Formation of rouge
Auxiliary and secondary equipments in the pharmaceutical and biotechnical industries such as tube systems for clean water (AP, PW, HPW, WFI, etc.), production destillers, storage tanks, clean steam systems, clean steam generators, autoclaves, lyophilisators usually consist of austenitic stainless steel (e.g. 1.4404, 1,4435, 316L, etc.).

After operation times of 6 – 12 months the internal surfaces of these systems often show reddish brown, rust coloured surface contaminations which can usually be verified when wiping with a white cloth. It normally concerns heavy metal particles which result from a change of the stainless steel surface the so called rouging.

Connected production systems such as fermenters, batching tanks, mixing vessels and tube systems are then contaminated in undesired form by displacement of the rouge particles. Even by regular CIP-cleaning of these systems the heavy metal particles cannot be removed.

Professional removal of rouge – derouging – is possible with specific cleaning measures. Such operations should be planned for the long-term. With optimized cleaning processes in connection with active rouge monitoring conditions can be achieved that correspond to factual rouge prevention.

On-site operations are carried out by our service teams which are specialized for working in GMP-relevant areas. Latest equipment technique and safety engineering is being applied. The cleaning chemicals have especially been developed for operations in sensitive pharmaceutical productions. All works are fully documented and accruing waste water is conditioned ecologically and professionally with certificate.

Bioderouging and biopassivation

Besides the well-known electrochemical processes also the sole chemical procedures and chemicals have consistently been enhanced following customers respective demands.

The new bioderouging solutions are diluted organic saline solutions in a pH-range between 6 and 8. Depending on the nature and intensity of the rouge contamination the pH-neutral solutions are applied between 1 and 10 w/w-% at 40 …85°C for a period of 1…10 h.

The appliance on site is carried out by filling the vessel/tube system with the solution and heating it respectively recirculating the system. The pumping into a biological purification plant, after consultation with the responsible person is possible without any further pretreatment.


  • Κnown rouge appearances are removed securely
  • Τhe disposal of the derouging solution is cost-saving
  • Α neutralization of the rinsing water is no longer necessaryη

Available HENKEL chemicals for bioderouging are:

  • HC 4200
  • HC 4000 (Biopassivation Solution)