1/2013
Product life cycle
Managing life cycles
• Retrofits improve pipeline pumps
• Process technology service ensures success
• EPDs foster ecological awareness
• Coatings increase product lifetime
Panorama
• Sulzer in Russia
• Vibrations under control
EDITORIAL
About Sulzer
Sulzer Pumps
Pump technology and solutions
Long-term thinking
Sulzer Pumps offers pumping solutions and
related equipment and services.
Customers benefit from intensive research and
development in fluid dynamics, process-oriented
products, and reliable services. The global manufacturing and service network of Sulzer Pumps
ensures high customer proximity.
Sulzer Metco
Surface technology
Sulzer Metco enhances surfaces with coating
solutions and equipment.
Customers benefit from a uniquely broad range
of surface technologies, coating solutions,
equipment, materials, and services, as well as
specialized machining services and components.
The innovative solutions of Sulzer Metco improve
performance and increase efficiency and reliability.
Sulzer Chemtech
Separation, mixing, and service solutions
Sulzer Chemtech offers products and services
for separation, reaction, and mixing technology.
Customers benefit from advanced solutions in the
fields of process technology, separation equipment,
as well as two-component mixing and dispensing
systems. The global footprint of Sulzer Chemtech
ensures local knowledge and competence.
Sulzer Turbo Services
Service solutions for rotating equipment
Sulzer Turbo Services offers repair and maintenance services for turbomachinery, generators,
and motors.
Customers benefit from reliable and efficient
repair and maintenance services for gas and steam
turbines, compressors, motors, and generators
of any brand. The global network of Sulzer Turbo
Services ensures high-quality local service.
Dear Technology Professionals, Customers, and Partners,
What a machine or a production plant can do and how much it costs are important
criteria for a purchasing decision. But the question of how long a machine will
continue to run perfectly is actually more interesting. How soon will repairs be
necessary? How high is the risk of a production stoppage? In the case of active
products such as pumps, the largest costs by far arise during their operation. It is
therefore essential to consider the complete product life cycle.
This issue of the Sulzer Technical Review shows the foresight and holistic thinking
of the engineers from Sulzer. They develop solutions that extend the service life of
products and maintain efficient, long-term operation. This includes the correct choice
of materials and surfaces for highly stressed components. Tools in the metal processing
industry last up to three times longer with the surface technologies from Sulzer.
And, with the right coating, turbo impellers can resist even heavily erosive gases.
But what happens when the operating conditions of a machine change or the
efficiency of an existing production plant decreases? Once again we have the right
solution: service is written with a capital ‘S’ at Sulzer. Thanks to our global presence
and great flexibility, our service technicians are quickly on the spot throughout the
world. One article impressively describes how pipeline pumps are brought back to
high performance with our retrofits. Our lifelong service for chemical process plants
ensures that production will continue, even when things get rough.
The use of environmental product declarations is a further example of our longterm thinking. Learn how our customers are able to make environmental and costconscious decisions thanks to this transparency.
I hope you enjoy reading these articles.
Sulzer was founded in 1834 in Winterthur, Switzerland,
and today is active in machinery and equipment
manufacturing and surface engineering at over
170 locations worldwide. The divisions are global
leaders in their respective customer segments,
which include the oil and gas, hydrocarbon
processing, power generation, water, aviation,
and automotive industries. www.sulzer.com
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| Sulzer Technical Review 1/2013
Klaus Stahlmann
CEO Sulzer
CONTENT
Product life cycle
4
Improved lifetime performance
Managing the life cycle of pipeline pumps with retrofits
8
Committed to long-term customer success
Process technology services beyond plant installation and start-up
11
Upcycling in nature
Sulzer analogy
4 Improving pipeline pumps
12
Longer lasting tools
Modern coating solutions for the machining industry
16
Conscious decisions thanks to environmental product declarations
In Focus
18
Lifetime extension with hardfacing
Improvement of compressor rotors
22
Analyzing and effectively avoiding corrosion
Practical examples of failure analysis
18 Handling erosive gases
Panorama
26
Welcome to Sulzer in Russia
Sulzer world
28
Faster service for Russian customers
Interview with Reiner Mehr, Sulzer Turbo Services
30
Controlling complex vibrations
Active vibration control for paper machines
26 Sulzer in Russia
34
Events & News
35
Imprint
On the cover:
The nautilus shell grows in the form of a logarithmic spiral and thus offers
a perfectly adapted housing for its steadily growing inhabitant during
each stage of its life. In nature, some snail shells are even upcycled after
the life of the inhabitant as the article on page 11 shows.
Sulzer Technical Review 1/2013
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PRODUCT LIFE CYCLE
Managing the life cycle of pipeline pumps with retrofits
Improved lifetime performance
Around the world, over 460 000 km of pipelines are used to move crude oil from wells to ports
and finally to refineries. These pipelines have to cross remote and hostile areas—often with
extreme temperatures and weather conditions. The pumps, which transport the crude oil over
significant distances, must be highly reliable, energy efficient, and perfectly designed to meet
these challenging operating conditions. Sulzer Pumps optimizes pipeline pumps to meet
continuously changing requirements and to ensure safe operation.
P
ipelines represent a considerable
investment, and their safety, efficiency, and reliability are essential
for their success. The pipeline can be
subject to internal and external corrosion,
fatigue cracking, third-party damage,
and manufacturing flaws. The pipeline
operating company is required to
monitor mechanical loads, pressure
changes, corrosion rates, etc. to evaluate
the risk of pipeline leaks. It is not enough
to monitor the pipes themselves; the
rotating equipment must be managed
and maintained as well.
Pumps are the heart of pipelines, and
their reliability determines the success
of the operations. The American Petroleum Institute (API) has published standards with which the equipment has to
comply. Over their entire life cycle,
pumps have to be checked regularly, and
Pipelines are generally the most
economical way to
transport large
quantities of oil,
refined oil products,
or natural gas
over land.
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| Sulzer Technical Review 1/2013
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PRODUCT LIFE CYCLE
they must be repaired or retrofitted if
they do not meet the necessary performance criteria.
Certain pumps may also have to be
hydraulically rerated because of the
changing operating conditions of a
pipeline. The following example shows
how Sulzer adapted pumps to new
requirements and ensured smooth operation, excellent reliability, and optimum
efficiency.
Adapting to changing requirements
to be changed. The light crude oil that
had to be transported had a lower density
than the oil for which the pumps had
been originally designed. Additionally,
the customer wanted the modified
pumps to be able to operate at varying
daily flow rates between 30 450 and
57 000 m3/d.
Reversible change provides flexibility
The client wanted to be able to reverse
the modification after two years, at which
point, following the completion of a new
pipeline, it planned to return the pipeline
to its original design operation. The
pipeline was a 1600 km oil pipeline in
One of North America’s largest pipeline
companies runs some of the world's
longest crude oil and products pipelines.
These pipeline sysThanks to the retrofit, the client needs less
tems have been operpower
to run its pipeline.
ated for over 60
years and comprise
North America, and it was integrated
more than 10 000 km of pipes, which
with the mainline oil pipeline system of
deliver over two million barrels of crude
the client.
oil and products per day.
Sulzer was asked to rerate 18 pumps
In one pipeline carrying oil in North
for pipeline operation, taking into
America, the pump hydraulics needed
account the temporary change in density
and flow. In order to meet these requests,
the Sulzer engineers suggested four different rerates for four different best efficiency points (BEP) ranging from approximately 44 000 to 57 000 m3/d to meet the
various pipeline flow rates. The shift of
the BEP could be achieved by reducing
the throat area and fitting low-capacity
impellers. The throat area of a pump
is the end section of the volute development, and it has a major influence on
the pump performance.
Reduced inventory cost
As interchangeability with the existing
pumps had to be ensured, Sulzer
supplied suitable impellers. In addition,
mechanical seals and bearings are interchangeable among all rerated units,
which significantly reduced the client's
inventory cost.
Before the modification was carried
out, one of each of the four hydraulic
designs with rerated hydraulic dimen-
Sulzer Technical Review 1/2013
| 5
PRODUCT LIFE CYCLE
ancillary pipes, and on several pipe supoffshore oil fields in Eurasia to the closest
port brackets. Also, the vibrations, which
harbor, from where the crude oil is
could be felt on the pump house floor,
shipped by tanker to refineries in the
European markets. It runs mainly over- had led to compaction of up to 200 mm
of the subsoil supporting the suction
ground along its entire length of more
than 1500 km and
Sulzer presented a retrofit and upgrade solution
is designed for a
as a way of improving the reliability and the
throughput capacity
mean time between failures.
of one million barrels
of oil per day. The
and discharge pipes where these conpipeline facilities include several pump
nected to the station. When the client
stations located across Europe.
approached Sulzer in search of a solution,
Reducing the risk of pipeline failure
the pipeline was operating at full
Four of the pumping stations were
capacity. However, it was in serious danequipped with Sulzer pumps, while the
ger of being shut down due to the excesremaining ones had pumps supplied by
sive vibrations.
a different original equipment manufacturer (OEM). The Sulzer pumps per- Analysis of dangerous vibrations
Sulzer presented a retrofit and upgrade
formed reliably, but the pipeline operator
solution as a way of improving the relinoticed intense pressure pulsations in
ability and the mean time between
suction and discharge lines on some
Retrofit ensures safe operation
failures (MTBF) on the third-party
of the non-Sulzer pumping stations. The
Vibrations and off-design operation of
pumps had been delivered by a third- pumps. In a first step, the Sulzer
pipeline pumps can compromise the
specialists analyzed the first-stage
party supplier during the construction
safe performance of a pipeline. A pump
impeller. It was equipped with four
of the pipeline in the early 2000s. These
retrofit carried out by Sulzer for the main
vanes, which led to strong periodic intersingle-case, axially split, two-stage pumps
oil line (MOL) pumps on a world-scale
action with the double volute casing. The
were designed to deliver a discharge of
pipeline shows how proper pump design
1674 m3/h with a pump head of 1000 m. throat of the suction impeller was overThe pressure pulsations caused by the
can reduce pressure pulsations and
designed, which meant that the flow area
MOL pumps caused cracking of welds
improve safety.
was too large for the required discharge.
on the units themselves, on small-bore
This pipeline transports crude oil from
This characteristic placed the duty point
very close to the onset of inlet backflow.
When a pump operates with inlet recirSulzer pumps and third-party pumps can be retrofitted in any of Sulzer Pumps’ 61 service
centers worldwide. They support customers 24/7 in the operation of pumping and other
culation, efficiency drops, and noise and
rotating equipment. More information: www.sulzer.com/PU-service-centers
vibration level increase.
The second-stage impeller had six
vanes. This even blade number also
increased the risk of strong periodic interaction of the runner with the double
volute casing. Also, neither of the vane
outlet tips were significantly skewed.
Straight impeller vane outlet edges very
often give rise to strong periodic
rotor/stator interaction.
sions went on the test stand in Sulzer's
facility in Burnaby, Canada. After the
tests had confirmed that the adapted
pump would perform according the
specification, the rework on the other
pumps started. To accommodate the customer’s tight schedule, Sulzer managed
to reduce the required time to three
weeks per pump—with the work split
between Sulzer’s Edmonton (Canada)
and Midwest (Chicago, IL, USA) service
centers.
Since the successful commissioning of
the rerated pumps, the client has needed
less power to run its pipeline because
the pumps work near their best efficiency
point at the various flow conditions. With
their design point adapted to the system
conditions, the pumps operate at beneficial hydraulic conditions over a wide
flow range with low vibrations.
