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The Past, Present and Future of Fire Testing

The Past, Present and Future of Fire Testing

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Advancements in Blue Laser Scanning

Advancements in Blue Laser Scanning

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Cavitation in Globe Valves—and Proposed Solutions

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Industry Headlines

Emerson Agrees to Buy Aventics

Friday, 18 May 2018  |  Chris Guy

Emerson has agreed on terms to acquire Aventics from Triton for a cash purchase price of $620 million. Aventics deals in smart pneumatics technologies...

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Industry Headlines

Emerson Agrees to Buy Aventics

2 DAYS AGO

Emerson has agreed on terms to acquire Aventics from Triton for a cash purchase price of $620 million. Aventics deals in smart pneumatics technologies that power machine and factory automation applications. Aventics significantly expands Emerson’s reach in a growing $13 billion market.

With cen...

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Conval Names Brian White Refining & Chemical Industry Manager

3 DAYS AGO

Conval has appointed Brian E. White as refining & chemical industry manager serving the petrochemical industry in the Gulf states and elsewhere as opportunities and needs arise.

Based in Houston, White has over 20 years of experience selling instrumentation and capital equipment to the oil & ga...

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Outside of U.S., Natural Gas Outlook Diminishing

3 DAYS AGO

The mood in the natural gas industry, at least outside the U.S., is not as optimistic as it once was. According to the International Energy Agency (IEA), demand has slowed considerably for most of the period since 2011, from an average of 2.8% per year between 2000 and 2010, to 1.4% per year from 2011...

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ExxonMobil, BASF Form Gas Treating Alliance

4 DAYS AGO

ExxonMobil Catalysts and Licensing LLC and BASF Corporation have signed an alliance agreement to jointly develop new gas treating solvents and process technologies for use in natural gas processing and petroleum refining. Under this new agreement , BASF will market and license technologies developed f...

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Leading Economic Indicators Up 0.4% in April

2 DAYS AGO

The Conference Board Leading Economic Index (LEI) for the U.S. increased 0.4% in April to 109.4, following a 0.4% increase in March, and a 0.7% increase in February.

April’s increase and continued uptrend in the U.S. LEI suggest solid growth should continue in the second half of 2018. How...

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U.S. Factory Output Rose in April

3 DAYS AGO

Industrial production rose 0.7% in April for its third consecutive monthly increase. The rates of change for industrial production for previous months were revised downward, on net; for the first quarter, output is now reported to have advanced 2.3% at an annual rate.

Manufacturing output moved up 0.5...

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Use of Hard Coatings for Valves

What types of coatings are available for valves in severe service abrasion service?
Valves operating in this type of service require enhanced durability and corrosion resistance. The coatings widely used for valves include HVOF, hard chrome and D-gun, all of which provide a hard surface with much better resistance to abrasion compared to uncoated parts.

Do these coating technologies have any limitations?
These traditional coating technologies do have some limitations and undesirable side-effects. The coatings are porous, especially HVOF, which when used with gas requires special sealing to stop gas diffusion through the coating pores. Both HVOF and D-gun coatings contain metal binder, usually cobalt or sometimes nickel or chrome. Most of the binders are prone to corrosion and attacks by aggressive media such as H2S, which is present in sour oil or nitric acid used for cleaning food processing equipment. The binder leaching dramatically increases coating abrasiveness, and seals wear much quicker. HVOF and D-gun coatings can only be applied to external surfaces, are very rough as applied, and require expensive grinding and finishing. Also, hard chrome plating causes significant environmental concerns and will be phased-out in many developed countries.

Are there any alternatives?
Yes, there is a new advanced coating that resolves these problems and is increasingly used in high-performance valves: Hardide is a nano-structured tungsten-carbide coating applied by an innovative low-temperature chemical vapor deposition (CVD). This coating became commercially available four years ago following more than 15 years of research and development. Since then it has been successfully used with valves serving in the oil and gas industry, food processing, cryogenics and for handling aggressive chemicals.

Please explain how Hardide works and describe some of its properties.
Hardide is a pore-free coating that is crystallised on the surface of steel parts in a vacuum furnace filled with a special recipe of mixed reactive gases. The coating is crystallised atom-by-atom from gas phase; the highly mobile reaction products fill pores and defects in the coating as it grows. The porosity measured as the difference between theoretical and actual material density is less than 0.04%, while the coating completely covers the substrate without any through pores starting from less than 1 micron thickness. Absence of porosity is important for gas valves where pores can result in explosive gas leaks.

Hardide coating thickness can vary between 5 and 100 microns. In most valve applications 40 to 60 microns coating is optimal. Typically, the coating increases the life of precipitation-hardened stainless-steel parts in abrasive conditions by a factor of three.

Dispersed tungsten-carbide nano particles give the material enhanced hardness of between 1100 and 1600 Hv, and abrasion resistance is up to 12 times better than hard chrome. Nano-structured materials sometimes show unique toughness, crack and impact-resistance and Hardide-T has proven this by withstanding 3000 microstrain deformations without any damage—this deformation will crack or chip any other thick hard coating.

How is this coating different than sprayed tungsten carbide?
Unlike sprayed tungsten carbide, Hardide does not use cobalt, which can be affected by corrosion. Binder-free Hardide resists attacks of salts, acids, H2S, molten metals and many other aggressive media. This is especially important for the petrochemical industry processing sour oil. The coating is resistant to acids and aggressive media. In fact, its resistance to H2S has been proven by NACE testing. A 17-4 stainless-steel sample coated with Hardide passed the test without any changes in appearance or structure, while an uncoated control sample was broken into two pieces due to sulphide stress cracking effect.

What are some of Hardide’s other features?
The Hardide coating allows use of standard steels in highly corrosive and aggressive environments, opens wider opportunities for the valve design and reduces machining costs.

The CVD process enables the coating of internal and shaped “out of line-of-sight” surfaces of parts made of steel, stainless steel, Monel, Inconel, copper, Stellite and other alloys.

In addition, the Hardide structure permits good quality surface finish and provides anti-galling properties.

Does it have any other applications?
Apart from valves, Hardide has commercial applications for tools in the oil industry and heavy-duty parts for earth-moving equipment, as well as pumps.

What do you see happening with Hardide in the future?
Future developments in Hardide coating technology should allow making coating self-lubricating by inclusion of solid lubricant materials. This will facilitate valve operation, especially for high-pressure valves, as well as permitting use of smaller actuators. VM

Dr.Yuri Zhuk is technical director of Hardide plc (www.hardide.com). In 2003, the company’s headquarters and coating facility were established in Bicester, Oxfordshire in the UK; Hardide Coatings’ first international coatings plant opened in Houston, TX in September 2006. To reach Dr. Zhuk, please email This email address is being protected from spambots. You need JavaScript enabled to view it..

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