Hydraulic Diagnostic Kit for the Automatic Expeditious Survey of in-line Valve Sealing in Long, Large Diameter Transmission Mains

In long transmission mains (TMs), maintenance operations and repairs often require the preliminary closure of some of the installed in-line valves. If perfectly sealed, these valves avoid leakage and then the possible emptying of the pipelines, air entry through leaks, and the successive unwanted transients at the filling completion. The poor accessibility of TMs makes the check of the valve sealing quite difficult since in most cases the confined space where they are installed implies the adoption of severe prevention measures. Therefore, expeditious and possibly remote survey procedures are strongly required by pipe system managers. In this paper, an innovative technique based on the execution of safe transient tests is proposed. It is tested on the Dorsale TM – a long, large diameter pipe system – in the northeast of Milan, Italy, where the sealing of three in-line valves had to be checked. The analysis of the test results allows pointing out successfully not only the valves sealing, but also refining a quick and reliable procedure – the so called “diagnostic kit” – that leads the way to automatic and periodic checks of the valve sealing. In the proposed procedure – that can be straightforwardly exported to other TMs – only a single pressure measurement section is required, that significantly simplifies the survey.