External coatings used for corrosion protection often have to perform under severely corrosive environments. One major concern regarding coating performance is the negative effect of soluble salts on the steel substrate at the time of coating application, particularly for marine maintenance coating applications. Work presented here focuses on removal of soluble salts contamination by commercially available decontamination processes in relation to external coating systems. We directly compared the effectiveness of four cleaning methods with the performance of ten coating systems. This work has been presented during NACE Corrosion 2014 Conference in San Antonio.

1. The Effect of Four Commercially Available
Steel Decontamination Processes
on the Performance of External Coatings
Michael Melancon
Chevron M&EE, Richmond, CA, USA
Amal Al-Borno, Ph.D.
Charter Coating Service (2000) Ltd., No. 6, 4604 13th Street NE,
Calgary, AB, T2E, Canada

2. CO-AUTHORS
Paul Hunter
Chevron M&EE, Richmond, CA, USA
Steve Hourcade
Chevron North America E&P, Northpark Boulevard, Covington, LA, USA
Tomasz Liskiewicz, Sherry Rao Bassem Salamah, Shailesh Dhoke,
Julius Cortes and Xianyi Chen
Charter Coating Service (2000) Ltd., Calgary, AB, Canada

3. Coating systems used for corrosion protection in external service
frequently have to perform under severely corrosive environments.
In such instances, it is important that these coatings must be able to
withstand:
 Effect of weather
 Ultraviolet light
 Industrial/marine atmospheres
External Tank Linings

4.  Even the best coating will fail if it is applied to a contaminated surface
 ISO 8502 Standard says: The behavior of protective coating
systems is affected mainly by the condition of the
substrate immediately before the coating system is
applied
 Behavior of protective coating systems is controlled by:
 Rust and mill scale
 Surface profile
 Debris contamination
 Soluble salts
Problem of Surface Contamination

5.  Most common salts in the industrial environment:
 chlorides (Cl-),
 sulphates (SO4
2-)
 nitrates (NO3
-)
Problem of soluble salts became more significant over recent years
Driven by environmental legislation replacing lead-bearing paints
The presence of soluble salts on the metallic substrate will lead to
osmotic coating blistering
Soluble Salts
Soluble salts
Interfacial water

6.  Most common salts in the industrial environment:
 chlorides (Cl-),
 sulphates (SO4
2-)
 nitrates (NO3
-)
Problem of soluble salts became more significant over recent years
Driven by environmental legislation replacing lead-bearing paints
The presence of soluble salts on the metallic substrate will lead to
osmotic coating blistering
Soluble Salts
Concentrated salt solution

7.  Most common salts in the industrial environment:
 chlorides (Cl-),
 sulphates (SO4
2-)
 nitrates (NO3
-)
Problem of soluble salts became more significant over recent years
Driven by environmental legislation replacing lead-bearing paints
The presence of soluble salts on the metallic substrate will lead to
osmotic coating blistering
Soluble Salts
Water drawn in
by osmotic pressure

8.  Most common salts in the industrial environment:
 chlorides (Cl-),
 sulphates (SO4
2-)
 nitrates (NO3
-)
Problem of soluble salts became more significant over recent years
Driven by environmental legislation replacing lead-bearing paints
The presence of soluble salts on the metallic substrate will lead to
osmotic coating blistering
Soluble Salts
Soluble salts
Interfacial water

9.  General trend  very low salt concentration values by coating
manufacturers and standard issuing organizations
BUT
 These low values seem to be very conservative as they must
represent different coating systems and different operational
conditions
Benefits of applying surface cleaning procedures
should be assessed on an individual
Soluble Salts
Scope of this project
 Maximum Cl- level advised by Chevron in this project: 5g/cm2

10. Project Motivation
 Chevron’s offshore facilities have been addressing
challenges of maintenance coating issues for a
number of years
 The service life of previous maintenance coating
systems has not met expectations
Project Objective

11.  To determine the effectiveness of three
commonly used surface pre-cleaning methods
along with a post blast chemical cleaning
method.
 It was anticipated that the results of this study
will assist Chevron in selecting cleaning
methods and coatings in order to improve the
service life of external coating systems
Project Objective

