As working sheet of the German Union of Gas and Water Specialists (DVGW), the Technical Rules for Gas Installations (TRGI) are a binding and important prescription for the concerned crafts. Hereby gas pipeworks checks are obligatory -depending on the building progess-:
- The stress test occurs during the building shell phase. The material strength and stability of the gas pipe connections are checked before plastering or coverage. A 1000 hPa test pressure is applied to the new installed pipes – without fittings and gas appliances - and checked. Air or an inert gas serves hereby as test medium. The pressure should not drop during 10 minutes. The pressure meter must have a minimal resolution of 0.1 bar.
- The tightness check is applied to test the tightness of the pipes and fittings without gas appliances being installed. The pressure should remain constant by 150 hPa test pressure and during 10 minutes at a minimum (depending on facility volume). Also in this application the pressure meter must have a resolution of at least 0.1 hPa.
- The suitability test is performed in normal operation. This check is prescribed every 12 years at heating plants acc. to TRGI. The gas loss in a heating plant can be determined in litre per hour by the instrumentation. A "leak rate" (= loss) of less than one litre is within the tolerance and the new installation will be certified usability-conform. Between one and five liters loss means a reduced usability capability and the installation must be fixed within the coming four weeks. A loss of more than five liters means the lock of the installation until it is successfully fixed. Besides the leak rate determination also the general stand of the gas pipework is ascertained within the frame of the suitability test.