1. Sanicro™ 25 – the high-performance boiler tube for high-efficiency,
ultra-supercritical coal-FIRED power production
For the foreseeable future, despite great progress with
renewables, we will still need coal-fired power plants.
The good news is that now, thanks to more advanced
technology, it is possible to produce cleaner energy
than ever with coal.
combatting oxidation and corrosion
One big challenge is finding advanced stainless steel
materials that enable the superheaters and reheaters
in ultra-supercritical steam boilers to combat steam
oxidation and corrosion at higher temperatures. Some
have proposed using a modified stainless steel alloy
like TP310HCbN (HR3C™)*, but customers tell us, “this
is not enough.” The other alternative is to go all the way
to a higher nickel alloy tube, but why pay a big premium
when an lower nickel alloy tube can do the same job?
This is where Sanicro™ 25 (UNS S31035) from Sandvik
comes in – letting you migrate upward in temperature.
A METAL THAT CAN TAKE THE HEAT
Our top-end tube, Sanicro™ 25 has the highest creep
strength among the commercial heat-resistant auste-
nitic stainless steels. And since the metal is designed
to help you withstand metal temperatures of 620°C
(1150°F) on up to 700°C (1290°F) with pressures of
35 MPa (5000 psi), it can help you safely and reliably
achieve higher efficiency in ultra-supercritical boilers.
In short, Sanicro™ 25 can handle the challenging de-
mands being placed on coal-fired energy. So get ready
to turn up the heat, because that’s what we are doing.
Key benefits of Sanicro™ 25
• Very high creep strength
• High oxidation resistance
• High structural stability
• Good fabricability
• Good welding properties
Solving today’s energy needs will require bold action, innovative new
thinking and plenty of hard work. The challenges are seemingly contra-
dictory: people want more and more electricity, lower prices, reduced CO2
emissions and cleaner air. But how do we solve this dilemma using coal?
Sanicro™ 25 is a high-alloy austenitic stainless steel tube that has
been engineered for the next generation of clean and efficient
coal-fired power boilers.
2 Sanicro™ 25 – Advanced coal-fired power production
* HR3C is a trademark of Sumitomo Metal Industries
3. 3Sanicro™ 25 – Advanced coal-fired power production
3Sanicro™ 25 – Advanced coal-fired power production
5. 5Sanicro™ 25 – Advanced coal-fired power production
alone we have delivered 60 million meters of tube for
hundreds of projects, many of them in China.
TOP 100 GLOBAL INNOVATOR
There’s a reason why Forbes Magazine ranked us as
one of the world’s Top 100 most innovative companies.
With 47,000 employees in 130 countries, we are work-
ing closely with our customers to develop energy-sav-
ing products and tackle the metallurgical and material
challenges of the future.
NEW IMPROVED BOILER TUBE
Sanicro™ 25 is our latest innovation – the best-
performing austenitic boiler tube on the market today.
It helps you future-proof your energy production by
letting you migrate upward to metal temperatures of
620°C (1150°F), 650°C (1200°F) or a maximum of 700°C
(1290°F). This way, you can continue to increase the
temperature and pressure in your boilers, while still im-
proving the efficiency of coal conversion. This not only
saves money over the lifecycle of the boiler, it reduces
emissions due to less coal consumption.
Our focus on advanced stainless steel and specialty
alloys gives you a competitive advantage. You gain
a trusted partner with more than 50 years of exper-
ience in providing high-quality stainless tube for
power plants. Not to mention an innovative steel-
making heritage dating back more than 150 years.
If you’re familiar with the Sandvik name, you also know
that we provide advanced stainless steel tube to some
of the most demanding industries on earth. These in-
clude the safety- and performance-conscious nuclear,
automotive, petrochemical and oil and gas sectors.
Over the years, we’ve collaborated closely with
our customers to design key metals and parts for
next-generation wind turbines, fuel cells, fuel lines and
fuel rails. Recently, our PressurfectTM
tube for gasoline direct injection and CNG engines was
singled out by the industry as a “game-changer.”
For many years, we’ve also teamed up with the energy
sector to boost productivity. In the nuclear industry
6. 6 Sanicro™ 25 – Advanced coal-fired power production
Sanicro™ 25 has already received approvals from
organizations such as ASME, VdTüV and more. Our
latest certification by the Chinese Pressure Vessel
Committee means that our high-pressure boiler
tube is fully compliant for the design, fabrication,
assembly and inspection of the most demanding
boilers. In other words, we really are “fit for purpose.”
In such a critical industry, there is simply no margin
for error. To ensure the tough requirements of this
high-quality tubing, we run a battery of quality control
tests. These are carefully designed to assess every-
thing from improved static tensile strength, creep
strength and crack resistance to immersion, dimen-
sional tolerance, cleanliness and hardness control.