Improving pump hydraulics
The Sulzer engineers identified the
hydraulic interaction of stator and rotor
as the root cause of strong pressure pulsations at blade-passing frequency. These
pulsations excited the small-bore piping
and an acoustic resonance in the station
pipework. From this analysis, it was clear
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| Sulzer Technical Review 1/2013
PRODUCT LIFE CYCLE
Successful reduction of vibrations
Life cycle costs of pipeline pumps
Sulzer maximizes pipeline profitability by
reducing the life cycle costs of pumping
systems.
Pipeline pumps have an expected lifetime of
more than 20 years. Over time, however,
changing conditions and equipment degradation can have negative effects on pump
reliability and efficiency.
More than 90% of a typical pipeline pump’s
life cycle cost originates from energy use. For
this reason, Sulzer focuses on efficiency
issues and identifies possible optimization
strategies and retrofits.
More information: www.sulzer.com/retrofit
Life cycle costs
Procurement /
manufacturing
3.6%
Use electricity
94.6%
Service
Manufacturing
Installation
On-site measurements clearly showed
that the pumps equipped with the new
impellers operated at acceptable pressure
pulsation levels. With the root cause of
the vibrations thus eliminated, the
fatigue cracks in the weld of the pipe
supports and the small-bore ancillary
pipes did not occur anymore. Consequently, the floor vibration was also
significantly reduced. Overall, the
Sulzer reduced the risk of
pipeline failure.
1.8%
retrofit by Sulzer Pumps reduced the
risk of pipeline failure and made possible
the safe operation of the pipeline at
the design flow of one million barrels
daily.
After Sulzer had delivered the last of
the ten upgraded rotors, the client
attested that recent pump house vibration
surveys had confirmed significant
improvements in all pipe vibrations from
the earlier damaging levels. In addition,
measurements near the operating pumps
showed clearly reduced noise levels.
Use
Retrofit service
Procurement
Resources
Disposal
Extended life cycle
that reducing the system excitation from
rotor/stator interaction was the key to
improving the performance of the
pumps.
The specialists from Sulzer Pumps
decided to change the number of impeller
vanes to shift the phase of the periodic
excitation caused by the passing impeller
vanes. The redesign of the suction
impellers increased the vane count from
Marc Heggemann
Sulzer Pumps Ltd
Zürcherstrasse 12
8401 Winterthur
Switzerland
Phone +41 52 262 82 36
[email protected]
four to five, and the number of vanes
in the second-stage impeller was increased
from six to seven. Moreover, the vane
exit tips of both impellers were skewed
to soften the hydraulic interaction with
the casing. Sulzer Pumps manufactured
precision cast impellers according to the
improved hydraulic design and delivered
new shafts made from a higher-grade
material than the original ones were.
David Linn
Sulzer Pumps (US) Inc.
4126 Caine Lane
Chattanooga, TN 37421
United States of America
Phone +1 423 296 1939
[email protected]
Kenny Thomson
Sulzer Pumps (US) Inc.
200 SW Market Street
Portland, OR 97201
United States of America
Phone +1 503 205 3620
[email protected]
Complex systems such as pipelines
require careful monitoring during their
useful operational life. In the event of
imminent failure, the operator has to
identify the critical components and to
decide whether they have to be replaced,
repaired, or retrofitted. Often, upgrading
or retrofitting critical components can
efficiently extend the product life cycle
by providing a reliable system. Because
every situation is unique, Sulzer Pumps
provides proven customized solutions
within tight deadlines, thus contributing
to the success of its customers.
Graham Warrington
Sulzer Pumps (UK) Ltd
Manor Mill Lane
LS11 8GR Leeds
United Kingdom
Phone +44 113 272 4446
[email protected]
Ron Palgrave
Sulzer Pumps (UK) Ltd
Manor Mill Lane
LS11 8GR Leeds
United Kingdom
Phone +44 113 272 5701
[email protected]
Sulzer Technical Review 1/2013
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PRODUCT LIFE CYCLE
Process technology services beyond plant installation and start-up
Committed to long-term
customer success
Sulzer meets customer needs by developing and building process plants with guaranteed
performance. But Sulzer’s customer dedication does not end when the plant is installed.
The Process Technology business unit of Sulzer Chemtech provides a full scope of services
after the start-up and supports customers throughout the whole lifetime of the plants.
S
imple mistakes during processing
can lead to serious problems and
unscheduled production breakdowns—the worst nightmare for process
plant owners. One of Sulzer’s customers
suddenly had to stop the operation of a
thin-film evaporation unit because of
grinding noises coming from the vessel.
This incident happened after the film
evaporator had been cleaned and restarted. The working principle of this unit is
to evaporate solvents or other liquids by
applying a thin film of the feed on the
heated wall of the vessel. A rotating
mechanical device with wipers that is
installed inside the vessel supports the
formation of a uniform thin film. These
wipers were causing the grinding noise
because the machine had been running
accidentally for several days without a
feed. The wipers were grinding the vessel
The after-sales team
of the Process Technology business unit
supports customers
on site during the
whole lifetime of
process plants.
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| Sulzer Technical Review 1/2013
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PRODUCT LIFE CYCLE
Service portfolio of the Process Technology business unit
The service offering of the Process Technology business unit is divided into three
groups:
• One group covers equipment as specified by customers. Examples of this are heat
exchangers, coolers, columns, evaporators, condensers, and various vessels such
as reactors. These are fabricated based on specifications provided by the customers.
• Another group deals with the sales of spare parts for all of Sulzer Process Technology’s proprietary process equipment such as thin-film evaporators, liquid-liquid
extraction columns, and skid-mounted units and plants.
• The third group covers on-site services such as inspection, troubleshooting, expertise, supervision of installation, and refurbishment of polymeric and ceramic
membranes modules.
The after-sales team relies on experienced staff, modern IT tools, and a database
covering an archive of more than 40 years. In addition, it can count on a large network
within Sulzer and provides its life cycle management services on a global scale.
More information: www.sulzer.com/PT_Lifecycle
group. This group had installed more
than 250 skid-mounted units worldwide
in 20 years and had erected and serviced
plants on site (mostly in Switzerland and
Europe) for an even longer period of 80
years. From all those years of on-site
experience, Sulzer had learned to understand the customers’ needs and to anticipate and solve their requests. This aftersales support, combined with Sulzer’s
activities in the fine chemical, pharmaceutical, biofuels and petrochemical
industry segments, gives the Process
Technology business unit the opportunity to offer a unique range of services.
Avoiding production breakdowns
Sulzer develops service solutions even
wall, damaging both the surface of the
Prerequisites for competent service
with challenging time schedules. A
Solving problems in such a short time
vessel and the wipers (both were made
French customer called Sulzer’s afterrequires extensive experience in a broad
of a nickel-chromium-molybdenum alloy
sales team because a condenser that
range of areas. The after-sales team of
C22, Figure 1).
Sulzer had provided seven years before
In this emergency, the after-sales team
Process Technology was created in 2010, for its wastewater recovery unit was leakof the Process Technology business unit
following the acquisition and integration
ing dramatically. A repair on site was
immediately came
not possible because the customer could
The full repair and restart of the film
to help. The Sulzer
not stop the production campaign at that
evaporation unit was completed in less than
team arrived the
stage. Checking in Sulzer’s archives, the
two weeks.
very next day,
after-sales team was able to find the originspected the plant,
inal drawing of the vessel. Sulzer proof the company Kühni into Sulzer’s port- posed that it would fabricate a new conand proposed a solution. The unit was
folio. The team was built upon the exten- denser and then repair the damaged one
transported straight from the plant’s site
to Sulzer’s workshop in Allschwil, sive experience of the former installation
after inspecting it. Upon customer's reply
Switzerland. There, the vessel, also
called the stator, was machined on a
1 After accidentally being operated for a number of days without feed, the thin-film evaporator
was seriously damaged. The picture shows grinding marks (stripes) on the inside of the vessel.
lathe to bring the surface state back to
its original smoothness. However,
through the lathing, the thickness of the
stator wall was reduced. The remaining
thickness was under the allowed tolerance for this type of equipment working
under vacuum. Sulzer’s solution was to
reinforce the vessel by welding rings
around the stator and to change the
wipers from metal alloy C22 to polytetrafluoroethylene (PTFE), which is a
softer material and does not damage the
vessel surface. All the while, the
customer was following the repair of its
equipment by paying visits to the workshop. The customer appreciated Sulzer’s
efforts and commitment to recovering
its key vessel. The full repair and restart
of the evaporation unit was completed
in less than two weeks.
Sulzer Technical Review 1/2013
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PRODUCT LIFE CYCLE
2 One of Sulzer’s after-sales team
members supports installation of
new equipment at a customer’s site.
that it could stop production for three
full days in five weeks’ time, all
concerned departments within the
Process Technology business unit (construction, fabrication, purchasing) were
immediately aligned and started the
work required on this project. Thanks to
their combined commitment, they even
managed to deliver the vessel one week
earlier than the planned installation. This
example shows that Sulzer’s after-sales
team helps customers to minimize interruptions of their production. The team
understands that unscheduled production
breakdowns result in severe financial
losses and may even undermine the customer's credibility to other parties.
Successful performance improvement
Sulzer’s service team also improves the
performance of plants. A Dutch company
had installed a pervaporation unit using
polymeric membranes. This unit was initially meant for bioethanol dehydration
and was subsequently used to produce
pharmaceutical-grade ethanol. The unit
was composed of two vacuum vessels
with four membrane modules installed
inside each vessel. The customer
approached Sulzer’s after-sales team
because the plant was not performing
10 | Sulzer Technical Review 1/2013
liquid-liquid extraction, crystallization,
according to the expectations, and the
membranes seemed to need replacement. membrane separation, hybrid solutions,
and polymer production). They also benIn Sulzer’s opinion, it was too early to
efit from a process solution that is jointly
replace the membranes because they
were not older than 18 months. Therefore, developed from first concept and pilot
Sulzer sent an experienced process engi- testing to an installed plant with guarneer to the facilities to check the perfor- anteed performance. Furthermore, after
the plant start-up and handover, Sulzer’s
mance of the unit and to investigate how
to improve it.
Sulzer replaced the polymeric membranes in
On site, Sulzer’s
the pervaporation unit and improved the ethanol
expert analyzed the
production.
data and proposed
changing
some
dedicated after-sales group continues to
parameters related to the feed and the
support all its customers, by providing
operating temperatures. This brought
good first results and gained the cus- spare parts and services during the whole
lifetime of the plant, wherever the customer's confidence in Sulzer’s membrane
tomers are located around the globe. The
technology and know-how. The customer
after-sales team reflects Sulzer’s customer
saw the opportunity to further improve
commitment and partnership. The team
the production and decided to replace
the membranes initially in four modules. members contribute their experience and
Sulzer replaced the membranes success- flexibility, and they provide quick and
efficient services, so that the customers
fully, and the highly satisfied customer
can optimally use Sulzer’s plant solucommissioned Sulzer to do the same on
tions.
further modules.
Continuous services worldwide
By choosing the Sulzer Process Technology business unit, customers not only
get the best from its innovative range of
technologies (distillation, evaporation,
Bruce Coll
Sulzer Chemtech Ltd
Gewerbestrasse 28
4123 Allschwil
Switzerland
Phone +41 61 486 37 68
[email protected]
SULZER ANALOGY
Upcycling in nature
Nature knows hardly any waste.
