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Model for calculation FAC (Erosion Corrosion) Rates of unalloyed and low-alloyed steels in water steam flow.
Wally Huijbregts
More detailed information see pdf
The FAC-Calculation file is available as excel.
In 1982, Heitmann and Kastner published the results of erosion corrosion experiments of KWU Siemens.
Some years after this publication KWU-Siemens has processed these experimental results in a model and made the software programme WATCHEC which is applied in many power stations over the world.
We used the basic facts of the WATCHEC model, published in 1986 by Kastner and Riedle, to make our own FAC-Calculation program in Excel.
In particularly in case of erosion corrosion failures a model for calculating erosion corrosion rates is very useful.
The FAC-Calculation file is available nearly for free.
I will send you the program when you make a donation to the Dutch Reumapatiëntenbond.
Send me an E-mail for terms of delivery.
The following graphs can be made:
- Erosion corrosion rate against Cr+Mo content of steel
- Erosion corrosion rate against oxygen content
- Erosion corrosion rate against the flow velocity
- Erosion corrosion rate against pH value
- Erosion corrosion rate against Keller number
- Erosion corrosion rate against temperature
See below for some examples:
 
Some erosion-corrosion failures.
With the help of the calculation model influence of various factors can be estimated rather well. Cr en Cu were incorporated in the correlation formula of KWU Siemens. Other elements as Cu and C were neglected.
From the extensive erosion-corrosion experiments of KEMA it was proven that Cu had a 40% more erosion-corrosion resistant effect than Cr.
The relative erosion-corrosion resistance of C-steels and 15Mo3 was expressed in the Cr-equivalence formula below:
Cr-equivalent = Cr +1.4 Cu + 0.3 Mo - 0.3 C > 0.09
By comparing the Cr equivalence of steels from failures and non-failures it appeared that steels from failures generally had a Cr-equivalence less than 0.09.
Some examples of erosion corrosion failures are given below. For more erosion corrosion information see published papers nr: 21, 22, 27, 28, 46, 47, 58 en 60 on my website www.hbscc.nl .
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Two eroded corroded switch levers of feed water pumps. (photo KEMA).
| On the left: Switch lever after 10.000 hr operation (2.83) |
Cr |
Cu |
Mo |
C |
Cr-eq. |
0.01 |
0.01 |
0.005 |
0.09 |
-0.0015 |
| On the right: Switch lever after 40.000 hr operation (2.108). |
Cr |
Cu |
Mo |
C |
Cr-eq. |
0.025 |
0.03 |
0.02 |
0.06 |
0.055 |
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Wet steam pipes. (photo KEMA)
Eroded corroded plate (2.89-1)
Cr |
Cu |
Mo |
C |
Cr-eq. |
0.01 |
0.02 |
0.003 |
0.17 |
-0.0121 |
Non eroded corroded plates (2.90 en 2.89-2)
Cr |
Cu |
Mo |
C |
Cr-eq. |
0.04 |
0.11 |
0.01 |
0.14 |
0.155 |
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High pressure water separator, tiger skin erosion corrosion pattern. (photo KEMA) (2.88).
Cr |
Cu |
Mo |
C |
Cr-eq. |
0.01 |
0.04 |
0.003 |
0.15 |
0.0219 |
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Welded plates in a water separator. (photo KEMA)
| Non eroded corroded plate (2.120-2) |
Cr |
Cu |
Mo |
C |
Cr-eq. |
0.1 |
0.21 |
0.02 |
0.12 |
0.364 |
| Eroded corroded plate (2.120-1) |
Cr |
Cu |
Mo |
C |
Cr-eq. |
0.01 |
0.006 |
0.01 |
0.12 |
-0.0146 |
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