06302016Thu
Last updateThu, 30 Jun 2016 6pm

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Fugitive Emissions—Issues and Opportunities

Fugitive Emissions—Issues and Opportunities

Fugitive emissions, ppm, consent decrees...

Problem-Driven Innovation

Problem-Driven Innovation

Developing Alternative Technology to Imp...

Valve Repair Takes Center Stage in Houston

Valve Repair Takes Center Stage in Houston

Attendees gathered June 2-3 in Houston t...

What Internal Best Practices Can Do for Valve Selection

What Internal Best Practices Can Do for Valve Selection

As time goes by, technology moves forwar...

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Industry Headlines

Watson Valve Upgrades Oxygen Clean Room

Thursday, 30 June 2016  |  Chris Guy

In an effort to ensure proper cleaning procedures are performed on valves intended for oxygen service, Watson Valve Services has upgraded its existing...

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Industry Headlines

Watson Valve Upgrades Oxygen Clean Room

1 HOUR AGO

In an effort to ensure proper cleaning procedures are performed on valves intended for oxygen service, Watson Valve Services has upgraded its existing clean room within its manufacturing plant in Houston. Watson Valve Services’ clean room is operated by trained technicians, and is constructed wi...

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Emerson Selected to Upgrade SE Virginia Wastewater Utility

1 DAY AGO

Emerson Process Management is replacing an outdated supervisory control and data acquisition (SCADA) system as well as remote terminal units (RTUs) used throughout Hampton Roads Sanitation District’s (HRSD) wastewater collection system. Currently, HRSD serves about 1.7 million people over an are...

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U.S. Natural Gas Making Up for Coal Plant Closures

3 HOURS AGO

"Five years ago, opponents of newly proposed clean-air rules sounded dire warnings of blackouts and surging electricity prices if coal-burning plants were shuttered,"  Bloomberg  reports .

"Instead of rising, the price of electricity in the nation’s largest grid is now 40% lower than it ...

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U.S. Crude Storage Capacity Utilization Rises Even as Capacity Grows

1 DAY AGO

Weekly U.S. commercial crude oil inventories have increased by more than 71 million barrels (15%) since the end of September, pushing crude oil storage capacity utilization to a near record high of 73% for the week ending June 10.

The U.S. Energy Information Administration (EIA) measures crude oil stor...

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Trump Comes Out Against Trade, Draws Pushback

1 DAY AGO

GOP presidential candidate Donald Trump, speaking Tuesday near Pittsburgh, expressed fierce opposition to free-trade agreements and criticized Hillary Clinton for supporting them. Trump blamed Clinton and her husband for the loss of millions of manufacturing jobs and threatened to pull the U.S. out ...

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Consumer Confidence Climbs to 8-Month High

2 DAYS AGO

The Conference Board Consumer Confidence Index, which had decreased in May, improved in June. The Index now stands at 98.0 , up from 92.4 in May. Those stating business conditions are “good” increased slightly from 26.1% to 26.9%, while those saying business conditions are “bad&rdquo...

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Less Expensive Stainless Steels

materials_q_and_a_graphicQ: High metal prices, especially for nickel and molybdenum, have our procurement people looking at less expensive stainless steels like the 200 series. Are these as good as 304 and 316 stainless steels?

A: Before answering this question, let’s look at the history and differences between the 200 and 300 series stainless steels. The original 200 series stainless steels were first developed in the 1930s by using manganese to replace some of the nickel in the 300 series austenitic stainless steels. Certain elements used in stainless steels either promote the formation of the austenitic or ferritic atomic structure, and the austenitic stainless steels are the more corrosion resistant. The austenitic-forming elements are nickel, manganese, nitrogen, copper and carbon. The primary ferrite-forming element is chromium.

Since a stainless steel needs 10-12% minimum chromium to be considered “stainless,” it then takes about 8-10% nickel to offset the ferritic-forming tendency of chromium to make a stainless-steel austenitic more corrosion resistant. Historically, manganese has always been a lower cost element than nickel. So whenever there is a scarcity of nickel (as there was in the 1970s) or when nickel prices are high, such as they are now, people look to the 200 series stainless steels as lower cost alternatives.

But before deciding to use a 200 series stainless steel, there are issues to be considered. To further complicate the matter, there has been an increase in newer chrome-manganese grades developed and produced in Southeast Asia and China. The 200 series now represent 34% of China’s production of stainless steels.

Facts About the 200 Series

There are two categories of the 200 series stainless steels—those that only replace some of the nickel with manganese, such as the original 201 or 202 grades, and those that replace most of the nickel, such as the newer grades now being seen in Asia. These newer low-nickel grades also tend to have lower chromium, which further decreases their corrosion resistance.

To date there are no international standards for the use of these newer grades. To add additional confusion, users of stainless equipment, such as valves, know that magnetism—or more correctly, the lack of magnetism—is a way of verifying they have received the superior 300 series stainless steels. Since 200 series grades are non-magnetic, this could cause a buyer to mistakenly believe they have the correct and more corrosion-resistant 300 series stainless steel. In fact, there have been a few instances of deliberate mislabeling of 200 series grades as being 304 stainless. Some scrap dealers also still rely on magnetism to sort the 300 series grades from the magnetic and less corrosion-resistant 400 series stainless steels. Thus, the proliferation of the non-magnetic 200 series grades could lead to some serious scrap contamination issues if recyclers are not careful.

The first indication as to whether these grades are equivalent to 304 and 316 is they receive little attention until nickel either becomes scarce or when nickel prices are high. The primary reason they do not see greater use is simply because they are not as corrosion resistant as 304 and 316 stainless steels. However, the 200 series grades do have several beneficial uses, including cookware, railcars, lighting columns, washing machines and most mildly corrosive applications.

Problems with Corrosion

While the 200 series alloys do have good atmospheric corrosion resistance, they do not have good resistance to most corrosive chemicals. In addition, because most of the 200 series alloys tend to have a higher carbon content to help promote the austenitic structure, it makes them more susceptible to intergranular corrosion. Other characteristics that make the 200 series less attractive include their tendency to be more work hardenable and their potential to have slightly inferior surface finish.

So if you really need to lower your cost, you need to be very careful in the application of these 200 series stainless steels. A better choice would be to look at some of the duplex stainless steels such as S31803. The duplexes have about half the nickel of the 300 series so at the higher nickel prices they may be less expensive than the 300 series while providing comparable corrosion resistance. There are also some new lean (lower nickel) duplex grades on the market that may be even more cost effective. In any case, be sure to deal with reputable and knowledgeable suppliers who can assist you with the proper material selection.


Thomas Spence is director of materials engineering of Flowserve Corporation (www.flowserve.com). Reach him at This email address is being protected from spambots. You need JavaScript enabled to view it.. The author wishes to acknowledge the assistance of Don Bush, materials engineer, Emerson Process Management-Fisher Division (www.emersonprocess.com).

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