12. Coating Systems
Coating Suppliers
Supplier 1 Supplier 2 Supplier 3 Supplier 4 Supplier 5
Coating
System 1
7-10 years
Coating
System 2
15-20 years
Coating
System 5
7-10 years
Coating
System 3
7-10 years
Coating
System 4
15-20 years
Coating
System 6
15-20 years
Coating
System 7
7-10 years
Coating
System 8
15-20 years
Coating
System 9
Coating
System 10
Approved suppliers
New suppliers
Coating Systems for
Gulf of Mexico Application

13. Supplier Coating system Coating Type
1
CS1  12-15 mils
7-10 year system
Epoxy Mastic (aluminum-pigmented high-solids mastic)
Cycloaliphatic Amine Epoxy- Top Coat
1
CS2  14-18 mils
7-10 year system
Polymeric Epoxy Amine
Epoxy Mastic – Top Coat
Cycloaliphatic Amine Epoxy – Top Coat
1
CS3  16-24 mils
15-20 year system
Solvent Based Organic Zinc-Rich Epoxy
Epoxy Mastic
Epoxy Mastic
Modified Siloxane Hybrid- Top Coat
1
CS4  18-26 mils
15-20 year system
Epoxy Mastic
Epoxy Mastic
Epoxy Mastic
Modified Siloxane Hybrid – Top Coat
2
CS5  16-20 mils
7-10 year system
Surface Tolerant Epoxy
Modified Epoxy – Top Coat
2
CS6  12-17 mils
15-20 year system
Aluminum Pure Epoxy
Aluminum Pure Epoxy
Acrylic Polysiloxane- To Coat
3
CS7  12-15 mils
7-10 year system High Solids Glass Flake Epoxy
Polyamide Epoxy (containing Zn phosphate)- Top Coat
3
CS8  25-27 mils
15-20 year system
4 CS9  6-9 mils
Zinc Silicate
Siloxane Epoxy – Top Coat
5 CS10  22 mils
Epoxy Primer/Sealer
Elastomeric Pure Polyurea – Top Coat

14. Cycloaliphatic
Amine Epoxy
20%
High Solids
Glass Flake
Epoxy
20%
Modified
Siloxane
Hybrid
20%Modified
Epoxy
10%
Acrylic
Polysiloxane
10%
Siloxane
Epoxy
10%
Elastomeric
Pure Polyurea
10%
Coating Systems- Top Coat
Epoxy Mastic:
Aluminum-
pigmented
high-solids
mastic
20%
Polymeric
Epoxy
Amine-
Aluminum-
pigmented
high-solids
mastic
10%
Organic Zinc-
Rich Epoxy-
Aluminum-
pigmented
high-solids
mastic
10%
Epoxy, Surface
Tolerant Epoxy
20%
Polyamide
Epoxy-contain
Zn phosphate
20%
Zinc Silicate
10%
Aluminium
Pure Epoxy
10%
Coating Systems-Midand base Coat
Coating Systems

15. • Four cleaning methods:
– Cleaning Method A :
Industry standard pressure wash
– Cleaning Method B:
Pressure wash with fresh 25% aqueous
cleaning solution used by Chevron
– Cleaning Method C:
New chemical treatment
– Cleaning Method D:
Simulates Chevron offshore
maintenance procedures
when surface blasting is not carried out
Solvent
Clean, Sweep
blast and
contaminated
Solvent Clean, Blast to
SSPC-SP 10 prior to
contamination
Cleaning Methods

16.  To simulate offshore chloride contaminations:
 Panels were exposed to a salt fog atmosphere in a salt spray
cabinet conducted as per ASTM B117-11
 The exposure time required to achieve a contamination level of
300 Cl- (µg/cm2) was 48 hours
 Heavly corroded substrates which showed general and localized
corrosion attack
FIRST STEP: Surface Contamination

17.  To simulate offshore chloride contaminations:
 Panels were exposed to a salt fog atmosphere in a salt spray
cabinet conducted as per ASTM B117-11
 The exposure time required to achieve a contamination level of
300 Cl- (µg/cm2) was 48 hours
 Heavly corroded substrates which showed general and localized
corrosion attack
FIRST STEP: Surface Contamination

18. Contaminate Surface Using Salt Fog
48 hours
Solvent Clean SP 1
Commercial blast to SP6
Panel After Contamination
Cleaning Method A