Hermit crabs look for abandoned
snail shells as homes and provide
a fine example of the reutilization
of used materials.
A
wave washes the house of a magnificent Common whelk, a type of
large sea snail, onto the beach. A hermit
crab soon comes scurrying across the
sand. Its six walking legs move nimbly;
its other four legs and the rear part of
its body are inside an empty snail shell.
The calcareous housing acts as the crab’s
protective armor, and the crab even
brings it along when hunting for food.
The crab inspects the washed-up house
carefully with its antenna and pincers.
When it realizes that the shell is empty
and that the shell offers more space than
the old container on its back, it quickly
exits its old home and slips into the
larger house. Minutes later, another
hermit crab appears by the now abandoned old house of the first crab. And,
because this shell also offers the second
crab the opportunity for an upgrade, it
also changes its home. In the course of
a few hours, a long chain of tenant
changes can thereby take place—similar
to what happens in our real estate market
when the availability of an attractive
object often triggers a whole series of
moves.
Temporary accommodation
The search for ever-larger houses is vital
for the hermit crab. Millions of years
ago, when it adopted the tactic of using
the armor of an empty snail shell as protection, the crab adapted its body accordingly. The abdomen of the crab lost its
usual outer skeleton and became a soft,
defenseless body part—its curved shape
matching the windings of the snail shell.
The rear legs were transformed into stub
limbs that, fitted with suckers, can hold
Snail shells have a long service life. Even 120 000-year-old fossil specimens
are used as homes for hermit crabs.
onto the housing from the inside. And
one of the two pincers on the front feet
has also become so enlarged that the
crab has an armored front door as soon
as it retreats into its snail shell.
Other kinds of crab can only grow by
breaking up their chalk-and-chitin armor
every few months and making themselves
a larger suit. For the hermit crab, an
increasingly portly figure also requires
an adequate home, which repeatedly
forces the animal to search for a new
home in the course of its development.
In difficult housing markets, this can
sometimes lead to brawls if two or more
crabs are interested in the same object.
Reutilization of fossils
The American biologist Stephen Gould
has shown how difficult the housing
market can be through the example of
Coenobita diogenes, a terrestrial hermit
crab in the Bermudas. Gould noticed that
the hermit crabs were squeezing their
bodies into the rather pathetic housing
of small nerite snails, whereby a part of
their body remained hanging out. Then,
one day however, he found a hermit crab
that lived in a more fitting manner, sitting
inside the large shell of a Common whelk.
On closer examination, the snail shell
actually turned out to be a 120 000-yearold fossil that had been washed out of
a sand dune. The Common whelk had
been native to the Bermudas since time
immemorial. Its tasty meat made
it into a favorite meal for the island’s
inhabitants and sailors, however, so that
the snail became extinct there around
200 years ago. The hermit crab thereby
lost its traditional accommodation; and
the housing of the smaller nerites is only
suitable for the younger crabs at the
most. Gould believes that the hermit
crabs on the Bermudas will continue to
survive for some time thanks to their
reutilization of the fossil Common whelk
shells. Eventually, however, they will die
out due to the housing shortage.
Herbert Cerutti
In every phase of its life, the hermit
crab searches for the housing that
best fits the size of its body.
4400
Sulzer Technical Review 1/2013
| 11
Product lIfe cycle
Modern coating solutions for the machining industry
Longer lasting tools
In metal processing, surface solutions such as PVD coatings (physical vapor deposition) improve
tools so much that customers can benefit from enormous economic advantages. Optimizing
tools for their use is a complex task, however. Standard coatings can help, but really impressive
results can only be achieved if all the factors are coordinated with one another, from the starting
material up to the posttreatment.
M
achining is a metal-cutting
process that has to fulfill
increasingly high demands
with regard to productivity and processing speed. The friction arising during
the process and the wear on components
and tools are major loss factors. According
to the German Society for Tribology, a
loss of about 5% of gross social product
arises annually in industrialized countries
through the effects of friction and wear
alone.
Tool coatings counter these mechanisms
and are thereby essential nowadays in
machining. As a provider of innovative
surface technologies, the Thin Film business unit of Sulzer Metco has been developing tailor-made system solutions for
many years to make tools more resistant,
more productive, and longer lasting. The
special feature of Sulzer’s holistic
Tool coatings are essential
nowadays in machining.
approach is the consideration and streamlining of all the influencing factors. Start-
In machining, everything depends on the optimal interplay of all the parameters of the tool, the coating, and the material.
12 | Sulzer technical review 1/2013
4401
Product lIfe cycle
How does wear on tools arise?
during the machining (the removal of
chips), the following wear mechanisms
take place in the area the tools contact
the material being worked on due to
the friction processes and the thermal
and chemical stresses:
• Adhesion between chips and the
cutting surface
• Abrasion through hard materials
within the material
• tribochemical reactions (chemical
material behavior due to mechanical
action and high temperatures)
these tribological stresses largely
characterize the efficiency of tools
because they reduce the cutting
forces and shorten service life.
A surface coating may reduce the
impact of the tribological stresses,
while the base material of the tool
takes over the supporting function and
absorbs the mechanical stresses. In
addition to increased productivity,
improvement in the tribological system
also leads to savings in material and
energy.
ing from the application-specific requirements, Sulzer finds the best-possible combination of
• Pre- and posttreatment of the tool
surface
• Coating material
• Layer architecture
• System technology with which
the coating will be applied
Targeted pre- and posttreatments
The cutting tool is subjected to high
pressure (more than 2 GPa), high temperatures, and thermal cycling stresses
in the modern machining process. The
pre- and posttreatment—as well as the
coating—must therefore also be adapted
to the application.
There are various pretreatment meth- factors. This applies, above all, to the
interaction between the base material
ods available that prepare the tools for
a subsequent coating process and signif- and the applied coating. The coating
material should have the least possible
icantly improve the coating adhesion at
the same time. Together with the coating, affinity to the material being worked on.
In this way—with suitable cutting geoma preparation of the cutting edge of the
tool leads to increased cutting speeds, etry and by smoothing or polishing of
the coating—the adhesion tendency can
feed rates, and longer service lives. The
be significantly reduced.
posttreatment (edge preparation, surface
treatment, and structuring) also plays a
Tailor-made coatings
decisive role, in particular, in avoiding
Aluminum-based coatings, such as AlTiN
the initial wear, which can occur, for
(titanium aluminum nitride), are often
example, through cutting-edge buildup
used in the machining industry. In these
(adhesion of material from the workpiece
aluminum-based coatings, a thin but
to the cutting tool).
dense aluminum oxide layer forms as a
Numerous tests have shown how great
result of the high temperatures during
the impact of the pre- and posttreatment
of tools can be on
Specific preparations can improve tool
productivity. For
performance by more than 100%.
example,
performance gains of more
the machining. This layer then continually
than 100% in gear-cutting tools can be
and independently renews itself and proachieved through specific preparations.
tects the coating and the base material
Coatings for demanding working
below it from oxidative decay. The
conditions
required hardness and resistance to oxiThe requirements that are placed on coat- dation can be adjusted through a
ings can be very different. As high tem- variation of the aluminum content and
peratures arise at the cutting edge during
the layer morphology. The resistance to
machining, high resistance to thermal
oxidation, for example, can be improved
wear becomes extremely important. The
through an increased aluminum content,
following properties are expected from
nano-structuring, or microalloying (i.e.,
modern coatings:
alloying with low-percentage element
• Excellent high-temperature properties
proportions).
• Resistance to oxidation
In addition to the chemical composition
• High hardness, even at high working
of the material, the layer architecture can
temperatures
also considerably alter the properties of
• Microductility (plasticity) through a
a coating. Different tool properties arise
nano-structured layer design
depending on the distribution of the ele(Figure 1)
ments in the microstructure of a layer
In the case of high-performance tools, (Figure 1). Today, several individual layoptimal adhesion of the coating and well- ers with different chemical compositions
can be combined to achieve customized
adapted residual stress are decisive
1 functional coating properties, such as the layer hardness, the phase stability, and the tribological properties, can
be adjusted by a different distribution of the elements within the layer.
Monolayer
Graduated layer
Multilayer
Microalloyed layer
Nano-composite layer
Sulzer technical review 1/2013
| 13
Product lIfe cycle
properties. This trend will increase even
more in the future—in particular,
through new system and process technologies, such as the HI3 technology.
Coating technology for the future
HI3 technology, developed by Sulzer,
combines three highly ionized arc
processes:
• AEGD (arc-enhanced glow discharge):
plasma etching process for good layer
adhesion (can also be used for the
pre-ionization of reactive gases during
the coating)
• HIPAC (high-ionization plasmaassisted coating): highly ionized
sputter process
• APA Arc (advanced plasma-assisted
arc): highly ionized arc process.
The combination of high-ionizationsputter and high-ionization-arc processes
makes it possible to achieve layer architectures that could not be realized previously. Up to now, many alloys could
only be partially deposited with the arc
process alone. The combination of the
How can costs be reduced in machining?
An important cost factor in the production cycle is the service life of the tools. Among
other things, this is understood as the period during which a machine can work
without interruption before it requires maintenance. the longer the service life, the
lower the costs that arise for production interruptions and maintenance work will be.
the use of coatings increases the service lives of the tools—even at high process
temperatures—and thereby considerably reduces the costs. In addition, fewer lubricants are needed. this not only reduces the material costs but also helps protect
the environment.
HI3-basis show outstanding results in
arc process with the HIPAC process
the machining of titanium, in the probrings advantages, as this process can
cessing of stainless steels, and with
evaporate a considerably larger spectrum
of materials, such as
The HI3 process technology of Sulzer opens up
SiB (silicon-boron),
completely
new application fields.
B4C (boron carbide),
and others. In this
thread-cutting tools. Examples are the
way, the process can open up completely
new application fields. With the META- new, SiBX-based coatings with increased
oxidation stability and VXN-based (vanaPLAS.DOMINO series, Sulzer offers
dium-nitrogen) coatings with improved
modular coating systems with which
coefficients of friction at high temperathe HI3 technology can be implemented
2
tures.
(Figure ).
The first coating developments on a
Powerful thanks to M.POWER
2 the MetAPlAS.doMINo coating system from Sulzer features the highly efficient, patented,
AeGd (arc-enhanced glow discharge) plasma-cleaning process. this additional cleaning step
considerably improves the adhesion of the coating to the substrate.
14 | Sulzer technical review 1/2013
Titanium-silicon-based (TiSi) M.POWER
coatings (Figure 3) provide outstanding
results as all-rounders. These coatings
can be used for very hard steels (up to
65 HRC Rockwell core hardness) with a
variable proportion of carbide as well as
for medium-hard steels (40 HRC Rockwell
core hardness). The layer design is similarly adapted in order to meet the
diverse range of application areas. As a
result, the surfaces are equipped for the
machining of everything from high- and
low-alloy steels up to hardened materials
and titanium.