QUALITY CONTROL IN EVERY STEP
When it comes to manufacturing, we guarantee con-
sistency in product quality that comes from controlling
the entire steelmaking process – from steel melting to
finished tube. Every tube has an identification number
and can be traced back to the original batch should a
APPROVALS & CERTIFICATIONS
• Chinese Pressure Vessel
• European Particular Material
• VdTüV Material Data Sheet 555,
• ASME Code Case 2753, Section I
and 2752, Section VIII Division I
CHEMICAL COMPOSITION (nominal) %
C Si Mn P S Cr Ni W Co Cu Nb N
≤0.1 0.2 0.5 ≤0.025 ≤0.015 22.5 25 3.6 1.5 3.0 0.5 0.23
9. 9Sanicro™ 25 – Advanced coal-fired power production
Until recently, designers of superheaters or re-
heaters for higher efficiency ultra-supercritical
coal-based power plants had to choose from two
options: migrate up to higher nickel-based tube
alloys or increase the wall thickness of a standard
alloy tube, to remain in the safe zone.
Now there is another path. Because Sanicro™ 25 has
a maximum allowable stress value that is higher than
any other iron-based austenitic stainless steel (see
diagram), you can reduce wall thickness while still han-
dling the same pressure. This allows for lighter, more
efficient and compact designs at a more competitive
price. A better, more compact boiler design also means
that you will use less material overall.
SUPERIOR CREEP STRENGTH
Five years after test installations in different European
boilers, the Sanicro™ 25 tubes are still in good con-
dition. Corrosion behavior and strength are excellent.
As shown in the diagram, Sanicro™ 25 has a much
higher creep strength at 100,000 hours than other
commercial grades, according to the TÜV standards.
For example, it achieves 180 MPa at 625°C (1160°F) and
155 MPa at 650°C (1200°F). The test also showed that
this stainless steel has a creep strength of about 100
MPa at 700°C (1290°F) for 100,000 hours – with recent
indications that it will probably reach 99+/-3 MPa.
Sanicro™ 25 high-
Maximum allowable stress
600 650 700 750
thinner WALL, higher performance
10. 10 Sanicro™ 25 – Advanced coal-fired power production10
Due to its high chromium content, Sanicro™ 25 has
unique, high hot corrosion resistance properties.
These are more than sufficient for upgrading your
superheater or boiler to handle temperatures of
620°C, 650°C or even 700°C (1290°F), which is where
we carried out our comparative tests.
In the hot corrosion tests, we repeatedly covered the
tube with ash and exposed it to gas flow for 3,000
hours. Then we put one of our competitor’s best steels
through the same tests. As shown in the diagram to the
right, the Sanicro™ 25 stainless steel tube clearly had a
much lower corrosion rate.
We also carried out oxidation resistance testing using
isothermal experiments as well as discontinuous tests
with cooling to room temperature after various lengths
of time. Both sets of tests showed a very low mass rate
change. Then we performed oxidation tests in aqueous
steam at 750°C (1380°F), which also demonstrated that
Sanicro™ 25 offers very good oxidation resistance.
0 500 1000 1500 2000 2500 3000
Weight loss [mg/cm2
Mass change [gm-2
Sanicro™ 25 TP310HCbN UNS S30432 UNS SN06617 TP347H
Hot corrosion tests at 700°C (1290°F) up to 3,000 hours.
Oxidation in air, discontinuous test at 750°C (1382°F).
13. 13Sanicro™ 25 – Advanced coal-fired power production
Sanicro™ 25 is easy to weld, bend and fabricate.
This is vital if you are striving to keep manufacturing
costs down and simplify your fabrication processes.
Since Sandvik has done extensive testing of com-
patible welding and filler metals, we can advise you
on the optimal process and materials.
Since good weldability is vital, you’ll be happy to know
that this is an area in which Sanicro™ 25 excels. As
with all austenitic stainless steels, it has low thermal
conductivity and high thermal expansion. We there-
fore recommend tungsten inert gas welding (TIG/
GTAW/141) with low heat input and interpass tempera-
ture to reduce the risk of hot cracking. Preheating and
post-weld heat treatments are not normally necessary.
As the filler metal, we recommend either Sandvik Sani-
cro™ 53 (alloy 617) or alloy 617 mod for optimal results.
In addition to favorable weldability, the metal is also
easy to bend into the desirable shapes. This opens up
CHEMICAL COMPOSITION - filler metal
CHEMICAL COMPOSITION WEIGHT %
C Si Mn P S Cr Ni Mo W Co Ti Al Fe
0.08 ≤1.0 ≤1.0 ≤0.010 ≤0.010 22.5 53.5 9 ≤0.5 12 ≤0.6 1 ≤1.0
the possibility to optimize your heat transfer surface
in a smaller space. To test this, we put Sanicro™ 25
through four different bends - two different 180° bends
and two different 90° bends. The studies showed that
it would be possible to safely and efficiently maximize
the heat transfer efficiency with a bending radius of up
to 30%. In short, this high-performance material allows
you to design smaller boilers that still provide a very
high efficiency level.
The bending trails were preformed successfully, the visual exa-
mination showed no cracks in the tube walls. Above is the results
from bending trails of Sanicro™ 25, 180° (A) and 90° (B) bends.
