DEROUGING & DEBLACKING
preventive maintenance for controlled surfaces
and long-term value retention
Surface corrosion often occurs during operation in high-temperature ultrapure media systems. The combination of demineralized ultrapure media such as WFI and PW or ultrapure steam in conjunction with high temperatures in contact with the surface of the stainless steel causes degradation of the corrosion-protective chromium oxide-rich passive layer. To the same extent, iron oxide-dominated layers build up in hot-operated ultrapure media systems.
Extensive reddish-brown deposits in liquid ultrapure media systems are referred to as rouging, while extensive purple-black deposits in ultrapure vapor systems are referred to as blacking.
Both corrosive deposits prevent the repassivation process of stainless steel, resulting in micro-roughening and the emission of particles. While rouging deposits can usually be easily wiped off, blacking deposits often adhere firmly because they involve deep morphological changes.
During derouging Corrosive red-brown deposits are chemically converted and safely removed without damaging surfaces. This enables permanent repassivation of the stainless steel. Acidic or pH-neutral chemicals are used for this purpose.
• Processes are carried out at high temperatures or at ambient temperature
• Use of minimal volumes of chemicals; containers and systems do not need to be flooded
• Can be done in circulation or segment by segment
• Use of CIP systems possible on site
• Chemicals/rinse water can optionally be disposed of on site.
• Processes can be repeated as often as desired without roughening the surface
• Chemicals compatible with all common plastics
• Regular monitoring of representative control points determines the optimal timing.
During deblacking Corrosive purple-black deposits are chemically converted and removed. This usually requires the use of acidic chemicals.
• Processes are carried out at high temperatures
• Use of minimal volumes of chemicals; containers and systems do not need to be flooded
• Can be done in circulation or segment by segment
• Chemicals/rinse water can optionally be disposed of on site.
• Chemicals compatible with all common plastics
• Wide range of process parameters: temperature, medium,
Concentration and time prevent over-pickling and critical
Gas emissions Please align paragraph flush with bullets
Globally active companies trust in our partnership-based monitoring concepts with foresight. Together, we define representative control points in your production facilities. This guarantees that the condition of your surfaces is always documented in real time, that process deviations are classified, and that you are well prepared for the next audit. It enables the implementation of preventive maintenance strategies with the aim of minimizing production downtime and ensuring the long-term value retention of your equipment.
If process deviations are detected early on, they can often be remedied without much effort.
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