07262016Tue
Last updateTue, 26 Jul 2016 4pm

i

Basics of Elastomeric Seal Design

Basics of Elastomeric Seal Design

Engineers need critical design informati...

Wastewater Treatment

Wastewater Treatment

Society’s desire for a clean envir...

Controlling Our Water Systems, Part II

Controlling Our Water Systems, Part II

To better understand the actuators and c...

Controlling Our Water Systems

Controlling Our Water Systems

Actuators and controls are a critical pr...

The Weekly Report

New Products

  • ja-news-2
  • ja-news-3

Industry Headlines

Advertisement
i

Industry Headlines

Crane Co. Reports Second Quarter 2016 Results

6 HOURS AGO

Crane Co. reported second quarter 2016 GAAP earnings of $1.15 per diluted share, compared to $0.95 per share in the second quarter of 2015. Excluding Special Items, second quarter 2016 earnings per diluted share were $1.21, compared to $1.06 per share in the second quarter of 2015.

Second quarter 2016 ...

Readmore

Emerson Exploring Acquisition of Pentair Valves & Controls

1 DAY AGO

Reuters UK has spoken to sources that confirm Emerson has made an offer to acquire Pentair Valves & Controls. Pentair Plc added the Valves & Controls division after its merger with Tyco Flow Control in 2012.

“Pentair has received offers for the valves and controls business from companies o...

Readmore

Chemical Activity Barometer Grows for Fourth Consecutive Month

6 HOURS AGO

The Chemical Activity Barometer (CAB) expanded 0.4% in July following a revised 0.7% increase in June, 0.8% increase in May and 0.6% increase in April. All data is measured on a three-month moving average. Accounting for adjustments, the CAB remains up 2.6% over this time last year, an improvement ove...

Readmore

SABIC, ExxonMobil Evaluating Joint Venture on U.S. Gulf Coast

6 HOURS AGO

SABIC and an affiliate of Exxon Mobil are considering the potential development of a jointly owned petrochemical complex on the U.S. Gulf Coast. If developed, the project would be located in Texas or Louisiana near natural gas feedstock and include a world-scale steam cracker and derivative units.

Befo...

Readmore

Sharpest Rise in U.S. Manufacturing Production Since November

1 DAY AGO

July data signaled a further rebound in business conditions across the U.S. manufacturing sector, led by a robust expansion of incoming new work and the fastest upturn in production volumes for eight months. Job creation also strengthened in July, with the latest increase in payroll numbers the fast...

Readmore

Texas Manufacturing Activity Stabilizes

1 DAY AGO

Texas factory activity held steady in July, according to business executives responding to the Texas Manufacturing Outlook Survey . The production index, a key measure of state manufacturing conditions, came in near zero after two months of negative readings, suggesting output stopped falling this mon...

Readmore

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..

  • 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