In short- and long-term tests,
M.POWER-coated copy mills showed
service lives that were almost doubled
due to reduced cutting-edge wear and
enhanced surface quality. Further tests
carried out in the fine-finish machining
operation (on flat workpieces with a
Rockwell-hardness of 44 HRC) made it
clear that a service life that is almost
three times as long and a tenfold
reduction in roughness can be achieved
with M.POWER-coated tools (see infobox
on page 15). The subsequent polishing
Product lIfe cycle
3 M.PoWer-coated milling tools have considerably increased
service lives, even in the high-speed machining of hard steels.
of the surface could be minimized. These
edge, and high metal removal rates are
are just a few examples from well-known
required.
tool and automobile
With Sulzer as partner, customers can increase
manufacturers who
the efficiency of tools throughout their
already rely on
complete life cycle.
this coating. The
M.POWER family
For additional PVD coatings (and, in
impressively underlines its potential in
applications in which high cutting
particular, for microalloyed coatings),
speeds, high temperatures at the cutting
Sulzer also carries out research on opti-
What is M.POWER?
the PVd-coating M.PoWer of Sulzer has an innovative microalloyed layer structure
and is especially suited for high-performance machining. the M.PoWer coating has
the following specifications:
• Material: tiSiXN (titanium silicon nitride)
• Possible structures: mono, multi, nano
• coating thickness: 1-3 μm
• Hardness: 3600 HV (Vickers hardness)
• Max. application temperature: 1150°c
Service life of reference tool
+100%
Service life of M.POWER-coated copy mills
Service life of reference tool
+200%
Service life of M.POWER-coated fine-finish machining tools
More information: www.sulzer.com/MPowerCoating
mized surface solutions in close cooperation with machining companies. Close
cooperation with the customer is important in order to be able to move ahead
with innovations. In this way, potential
improvements in productivity, in the use
of tools, in quality, and, last but not least,
in the interplay between material,
coating, and application can be realized
and utilized. Through expert partners
like Sulzer, customers can increase the
efficiency of machining tools throughout
their complete life cycle.
Annette Norin
Sulzer Metaplas GmbH
Am Böttcherberg 30-38
51427 Bergisch Gladbach
Germany
Phone +49 2204 299 262
[email protected]
Georg Erkens
Sulzer Metaplas GmbH
Am Böttcherberg 30-38
51427 Bergisch Gladbach
Germany
Phone +49 2204 299 354
[email protected]
Sulzer technical review 1/2013
| 15
IN FOCUS
Conscious decisions thanks to
environmental product declarations
Customers want to buy sustainable products. To be able to assess which product has the
lowest environmental impact, it is necessary to have comparable data on the complete product
life cycle. By introducing standardized environmental product declarations (EPD), Sulzer has
started supplying its customers with transparent and comparable environmental data. The
EPDs from Sulzer help customers in their investment decisions and in the sustainable design
of their value-added chain.
EPDs are based on life cycle assessments (LCA)
EPD
LCA
Life cycle assessments analyze the environmental
impact of products during their complete lifetime. The
ISO standard 14 040 describes the basic elements of
a life cycle assessment.
However, reviews can differ since different methods of
analysis and different standards may be used. That
makes the interpretation of the LCAs and a comparison
of the products difficult.
Environmental product
declaration
Product category rules (PCR) make it possible to compare EPDs
A comparability of life cycle assessments can be
achieved by applying ISO standard 14 025 type III and
by using product category rules. PCRs are based on
globally recognized product classifications (CPC = central product classification) and define the standards and
the necessary assumptions for certain product categories. PCRs are drawn up and adopted based on the
initiative of companies within the context of a
stakeholder dialog. Sulzer has already been involved in
the creation of a PCR for pumps.
More information:
www.sulzer.com/EPD
“The EPDs of Sulzer promote environmentally
conscious life cycle thinking.”
Sebastiaan Stiller
Sulzer Corporate Quality,
Environment, Safety and Health
Zürcherstrasse 14
8401 Winterthur
Switzerland
Phone +41 52 262 36 17
[email protected]
16 | Sulzer Technical Review 1/2013
“With the EPDs, our customers gain a comprehensive
picture of the products and can take the environmental
impacts into account in their investment considerations.
Many of our customers are the focus of great public
interest and would like to arrange their complete valueadded chain in a sustainable manner. This desire is particularly strong in energy-intensive markets such as oil
and gas. An intensive discussion regarding sustainability
is also taking place in the power generation market. Our
customers can search for the best possible sustainability
solutions with the help of EPDs. In this way, Sulzer makes
a contribution to transparency and the promotion of new,
environmentally conscious life cycle thinking.”
Which Sulzer products
already have EPDs?
Sulzer has already drawn up EPDs
for 20 products. The first product
categories to be covered were
pumps. In the meantime, EPDs
also exist for separation technology
and surface-coating products. As
the next step, Sulzer has also contemplated the environmental declaration of services.
4402
IN FOCUS
EPDs describe verified environmental
impacts
In an environmental product declaration, data from life
cycle assessments are prepared, and statements about
environmental impacts are made. These data can be
compared with other EPDs of the same product category.
There are several EPD initiatives. Sulzer has decided
in favor of the Swedish “International EPD System,”
because this standard prescribes external verification
of the information in the EPD by third parties
(in accordance with the ISO 14 025 type III standard).
More information on this EPD system can be found at
www.environdec.com
EPDs provide information on resource
consumption and emissions
Customers profit from EPDs in many ways
• Thanks to EPDs, customers know the environmental
impacts of products over their complete lifetime.
• Customers can compare the data of different products
for investment decisions.
• Customers have the assurance that the statements
regarding environmental impacts are based on verified
data and comply with the ISO 14 025 type III standard.
• Customers can use the information from the EPDs in
order to save costs—for example, through investment
in particularly energy-efficient products.
• Based on the data provided by the EPDs, customers can
improve the sustainability of their value-added chain.
• Customers can demonstrate the environmental awareness of their actions and can use this for image building
and as a sales argument.
The consumption of resources (materials, water, energy)
is accounted for in the EPDs, and the environmental
impacts (emissions) are assessed. These include:
CO2 emissions
Acidification of water and the soil
Photochemical smog through the
formation of ground-level ozone
Depletion of the ozone layer
Water pollution through the demand
for biochemical oxygen
Customers praise Sulzer’s pioneering role—
one example
A number of EPDs from Sulzer go beyond the mandatory
minimum standard. They not only contain the environmental data, but also information on the product costs
that arise. This information is very important for the customers because the greatest costs and most of the emissions for “active” products, such as pumps, take place
in the operating phase.
The product costs are presented in clear diagrams in
the EPDs from Sulzer:
Proportion of procurement and manufacturing costs
Proportion of operating costs: power consumption
(more than 90% for pumps)
Proportion of operating costs: service
The Abengoa SA company (Seville, Spain) is active in
the areas of energy and environmental technology and
makes use of Sulzer pumps for solar-thermal plants.
Abengoa has positioned itself as a sustainable company
and demands that all suppliers map the complete life
of their products. With the EPDs from Sulzer, Abengoa
can be sure it is selecting the most energy-efficient
pumps. Abengoa praises Sulzer’s efforts in making the
sustainability of the entire product life cycle transparent
and in improving this sustainability. As an acknowledgment
of Sulzer’s pioneering role in energy and resource
efficiency, Abengoa awarded Sulzer the “Sustainable
Business Award” in 2011.
Sulzer Pumps
Sulzer Chemtech
Pumps: GSG, ME, MD, SJT, OHH, MSD, HSB, BBS, AHLSTAR,
EffeX, BNO, ZFN, SMD, XFP, XJ / Agitators: XRW, SLF, EffeX
GreenLine/PP 2-component
mixing system
Sulzer Metco
Metco601
coating material
SinplexPro™
plasma spray gun
Sulzer Technical Review 1/2013 | 17
PRODUCT LIFE CYCLE
Improvement of compressor rotors
Lifetime extension with hardfacing
The wear and erosion of critical machine parts are problems often encountered in turbomachinery maintenance. With its combined knowledge of turbomachines and surface
technology, Sulzer can increase the machines’ lifetime and reduce the risk of emergency
shutdowns. The following project provides insights into the benefits and challenges of
applying new technology to existing machines with innovative manufacturing approaches.
S
ulzer carried out a lifetime increase
of a single-stage, integral compressor rotor (KKK SL 10.00a) that was
badly eroded (Fig. 1) and not meeting
its expected performance. The rotor was
used for compressing large amounts
(70 000 m3/hr) of converter gas. This gas
is a byproduct of the steel manufacturing
process and is highly erosive due to its
high solid-particle content. The damage
to the rotor impeller was progressing
rapidly because the additional turbulence
created by the initial damage was increasing the rate of erosion. This factor com-
The damaged rotor caused
unbalance and vibrations.
bined with the high solids content in the
gas flow and remains of the old epoxy
coating were causing unbalance and
vibrations.
The customer had previously tried to
protect the impeller by applying different
wear protection coatings on the most
damaged areas of the impeller:
• Epoxy coating
• Arc-welded hardfacing of Stellite®,
which is a special alloy (see infobox)
• Thermally sprayed hardfacing
Steel production processes dispose large volumes of specialty gases. Three different process stages—from coal to steel—
create three different gas types: coke gas, blast furnace gas, and converter gas. These gases are used for heat and power
generation but are highly erosive and cause damage in the compressors.
18 | Sulzer Technical Review 1/2013
4403
PRODUCT LIFE CYCLE
What is Stellite®?
Around 1907, Haynes International developed Stellite as a corrosionresistant alloy. Stellite is now a registered trademark of Deloro Stellite
Company. With its constituent components of cobalt, chromium molybdenum, tungsten, and nickel, it is
highly resistant to corrosion, wear, and
heat.
First implemented as a lifetime extender for cutting tools, it enabled
longer operational time and higher
cutting speeds. During the Second
World War, the alloy proved to be suitable for investment casting of turbine
blades. Nowadays, Stellite is used
as a protective top layer on wearsensitive critical steam or gas turbine
blades, for example.
The high wear resistance of these
alloys is created by the formation of
carbides M7C3. The carbon percentage
influences the amount of carbides
being precipitated, which reflects in
the hardness and brittlement of the
material. Stellite 21 has a lower carbon
weight percentage (0.25%) than other
Stellites that have no wolfram component but a high molybdenum percentage (5.5%). For Stellite 21, this translates into less carbide precipitation,
which thus provides a lower hardness
but better ductility. A higher percentage
of the chromium content stays dissolved in the alloy, which results in
higher corrosion resistance.
Of these solutions, only the Stellite welding gave encouraging results. However,
the downside of the Stellite solution was
that it was applied by hand arc welding,
and therefore the resulting layer thickness
and surface quality were inconsistent.
Furthermore, it was difficult to apply
the Stellite layer welding to larger surfaces.
1 The impeller was eroded at its most turbulent locations in the flow path:
blade tip, leading edge, and shroud.
• Cladding of the impeller blades on the
the vanes had to be welded onto the
intake and pressure sides and of the
premachined backplate. To decide in
shroud ring with Stellite 21 using a
which stage of the production process
suitable welding and manufacturing
the Stellite wear shield could be applied,
process
Sulzer’s unique combination of turbomachinery
• High-velocity oxyand surface technology know-how was ideal to
gen fuel (HVOF)
solve this problem.
coating of the shaft
with Metco Diamalloy 1008
Sulzer engineers needed to evaluate the
different production stages and to conSearch for a manufacturing approach
sider the specific material characteristics
The most challenging task was to find
of the Stellite shielding material.
a suitable manufacturing process for
Previous experience with Stellite
the rotor with integrated impeller and
cladding showed that the remaining
Stellite-cladded vanes. The rotor body
internal stresses generated by the
and impeller backplate had to be man- welding process and shrinkage resulted
ufactured from a one-piece forging, and
in considerable deformation of the parts.
