Our own observations show that

• rouging formation increases with the increasing temperature of the water systems
• pumps are far more susceptible than pipelines
• water treatment with ozone promotes rouge formation
• installations with defects (bad welding, using low alloy steels) can influence  the whole system
• on one and the same component rouging can occur in separate places with totally different adherence characteristics
• in the cases of nearly all thicker layers it can be wiped off to a certain amount
• the thicker the layer the greater the effort required to remove it
• phosphoric acid-based solutions have only a limited dissolving capacity for rouging layers
• systems which have been cleaned and passivated from the beginning are less susceptible to rouging
• systems which are regularly cleaned are generally less susceptible to the  formation of new rouging layers