Three years of data collection on the field have allowed to examine trends in kettle corrosion and present them to the public.

1. Trends in Kettle Corrosion:
Three Years of Data Collection
and Its Meaning for the Hot-Dip
Galvanizing Industry
Mario Ubiali
AGA Tech Forum,
Omaha, NE - 7-9 Oct 2009

2. Background
• Zinco Service introduced the KID technology
at Intergalva 2006, in Naples
• Since then, over 220 kettles have been
inspected in Europe, Canada and USA by the
Zinco Global Network
• Enough data to start looking for meaningful
connections and trends

3. FUNDAMENTALS: WHAT TO
EXAMINE?
• Thickness readings: a set of numerical values
1300 1200 1100 1000 900 800 700 600 500 400 300 200 150 140 120 110 50
40 45.9 46.9 47 48.5 47.6 48.2 46.6 48.2 46.8 47.4 47.2 43.7 46.5 48.1 46.6 45.7 46.8
70 45.3 47.4 48.3 46.8 48 47.5 48.1 48.9 46.7 48.7 47.8 47.1 45.9 46.5 45 45.5 46
120 46.3 47.3 48 47.6 47.3 47.2 47.4 48.8 48 47.4 48 46.9 45.7 46.2 45.8 45.2 45.4
160
• Corrosion maps: a graphic representation of
47.9 47.9 47.9 47.2 47.9 46.7 47.8 47.8 47.8 48.2 48.2 47.4 47.5 47.6 47.2 47.1 45.2
corrosion distribution on the wall of the kettle
200 48.1 48.2 48.9 48.9 47.7 48.2 48.5 48.5 48.4 48.9 48.9 47.6 48.4 48.1 48.1 47.5 47.8
250 48.9 48.7 45 48.2 48.1 48.5 48.4 48 47.2 48 48.3 47.8 47.9 46.6 47.8 48.4 48

4. STEP 1: ANALYZING
NUMERICAL DATA
• KETTLES ARE CATEGORIZED AS FOLLOWS:
• By furnace type: Flat Flame VS. High Velocity
• By kettle size: Three Lenght Categories
» 10 to 24 feet long
» 25 to 40 feet long
» 41 feet and more
• By age in service: From 2 to 10 years of service life

5. STEP 1: ANALYZING
NUMERICAL DATA
• WHAT FIGURES DO WE USE FOR ANALYSIS ?
• AVERAGE THICKNESS: Calculated according to normal
statistical rules
• MINIMUM THICKNESS READING: A significant index !

6. AVERAGE THICKNESS
STEP 1: ANALYZING
COMPARISON
NUMERICAL DATA
Kettle Age (years in service)
Kettle
2 3 4 5 6 7 8 9 10
FLAT Size (ft)
10-24 NA 1.81 1.66 1.82 1.66 1.67 1.43 NA NA
FLAME 25-40
41up
NA
NA
1.73
1.79
NA
1.64
NA
1.77
NA
NA
1.35
1.64
1.29
1.55
NA
1.36
NA
1.35
LET’S TAKE A LOOK AT RESULTS…..
Kettle Age (years in service)
Kettle
END Size (ft)
2 3 4 5 6 7 8 9 10
10-24 1.81 NA 1.78 1.74 1.73 1.70 1.69 NA NA
FIRED 25-40
41up
NA
NA
1.67
NA
1.82
NA
1.79
1.77
1.72
1.75
NA
NA
NA
1.67
NA
1.62
NA
NA

7. MINIMUM THICKNESS
COMPARISON
Kettle Age (years in service)
Kettle
2 3 4 5 6 7 8 9 10
FLAT Size (ft)
10-24 NA 1.61 1.52 1.66 1.49 1.26 1.18 NA NA
FLAME 25-40
41up
NA
NA
1.57
1.66
NA
1.43
NA
1.62
NA
NA
1.20
1.22
1.13
1.18
NA
1.18
NA
1.03
Kettle Age (years in service)
Kettle
END Size (ft)
2 3 4 5 6 7 8 9 10
10-24 1.61 NA 1.03 1.48 1.57 1.64 1.52 NA NA
FIRED 25-40
41up
NA
NA
1.57
NA
1.61
NA
1.64
1.64
1.44
1.40
NA
NA
NA
1.24
NA
0.96
NA
NA

8. STEP 1 : DATA COMPARISON
AVERAGE THICKNESS - 10Meters FEET
Average Thickness - 4 to 8
TO 24
50
lklklklklklklklklklklklklklklklklkl
1,78 1,82
46,4
45,4
45 1,74
44,2 1,73
44,1 1,78
43,2 1,69
43,1
1,66
42,3 1,68 1,66
42,5
42,2
40
1,43
36,5
35
Thickness (mm)
30
25
4 5 6 7 8
Age (YRS)
Flat Flame High Velocity

9. STEP 1 : DATA COMPARISON
AVERAGE Thickness - Longer41 FEET AND MORE
Average THICKNESS - than 13 Meters
50
lklklklklklklklklklklklklklklklklkl
1,77
45,1 1,77
45,2
1,74
45 44,5
1,67
42,5
1,64
41,7 1,62
41,4
40
1,55
39,4
1,36
34,6
35
Thickness (mm)
30
25
5 6 7 8 9
Age (YRS)
NA Flat Flame NA
High Velocity