2 Laser cladding is particularly suitable for applications that demand high dimensional accuracy.
Because of the superior focusing ability of laser, components can be processed with minimal
thermal loading and distortion. Sulzer has long-standing experience in laser cladding and has
performed a great variety of laser applications for customers all around the world.
Sulzer divisions join forces for
customer solution
Sulzer’s unique combination of turbomachinery and surface technology knowhow was ideal to solve this problem. The
experts from Sulzer Turbo Services,
Sulzer Metco, and Sulzer Innotec worked
together closely to find the best solution
for the customer. Sulzer recommended
the following life-extending measures
to slow the wear on the impeller vanes
and decrease the machine’s downtime:
Sulzer Technical Review 1/2013
| 19
PRODUCT LIFE CYCLE
If the vanes were cladded with Stellite
after they were assembled onto the backplate, the risk of unacceptable deformation
of the vanes was high. Furthermore, the
welding would have to be done manually,
as some areas would be difficult to reach
Sulzer decided to apply the
layer by laser cladding in order
to overcome the disadvantages of manual arc welding.
with automated welding. In addition to
the possibly uncontrollable deformation
of the impeller vane, the manual arc
welding approach had some other disadvantages:
• Additional laborious grinding procedures necessary to achieve a consistent
layer thickness and surface quality
• More time-demanding balancing of
the rotor due to a larger variation in
individual blade weight
• Lower wear resistance of the Stellite
layer due to manual application
Developing a laser-cladding solution
To keep the Stellite layer within controlled
parameters (thickness and location),
Sulzer engineers decided to apply the
layer by laser cladding (Fig. 2) on the
individual vanes before they were assembled and final welding was performed.
In a cooperative effort with the welding
department of Sulzer Innotec, Sulzer
Turbo Services performed tests to assess
the quality and continuity of the welding
layer. After several test welds on a base
material comparable to that of the
impeller vane, samples were made to
3 A finite element analysis of the rotor
confirmed that the Stellite layer caused no
unacceptable distortions or stress levels.
Max.
350
0
Min.
[MPa]
20 | Sulzer Technical Review 1/2013
What are typical causes of damage?
Damage to turbomachines can be classified in two categories:
Predictable wear: as caused by the attack of the machines parts or by chemical,
thermal, or mechanical influences. This kind of damage can be characterized by its
slow and expected degradation of the base materials. Predictable degradation can
be taken into account by periodic inspections and planned production stops for
maintenance, thus preventing further damage and keeping a handle on expected
costs.
Unpredictable wear: This kind of wear is most feared—as it can emerge at any time
and disturb critical processes, causing emergency shutdowns with consequential
high outage costs. Unpredictable wear can be characterized by its unsuspected and
sometimes rapid progress, and, in some cases, catastrophic failure of the part. The
root cause of unpredictable wear can be found in operational conditions not taken
into account at the initial design stage of the part or the part being operated outside
its original design parameters.
With an extensive knowledge of process conditions and the use of better-performing
materials, Sulzer is able to slow down the predictable wear process and to avoid
unpredictable damage.
determine the achievable weld quality. During production, during laser cladding,
and after final machining, the engineers
Based on the best results, the welding
confirmed the correct geometry of all
procedure parameters for the laser
blades by 3D measuring the blade curve
cladding of the vanes were selected.
and comparing the found coordinates
The rotor model was analyzed by
means of a finite element model simu- with the nominal model. After they had
lation (Fig. 3) to assess whether the addi- passed the final inspection in the Stellite
tional centrifugal
The cladded Stellite layer was tested in a
forces generated by
cooperative effort with the welding department
the added weight of
of Sulzer Innotec.
the cladded Stellite
layer would result in
unacceptable stress levels or in deforma- cladding process, the blades were cut
free by means of 3D laser cutting and
tion of the impeller material. The values
were ready to be welded onto the premafound were acceptable for the specified
material characteristics so that the pro- chined rotor body.
duction could start.
Production step 2: Assembly
Production step 1: Machining and
laser cladding
The vane’s geometry was machined
using 5-axis computer numerical control
(CNC) out of a solid piece of forging.
The machining was executed in several
individual steps with intermediate dimensional inspections. This approach made
it possible to measure and correct any
deviations from the desired geometry
after laser cladding and heat treatment.
To generate the model for the 5-axis
machining, Sulzer engineers extracted
the blade geometry from the available
3D model of the rotor/impeller and positioned it in the most convenient setup
for machining and laser cladding (Fig. 4).
Because all welds needed to be correct
the first time, the process for welding
the blades to the rotor disk was qualified
with a testing protocol. A reference template with precut slots was used to ensure
the correct placement of each individual
blade before welding. At this stage, the
vane support ring (which was also
Stellite cladded on its axial inlet side and
its inner diameter) was assembled and
welded onto the rotor assembly. The temperature during final welding of the
vanes and inlet ring was controlled so
as not to influence the properties and
quality of the Stellite layer. After welding
activities had been completed, the whole
rotor assembly was given a final heat
PRODUCT LIFE CYCLE
treatment to relieve any residual material
stresses in the rotor assembly.
Production step 3: Inspection and
delivery
To confirm that there were no material
defects as result of the heat treatment,
the rotor was given a complete nondestructive inspection. Once it had successfully passed the non-destructive
inspection, the rotor was machined to
its final dimensions. After engineers had
inspected it for defects and geometry,
The expected lifetime of the
rotor increased significantly.
spin testing at 115% was performed and
the rotor was balanced. When it was
returned to the machine shop, the rotor
was given a final inspection to ensure
that there were no deformations. After
it passed final inspection, the rotor was
cleaned, conserved, and prepared for
shipping to the customer (Fig. 5), where
5 The measures of Sulzer slowed down the wear on the impeller vanes thus increasing
the lifetime and—at the same time—decreasing the machine’s downtime.
it was installed the following week
during a planned maintenance stop.
The rotor has been running with
satisfactory performance for over eight
months now, and it is expected to have
a significantly longer liftetime than
the original configuration, thanks to the
solution developed by the Sulzer team.
4 To keep the relative position of the blade in the base material measurable during the produc-
tion process, Sulzer engineers machined reference planes and notches into the base block.
Danny Ketelaar
Sulzer Turbo Services
Moezelweg 190
3198LS Europoort Rotterdam
Netherlands
Phone +31 181 282000
[email protected]
Jan-Jaap van Wijk
Sulzer Turbo Services
Moezelweg 190
3198LS Europoort Rotterdam
Netherlands
Phone +31 (0)181 282000
[email protected]
Sulzer Technical Review 1/2013
| 21
PRODUCT LIFE CYCLE
Practical examples of failure analysis
Analyzing and effectively avoiding
corrosion
Corrosion is the worst enemy of metallic components. It shortens their lifetime and causes
immense costs. Experts from Sulzer Innotec show how to fight corrosion effectively.
C
orrosion is a well-known and
annoying phenomenon. Everyone
has had experience with rust damage to their car, to the garden fence, or
to other metallic objects that are used
daily. However, corrosion is not only
present in private daily life. Although
anticorrosion measures have been implemented and improved over decades, corrosion is also an omnipresent theme in
industry. Billions of dollars of industrial
corrosion damage are incurred every
year, and often the damage caused by
operational shutdowns and loss of production exceeds the primary material
and repair costs many times over.
On a daily basis, the specialists of the
Materials and Failure Analysis group at
Sulzer Innotec work on many different
cases of damage caused by corrosion. As
a service provider for various branches
of industry, the laboratory is confronted
with many different types of materials,
corrosion conditions, and resulting dam-
age. Thanks to their broad experience
acquired over many years, Sulzer's
experts find solutions with which corrosion damage can be avoided and the
service lives of components extended. The
following two examples illustrate how,
time and again, unexpected phenomena
and different forms of corrosion are
encountered when clarifying failures. In
particular, the overlap of different damage
mechanisms creates challenges when
searching for the causes of a failure.
1 The branched crack in a brass housing is a typical sign of stress corrosion cracking.
40 µm
22 | Sulzer Technical Review 1/2013
4404
PRODUCT LIFE CYCLE
What is corrosion?
Corrosion is an electrochemical redox
process (a reaction involving the
transfer of electrons) that takes place
between a metal and its surroundings.
The metal is oxidized, and a component in the surrounding medium is
reduced. There are many different
types of corrosion, which manifest
themselves in different ways.
Stress corrosion cracking arises
through the interaction between a susceptible material, tensile stresses, and
a specific corrosion medium.
Stress corrosion cracking only can happen if all three
conditions are fullfilled:
Susceptible
material
Corrosive
medium
Tensile stresses
Pitting corrosion leads to the local
destruction of the protective oxide
layer of passive materials under the
influence of halide ions.
Crevice corrosion is similar to pitting
corrosion. The protective oxide layer
is destroyed through the accumulation
of halides and the reduction of the
pH value in a narrow gap, e.g., under
deposits.
ronmental influences. Ammonia, as well
as ammonium and nitrate solutions, are
known to trigger stress corrosion cracking
in brass.
The problems bacteria can cause
inous mass. These microorganisms had
chemically reduced the nitrate present
in the drinking water to ammonia (NH4+),
which accumulated in the biofilm.
Ammonia is a critical medium for brass,
and, together with the stresses in the
component, can trigger stress corrosion
cracking.
As it turned out, mechanical stresses in
the component had been generated
during installation. However, answering
Is the rural air to blame?
the question of what medium had been
Now the question remained, which
critical for the material proved to be
critical medium had affected the housing
more complicated: Because cracks had
from the outside? Sulzer was able to
originated on both the inside and the
detect ammonia on the outer surface of
outside of the housing, there must have
been a critical medium on both sides. the housing and identified gaseous
ammonia in the ambient air resulting
Drinking water flowed on the inside of
from nearby livestock farming as a posthe brass housing, but the analysis of
this drinking water showed no abnor- sible source. The experts from Sulzer dismalities, such as a
Sulzer identified gaseous ammonia in the
high nitrate or
ambient air as a possible corrosive medium.
ammonia content.
Nevertheless, clear
covered that a condensate film had
deposits and corrosion products could
formed on the surface of the drinking
be observed on the inner surface of the
2
water-cooled housing and that this film
housing (Figure ). A microbiological
analysis of these products revealed an
had acted as an electrolyte. The ammonia
elevated microbial count, which suggest- gases in the environment had dissolved
ed that a biofilm had formed. “Biofilms” in this thin film of water, thereby forming
can be described as larger colonies of
a medium that corrodes brass. In conbacteria that encase themselves in a gelat- junction with the mechanical stresses
2 A corrosive medium critical for brass forms on the inside of the housing due to
the presence of metabolic products excreted by microorganisms.
Case 1: Cracks in brass fittings
In one case, Sulzer investigated cracks
in the brass housings of the flow
meters of drinking water pipes. Various
housings were affected, but only in the
piping installed in rural areas. A microsection of a cracked brass housing
revealed branched, transcrystalline cracks
(Figure 1) that are typical for stress
corrosion cracking. This well-researched
type of corrosion occurs when tensile
stresses in the material as well as a triggering medium are present. The stresses
can arise through external influences during operation or can have already been
introduced as internal residual stresses
during the manufacturing process. The
triggering medium does not necessarily
have to be present from the start; it can
also be formed over time through envi-
10 mm
Sulzer Technical Review 1/2013
| 23
PRODUCT LIFE CYCLE
present, this corrosive substance led to
inclined surfaces of the pump, forming
cracks starting from the outside of the
a deposit of variable thickness (Figure 3).
