UL 142-2021 pdf free download.Steel Aboveground Tanks for Flammable and Combustible Liquids.
3.3 ATMOSPHERIC TANK — A storage tank that has been designed to operate at pressures from — 0.5 psig to 1.0 psig (— 3.4 kPa to 6.9 kPa) measured at the top of the tank.
3.4 DIKE — A single wall construction forming a bottom and sides with open or dosed top intended to provide secondary containment of aboveground tank(s) but not intended to be pressurized for leak testing. Dike types include combinations of rectangular or cylindrical shapes or horizontal or vertical orientations, Open top dike constructions do not have covers to prevent precipitation or debris from entering the dike area. Closed top dike constructions have covers to resist precipitation or debris from entering the dike area.
3.5 DIKED TANK — A primary or secondary containment tank within a steel open or closed dike intended to provide at least 110 percent containment capacity of the primary tank(s) and spill containment.
3.6 EMERGENCY VENT — A storage tank opening or device that automatically relieves excessive internal pressure due to an external fire exposure or blockage of the normal vent.
3.7 INTERSTITIAL SPACE (ANNULAR SPACE or INTERSTICE) — A space between the walls of a multiple wall tank that is capable of communicating fluid from a leak in an adjacent wall to a collection point for monitoring.
3.8 NORMAL VENT — A storage tank opening or device that automatically relieves internal pressure or vacuum during normal storage (atmospheric pressure equalization) and during normal operations (fill or withdraw). Normal vents are designed so as not to exceed 1.0 psi9 (6.9 kPa) pressure and minus 0.5 psig (minus 3.4 kPa) in the tank.
3.9 PERFORMANCE TESTS — A complete evaluation conducted on a limited quantity of representative tanks. These tests are intended to verify compliance with all applicable performance requirements in a standard.
3.10 PRIMARY CONTAINMENT — The ability of a tank design and construction to contain a liquid while in normal use.
3.11 PRIMARY CONTAINMENT TANK — The wall of a tank construction that provides primary containment.
3.12 PRODUCTION TESTS — A limited evaluation conducted on each tank prior to shipping. These tests are intended to verify compliance with production requirements in a standard, such as leakage.
3.13 SECONDARY CONTAINMENT — The ability of a tank design or construction to contain a liquid only in abnormal use (from primary containment leakage or rupture).
3.14 SECONDARY CONTAINMENT ABOVEGROUND TANK FOR FLAMMABLE LIQUIDS – A primary containment aboveground tank contained within a steel secondary containment shell forming an interstitial (annular) space, which is capable of being monitored for leakage into the space from either the interior or exterior walls. Secondary containment aboveground tank types include: horizontal cylindrical, vertical cylindrical, and rectangular.UL 142 pdf download.