10. STEP 1 : DATA COMPARISON
LOWEST Thickness - 4 to 8 Meters 24 FEET
Lowest THICKNESS - 10 TO
lklklklklklklklklklklklklklklklklkl
45
1,66
42,3 1,64
41,7
1,57
40,1 1,52
38,8
40 1,52
38,7
1,48 1,47
37,8 37,9
35
1,26
32,2
1,18
30
30
Thickness (mm)
1,03
26,2
25
20
4 5 6 7 8
Age (YRS)
Flat Flame High Velocity

11. STEP 1 : DATA COMPARISON
LOWESTThickness - Longer41 FEET AND MORE
Lowest THICKNESS - than 13 Meters
45
lklklklklklklklklklklklklklklklklkl
1,62
41,4
1,64
41,9
40
1,40
35,7
35
1,22 1,24
31,5
31,2 1,18
30,2 1,18
30
30
Thickness (mm)
0,96
24,5
25
20
4 5 6 7 8
Age (YRS)
Flat Flame NA
High Velocity

12. STEP 1: CONCLUSIONS
• WHAT INDICATIONS FROM DATA ANALYSIS ?
• KETTLE SIZE INFLUENCE
• LOSS OF THICKNESS IN TIME
• AVERAGE CORROSION IN COMPARISON
• LOWEST READINGS IN COMPARISON
• END FIRED OR FLAT FLAME?
• INFLUENCE OF PRODUCTION THROUGHPUT

13. STEP 1: CONCLUSIONS
• BY LOOKING AT AVAILABLE DATA, THERE IS NO
EVIDENCE OF A DIRECT INFLUENCE OF KETTLE SIZE
ON CORROSION BEHAVIOUR.
• LACK OF CORRELATION BETWEEN KETTLE SIZE AND
CORROSION BEHAVIOUR MIGHT HELP IN ANALYSIS
OF CORRELATION BETWEEN PRODUCTION
THROUGHPUT AND CORROSION (SEE NEXT SLIDES!)

14. STEP 1: CONCLUSIONS
• COLLECTED DATA SHOWS THAT IN BOTH FLAT FLAME AND
END FIRED SYSTEMS THERE IS A DIRECT RELATIONSHIP
BETWEEN AGE AND THICKNESS LOSS.
• COLLECTED DATA ALSO SHOWS THAT THICKNESS DROPS
FASTER AFTER AN AGE OF FIVE YEARS, CONFIRMING KNOWN
THEORIES ON HEAT EXCHANGE AS A FUNCTION OFTHICKNESS
LOSS.

15. STEP 1: CONCLUSIONS
• AVERAGE CORROSION APPEARS, ACCORDING TO AVAILABLE
DATA, BETTER IN HIGH VELOCITY SETTINGS THAN IN FLAT
FLAME ONES.
• ALTHOUGH THIS INDICATION MIGHT LEAD TO DRAW SOME
CONCLUSIONS, FURTHER INVESTIGATION MUST BE
PERFORMED ON A WIDER STATISTICAL BASE.
• ALSO, BEFORE JUMPING TO CONCLUSIONS, ONE MIGHT TAKE
A LOOK AT LOWEST READINGS!

16. STEP 1: CONCLUSIONS
• LOWEST READINGS SHOW THAT IT IS VERY HARD TO
COMPARE ALTERNATIVE HEATING SYSTEMS
• IT SEEMS BY LOOKING AT HARD DATA THAT END FIRED
SYSTEMS ARE PRODUCING BETTER LOWER VALUES THAN FLAT
FLAMES ONLY IN SHORT KETTLES.
• WE MUST THINK OF A MODEL TO EXPLAIN THIS DIFFERENCE. IT
COULD BE RELATED TO HEAT EFFICIENCY AS KETTLES BECOME
BIGGER.

17. STEP 2: ANALYZING
CORROSION MAPS
• HOW DO WE READ THEM ?
• CORROSION DISTRIBUTION: Corrosion Maps provide a
snapshot view of how corrosion is distributed in kettles
and help performing comparisons.
• CORROSION PROGRESSION: Repeated inspections on
kettles have allowed some consideration for corrosion
progression.

18. STEP 2: ANALYZING
CORROSION MAPS
• Corrosion is a function of heat distribution and
exhaust velocity.

19. STEP 2: ANALYZING
CORROSION MAPS
• Productive age of the kettle is important, but focus must be on total
usage of furnace heat potential.
• TWO KETTLES: SAME SIZE, SAME KIND OF FURNACE - DIFFERENT
PRODUCTION THROUGHPUT
KETTLE 1 KETTLE 2

20. STEP 2: ANALYZING
CORROSION MAPS
• Moving parts and regular flows inside the kettle can seriously
affect corrosion.
QuickTimeª e un
decompressore TIFF (Non compresso)
sono necessari per visualizzare quest'immagine.

21. WHAT’S NEXT?
• A SERIOUS INTEGRATED STUDY ON HEAT DYNAMICS OF
FURNACE/KETTLE SYSTEMS, IN RELATION TO EXISTING CORROSION
DATA
• MORE KID INSPECTIONS, TO BUILD A LARGER STATISTICAL BASE TO BE
PERIODICALLY ANALYZED TO CONFIRM OR CHANGE CONCLUSIONS
• POSSIBLE INTERACTION WITH FURNACE MANUFACTURERS AND
GALVANIZERS TO PUT KID INSPECTION DATA ON THE COMPLETE
BACKGROUND OF FURNACE HISTORY, STRUCTURE AND TECH DATA