Scaling UP! H2O

037 The One That’s All About White Rust


Today on the show, we welcome Chris Nagle. Chris has a background in water treatment and today works at Evapco, one of the largest cooling tower manufacturers in the world. Have you ever heard the term white rust? It is a problem that many water treaters face and is the topic of this episode today. In a nutshell, white rust is the galvanizing coming off of a cooling tower. Galvanizing is a coating of zinc over the steal surface, which is done so that the zinc corrodes instead of the steel below it. White rust is the premature corroding of that zinc and this is a serious problem, one that it often blamed on the water treater.

Evapco have been doing an amazing job at teaming up to gather and share information on white rust and how we can help solve this issue in new ways, together. Chris has a unique perspective and a wealth of insight on the topic of white rust and today, he explains the process of galvanizing and passivation and the challenges white rust has placed on the industry today. Chris shares some of the fascinating things Evapco are doing to help solve this issue and provides some great advice for water treaters on how to prevent and manage white rust.



Find out how Chris Nagle got involved in water treatment [04:35]

How Chris came to work for Evapco in 2006 [06:15]

Chris explains the process of galvanizing [09:00]

Mill galvanizing versus hot-dip galvanizing [09:30]

The challenge with galvanizing in the industry today [11:15]

How Evapco are addressing the issue of white rust [15:10]

The importance of heat-load in addressing galvanization [18:02]

Advise for water treaters who are faced with white rust [21:40]

What is the best procedure for passivation? [23:25]

The magic numbers when it comes to pH and alkalinity [26:28]

Communicating with your customer about white rust [27:35]

The longevity of properly passivated equipment [36:08]

Selecting the best cooling tower equipment for your area [38:17]

The biggest passivation mistakes water treaters make [41:33]



“It’s important that your customer knows that minimizing white rust is a team effort.” – Chris Nagle

“When it comes to pH control, either do it right or don’t do it.” – Chris Nagle


Connect with Chris Nagle:




Links Mentioned:

Beyond Laboratory Research on White Rust and Passivation – Chris Nagle

Association of Water Technologies

Understanding Passivation and White Rust 


Water Treatment education


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