Teledyne, Inc. merges with metals maker
Teledyne Wah Chang's parent company,
Teledyne, Inc., announced on April 1 a strategic merger with Allegheny Ludlum
Corporation. The new company will be called Allegheny Teledyne Incorporated.
The combined company, with $4 billion in annual sales, will be a world-class
producer in specialty metals and will maintain strong market positions in
aviation and electronics, industrial, and consumer products businesses.
Allegheny Ludlum is a leading producer
of a wide range of specialty materials, including stainless steel, tool steels,
high technology alloys, and grain-oriented silicon steel. The company is based
in Pittsburgh, Pa.
William P. Rutledge, Teledyne's
Chairman and Chief Executive Officer stated that the company is "extremely
pleased to join forces with Allegheny Ludlum."
According to Arthur H. Aronson,
Allegheny Ludlum's President and Chief Executive Officer, "In specialty
metals, Teledyne's high-quality products, production capabilities and strong
distribution system provide immediate cross-marketing opportunities worldwide,
while its engineering and technological expertise presents exciting
possibilities for new product development."
Allegheny Teledyne will be
headquartered in Pittsburgh.
Teledyne Wah Chang has trained welders
around the world to work with zirconium, titanium and other metals. Here, a
CTCI welder works on titanium pipe. TWC will hold its 14th Annual Welding
Seminar in Oregon this July. For information on registration, call
1-541-967-6924.
Fabricators worldwide rely on TWC alloys and support
When CTCI, a major equipment fabricator
for the Chemical Processing Industry, fabricated zirconium equipment for the
first time in 1981, it looked to Teledyne Wah Chang for more than Zircadyne®. The Taiwan-based company was hired to
build a zirconium tower and heat exchanger for CPDC, a large chemical
processing company, but needed instruction in working with the alloy,
particularly in welding. TWC sent a team to Kaohsiung to train CTCI personnel
who then successfully completed the project. (According to Mr. Shui-Jin Tsai,
CPDC Plant Manager, the zirconium equipment hasn't shown any corrosion, unlike
alloy B-2, which was also installed and suffered pitting.)
Taiwanese fabricators also repaired Zr
equipment used by TASCO to concentrate H2 SO4 from 30% to 65% at 80 to
150°C. Today, the equipment is performing well thanks in part to TWC's
technical support.
There are many companies in Taiwan (and
around the world) that are able to work with alloys because of strong technical
support from Teledyne Wah Chang. For example, Perfect Enterprise Company owner
Han-Pin Lien recently used knowledge gained in a welding seminar to repair
niobium pipe for use in recovery of spent HCl pickling solutions. Another
Taiwan-based fabricator, SPEMET Co., Ltd. has used Teledyne Wah Chang resources
to help it fabricate zirconium and titanium coils for pickling and anodization
applications.
Fabricators have looked to TWC for
corrosion resistant alloys and support for more than 25 years. For more
information, call Customer Service at 541-967-6977. For more information on
fabricators in Taiwan, contact The Up Seven Trading Co., Ltd. at 886-2-5066681.
Matching characteristics of your medium to capabilities of
structural materials; zirconium useful in H2SO4
applications
-by Te-Lin Yau, Corrosion Engineer
There are many factors to consider in selecting structural
materials for chemical applications. Major factors include cost, corrosion
resistance, physical and mechanical properties, availability, fabricability,
and codes and regulations.
Nevertheless, the initial cost is often the decisive factor
in materials selection, since it is costly and time consuming to follow the
proper selection procedures. This much-simplified approach was more acceptable
in the past than it is now for the following reasons:
1. Getting a quick start on production dictated the time
allowed for materials selection. The idea was to try the cheapest material
first. When this material failed, it became easier to justify a more expensive
material. Trial and error was a common engineering practice. Today, we
emphasize doing it right the first time.
2. Shutdown, repair and replacement costs were not
prohibitively high. These costs could be absorbed when the competition was not
strong. Today, keeping a plant running without any unscheduled shutdown is a
very high priority. Having the lowest overall cost, which includes equipment,
shutdown, repair, replacement and penalty costs, is the goal.
3. It was once acceptable to release low levels of corrosion
products to the product or the environment. Today, there are very tight
controls limiting heavy metal ion discharge in discharge permits. Moreover, for
certain fine products, the presence of more than 1 part per billion of metal
ions could be excessive. Products of the highest quality meet the least
competition and command the maximum premium.
