06282017Wed
Last updateWed, 28 Jun 2017 3pm

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Lubricants: Always Important—Sometimes Essential

Lubricants: Always Important—Sometimes Essential

Most valve professionals take more notic...

Why Air Valves are Needed in Water Applications

Why Air Valves are Needed in Water Applications

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Achieving Profitability Through Maintenance Management

Achieving Profitability Through Maintenance Management

One of the distinctions between maintena...

Control Valve Positioner Performance Diagnostics

Control Valve Positioner Performance Diagnostics

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Industry Headlines

IMF Lowers Forecast for U.S. Growth to 2.1%

Wednesday, 28 June 2017  |  Chris Guy

According to the newest forecast from the International Monetary Fund (IMF), growth in the U.S. is expected to rise 2.1% both this year and next, driv...

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Industry Headlines

Emerson in Talks to Acquire Software Company Paradigm Ltd.

19 HOURS AGO

According to Bloomberg , Emerson is in talks to acquire software company Paradigm Ltd. for approximately $1.5 billion.

“Paradigm specializes in seismic data interpretation and imaging equipment to help oil and gas companies know where to drill. The logic of such a deal seems sound and will help Eme...

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VMA Members Lead MDM Top Industrial PVF Distributors List

1 DAY AGO

Modern Distribution Management (MDM) recently published its Top Distributors list for 2017. Four of the top 5 distributors in the Industrial PVF category ; MRC Global, NOW Inc., Wolseley Industrial Group and FloWorks International; are currently VMA members.

“While oil & gas markets have start...

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Mountain Valley Pipeline Gets Environmental Approval

21 HOURS AGO

The Federal Energy Regulatory Commission (FERC) determined that construction and operation of the Mountain Valley Pipeline would result in some adverse environmental impacts, but the majority of these impacts would be reduced to less-than-significant levels. This determination is based on a review o...

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Delta Chemical Plant Planned for Houston Area

1 DAY AGO

Braskem will commit up to $675 million in investment capital towards the design and construction of a new facility, named Delta, located next to Braskem's existing production facilities. Construction is expected to begin mid-summer, with the final phase of main construction targeted for the first qu...

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IMF Lowers Forecast for U.S. Growth to 2.1%

-1 DAYS AGO

According to the newest forecast from the International Monetary Fund (IMF), growth in the U.S. is expected to rise 2.1% both this year and next, driven by continued solid consumption growth and a cyclical rebound in private investment. In its last forecast the IMF predicted 2.3% growth this year an...

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U.S. Durable Goods Orders Fell the Most in 18 Months

21 HOURS AGO

New orders for manufactured durable goods in May decreased $2.5 billion or 1.1% to $228.2 billion, the U.S. Department of Commerce announced. This decrease, down two consecutive months, followed a 0.9% April decrease. Excluding transportation, new orders increased 0.1%. Excluding defense, new orders...

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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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