The leak test (or more aptly, serviceability test, also known as leakage measurement) for the pipeline system is to be repeated every 12 years using a measuring instrument and recorded in a test results report. The operator thus has a technical expert report. Some buildings insurers include these inspections and certificates/reports in their general insurance terms. For the serviceability test or leakage measurement, the gas pipe is always tested in operating conditions/with operating pressure (no increased test pressure). During this test, a measuring instrument detects whether gas is leaking from the pipe and how much.