07272017Thu
Last updateWed, 26 Jul 2017 7pm

i

How to Choose the Best Rapid Prototyping Method

How to Choose the Best Rapid Prototyping Method

As new products are designed, including ...

Monitoring Valve Health via the Internet

Monitoring Valve Health via the Internet

Most valve end users are already using s...

Valves in Oxygen Service

Valves in Oxygen Service

In his presentation at VMA’s 2017 ...

Thermal Spray Coating

Thermal Spray Coating

Q: What are the pros and cons of us...

Subscribe SUM17

FREE SUBSCRIPTION*

•  Print magazine
•  Digital magazine
•  VALVE eNews
Read the latest issue

*to qualified valve professionals in the U.S./Canada

The Weekly Report

New Products

  • ja-news-2
  • ja-news-3

Industry Headlines

TAQA Awards Schlumberger EPCIC Contract for Otter Field

Wednesday, 26 July 2017  |  Chris Guy

OneSubsea, a Schlumberger company, has been awarded an engineering, procurement, construction, installation and commissioning (EPCIC) contract for a s...

Readmore

Loading...
Advertisement
i

Web Only

The Actuation Selection Process

The Actuation Selection Process

Tuesday, 25 July 2017  |  Carlos Gamero

A common misconception in our industry is that actuating a valve is as simple as putting the most cost-efficient actuator on top of your valve of choi...

Readmore

Loading...

Industry Headlines

TAQA Awards Schlumberger EPCIC Contract for Otter Field

8 HOURS AGO

OneSubsea, a Schlumberger company, has been awarded an engineering, procurement, construction, installation and commissioning (EPCIC) contract for a subsea multiphase boosting system by TAQA for the Otter field in the UK North Sea. OneSubsea leverages Cameron flow control, process technologies and m...

Readmore

Crane Co. Reports Second Quarter Results

1 DAY AGO

Crane Co. reported second quarter 2017 earnings of $1.14 per diluted share, compared to $1.15 per share in the second quarter of 2016. Excluding Special Items, second quarter 2017 earnings per diluted share were $1.17, compared to $1.21 per share in the second quarter of 2016.

Second quarter 2017 sale...

Readmore

Shale Sector to Be Cash Flow Positive by 2020

8 HOURS AGO

The tight oil sector has struggled to generate positive cash flow since 2010. Last year, only one company in the sector posted positive cash flow. But there is light at the end of the tunnel. Wood Mackenzie’s new report " When will tight oil make money? " calculates that the five largest tight oil...

Readmore

U.S. Chemical Production Moved Higher in June

1 DAY AGO

According to the American Chemistry Council (ACC), the U.S. Chemical Production Regional Index (U.S. CPRI) edged higher by 0.3% in June, following a 0.3% gain in May, and a 0.4% decline in April, as measured on a three-month moving average (3MMA) basis. During June, output grew in all regions except t...

Readmore

U.S. Consumer Confidence Rebounds in July

14 HOURS AGO

The Conference Board Consumer Confidence Index, which had declined marginally in June (a downward revision), improved in July . The Index now stands at 121.1, up from 117.3 in June. The Present Situation Index increased from 143.9 to 147.8, while the Expectations Index rose from 99.6 last month to 103...

Readmore

IHS Market PMI Index Reached Four-Month High in July

1 DAY AGO

July data revealed a further acceleration in business activity growth across the U.S. private sector. At 54.2, up from 53.9 in June, the seasonally adjusted IHS Markit Flash U.S. Composite PMI Output Index signaled the strongest rate of expansion since January.

The pickup in business activity growth ...

Readmore

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.

  • Latest Post

  • Popular

  • Links

  • Events

Advertisement

Looking for a career in the Valve Industry?

ValveCareers Horiz

To learn more, watch the videos below or visit ValveCareers.com a special initiative of the Valve Manufacturers Association