4. Leakages and breakdowns were part of life. We learned to
live with and around them. Today, we face potential huge penalties when these
problems happen. Even fugitive emissions need to be well controlled. The goal
is to achieve zero discharge.
5. Chemical companies used to have great concern of cyclical
changes. Today, the rise of global manufacturers has overshadowed conventional
cycles. Globally exposed companies need to place a balanced emphasis on cost,
equipment durability, process efficiency, product quality, variety and choice,
safety, and environmental protection.
Consequently, materials selection plays a pivotal role in
building modem chemical plants. It is important to have materials/corrosion
professionals who are allowed to properly follow selecting procedures,
including identifying property requirements, collecting corrosion data and case
histories, conducting laboratory and field tests, etc. It takes time and money
when you want to do it right. However, one can take certain measures to lower
time and money without making any compromise. For example, it is advantageous
to thoroughly understand the corrosive characteristics of process streams.
Then, there will be fewer candidate materials to consider that can match these
characteristics. Imposing other requirements, such as the tolerable impurity
level, can further reduce the number of candidates.
A General Example
Figure 1 gives a general indication on the useful ranges of
several materials in acidic solutions with varying electrochemical power. As
demonstrated in the figure, when the medium is not highly oxidizing or
reducing, the choices are plentiful. In addition, it is essential to know
whether the medium contains chlorides. The presence of chlorides may greatly
alter metals' capability to form protective films.
Fig. 1. Zirconium has a wide range of applicability in
oxidizing and reducing acids
Chloride-free Acids
Type 300-series stainless steels have some usefulness in
oxidizing acids, such as nitric and chromic, if acid concentration and
temperature are not excessive. They would be a poor choice for reducing acids,
such as formic, phosphoric and <70% sulfuric acids. It should be noted that
concentrated sulfuric acid is regarded as an oxidizing acid. Alloy 20, which
has more nickel, chromium, molybdenum and copper than the 300-series stainless
steels, has the added capability to handle reducing acids.
Nickel-based alloys aim at different ranges, depending on
their alloying elements. Monels, with copper as their primary alloying element,
are suitable for reducing acids but are very sensitive to the presence of
oxidizing agents. In an apparent reducing acid, even aeration may make Monels
unsuitable. It pays to know the details.
Moreover, Cr-containing but free of Mo alloys, such as Alloy
600, are more appropriate for mildly oxidizing acids than for reducing acids.
Ni-Cr-Mo alloys, such as Alloy C, can be considered for mildly reducing acids
but not for oxidizing acids.
Original data used in creating Figure 1 shows that zirconium
is superior in oxidizing acids.1 This is true. For example,
zirconium has much higher concentration and temperature limits than stainless
alloys in nitric acid. But zirconium is also superior in reducing acids
(sulfuric acid is discussed as a specific example later in this article). The
red bar in Figure 1 expands on the original data1, showing
zirconium's full range of utility in reducing acids.
Chloride-containing Acids
When chlorides are present, materials selection becomes even
more demanding. The specifier not only has to consider the materials' general
corrosion but also their localized corrosion, i.e., pitting, crevice corrosion
and stress corrosion cracking. Type 300-series stainless steels can be excluded
because of their high susceptibility to localized corrosion in
chloride-containing acids.
Nickel-based alloys, such as Alloy B and Monels, can be used
to handle certain truly reducing acids, i.e., very low tolerance for oxidizing
impurities. On the other hand, nickel-based alloys, such as Alloy C, require
the presence of some oxidizing agents to form protective films.
Titanium is a popular, competent choice for oxidizing
chloride-containing acids because of its decent breakdown potentials in
chloride solutions. It is, however, poor in reducing acids. One of the major
efforts in alloy development is to extend titanium's capability into the
reducing region. Addition of 0.04 to 0.25% palladium to titanium achieves this
objective with a small penalty at the oxidizing end.
Tantalum and glass-lined materials have a wide range for
their applicability in chloride-containing acids. One of the major limitations
for tantalum is its susceptibility to hydrogen embrittlement under reducing
conditions. The fragility of glass-lined materials is a great concern in
meeting mechanical requirements.