The 1.4460 duplex steel housing of the
housing.
submersion pump showed massive corThe formation of the critical media inside
and outside the housing was unavoidable. rosion on all its outer surfaces after a
relatively short time in operation. The
Sulzer therefore recommended the use
of a housing material that is less suscep- heaviest attack was observed on the horizontal surfaces under the thick layer of
tible to stress corrosion cracking. Copper
silt. The failure analysis revealed that
alloys with a zinc content of less than
15%, such as bronze (e.g., CuSn5ZnPb2), several different corrosion mechanisms
are particularly suitDifferent corrosion mechanisms were
able
for
this
responsible for the damage to the submersible
application and are
pump housings.
also
compatible
with drinking water
according to DIN 50930-6. Furthermore, were responsible for the damage. On the
horizontal surfaces, a fairly aggressive
the need to avoid external stresses during
the installation and operation was high- medium had been able to form under
the silt deposits. This is referred to as
lighted.
crevice corrosion under deposits. In this
Case 2: Pump housings under extype of corrosion, the medium in the
treme conditions
crevice (under the silt) becomes chloride
How damaging environmental influences
enriched, and, at the same time, the pH
can be was shown in a case involving
value is shifted into the acidic range.
the corrosion of cooling-water pumps. Furthermore, the liquid in the crevice is
Brackish water containing a considerable
depleted of the dissolved oxygen, which
amount of undissolved solids (silt), in
is necessary for the passivation of highaddition to a high chloride content of
alloy steel. For the pump in question,
around 14 g/l, had been used as a cooling
relatively wide corrosion pits had
medium in these submersion pumps. The
formed under these corrosion conditions
silt had settled on all horizontal and
(Figure 4).
3 Submersion cooling-water pumps are often used under extreme conditions, such as here,
where a thick layer of silt covers the pump surface.
24 | Sulzer Technical Review 1/2013
Corrosion is preventable
Corrosion damage can be largely
avoided by applying available knowledge. Sulzer's corrosion specialists
command expertise gleaned from
many years of industrial experience.
They offer the following services:
• Failure analysis
• Consultation regarding the choice of
the material, the selection of protective coatings, or the application of
alternative corrosion protection measures
• Corrosion testing
• Quality monitoring through
application-oriented tests
• Estimation of the remaining service
life and corrosion risk
More information: www.sulzer.com/corrosion-analysis
Overlapping damage mechanisms
In addition to diagnosing the occurrence
of crevice corrosion, the experts from
Sulzer also identified a further damage
mechanism. Small, deep corrosion cavities
were found on the vertical surfaces at
the top of the pump, where no sludge
had deposited. This damage was identified as the result of pitting corrosion.
Although the pitting and crevice corrosion
mechanisms are similar, there is often a
clear difference in the appearance of the
damage caused. Pitting occurs on free
metal surfaces and results in hemispherical to pinhole-like depressions. Crevice
corrosion leads to larger, wider areas of
attack or shallow corrosion depressions.
Both mechanisms are characterized by
the local formation of an electrolyte with
a low pH value and a high chloride
content. The better the local corrosion
sites are protected from the surrounding
medium, and hence the slower the concentration equalization process is, the
stronger the effect will be. In crevice
corrosion, this shielded geometry is
already existent through the presence
of the crevice. By contrast, the development of pitting requires the initial formation of a cave-like attack site where
electrolyte can subsequently form. This
attack occurs through an interaction of
chlorides with the passivation layer on
the metal.
PRODUCT LIFE CYCLE
material used (1.4460 steel) is, according
to its specification, resistant to brackish
water.
This example makes it clear how unfavorable environmental influences (silt
deposits, elevated material temperatures)
and fabrication deficiencies (sigma phase
precipitates) can bring even high-performance steel to the limits of its
resistance and cause damage.
Effective protection against corrosion
4 Heavy corrosion damage to the pump occurred underneath the silt deposits.
What brings steel to its limits?
is a brittle, intermetallic phase, which,
in this case, probably arose from the
In the case described above, two factors
were primarily responsible for the occur- housing cooling down too slowly after
casting. The steel surrounding these
rence of pitting. First, the waste heat of
the motor had led to
With the right measures even heavily stressed
locally elevated temmetallic
components last long.
peratures in the
pump casing, which
reduced the pitting resistance of the mate- sigma precipitates is depleted of chromium and becomes more susceptible to corrial in these areas. Second, the material
rosion. As a result, the chlorides present
showed a high sigma phase content in
in the brackish water triggered pitting
some areas (visible in the microsection
5
corrosion, even though the high-alloy
of the material, Figure ). Sigma phase
5 The optical micrograph of a microsection through the pump housing shows so-called
sigma phase precipitates. These precipitates are the black-white mottled areas marked with
arrows (light areas: ferrite, brown areas: austenite).
In order to reduce the risk of corrosion
damage in the future, Sulzer recommended that the formation of thick silt deposits
on horizontal surfaces of the pumps be
prevented (e.g., by introducing flowing
water into the pumps or by periodic
cleaning). Furthermore, the experts
advised that a more pitting-resistant steel
(i.e., one with a higher PRE—pitting
resistance equivalent—value) be chosen
in order to provide sufficient resistance
to corrosion, even with the special operating conditions that were present locally.
The PRE value is defined by the content
of alloying elements relevant to corrosion
in the steel (chromium, molybdenum,
nitrogen), weighted with their effect on
the corrosion behavior. Furthermore, the
manufacturers of new pump housings
should take measures either to avoid the
formation of harmful phases (in particular
the sigma phase) or to subsequently eliminate these phases by applying a suitable
heat treatment. With the right measures—as shown in this case—the
lifetime of even heavily-stressed metallic
components can be extended, and enormous costs can be saved.
Daniel Galsterer
Sulzer Innotec
Sulzer-Allee 25
8404 Zurich
Switzerland
Phone +41 52 262 69 38
[email protected]
40 µm
Peter Heimgartner
Sulzer Innotec
Sulzer-Allee 25
8404 Zurich
Switzerland
Phone +41 52 262 21 65
[email protected]
Sulzer Technical Review 1/2013
| 25
SULZER WORLD
Welcome to Sulzer in Russia
Sulzer has successfully served the large oil and gas, power, and automotive industries in
Russia and the states of the former Soviet Union for quite some time now. Recently, the
need for sophisticated technological solutions in these industries has risen dramatically.
All of Sulzer’s divisions have experienced an increase in demand for their products and
services there. In order to bring Sulzer’s technology, its quality products, and its excellent
service even closer to the customers in this area, Sulzer has begun substantially expanding
its presence in Russia.
Sulzer Pumps
Moscow: Main office of Sulzer Pumps Russia
Moscow, Khimki: Pump service center
Saint Petersburg: Sales offices of Process
Pumps and Wastewater Solutions
Oktyabrsky: Pump service center
Yekaterinburg: Sales office and service
station of Process Pumps
Saint Petersburg
Moscow
The service centers of Sulzer Pumps in Russia are
equipped for repair, retrofit, and efficiency improvement activities.
Serpukhov
Togliatti
Yekaterinburg
Oktyabrsky
26 | Sulzer Technical Review 1/2013
In 2011 and 2012, Sulzer Pumps opened two
new service centers in Russia. The first one is
located in Khimki, Moscow, and the second one
in Oktyabrsky, Republic of Bashkortostan. The
two state-of-the-art service centers provide customers with round-the-clock response and are
fully equipped to overhaul and repair all
types of rotating equipment. The service centers
house service technicians, engineering, contract
administration, and sales staff. They provide
services for a wide range of pumps used for
different applications. Sulzer Pumps now has
83 employees in Russia.
4405
SULZER WORLD
Sulzer Metco
Togliatti: Thin-film coating center
Moscow, Lyubertsy: Production of thermalspray material
Sulzer Chemtech
Serpukhov: Production facility for mass transfer
technology (MTT)
Moscow: Sales office for MTT
Saint Petersburg: Sales office for MTT
Sulzer Turbo Services
Moscow: Sales office for turbomachinery services
In Russia, there is a growing demand for maintenance of turbomachines like gas turbines.
In its facility in Togliatti, Sulzer will offer PVD-coating
services, e.g., for cutting tools for the automobile
industry.
Coating services: In 2012, Sulzer signed a shopin-shop agreement with Lada Tools Ltd. in
Togliatti (Russia). With this partnership, Sulzer
Metco will expand its service offering for
physical vapor deposition (PVD) coatings in
Russia. Sulzer is planning to integrate a new
coating system (METAPLAS.DOMINO L) and
wet blasting equipment into this existing PVD
center and is arranging to provide services to
customers in the Russian market. PVD-coating
technology can be used to increase resistance
to wear and oxidation even at high temperatures.
To date, this advanced coating technology is
applied in various industries—especially in the
automobile sector.
Coating materials: Sulzer Metco also has
strengthened its presence in Russia in the
area of coating materials. In December 2012,
Sulzer acquired the Russian company Protective
Coatings LLC, formerly SP Technicord LLC,
which is a producer of coating materials for
thermal-spray and hard surfacing applications.
Visitors inspect Sulzer Chemtech’s
structured packings Mellapak™ in Serpukhov.
The Sulzer Chemtech production site in
Serpukhov was opened in April 2009 and
delivers products and services to the oil and
gas industry as well as the petrochemical
industry. The location in Serpukhov has 69
employees. It produces structured packings,
internals, and trays for thermal separation.
Sulzer Chemtech also has sales offices in Moscow
and Saint Petersburg with 15 employees in total.
With these locations, Sulzer Chemtech can
ensure that customers in the large Russian
market are well supplied. In addition to Russia,
the oil and gas countries such as Kazakhstan,
Uzbekistan, Turkmenistan, and Azerbaijan can
be served as well.
In the field of mass transfer technology, Sulzer
Chemtech is the leading supplier in Russia. For
the future, Sulzer plans to expand the facility
in Serpukhov and start activities in process
technology and tower field services.
In 2011, Sulzer Turbo Services opened a
subsidiary in Moscow. A team of seven
employees provides field services for gas
turbines and related equipment. Thanks to the
local facility, Sulzer can react quickly and send
service engineers promptly to a customer’s site.
Sulzer Turbo Services can mobilize this team
24 hours a day, 7 days a week. Mobile tool
containers ensure that the equipment is always
available even for short-notice maintenance
work.
The repair of components can be carried out in
cooperation with Sulzer Turbo Services in Venlo
and Rotterdam, Netherlands. Sulzer plans to
build up a service facility in Russia to expand
the local repair offerings for turbomachines,
generators, and motors in the future.
Sulzer Technical Review 1/2013
| 27
INTERVIEW
Reiner Mehr:
“Now we can service Russian
customers even faster.“
Reiner Mehr has been managing the Russian
subsidiary of Sulzer Turbo Services in Moscow
since the start of 2012. In this interview, he
describes the initial successes and the plans
for the future.
Why did Sulzer Turbo Services decide
to set up a subsidiary in Russia?
There is a lot of demand for service work
on turbomachinery in Russia. Russian
customers are particularly interested in
our services for large gas turbines and
have already entered into a number of
maintenance contracts with Sulzer Turbo
Services. In order to be even closer to
these customers and to be able to fulfill
the contracts in a more flexible way, we
founded our subsidiary in Moscow in
April 2011.
How has the facility developed since
its founding?
The year 2012 was a very dynamic one.
