Last updateTue, 25 Oct 2016 6pm


Warriors, Welding and Wooing the Workforce

Warriors, Welding and Wooing the Workforce

For the last several years, one of the b...

New Test Standards for Low-E Compliance

New Test Standards for Low-E Compliance

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Train Named Executive President of Emerson Automation Solutions


Emerson recently named new senior leadership appointments to its Office of the Chief Executive who now report directly to chairman and CEO David N. Farr, and help develop and guide the company’s global strategies.

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All-Pro Fasteners Receives Monogram Licensing


All-Pro Threaded Products, an All-Pro Fasteners company, received the official API Q1 registration and on September 23, 2016 become the second of only two within the industry to have obtained both the API 20E & 20F monogram licenses.

The American Petroleum Institute (API) has confirmed that All-Pro...


New 2017 Construction Starts Increasing 5% to $713 Billion


The 2017 Dodge Construction Outlook predicts that total U.S. construction starts for 2017 will advance 5% to $713 billion, following gains of 11% in 2015 and an estimated 1% in 2016.

Manufacturing plant construction will increase 6%, beginning to recover after steep declines in 2015 and 2016 that refle...


U.S. Natural Gas Production Gives Back August Gains in September


U.S. natural gas production levels in the lower 48 states declined by nearly 1.2% in September 2016 compared to August 2016 levels, according to analysis from IHS Markit. September’s decline drops year-to-date production levels 1% compared to the same period in 2015.

Overall, lower 48 U.S. dry ga...


BCG: Technology Matters to Economic Growth


Despite its starring role in business and everyday life, many economists openly question whether technology is visible in traditional economic metrics such as GDP, productivity, and corporate profits.

The Boston Consulting Group (BCG) shows that, on the contrary, declines in technology investment are f...


Mid-Atlantic Manufacturing Activity Expands More Than Expected


Results from the Federal Reserve Bank of Philadelphia’s October Manufacturing Business Outlook Survey suggest that regional manufacturing conditions continued to improve. Indexes for general activity, new orders, and shipments were all positive this month. But firms in the Mid-Atlantic region re...


Multi-colored Stain on Valves

materials_q_and_a_graphicQ: I am handling high purity-water and keep getting a multi-colored stain on my valves and other equipment. What is this, and how can I prevent it?

A: You are describing a phenomenon called "rouging," a term that pertains to the multi-colored stain you are seeing. Rouging is a problem that is seen primarily in high-purity water applications or steam. Though more commonly associated with the pharmaceutical and electronics industries, it can occur most anywhere. At the lower temperatures rouge is red or yellowish in appearance, but in high-temperature steam it will be dark gray or black. The FDA has not made any formal opinion about rouging, but pharmaceutical companies are concerned about contamination of their products so they go to great lengths to prevent it and to clean their systems when it occurs-incurring undesired downtime and expense.

The mechanism of rouging is still not fully understood and as a result there are some myths and misconceptions about what it is and how to prevent it. Essentially, rouge is a form of rust, i.e., iron oxide, but different than the heavy rust seen when stainless steel is not cleaned properly after heat treatment or welding. While normal rust is a result of improper cleaning during manufacture, rouge is a much thinner layer that occurs when perfectly cleaned stainless steel reacts with high-purity water environments. Rouge seems to be more prevalent at temperatures in excess or 60° C.

We know that stainless steels achieve their corrosion resistance by developing a very thin microscopic chromium oxide layer. The general consensus about rouging is that certain services, such as high purity water with very low oxygen content, dissolve this protective layer and allow the stainless steel to resume corroding. This corrosion is then responsible for the staining we call rouging. These stains have been analyzed as being various types of iron oxide as well as containing traces of chromium and nickel.

While mainly an aesthetics problem, most people still want to prevent rouge in their systems. One commonly held belief is that the ferrite phase in cast stainless steels or welds causes rouging, and purchasers of valves and other equipment frequently impose strict limits on the ferrite content of cast stainless steels. Since wrought stainless steels with no ferrite also experience rouging, it doesn't appear that ferrite is the culprit.

A study conducted by AvestaPolarit1, found that the water's gas content and a metal's surface finish were influential for rouging. Basically, water with high oxygen and low carbon dioxide content was less likely to cause rouging as were electro-polished surfaces of the metal components. This study also found no significant correlation for the different alloy grades, including duplex stainless steels with their high ferrite content.

Since most people find rouge objectionable in their systems, much attention has been given to its removal. Various acids and chelates are used to clean systems of rouge, but these can leave behind their own contaminates or films. In addition, if acid exposure is not controlled closely, the acid can etch the metal surfaces thus destroying the expensive electro-polished surfaces. Therefore, the most effective way to prevent rouge is by somehow introducing sufficient oxygen to the system, which helps maintain the protective chromium oxide layer.

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