In search of the rehabilitations of the natural gas steel network valves and vaults exposed to corrosive effects

Natural gas is a combustible, odourless, colourless, lighter than air and enviromentally friendly. On top of these properties, there are potential dangers associated with natural gas usage, like explosion an uncontrolled combustion if gas leakeage occurs. On the natural gas steel network, these valves have been built under the ground like a concrete room named vault to give a spacious place for the natural gas maintenance technicians to work easily to shut down the flowing when the emergency case occured. The natural gas valve vaults may be on the main streets, streets or in the local park.In this study, firstly exists different city distribution companies natural gas valve vaults studied and inspected which are easy water entered and badly corroded. Entering water to the valve rooms especially in the rainy days was seen from the manhole covers, room walls, ventilation pipes, floor, pipe and wall connection places. Water filled natural gas vaults were drained by helping sewage trucks or automatic controlled pumping systems. Sometimes the valves stayed with penetrated water inside the vaults for a while for the reason of frequently entering water, due to this reasons, valves can be so dirty and muddy. Inside the vaults because of the extremely highness value of moisture and humidity, condensation has been continuously occurring, at the ceiling. These places are very suitable for the corrosion evolving. In many valves were detected crevice corrosion, filiform corrosion, uniform corrosion and pitting corrosion. Somewhere on the valves due to pitting corrosion metal lost severity has arrived 2-2,5 mm.After the widely inspection of the sector standarts, these are ASME PCC-2 ve ASME B31G, which are thought as an important information source, were given alternative applicable solutions, especially for the pitting corroded pipes and valves which had suffered metal losts . One of the innovative solutions is fiber carbon composite wrapping seems the best application because of its easy, quick and cheap properties. In addition, it was given solutions to prevent entering water to the natural gas valve vaults.