Zirconium is one of the most corrosion resistant metals for
handling reducing acids, including the highly venerable hydrochloric acid.
Note: the author of this article disagrees that tantalum has a higher limit
than zirconium in reducing acids, as indicated in previously published data.1
In fact, zirconium is more resistant to hydrogen embrittlement than tantalum in
reducing acids. At a minimum, the limit for zirconium should be extended to
that of tantalum, as shown by the red bar in Figure 1.
The major concern for using zirconium in acidic chloride
solutions has been its low breakdown potential. Consequently, zirconium becomes
vulnerable to localized corrosion under oxidizing conditions, such as the
presence of oxidizing impurities and coupling with a noble material. Results of
recent tests indicate that this vulnerability can be suppressed when zirconium
has a clean surface.
A Specific Example
In a specific medium, the reciprocal of corrosion rate can
be used to compare the applicable range of candidate materials. That is, the
lower the corrosion rate, the broader the applicable range. It is advantageous
to choose a material that has a range broad enough to allow some fluctuation in
operating conditions. In production, operating conditions rarely stay constant.
Sulfuric acid is a good example because of its popularity
and complexity. It changes from the reducing nature of dilute solutions to the
oxidizing nature of concentrated solutions. Under the reducing conditions, many
passive metals form nonprotective sulfate films rather than protective oxide
films. Zirconium is one of very few metals that can form highly protective
oxide films in handling >70% sulfuric acid, since the formation of zirconium
sulfate becomes possible.
Fig. 2. Zircadyne ®
zirconium has a broad range of uses in sulfuric acid solutions
As shown in Figure 2, 60% sulfuric acid represents a severe
reducing condition and 50% sulfuric acid + 42 g/l ferric sulfate represents a
severe oxidizing condition? Typical corrosion rates for the Ni-Cr-Mo alloys
range from 15 to 50 mpy in the reducing acid and from 25 to 250 mpy in the
oxidizing acid.
Typical corrosion rates for zirconium are 0.3 mpy in the
reducing acid and 0.2 mpy in the oxidizing acid. As Figure 2 indicates, zirconium
has a broad range of utility in sulfuric acid solutions. Indeed, versatile
zirconium has been used to solve many complicated corrosion problems that have
occurred in H2SO4
applications.
Conclusion
This article addresses a small part but an important step in
materials selection for corrosive applications, i.e., thoroughly understanding
the process streams. It is important not
to omit any minor details, which may dramatically alter
corrosive characteristics. When the characteristics of the process streams are
established, only those materials that have the capability to match these
characteristics need to be considered. The list can be further shrunk when
other requirements are imposed. Time and money can be saved when efforts are
well focused. Also, a better understanding about the process streams will give
operators a better capability to make modifications as a corrosion-control
measure.
References
1. Hunkeler, F. J., "Properties of Tantalum for
Applications in the Chemical Process Industry," Refractory Metals and
Their Industrial Applications. ASTM STP 849, R. E. Smallwood, Ed., American
Society for Testing and Materials, Philadelphia, 1984, pp.28-49.
2. Paul Crook, "Development of a New Ni-Cr-Mo
Alloy." Paper No. 96410, Corrosion/'96, NACE, Houston (1996).
Teledyne Wah Chang earns supplier award from ASiMI for
superior effort
In January, Advanced Silicon Materials
Inc. (ASiMI) presented Teledyne Wah Chang with its Critical Material Certified
Supplier Award for supply of silicon tetrachloride. The ASiMI Certified
Supplier Program recognizes superior performance in these areas:
•Product
quality/reliability
•On-time delivery
•Innovation through ASiMI/ supplier
teamwork
•A commitment to continuous improvement
TWC was only the second supplier to
receive the company's certification award according to David Matthews, Safety,
Environmental and Quality Resources Manager at ASiMI. "Teledyne Wah Chang
has just the things we are looking for," he said, "-consistent
on-time delivery and 100% quality. They have given us good technical support,
and we have had no issues with quality."
ASiMI manufactures high quality
polysilicon nuggets, rods, rod sections, and silane gas for the semiconductor
industry. ASiMI's customers include a broad spectrum of silicon wafer, integrated
circuit, photovoltaic, and advanced ceramics industries. These industries
employ the company's polysilicon products to produce single crystals that meet
the exacting requirements of high density DRAMs, CCDs and advanced VLSI
structures. They transform silane into the amorphous thin films used in solar
cells and photodetectors, photosensitive drums and LCDs. New applications for
ASiMI silane include fiber optics, multilayer reflective coatings, and advanced
ceramic materials.
