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A10. Piping and Sump Clearances Al2. Filling Tanks External Piping (con't) • Take precaution during construction to make sure no damage occurs to the exposed piping and fittings. External Piping Isolate Piping from Traffic Slabs Internal Piping • Internal piping must terminate a minimum of: ❑ 4" from the tank bottom (4', 6, 8', 10' diameter tanks). ❑ 6" from tank bottom for 12' diameter tanks. Internal Piping 4'-10' I 12' Tanks Dia. Dia -Tanks 4" Min. 6" Min. A 11. Tank Fill Tube Insert • A fill tube insert must be installed at the tank gauging fitting if the manual dipstick method is used to inven- tory tanks. • This ensures the dipstick point of impact is aligned with the tank bottom protector plate. • See section A 10 for minimum clearances. • Do not fill tank until backfill is even with top of tank. • Never add product or water for hold-down in dry hole conditions until backfilling is even with tank top. • Exception - See Installation Procedure - Wet Hole - Sec- tion A9. A 13. Venting • All tanks must be vented. • Tanks are designed for operation at atmospheric pres- sure only (except for use with vapor recovery systems provided the pressure or vacuum does not exceed 1psi.) • The vent opening should be the same diameter or larger than the piping used to remove product. • For double-wall tanks, if the annular space is vented, it must be vented independently from the primary tank. • The annular space of hydrostatically monitored tanks must be vented. Pressurized Product Deliveries CAUTION: • Pressurized product deliveries are not recommended. • If the delivery vehicle uses pumps to fill the tank: ❑ Install overfill, shut-off equipment in the lines and on the truck to prevent the tank from being over- filled. ❑ Overfilling the tank under pressure will damage the tank, even if the tank vent is unrestricted. ❑ Do not use a ball float valve for overfill protection. A 14. Manway and IN/Ianway Extensions • The standard 22" manway installed in single-wall tanks ❑ Has a load bearing capacity of 1200 lbs. • Optional heavy duty manway ❑ Has a load bearing capacity of 2400 lbs. • Fiberglass heavy duty manways must be specified on tanks equipped with helical heating coils, agitators or pumps with a total downward load greater than 1200 lbs. but less than 2400 lbs. ❑ Do not exceed 50 foot pounds torque during bolt tightening or manway flange damage may occur. Note: All 30" and 36" manways installed on single-wall tanks and all manways on double-wall tanks are heavy duty. 10