14. 14 Sanicro™ 25 – Advanced coal-fired power production14
At Sandvik, we know that there is a clear relationship
between safety and quality. Better, more reliable,
quality products improve the safety of the people
who work with them – resulting in less downtime and
For many of our customers working with steam boilers
or other demanding industrial applications, this em-
phasis on “safety first” is a vital prerequisite. As one
customer told us: “Everything starts with safety, or ev-
erything stops.” Our “Zero Accidents” ambition applies
to our staff, customers, suppliers, strategic partners
and the environment.
A SAFER PRODUCT MEANS LESS DOWNTIME
We apply safety measures in every step of our tube
manufacturing process, backed by complete doc-
umentation and traceability. So when you choose
Sanicro™ 25, you are also making a safe choice. All
our hours of testing for creep and corrosion aren’t just
about return on investment – they’re about making a
safer, more reliable product for you.
17. 17Sanicro™ 25 – Advanced coal-fired power production
As a Sandvik customer you not only get the support
of our local sales representatives, you also gain ac-
cess to our team of 2,700 RD and materials experts
- one of the largest of its type in the world.
Our metallurgical experts are working hard to develop
new advanced stainless steels and alloys as well as
making improvements to existing products in order to
satisfy new and future market needs. Each year we in-
vest a significant amount of our turnover in RD. In the
past year alone we filed hundreds of patents, and our
total number of registered patents is in the thousands.
A HISTORY OF INNOVATION
Our strong track record of innovation dates back to the
1930s when we began experimenting with austenite
and ferrite alloys to create duplex stainless steel. In the
1970s our RD team developed a new group of aus-
tenitic-ferritic steels that were welcomed by industrial
companies in search of stronger, more cost-effective
and corrosion-resistant materials. In addition to our
Sanicro™ 25 grade, recent innovations have included
hyper-duplex stainless steel and pre-coated precision
strip steel for fuel cells, to name just a few.
TO JOIN YOUR
COLLABORATING WITH POWER COMPANIES
Our work with power engineering companies, power
utilities and other leading power companies is even
further proof of our determination to be a market leader
in this sector. In us you’ll have a knowledgeable advisor
and guide in the developing field of clean and efficient
18. 18 Sanicro™ 25 – Advanced coal-fired power production
MAXIMUM ALLOWABLE STRESS
SANICRO™ 25 APPROVAL #210 FOR MANU-
FACTURING OF PRESSURE VESSELS IN CHINA
Sandvik has received Licence No. 210 for the industrial
production of Sandvik Sanicro™ 25 tube for steam boilers
from China’s Special Equipment Licensing Office (SELO).
Outside diameter range: 25 to 114.3 mm (0.984 to 4.5 in.)
Wall thickness range: 3 to 14 mm (0.118 to 0.551 in.)
Straight length: Up to 16 meters
Surface structure: Cold pilgered, annealed and pickled seamless
600 650 700 750
What are the big challenges you face in your coal-
fired power plant? Corrosion problems in the super-
heater or reheater? Selecting a high-performance
tube that meets even higher stress levels at higher
temperatures in your ultra-supercritical boilers?
Whatever your specific challenge may be, you can rest
assured that we’ve been helping to meet some of the
toughest requirements of energy producing industries
for over 50 years – tailoring each delivery to very
specific needs. Each project is unique. Each delivery
has its own set of specifications and requirements.
Below you can see how Sanicro™ 25 tube rates in
terms of maximum allowable stress, compared to
competing steel grades. You will also find our range of
deliverable formats as well as stress performance and
heat capacity / thermal conductivity levels. If you have
needs beyond those below, please don’t hesitate to
contact us for further discussions.
19. 19Sanicro™ 25 – Advanced coal-fired power production
This is Sandvik
The Sandvik Group is a global high tech-
nology enterprise with 49,000 employees
in 130 countries. Sandvik’s operations are
concentrated on five business areas in
which the group holds leading global po-
sitions in selected niches: Sandvik Mining,
Sandvik Machining Solutions, Sandvik Ma-
terials Technology, Sandvik Construction
and Sandvik Venture.
SANDVIK MATERIALS TECHNOLOGY
Sandvik Materials Technology is a
world-leading developer and manufacturer
of products in advanced stainless steels
and special alloys for the most demanding
environments, as well as products and
systems for industrial heating.
Sandvik Materials Technology has qual-
ity management systems approved by
internationally recognized organizations.
We hold, for example, the ASME Quality
System Certificates as a Material Organi-
zation, approvals to ISO 9001:2008, ISO
17025:2005 and PED 97/23/EC. We also
have product and/or shop approvals from
bodies such as TÜV, JIS, DNV and Lloyd’s
ENVIRONMENT, HEALTH AND SAFETY
Environmental awareness, health and
safety are integral parts of our business
and are at the forefront of all activities
within our operation. We hold ISO 14001
and OHSAS 18001 approvals. Sandvik,
Sanicro and Pressurfect are trademarks
owned by Sandvik Intellectual Property AB.