How to avoid contact corrosion on stainless steel pipe systems

The risk of contact corrosion can be eliminated already in the planing and construction phases. In the example of a drinking water storage tanks a connection by flanges connecting two different materials with each other should be made in the valve chamber, where an external moisture effect is minimized. Furthermore it is recommended to carry out an electrolytical separation of both the flanges as is shown in the picture at the right.

This happens through the seal "A" which should be present in any case and which may not contain a steel insertion or any graphitic portions! Additionally, the stainless steel screws have to be included into this electrolytical screening. Since cast iron or galvanised flanges are to be classified as lower-grade metals, the material decrease, i.e. the corrosion, will always occur on these items. Using plastic cases and washers that are pushed onto the stainless steel screws, corrosion can be avoided!

For these special cases, HUBER offers standardized solutions. Flange connections for the purpose of electrolytical separation are used especially for renovations, e. g. with elevated reservoirs or sewage treatment plants, where new stainless steel pipe line systems are flanged onto existing, concrete-embedded in- or outflow pipes made out of cast-iron or steel. The particular necessary components of these "electrolytical separation sets" are exactly defined by the specification of different data as for example by the DIN-specification of both flanges, or the diameter. A corresponding "DN 200 - separation" contains all necessary screws, nuts, seals, plastic cases and washers as well as stainless steel washers.

These sets can be delivered at short notice for most diameters! A secure "functioning" of such a connection naturally requires a skilled assembly at the construction site as can be carried out by HUBER mechanics!