Derouging

Rouging is often found in high purity, hot water systems, usually appearing as reddish-brown or black in colour, of iron oxide or hydroxide. What exactly causes rouging does not appear to be fully understood, but we do know that it is connected to destabilization of the passive layer. Certain measures can be taken to improve corrosion resistance, which can help to prevent rouging. Research has shown that passivation reduces the risk of rouging within the system. Removing rouge (derouging) is critical as very small amounts of metal ions can significantly impact the stability of products. Rouge not only causes surface degradation, but also distributes contaminants into the final product.In addition, derouging also extends the life of the systems and equipment.

Rouge can be classified into three classes:

• Class I Rouge is deposited corrosion product, consisting of iron oxides and hydroxides originating elsewhere in the system and deposited downstream. The underlying stainless-steel surface beneath such deposits usually remains unaltered. This rouge deposit can usually be easily wiped away
• Class II Rouge is an adherent corrosion product originating in-situ on unpassivated or improperly passivated stainless steel surfaces. By its formation, the normally passive-protective film on the stainless-steel surface is altered
• Class III Rouge is a blue or black, mostly iron oxide corrosion product, commonly called magnetite, which forms on surfaces in high-temperature steam systems. On electropolished surfaces, corrosion deposit may be glossy black, stable, and adherent. On unpassivated mechanically polished surfaces, the corrosion deposit may be powdery black and may slough off

We recommend performing surface re-passivation at regular intervals to reduce the risk of rouging. Our proprietary PUREPASS® passivation process ensures removal of all types of rouging and provides the greatest chromium levels on the surface, in turn, yielding the most optimal resistance to future corrosion.

Purepass Services Inc.will mobilize to your facility with our highly trained staff providing complete turnkey services delivering quality chemical cleaning, derouging and passivation to installed systems: pre-operational, pre-commissioning of new construction, post modification, preventative maintenance and shutdowns. We also provide in shop derouging and passivation at our facility in Hamilton, Ontario. Here we can process a wide range of parts from small components and fittings to process piping and mobile tanks.

We stand behind our projects and support our results with industry defining certification documentation. Upon completion of each job, we will provide you with a quality GMP documentation package for your systems and equipment maintenance records.