Once I took over the management of the
site at the beginning of the year, we were
able to accelerate the buildup of our
team. Meanwhile, we already employ
seven people, including several field
service engineers for on-site service. Four
engineers from Sulzer Turbo Services
Venlo, Netherlands, are also currently
under contract with us, in order to be
able to guarantee the highest flexibility
and availability of highly qualified
specialists for our Russian customers.
28 | Sulzer Technical Review 1/2013
What kind of contracts are you mainly
working on?
We are currently focusing on carrying
out service work for gas turbines. Thanks
to our local presence, we are very quick
with regard to on-site deployments. Our
range of services includes on-site service
work, the delivery of new spare parts,
and the repair of components, which are
largely carried out in the Sulzer Turbo
Services locations in Venlo, Netherlands,
and Lublin, Poland.
We are currently developing steam turbine and gas compressor services in close
cooperation with the Sulzer team in Rotterdam, Netherlands. We thereby intend
to make full use of synergies with our
colleagues from Sulzer Pumps, such as
the use of local workshops for inspections.
We want to increase the localization level
further in the future in order to be able
to react to customer inquiries even better.
But your team is also active outside
Russia?
Yes, that’s right. Our employees are also
in demand in other countries. We will
probably also be asked to send our engineers to the Middle East in the near
future. Our pool of employees serves
customer needs as well as possible, even
beyond the frontiers of Russia, whereby
Sulzer Turbo Services in Venlo centrally
manages these field service deployments.
What benefits do your customers
appreciate in particular?
We provide our customers with an excellent cost-benefit ratio, by simultaneously
providing high flexibility and quick reactions. Our customers value that our
service teams can be mobilized around
“Our customers benefit from
our close work with other
divisions of Sulzer.”
the clock, seven days a week and that
we can find a solution for almost every
problem, thanks to our broad-ranging
experience and state-of-the-art technology.
What role does the cooperation with
other business areas of Sulzer play in
that?
Our customers benefit from our close
work with other divisions of Sulzer—
4406
INTERVIEW
such as Sulzer Pumps and Sulzer
Chemtech. Our ranges of services complement one another in many areas, making it possible for us to create attractive
complete packages for our customers.
Companies from the paper industry, for
“Thanks to our new tool
containers the maintenance
tools are always available.”
example, often operate pumps and turbines, and they appreciate it when they
can conclude comprehensive service
packages for both types of machinery
with Sulzer and can thereby reduce interfaces. We are currently working closely
together with Sulzer Pumps to achieve
these possible synergies.
Do customers also enjoy cost advantages as a result of these synergies?
Yes, indeed. A current example is the
storage space of Sulzer Chemtech near
Moscow, which we are able to use for
our tool containers. We thereby save
warehousing costs, which ultimately
benefits our customers.
The development of further synergies
with our colleagues from Sulzer Pumps
and Sulzer Metco is also in full swing—
in both administration and in sales.
Could you tell us a little more about
the tool containers? What is the idea
behind them?
We are continuously striving to increase
the productivity of our maintenance services. A specific measure that we have
implemented is the introduction of tool
containers. Thanks to these containers,
the tools are permanently available in
the country over the long term. The right
tools for even short-notice maintenance
work are thereby always available. One
of the containers focuses on service work
on generators. We have already quickly
brought this container to our customers’
locations several times and have used it
successfully with our colleagues from
Sulzer Dowding & Mills, United Kingdom.
A second container stands ready in
Moscow, and supports maintenance
work on gas turbines.
What are the goals of Sulzer Turbo
Services in Russia?
We want to be the leader in maintenance
work on gas turbines, and, in the medium
term, also for work on steam turbines
and compressors. We will build up our
range of services in a number of steps
until, at some point in the future, we
can offer a comprehensive range of
turbomachinery services.
One can see that you approach this
buildup work with great enthusiasm.
Yes, I'm looking forward to this task.
I have a great affinity for Russia—not
only because I speak the language, but
also because I’m fascinated by the
country. I worked in Russia for several
years before I joined Sulzer. I like the
fact that there is no daily grind here and
that every day brings new challenges
and ideas.
Interview: Tünde Kirstein
Reiner Mehr
studied mechanical engineering at the
Technische Universität München, Germany.
He then supplemented his technical expertise
with language studies at the Pushkin Institute
of the Russian Language in Moscow. After
returning to Germany, Reiner Mehr worked in
various positions in the sales of capital goods
with a technical orientation, where he was
always responsible for Russian-speaking
countries.
Before joining Sulzer, Reiner Mehr was head of
the representation of a major German machine
engineering company in Moscow. He has been
the head of the Russian Sulzer Turbo Services
LLC company in Moscow since January 2012.
The new subsidiary of Sulzer Turbo Services in Moscow mainly focuses on service work for gas turbines.
Sulzer Technical Review 1/2013
| 29
PANORAMA
Active vibration control for paper machines
Controlling complex vibrations
Although paper is a low-cost everyday commodity, it requires a high-tech precision manufacturing
process. In paper machines, complex vibration problems can occur which substantially affect the
paper quality. Sulzer Innotec has developed an innovative approach to control the vibrations.
M
odern paper machines have
building-like dimensions of
more than 100 m in length and
up to 12 m in width and impressive production speeds of up to 120 km/h. A
mixture of cellulose fibers and water
(the main ingredients for paper making)
is fed onto a moving screen, which in
paper technology is called „wire.” In the
wire section, a large portion of the water
drains through the wire, but the fiber
web is still wet with very little
consistency. Then, revolving felts carry
the web through the nip of two press
rollers that squeeze more water out of
the paper. In the following drying section,
heat removes the remaining water. Many
In the affected paper areas, the stripes
product parameters such as thickness, occurred at intervals of 0.2 to 0.5 m, and
grammage (mass per unit area), ratio of
the paper density was reduced. Several
fibers to other ingredients, fiber orienta- conventional approaches for reducing
tion, and surface texture must be kept
the cross stripes were unsuccessful.
within tight limits.
Vibration control ensures high product quality.
Because the manufacturing process is
complex, high product quality can only
A comprehensive vibration analysis
be achieved with advanced control tech- revealed that the variations in paper denniques.
sity were caused by a superposition of
One of Sulzer Innotec’s customers had
many discrete frequencies and that they
trouble with a newly commissioned
were correlated to vibrations of the headpaper machine. Cross stripes occurred
box. It was presumed that the vibrations
in the paper at irregular intervals and
were excited when variations in felt thicklimited the printability of the product. ness passed through the press section.
1 Vibrations originate in the press section of the paper machine. They are transmitted
through the building structure to the headbox and affect the paper quality.
Press section
Headbox
Wire
Path of vibration transmission
30 | Sulzer Technical Review 1/2013
4407
PANORAMA
In modern paper machines, advanced control techniques are necessary to achieve the required product quality.
These vibrations were then transferred
through the structure of the building as
indicated in Fig. 1 and amplified by
structural resonances of the headbox.
This resulted in variations of the headbox
opening (slice lip, Fig. 2), which consequently affected the paper density.
Overall, five different sources of vibrations
were found:
• Three felts within the press section of
the machine (period of circulation ≈ 2 s)
• The drive mechanism of a particular
roll (frequency ≈ 23 Hz)
• Residual reaction forces of the shake
mechanism that drives the breast roll
(frequency ≈ 8 Hz)
Innovative feed-forward concept
Sulzer Innotec developed and implemented an active vibration control
system to cancel the vibrations at the
headbox. In contrast to passive damping
concepts, this system actively applies
forces to the vibrating machine component. The Machinery Dynamics and
Acoustics group of Sulzer Innotec has
broad expertise in this technology from
earlier fundamental research projects.
Nevertheless, the scale-up of the technology from lab demonstrators to an
industrial application required a considerable engineering effort. An innovative
feed-forward approach was used to
Headbox
Slice lip
Wire
Jet
Breast roll
2 The headbox slice sprays the fiber-water
suspension onto a fast-moving wire. Vibrations of the headbox affect the opening of the
slice and, thus, the resulting paper density.
Dryer section
Sulzer Technical Review 1/2013
| 31
PANORAMA
Successful industrial implementation
How does the feed-forward active control work?
Vibrations due to felts, rollers, and shake mechanism are superimposed
and reach the headbox. The resulting vibrations of the headbox are to be
canceled.
Sensors measure the timing of the revolutions of the vibration sources and
deliver trigger signals to the controller. This method is called feed-forward
control. In contrast, conventional feedback concepts only measure the
vibrations at the headbox and use them as input signal as well as for the
adaptation algorithm.
The controller calculates the necessary forces to be exerted by the electrodynamic actuators. These are mounted on the headbox front wall and cancel
the vibrations.
A residual vibration sensor measures the remaining vibrations of the headbox.
This feedback is used to optimize the parameters of the control algorithm.
More details of the control algorithm can be found in the publication listed below1.
Excitations
Superposition of vibration and cancellation
Felt
Drive
∑
Headbox
Vibration transfer path
Residual
vibration
sensor
Shake
mechanism
Actuator
Cancellation signal
Adaptive controller
Trigger signals
Residual vibration signal
simultaneously cancel the vibrations
caused by five different periodic sources
with fundamental frequencies between
0.4 Hz and 25 Hz. The applied feedforward concept has fundamental advantages over feedback configurations. In
feedback systems, the level of cancellation
is limited because the residual vibration
signal becomes very weak and noisy
when the cancellation approaches the
optimum level. Furthermore, feedforward control typically provides superior stability and adaptation performance,
The feed-forward concept has
fundamental advantages.
so that the additional complexity of the
trigger sensors is worthwhile. The basic
approach is explained in the infobox.
3 After starting the active control, the residual vibration signal is significantly reduced.
Residual vibration signal [RMS]
Start of active control
Optimum
coefficients reached
10:13
32 | Sulzer Technical Review 1/2013
10:19
10:25
10:31
10:37
Time
10:43
10:49
10:55
11:00
The sensors for the felt triggers are optical
detectors. A black mark, which must not
be bleached by the process, is applied
to each felt. For illumination, a long-life
LED is used. Soiling of the optics is prevented by continuous flushing with clean
air. Even with these provisions, a reliable
trigger signal cannot be guaranteed
under all circumstances. Therefore, the
algorithm monitors the consistency of
the trigger signals and, in the case of a
fault, disables the cancellation of the corresponding vibration source and displays
a warning on the process control system.
Two actuators are attached at two spanwise positions on the headbox. They are
based on the inertial mass principle,
where the mass is moved linearly by an
electrodynamic voice coil drive mechanism. The resulting vertical reaction
force, which is proportional to the
current, acts on the base of the actuator
and, thus, also on the front wall of the
headbox. The power required to drive
the actuators is only around 30 W.
The algorithm, which represents the
core technology in active vibration
control, is programmed with MATLAB
and runs on a standard National Instruments PXI controller. The performance
can be monitored by remote access over
the Internet, which also allows software
updates to be implemented. All raw signals, harmonic coefficients, and other control parameters are continuously stored
for several days, so they can be analyzed
in detail if performance issues arise.
Convincing performance
When the active vibration control system
is started, the controller begins to
optimize the parameters for the cancellation signal. This procedure requires
some time for the exponential averaging
to reach the optimum. Figure 3 shows
a typical trend of the residual vibration
signal as displayed by the process control
system. The RMS (root-mean-square
value) of the residual vibration signal
follows an exponential descent with a
time constant of ≈ 400 s. A significant
reduction can be observed when cancellation is active.
