads, <br /> more than 6 inches clearance from the tank making a tight seal impossible. <br /> 19 <br />