Anti-Corrosion Protection

Anti-corrosion protection

Outdoor steel constructions like bridges, pylons, tanks or pipelines will corrode sooner or later if they are not protected appropriately. Consequently, protective zinc coatings (galvanization) or anti-corrosion paints are applied in order to prevent rusting.

Large quantities of problematic and hazardous substances were used for such anti-corrosion purposes, for example PCBs, CPs, PAHs, lead, zinc and chromium. These pollutants can find their way into the environment if the coating is damaged or not maintained and treated in a sound manner.  

Grinding and water-jetting obviously release a great amount of particles and flakes of paint. Coatings can also be affected by weathering and thus have an impact on the environment, watercourses and surrounding land. 

Consequently, it is important that BAT/BEP measures are taken whenever outdoor works are performed on anti-corrosion coatings. Of course, this also applies to maintenance work carried out inside buildings or plants.

Risk for the environment

Industrial paints and coatings have a long operational lifetime of perhaps 40 to 60 years if they are maintained at regular intervals. Such maintenance work can pose real challenges, because it should be economical, sustainable and environmentally sound at the same time. Not only can maintenance have an adverse impact on the environment, but also affect human health and safety. If maintenance is not carried out professionally, it must be assumed that large amounts of pollutants are unintentionally released, resulting in a contamination of the surrounding soil, water and air.

As one example of many, high concentrations of PCBs were measured in the water of the river Spöl in the Swiss National Park, after several kilometres of the river had been contaminated with PCBs during remediation and renovation works in a hydro power plant in 2016. Due to abrasion, there had been a contamination of the river even before the incident in 2016. The challenging clean-up of the river Spöl shall commence in the coming years. The estimated clean-up costs as of 2019 are over CHF 15 million and due to its location, three countries are involved with Switzerland and neighbouring Austria and Italy.

The concentration of hazardous substances in anti-corrosion coatings can be enormous. Unfortunately, owners and contractors are not always aware of this circumstance, and thus the problem is still not sufficiently addressed in Switzerland, although there are specific regulations and guidelines in place.

Diagnostics

Maintenance work on materials with anti-corrosion coatings has to be planned very carefully.

Thorough checking, sampling and analysis of the materials prior to the start of the work will enable the owner or the contractor to take appropriate measures and precautions and to prepare a waste management plan for the arising wastes. 

In particular, coatings which were applied or renewed between 1945 and 1983 have to be tested for PCBs. Also CPs, which were used to replace PCBs, should not be excluded from the screening. CPs are persistent organic pollutants and have a similarly negative impact on the environment. They are however not as acutely toxic as PCBs. Moreover, the concentration of many heavy metals must be analytically determined, for example zinc (Zn), lead (Pb), mercury (Hg) and chromium VI (CrVI). Based on the analysis results, precautions for the maintenance or remediation can be defined, and taken.

Remediation or decontamination of steel components

Even if precautions are taken, such as enclosure of the working area, appropriate chemical, physical or mechanical treatment of the coatings or exhaust air purification, emissions into the environment can still occur.

Therefore, only an early, professional and careful planning can guarantee a BAT/BEP remediation and an environmentally sound disposal of wastes like filter dust and blasting material.

Swiss guidelines and laws

The following guidelines are available in German, French and Italian.

- Umweltschutz bei Korrosionsschutzarbeiten
- Korrosionsschutz im Freien
- PCB-Emissionen beim Korrosionsschutz