19. Low Pressure Wash
3000 psi, fresh tap water
2 minutes
Low Pressure Wash
3000 psi, fresh tap water
2 minutes
Low Pressure Wash
3000 psi, fresh tap water
2 minutes
Low Pressure Wash
3000 psi, fresh tap water
2 minutes
Contaminate Surface Using Salt Fog
48 hours
Solvent Clean SP 1
Commercial blast to SP6
Panels After Fourth Wash
Cleaning Method A

20. Blast Cleaning
NACE 2 / SSPC-SP 10
Low Pressure Wash
3000 psi, fresh tap water
2 minutes
Low Pressure Wash
3000 psi, fresh tap water
2 minutes
Low Pressure Wash
3000 psi, fresh tap water
2 minutes
Low Pressure Wash
3000 psi, fresh tap water
2 minutes
Contaminate Surface Using Salt Fog
48 hours
Solvent Clean SP 1
Commercial blast to SP6
Panels After Blasting
Cleaning Method A

21. Contaminate Surface Using Salt Fog
48 hours
Solvent Clean SP 1
Commercial blast to SP6
Panel After Contamination
Cleaning Method B

22. Low Pressure Wash
3000 psi, 25% cleaning solution
(1 minute) followed by fresh tap
water (1 minute)
Contaminate Surface Using Salt Fog
48 hours
Solvent Clean SP 1
Commercial blast to SP6
Low Pressure Wash
3000 psi, 25% cleaning solution
(1 minute) followed by fresh tap
water (1 minute)
Low Pressure Wash
3000 psi, 25% cleaning solution
(1 minute) followed by fresh tap
water (1 minute)
Panels After Third Wash
Cleaning Method B

23. Blast Cleaning
NACE 2 / SSPC-SP 10
Low Pressure Wash
3000 psi, 25% cleaning solution
(1 minute) followed by fresh tap
water (1 minute)
Contaminate Surface Using Salt Fog
48 hours
Solvent Clean SP 1
Commercial blast to SP6
Low Pressure Wash
3000 psi, 25% cleaning solution
(1 minute) followed by fresh tap
water (1 minute)
Low Pressure Wash
3000 psi, 25% cleaning solution
(1 minute) followed by fresh tap
water (1 minute)
Panels After Blasting
Cleaning Method B

24. Solvent Clean SP 1
Commercial blast to SP6
Contaminate Surface Using Salt Fog
48 hours
Panel After Contamination
Cleaning Method C

25. Blast Cleaning
NACE 2 / SSPC-SP 10
Solvent Clean SP 1
Commercial blast to SP6
Contaminate Surface Using Salt Fog
48 hours
Panels After Blasting
Cleaning Method C

26. Blast Cleaning
NACE 2 / SSPC-SP 10
Chemical Treatment
commercial cleaning solution,
45 minutes
Solvent Clean SP 1
Commercial blast to SP6
Contaminate Surface Using Salt Fog
48 hours
Panels During Chemical Treatment
Cleaning Method C

27. Blast Cleaning
NACE 2 / SSPC-SP 10
Chemical Treatment
commercial cleaning solution,
45 minutes
Washing
proprietary wash solution
Solvent Clean SP 1
Commercial blast to SP6
Contaminate Surface Using Salt Fog
48 hours
Panels After Wash
Cleaning Method C

28. Panel After Contamination
Blast Cleaning
NACE 2 / SSPC-SP 10
Contaminate Surface Using Salt Fog
48 hours
Solvent Clean SP 1
Commercial blast to SP6
Cleaning Method D

29. Panels After UHP Wash
Ultra-high Pressure
Water Jetting
36000 psi, fresh tap water
2 minutes
Blast Cleaning
NACE 2 / SSPC-SP 10
Contaminate Surface Using Salt Fog
48 hours
Solvent Clean SP 1
Commercial blast to SP6
Cleaning Method D

30. Two methods for measuring the chloride contamination level were used in
this study:
1. Laboratory Ion Chromatography
 Dionex DX-120 Ion Chromatography system
2. Field method
 commercial chloride ion detection kit
• Chloride analysis was conducted using a laboratory extraction process
conducted according to Mayne approach
Chloride Analysis
 Maximum Cl- level advised by Chevron in this project: 5g/cm2

