Mario Ubiali's presentation at Intergalva 2009 about general trends observed in kettle corrosion thanks to extensive use of the KID Technology.

1. DYNAMICS OF
KETTLE CORROSION IN THE
HOT DIP GALVANIZING
INDUSTRY
Mario Ubiali
Intergalva, 8‐12 June 2009
Madrid, Spain

2. Background
• Zinco Service introduced the KID technology
at Intergalva 2006, in Naples
• Since then, over 220 ke?les have been
inspected in Europe, Canada and USA
• Enough data to start looking for meaningful
connecGons 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 representaGon 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 distribuGon on the wall of the ke?le
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 ke?le size: Three Lenght Categories
» 4‐8 meters long
» 9‐12 meters long
» 13 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
staGsGcal 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 (mt)
4-8 NA 46 42,3 46,4 42,2 42,5 36,5 NA NA
FLAME 9-12
13 and up
NA
NA
44,1
45,7
NA
41,8
NA
45,1
NA
NA
34,5
41,7
32,9
39,4
NA
34,6
NA
34,5
LET’S TAKE A LOOK AT RESULTS…..
Kettle Age (years in service)
END Kettle
Size (mt)
2 3 4 5 6 7 8 9 10
4-8 46 NA 45,4 44,2 44,1 43,2 43,1 NA NA
FIRED 9-12 NA 42,6 46,3 45,5 43,9 NA NA NA NA
13 and up NA NA NA 45,2 44,5 NA 42,5 41,4 NA

7. MINIMUM THICKNESS
COMPARISON
Kettle Age (years in service)
Kettle 2 3 4 5 6 7 8 9 10
FLAT Size (mt)
4-8 NA 40,9 38,7 42,3 37,9 32,2 30 NA NA
FLAME 9-12
13 and up
NA
NA
39,9
42,2
NA
36,5
NA
41,4
NA
NA
30,6
31,2
28,9
30,2
NA
30
NA
26,2
Kettle Age (years in service)
END Kettle
Size (mt)
2 3 4 5 6 7 8 9 10
FIRED 4-8
9-12
41,1
NA
NA
39,9
26,2
41,1
37,8
41,9
40,1
36,7
41,7
NA
38,8
NA
NA
NA
NA
NA
13 and up NA NA NA 41,9 35,7 NA 31,5 24,5 NA

8. STEP 1 : DATA COMPARISON

9. STEP 1 : DATA COMPARISON

10. STEP 1 : DATA COMPARISON

11. STEP 1 : DATA COMPARISON

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 ON THICKNESS.

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 HIGHER 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 ke?les
and help performing comparisons.
• CORROSION PROGRESSION: Repeated inspecGons on
ke?les have allowed some consideraGon for corrosion
progression.

18. STEP 2: ANALYZING h!)
aug
CORROSION MAPS don’t l
se,
(p lea
• Corrosion is a funcGon of heat distribuGon and
exhaust velocity.

19. STEP 2: ANALYZING
CORROSION MAPS
• ProducGve age of the ke?le is important, but focus must be on
total usage of furnace heat potenGal.

20. STEP 2: ANALYZING
CORROSION MAPS
• Moving parts and regular flows inside the ke?le can seriously
affect corrosion.

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