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5. PIPING SECONDARY CONTAINMENT INTEGRITY TESTING 5.1 General. Underground product piping is available with single and double walls. Double-walled piping pro- vides containment for leaks from primary containment and must be leak-free to prevent release of product into the environment. 5.2 Purpose. This method is used to test the integrity of piping interstitial space(s). 5.3 Testing Piping Under Pressure. 5.3.1 Description of Test. The interstitial space is sealed at the ends arid is pressurized with an inert gas. The pressure is monitored for I hour. If any pressure drop occurs, the secondary containment fails the test. 5.3.2 Test Conditions. The primary pipe may contain fuel, and dispensing activities may con- tinue during the test without affecting test results. 5.3.3 Preparation. If the interstitial space con- tains product, ensure that the interstice is open to the atmosphere and perform a precision test on the primary piping before conducting a test on the sec- ondary containment piping. FIGURE 5-1. Boots on pfoing transttions and through sump wails must be leak-tight when piping secondary containment integrity testing is performed. PEI/RP1.200 17 Termination fittings must be sealed at all piping terminations, and test fittings must be accessible to perform the test. Check with the piping manufacturer regarding testing procedures and the proper pressure before testing. Testing requirements stated in this recom- mended practice are general statements and may vary. Recommended pressure levels and test dura- tions are addressed in Section 5.3.5. Piping manu- facturers' test procedures may differ. This test can be conducted in sections or as one continuous pipe depending on the installation. Care should be taken to ensure that the entire secondary containment of the piping system is tested. 5.3.4 Test Equipment. Test equipment shall include: inert gas source (nitrogen, helium, etc.); stopwatch or other time-measurement device capable of measuring a 1-second increment; test tubing assemblies (Tubing assemblies pro- vide access to the beginning and end of the interstitial space.); pressure gauge with a 15 psig maximum pres- sure reading with 0.5 increments. 5.3.5 Test Procedure. I.. If necessary, re-install termination (test) boots at piping terminations. If necessary, connect the tubing assemblies to the secondary containment termination fitting on each end of the section of piping to be tested. Connect the inert gas source and pressure gauge. Gradually pressurize the interstitial space to 5 psig. Close the valve and allow the pressure to stabilize. Repressurize to the specified test pres- sure if necessary. Observe the pressure for a period of 1 hour. If the piping pressure after I hour is less than the test pressure, check termination fittings and test assemblies for leaks. Release the pressure on the system slowly. Remove the test equipment. Restore the piping to its normal operating conch- :ion. pei.org