Valve casing filling with DENSO® KS-Mastic
Corrosion protection for gas transport and supply networks has reached a high standard these days thanks to high quality coating materials and additional active protection measures (cathodic protection). Even parts of networks with varying coating qualities, e.g. old bitumen coatings adjacent to modern synthetic ones, can have effective cathodic protection. Problems may arise in places where large defective areas overlay adjacent smaller defective areas and so make the finding and monitoring of the latter at least more difficult or in part even impossible. Such situations can be found for example with buried valves where the slide valve rods are often conductively connected with the soil through casings filled with water, which means they have the effect of a large defective area. This can appear, if the local protective voltage is measured, as a voltage drop of up to several 100 mV.
An effective option for avoiding this problem is the filling of the valve rod casing with a petrolatum-based permanently plastic corrosion protection mastic. Petrolatum corrosion protection tapes and fillers have been used for more than 80 years for the coating of buried pipelines and components and ever since have been proved to have good corrosion protection qualities. Although in the meantime modern synthetic materials have come onto the market, for example in the form of synthetic tapes, displaying far greater mechanical stability than petrolatum materials, the latter have nonetheless retained their position in their areas of use thanks to their application characteristics. Also, today they even find new applications where the combination of proven corrosion protection quality combined with easy application is required. In corrosion protection, the filling of valve casings is such an area of use.