Derouging & passivation

Formation of rouge

Auxiliary and secondary equipment in the pharmaceutical and biotechnology industries such as tube systems for clean water (AP, PW, HPW, WFI, etc.), production destillers, storage tanks, clean steam systems, clean steam generators, autoclaves and dry freezers usually consist of austenitic stainless steel (e.g. 1.4404, 1.4435, 316L, etc.).

After operating periods of 6 – 12 months, the inner surfaces of these systems often show red-brown, rusty surface contamination, which can be detected with a white cloth test. These are usually heavy metal particles resulting from a change in the stainless steel surface, so-called rouging.

Downstream production systems such as fermenters, batch and mixing vessels, together with their tube systems, are contaminated by the spread of the rouge particles. Even with the regular CIP cleaning of these systems, the heavy metal particles cannot be cleaned.


Expert removal of rouging, i.e. derouging, is possible through targeted cleaning measures. Such operations should be planned in the long term. Optimised cleaning methods in conjunction with active rouge monitoring allow for ratios that correspond to effective rouge avoidance.

On-site work is carried out by our specially trained teams for the GMP-relevant area.

Only state-of-the-art equipment and safety technologies are used. The cleaning chemicals are specially developed for use on sensitive pharmaceutical production plants. All work is thoroughly documented and the rinsing water produced is processed in an environmentally responsible and professional manner with certificate.

Bioderouging and biopassivation

Apart from the well-known electrochemical processes, in recent years purely chemical processes and chemicals have also been consistently developed due to corresponding demands of the users.

The new bioderouging solutions are aqueous organic salt solutions in a pH range between 6 and 8. Depending on the nature and intensity of the present rouge deposit, the pH-neutral solutions will be between 1 and 10% by weight
applied at 40-85°C over 1-10 hours.

The practical application on site is such that the tank/tube system to be derouged is filled with the solution and heated or the tube system is recirculated. Discharge into a biological sewage treatment plant after consultation with the person responsible for discharge is possible without further pretreatment.


Known appearances of rouging are removed securely
Disposal of the derouging solutions is more economical
Neutralisation of the rinse water is no longer required.

Available HENKEL chemicals for bioderouging:

  • Bioderouging solution HC 4200
  • Biopassivation solution HC 4000.

Our services

  • Plant/system inspection
  • Electrochemical derouging
  • Chemical passivation
  • Chemicals produced in accordance with GMP
  • Documentation of process in accordance with GMP
  • Expert processing of waste chemicals and chemical solutions.