Pressure and leakage tests are used to assess the completed components and are considered a part of the quality inspection. Tanks, vessels and pipe systems can all be tested. These can be customer specified tests or legally required inspections, such as the final inspection and pressure test for pressure vessels. In addition to the stability, the tightness of the weld seams and the flange connectors is verified. This can be done at the factory for pre-assembled components, or on site for complete systems.