ASiMI has enhanced and expanded a
revolutionary silane to polysilicon process. The result is products with
impurities measured at the low parts per trillion level and exhibiting
excellent lot-to-lot uniformity--all supplied in world-scale production
volumes.
Advanced Silicon Materials Inc. is
working closely with its suppliers in the belief that teamwork and a partner
relationship make 100% performance an achievable goal. ASiMI will continue to
recognize suppliers, such as Teledyne Wah Chang, who are making that goal a
reality.
TWC earned ASiMI Certification by
meeting stringent criteria in quality, delivery, total cost, service, and
approval by audit. Here, TWC's Director of Chemical Operations, Lynn Davis
(right), accepts the certification award from ASiMI's Vice President of
Manufacturing, Mike Kerschen (left).
Advanced Silicon Materials Inc.'s
chunk-form and rod-form polysilicon products are used in the semiconductor
industry. ASiMI's customers include a wide range of silicon wafer, integrated
circuit, photovoltaic, and advanced ceramics producers.
Distillation towers at ASiMI's Moses
Lake, Washington silane production unit. The complex has a capacity for 3000
metric tons of high-purity silane annually. The company announced that it is
adding a 3800-metric-ton/yr facility for production of high purity
polycrystalline silicon (used for producing single-crystal silicon wafers).
Outlook, more available on the Web
Teledyne Wah Chang announces its new World Wide Web site on
the Internet at http://www.twca.com. TWC's homepage leads web surfers to
technical information on reactive and refractory metals and chemicals, such as
zirconium, titanium, niobium, hafnium, and vanadium, used in a variety of industries
(e.g. aerospace, chemical and mineral processing, energy generation, medicine,
and recreational equipment).
The site also features access to this newsletter. Text and
thumbnail photos are displayed for each article. Readers can enlarge photos by
clicking on the thumbnails. Readers can also choose a text-only version for
speed-reading. The TWC site contains the last four issues of Outlook (including
this issue). If you wish to cancel your hardcopy subscription to the Outlook
and access it on-line, please contact Customer Service by phone at 541-967-6977
or by e-mail at custserv@twca.com.
We can even e-mail a text-only version to you quarterly. Of course, hard copies
of Outlook will continue to be available.
TWC's web site has a customer service interface that allows
customers, potential customers, and vendors to ask for more information. The
site's customer service-related pages are directly linked by e-mail to TWC.
Information on TWC's products and services is now available
on the Internet. Kirk Richardson (left) and Bruce
Rash (right) display the company's homepage.
In addition, http://www.twca.com contains a collection of
photomicrographs shot by well known metallurgist Paul Danielson.
Teledyne Wah Chang developed a presence on the Internet for
its customers. You can now access technical information on reactive and
refractory metals and chemicals when you need it, regardless of your location.
TWC is updating its Web site regularly, with technical
papers, data sheets, a frequently asked questions (FAQs) file, and other
information.
We are interested in making this resource more helpful to
you. Please send your comments by e-mail to krichardson@proaxis.com or to
webmaster@twca.com. Remember to bookmark TWC on your browser for quick answers
to tough questions.
TWC to co-host event at Nitric Acid Meeting
Teledyne Wah Chang invites you to a hospitality suite this
spring at the Nitric Acid Producers Meeting in Banff, Canada.
TWC will co-host the event May 27 and 28 from 5 to 9 PM in
the Glacier Room at the Banff Park Lodge. Other participants include B.S.L.,
Chemineer, Cosmos Mineral Corporation, Ellett Industries, H. C. Stark, Hickam
Industries, Industrial Alloy Fabricators inc., Koch Engineering, Ohmstede,
Inc., Phoenix Division of Kodiak, SPF America, Inc., and Weatherly, Inc.
Representatives will be on-hand to provide information on
and answer questions about TWC's Zircadyne® Zirconium and other products/services.
For more information on the conference, call 403-936-2350 X 226.
One-stop shopping
TWC's new brochure covers all of its
reactive and refractory metal and chemical products. Call Customer Service at
541-967-6977 for a copy.
