In pharmaceutical manufacturing, 'rouging' describes the development of colored deposits on stainless steel equipment and piping. This discolouration occurs when iron oxides form due to corrosive conditions, particularly in systems handling purified water, water for injection (WFI), and clean/pure steam, where maintaining surface integrity is paramount for product quality and regulatory compliance.
This process is accelerated by several factors, including elevated temperatures, variations in flow rates, and the presence of dissolved gases.
Rouge formation, what is it?
Rouging is a very thin film of iron oxide, typically reddish-brown in colour, and is particularly common in pharmaceutical facilities where stainless steel equipment operates at high temperatures.
The oxide particles pose a significant risk as they can circulate throughout the water distribution system and potentially accumulate on various system components. This contamination risk extends to critical production equipment such as mixing vessels, their piping systems, and ultimately it may compromise finished product quality. Therefore, it is essential to take preventive measures to minimise the risk of contamination throughout the production chain.
The problem related to rouging surfaces
Rouging in stainless steel systems presents multiple challenges that impact both equipment performance and product quality. Some of the most common problems associated with rouging are:
- Deterioration of the surface finish: affects crucial components like pumps and instruments.
- Breakdowns and malfunctions: rouge can cause failures in critical components such as pumping units, instrumentation, and so on.
- Contamination of water, manufactured products, and sterile systems.
- Increased costs due to maintenance caused by the corrosion of surfaces.
The comprehensive understanding and proactive management of rouging is crucial for maintaining operational efficiency, ensuring product quality, and controlling maintenance costs in pharmaceutical manufacturing.
How many typologies of rouging are there?
There are three main classes of rouging, which vary in resistance/adhesion to surfaces and in removal difficulty:
- Class I: the most common type and also the easiest to remove, presenting as a non-adherent oxide that migrates within the system. It doesn’t affect or interact with the surface and can be easily removed with a cloth.
- Class II: stronger adhesion than the previous type, it interacts with the stainless steel surfaces, requiring a chemical removal treatment.
- Class III: characterised by a blue, black or a dark purple colour, this type has the strongest adhesion of all. It can only be removed by chemical treatment.
Our derouging offer
At Veolia, we offer an effective derouging service in four steps. First, we conduct a customised technical inspection of your facilities to identify possible rouging issues. If detected, we develop a tailored action plan that addresses your specific needs and challenges. Our services encompass the use of pH-neutral derouging processes to minimise the risk of corrosion and damage to your equipment. We also provide ongoing support through optimized cleaning schedules, monitoring, preventive maintenance, regular system health checks, and cleaning interval optimization. This proactive approach maintains system integrity, extends treatment intervals, and prevents product quality issues.
Our industry specialists in stainless steel system maintenance, recognise the crucial importance of system integrity, particularly in pharmaceutical, cosmetic, and biotechnology applications. The professional service that we offer, provides customised solutions based on each facility's unique requirements, ensuring optimal results through personalised treatment approaches and industry-specific expertise.