PANORAMA
Figure 4 shows a comparison of the
periodic variations in grammage remain
frequency spectra of the residual vibration
due to residual vibrations of the bottom
signal with and without active control. lip. In the future, a more advanced system
All harmonic comThe active control system that was implemented
ponents of trigger
substantially reduces vibrations.
frequencies (marked
with a colored circle)
could measure the variations of gramare substantially reduced with active
mage online and use them as a residual
control.
vibration signal to further optimize the
High potential of active control
adaptation procedure.
The active control system reduces vibraThe implemented system has now
tions due to the known periodic
been in operation for several years, and
excitation at the residual vibration sensor
has substantially improved the product
on the headbox very effectively. Some
quality of the paper produced. The
Active control has various
possible applications
Active control is particularly suited for
problems where conventional approaches are not effective enough or
are not applicable due to weight or size
limitations. Active control can be designed to operate very selectively. E.g.,
it will not affect system dynamics at frequencies outside the specified range.
Possible applications are:
• Vibration isolation of sensitive
measuring instruments such as
electron microscopes
• Active suspension of cars and elevators
• Active damping of high-rise buildings and bridges
• Active noise control in pipes
• Active noise control in passenger
compartments of cars and aircraft
• Active noise control headsets
• Active control of instabilities such
as flow, combustion, rotordynamic
instabilities
Typically, the control algorithm must be
adapted and fine-tuned to the
particular applications. This requires
some expert knowledge and a considerable engineering effort, which is
justified by the good performance.
Also, the robustness of the sensors
and actuators can be critical, depending on the application. The computing
power of low-cost digital signal
processors is ample and is generally
not a limiting issue.
Without control
16
Residual vibration signal [mV(ms)]
14
12
10
8
6
4
2
0
0
10
20
30
40
Frequency [Hz]
50
60
70
80
More information:
www.sulzer.com/machinery-dynamics
4 a A high-resolution frequency spectrum (∆f = 0.0031 Hz) of the residual vibration signal without
active control shows many peaks (marked with colored circles) at the harmonic frequencies of the
five fundamental trigger frequencies. Each color represents a trigger channel. The peak at 31.5 Hz
is not a multiple of any of the trigger frequencies and is caused by an extraneous source.
system functions autonomously, is very
robust, and can be operated without
expert knowledge. After a few initial
modifications, the system has required
hardly any maintenance. The experience
gained with this customized implementation of active vibration control is useful
for solving other vibration problems with
the same basic concept.
With active vibration control
16
Residual vibration signal [mV(ms)]
14
12
10
8
6
4
2
0
0
10
20
30
40
Frequency [Hz]
50
60
70
4 b The corresponding frequency spectrum with active vibration control shows that
all harmonic components of the trigger frequencies (marked with a colored circle) are
substantially reduced. All the dominating peaks remaining have no associated marker
and are thus not harmonics of any of the trigger frequencies.
80
Hans Rudolf Graf
Sulzer Innotec
Sulzer-Allee 25
8404 Winterthur
Switzerland
Phone +41 52 262 82 40
[email protected]
References
1
Hans Rudolf Graf and Erich Kläui, “Active vibration control of a paper machine headbox,” 19th International Congress on Sound and Vibration (Vilnius, Lithuania, July
8–12, 2012).
Sulzer Technical Review 1/2013
| 33
EVENTS & NEWS
March 12–16, 2013, Cologne, Germany
IDS – International Dental Show
www.ids-cologne.de
Well-informed with Sulzer apps
March 18–21, 2013, Charlotte, NC, USA
501 F&G Users Conference
http://501f.users-groups.com/Events/2013/Info
March 19–21, 2013, Beijing, China
CIPPE – The 13th China International Petroleum &
Petrochemical Technology and Equipment Exhibition
www.cippe.com.cn/2013/en
April 9–13, 2013, Buenos Aires, Argentina
EMAQH International Machine Tool, Tools and
Ancillaries Exhibition
www.emaqh.com/index_eng.html
April 15–21, 2013, Munich, Germany
Bauma 2013 – 30th International Trade Fair for
Construction Machinery, Building Material Machines,
Mining Machines, Construction Vehicles and
Construction Equipment
www.bauma.de
April 28–May 2, 2013, San Antonio, TX, US
AICHE Spring Meeting
www.aiche.org
April 29–May 1, 2013, Doha, Qatar
3rd Annual Refining Global Technology Forum
www.fleminggulf.com
April 29–May 3, 2013, Baton Rouge, LA, USA
Gulf South Rotating Machinery Symposium (GSRMS)
http://is.lsu.edu/newDOCE/GSRMS
April 29–May 3, 2013, San Diego, CA, USA
ICMCTF 2013 International Conference on
Metallurgical Coatings and Thin Films
www2.avs.org/conferences/icmctf
May 7–9, 2013, Perth, Australia
OZ Water '13 – Australia’s International Water
Conference & Exhibition
www.ozwater.org
May 7–10, 2013, Melbourne, Australia
National Manufacturing Week
www.nationalmanufacturingweek.com.au
May13–15, 2013, Busan, Korea
ITSC 2013 International Thermal Spray Conference
and Exposition
www.asminternational.org/content/Events/itsc
May 13–16, 2013, Beijing, China
ACHEMASIA
www.achemasia.com
June 4–6, 2013, Vienna, Austria
Power-Gen Europe 2013
www.powergeneurope.com
June 11–14, 2013, Macaé-RJ, Brazil
Brasil Offshore International Conference and
Exhibition of the Oil and Gas Industry
www.brasiloffshore.com
June17–21, 2013, Antofagasta, Chile
EXPONOR The International Exhibition for the Mining
Industry
www.exponor.cl
June 18–19, 2013, Friedrichshafen, Germany
VDI Drive train for vehicles
www.vdi-wissensforum.de
June 26–28, 2013, Brisbane, Australia
Mining Electrical Safety Conference 2013
http://mesc.iamevents.com.au
June 30–July 2, 2013, Las Vegas, NV, USA
EASA Convention
www.easa.com/convention
More events:
www.sulzer.com/events
34 | Sulzer Technical Review 1/2013
In December 2012, Sulzer Turbo Services
launched the new iPad app “TS
Solutions.” With this app, the users have
quick and easy access to the most upto-date information about service solutions. The app contains a library of videos
and brochures as well as a picture gallery
and ensures that customers always have
the latest information at hand.
At the same time, Sulzer has also
expanded its existing corporate iPad app
“Sulzer report library.” In addition to the
Sulzer Annual Report, the Sulzer Midyear
Report, and the Sulzer Sustainability
Report, it now contains the issues of the
Sulzer Technical Review as well.
More information: www.sulzer.com/online-tools
Acquisition of carbon business
In January 2013, Sulzer Metco acquired
the carbon business of Thermoset Inc. in
Mequon, Wisconsin, USA. Thermoset
develops carbon friction materials for
power train applications for trucks as
well as for selected car applications. This
acquisition complements Sulzer Metco’s
high-performance carbon friction product
line with a well-proven woven carbon
friction material. It also strengthens
Sulzer Metco’s position in the global
truck and passenger car market. Sulzer’s
global presence will foster the worldwide
market penetration of Thermoset’s products.
New Sulzer Pumps facilities
The global network of Sulzer Pumps is
always expanding. At the end of 2012,
Sulzer Pumps opened a wastewater
pumps production plant in China and
a customer support service center in
Sweden.
The new production plant located in
Kunshan, China, is Sulzer Pumps’ third
plant in the country. Around 70 employees will assemble approximately 10 000
wastewater pumps, mixers, and compressors annually, mainly for the Chinese
market and also for other Asian countries.
The second expansion was the opening
of a new service center in Vadstena,
Sweden, adjacent to Sulzer’s existing
pump- and agitator-manufacturing site.
The fully equipped workshop performs
repairs, refurbishments, and advanced
services for centrifugal pumps and
agitators.
With this new service facility, Sulzer
is well positioned to serve the pulp
and paper, power, general industry, and
chemical processing industry markets
in the Nordic countries.
IMPRINT
Innovations for medical technology
Sulzer Mixpac presented its healthcare
and dental expertise at the Compamed
trade fair in Germany in November 2012.
Several innovations at the Sulzer booth
attracted the visitors:
• The new MIXPAC™ S-Dispenser II is
significantly more ergonomic and
more user-friendly than its predecessor.
• The new MIXPAC™ T-Mixer mixes
two components in a far more homogeneous way. In addition, this mixer
is more compact so that less waste
material remains in the mixer.
• Sulzer demonstrated its CFD (computational fluid dynamics) simulation
approach to calculating the mixing
results and to choosing the most suitable mixing system. The next issue of
the Sulzer Technical Review will report
on this approach in detail.
All-round success
Several new major contracts prove
the leading position of Sulzer Pumps
in diverse markets around the world.
One large order is the supply of
40 pumps for a large Chinese project
in the hydrocarbon processing industry.
The Guangxi Oil Refinery project
plans to refine 10 million tons of
imported high-sulfur crude oil annually
and Sulzer will deliver pumps for
different units of the refinery. These
pumps will contribute to the production
of gasoline, diesel, jet fuel, and liquefied
petroleum gas as well as petrochemical
products for the southwestern areas of
China.
A second large order demonstrates the
capability that Sulzer Pumps brings to
the dewatering industry. Sulzer will supply 12 large dewatering pump sets to a
copper mine in Zambia—one of the
largest construction projects currently
underway in the country.
Sulzer Pumps is also successful in the
power generation market. In 2012, the
company was selected to supply pumping
solutions for several concentrated solar
power (CSP) projects in Spain and India.
These orders further reinforce Sulzer’s
position and commitment as a major
supplier to the global CSP market.
More information: www.sulzer.com/newsroom
The Sulzer Technical Review (STR) is a customer
magazine produced by Sulzer. It is published periodically in English and German and annually
in Chinese. The articles are also available at:
www.sulzer.com/str
1/2013
95th year of the STR
ISSN 1660-9042
Publisher
Sulzer Management Ltd.
P.O. Box
8401 Winterthur, Switzerland
Editor-in-Chief
Tünde Kirstein
[email protected]
Editorial Assistant
Laura Gasperi
[email protected]
Advisory Board
Mia Claselius
Samuel Eckstein
Thomas Gerlach
Hans-Michael Höhle
Ernst Lutz
Claudia Pröger
Heinz Schmid
Daniel Schnyder
Translations
Interserv AG, Zürich
Design
Typografisches Atelier
Felix Muntwyler, Winterthur
Printer
Mattenbach AG, Winterthur
© March 2013
Reprints of articles and illustrations are permitted
subject to the prior approval of the editor.
The Sulzer Technical Review (STR) has been
compiled according to the best knowledge and
belief of Sulzer Management Ltd. and the
authors. However, Sulzer Management Ltd. and
the authors cannot assume any responsibility
for the quality of the information, and make no
representations or warranties, explicit or implied,
as to the accuracy or completeness of the
information contained in this publication.
Circulation: 16 000 copies.
Magno Satin 135 g/m2
from sustainably managed forests.
For readers in the United States of America only:
The Sulzer Technical Review is published periodically by
Sulzer Management Ltd., P.O. Box, 8401 Winterthur, Switzerland. Periodicals postage paid at Folcroft, PA,
by US Mail Agent— La Poste, 700 Carpenters Crossing,
Folcroft, PA 19032.
Postmaster: Please send address changes to Sulzer
Technical Review, P.O. Box 202, Folcroft, PA 19032.
Sulzer Technical Review 1/2013
| 35
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Whether you are active in the chemical, pharmaceutical, biofuels,
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