UL 142-2019 pdf free download

UL 142-2019 pdf free download.Steel Aboveqround Tanks for Flammable and Combustible Liquids.
42.2 Primary containment tanks
42.2.1 The leakage test is to be conducted before painting the tank by a method described in (a) — (b). There shall be no evidence of leakage or sign of permanent deformation following the leakage test. If subjected to a leakage test pressure, the tank wall, head, or roof may deflect but shall return to its original position and shape when the test pressure is released.
a) Apply internal air pressure and use soap-suds, or equivalent material for the detection of leaks. For a horizontal tank, the test gauge pressure is to be not less than 3 psi (21 kPa) or more than 5 psi (35 kPa). For a vertical tank, the test gauge pressure is not to be less than 1-1/2 psi (10 kPa) nor more than 2-1/2 psi (17 kPa) or that gauge pressure above 1-112 psi which first causes visible deformation of the tank. For a rectangular tank, the test gauge pressure is not to be less than 1-1/2 psi (10 kPa) nor more than 3 psi (21 kPa) or that gauge pressure above 1-112 psi which first causes visible deformation of the tank: or
b) Completely fill the tank with water, applying the pressure specified in (a) hydrostatically, and examine the tank for leakage.
42.2.2 Each compartment of a tank having two or more compartments is to be tested separately for leakage
42.3 Secondary containment tanks
423.1 After completion of the primary containment shell, the tank is to be checked for leakage using the method described in 42.2.1 and 42.2.2 for pnmary containment tanks.
423.2 Upon completion of the finished secondary containment tank, the primary tank is again to be pressurized using the applicable method described in 42.2.1 – 42.2.2. For Performance Tests. the pressure shall be held for 1 hour to check For leakage. A continuous drop in pressure will be considered evidence of leakage. For production testing. the pressure shall be held in the primary tank only for the duration required to test the interstice using the method described in 42.3.3.
42 3.3 While maintaining pressure on the primary tank, the interstitial (annular) space bounded by the primary and secondary tank is to be pressurized to the pressures indicated in 42.2.1 and checked for external leakage by applying a leak detection solution. There shall be no evidence of leakage or sign of permanent deformation following the leakage test A tank wall, head, or roof may deflect when subjected to the leakage test pressure, but shall return to its original position and shape when the test pressure is released
42.3.4 As an option to the leakage test described in 42.3.2 and 42.3.3, the annular space may be tested by applying a vacuum of at least 13 inches of mercury for a minimum of 12 hours. If the tank is unable to maintain the vacuum (plus or minus 2 inches of mercury) for the specified time, the tank shall be retested using the method descnbed in 42.12 and 42.3.3.UL 142-2019 pdf free download.