Cast iron pipes were the basic stock when it came to the installation of urban drinking water supplies 150 years ago. With increasing requirements from users for efficiency and simultaneously increasing chemical and mechanical loads, an innovative foundry industry responded with some sophisticated solutions.
System Analysis
Once the classification of a soil had been established with the help of a type of system analysis, all that was now missing as a link to the type of protection for metallic pipelines mentioned above was a technical rule with which the aggressiveness of the soil surrounding a pipe route could be assigned to a pipe coating to match it. This was DIN 30675-2 for ductile iron pipes. In the revised version of DIN 30675-2 issued in 1993, the areas of application for the different coatings were extended to include the term anode backfill. This documented the fact that, in addition to the coating, the bedding of a pipeline is also part of the passive corrosion protection system and should be taken into account in the areas of application. DIN 30675-2 was revised for the second time in 2019.
The correct choice of external protection for ductile iron pipe systems against chemical attack in a self-contained set of technical rules is relatively simple, particularly if, when considering the local circumstances, it turns out that route is recognisably contaminated with organic admixtures.