31. Two methods for measuring the chloride contamination level were used in
this study:
1. Laboratory Ion Chromatography
 Dionex DX-120 Ion Chromatography system
2. Field method
 commercial chloride ion detection kit
• Chloride analysis was conducted using a laboratory extraction process
conducted according to Mayne approach
Cleaning Method
Laboratory Method
Ion Chromatography
Cl- (µg/cm2)
Field Method
Cl- (µg/cm2)
Cleaning Method A 0.8 - 2.33 0
Cleaning Method B 1.4 - 1.9 0
Cleaning Method C 1.4 - 2.13 0
Cleaning Method D 1.2 - 2.7 0
Chloride Analysis
 Maximum Cl- level advised by Chevron in this project: 5g/cm2

32. Before cleaning
• Highly contaminated steel
surface with many deposit
patches (1.88% wt. chloride
contamination by EDX)
After cleaning
• Highly deformed, rough surface
resulting from blasting
• No significant contamination
deposits observed by SEM
• However EDX showed traces of
chloride
Before Cleaning
Cleaning Method A
Cleaning Method B
Cleaning Method C
Cleaning Method D
oxides
SEM/EDX Analysis

33.  In order to achieve conformity of application conditions, all the
coatings were applied at the same location by the same applicator.
 The applications were observed by a Charter Coating inspector and
witnessed by a representative of each coating supplier.
Coating Application

34. Ultra-high Pressure Cleaning

35. Ultra-high Pressure Cleaning

36. Tests performed included:
1. Adhesion
 Pull-off - ASTM D4541-09
 X-scribe - ASTM D6677
2. Cross-section porosity - CSA Z245.20
3. EIS - ISO 16773-2: 2007
4. Cycling testing - ASTM D5894
Laboratory Testing

37.  Duration: 1008 hours (6 weeks) in total
 Post-test evaluation:
 Blistering
 Checking rating
 Color change
 Gloss
 Chalking
 Rusting
 Undercreep
Cycling Test - ASTM D5894

38.  Duration: 1008 hours (6 weeks) in total
 Post-test evaluation:
 Blistering
 Checking rating
 Color change
 Gloss
 Chalking
 Rusting
 Undercreep
Fluorescent
UV/condensation
1 week (168h) Cycle
Cyclic Salt Fog/Dry Exposure
1 week (168h) Cycle
 4h UV Light at 60oC
 4h Condensation at 50oC
 1h Fog at Ambient
Temperature
 1h Dry-Off at 35oC
 Salt Solution: 5% NaCl
Cycling Test - ASTM D5894

39.  No adhesive failure at the coating system/substrate interface has
been reported for any coating system
 The cleaning methods indicate good coating application process
leading to high interface strength.
 The pull-off strength of the coating system was found to be a factor of
the coating type and not the cleaning method.
 Sample results – Coating System 5:
Cleaning
Method A
Cleaning
Method B
Cleaning
Method C
Cleaning
Method D
Pull-off Adhesion - ASTM D4541-09

40. 0
500
1000
1500
2000
2500
3000
3500
A B C D A B C D A B C D A B C D A B C D A B C D A B C D A B C D
CS1 CS2 CS3 CS4 CS5 CS6 CS7 CS8 CS9 CS10
Pull-OffPsi
Coating System"CS1-10 and Cleaning Methods A-D"
Pull-off Adhesion (psi)
Pull-off Adhesion Test Results

41.  All coating systems showed no sign of any adhesive or brittle
breakaway from the substrate indicating excellent coating to substrate
adhesion.
 For the same type of coating, the variation in the substrate cleaning
method did not affect the coating adhesion.
 Sample results – Coating System 9:
Cleaning
Method A
Cleaning
Method B
Cleaning
Method C
Cleaning
Method D
X-cut Adhesion - ASTM D6677

42.  According to CAN/CSA Z245.20 - 10, Clause 12.10, cross-section
porosity is ranked between 1 and 5, with 1 indicating the lowest and 5
the highest porosity.
 For all analyzed samples, both cross-section porosity and interface
porosity were ranked between 1 and 2 indicating very low porosity.
 Sample results – Coating System 3:
Cross-section Porosity - CSA Z245.20, section 12.10

43. EIS - ISO 16773-2: 2007
6
6.5
7
7.5
8
8.5
9
9.5
10
10.5
11
A B C D A B C D A B C D A B C D A B C D A B C D A B C D A B C D
CS1 CS2 CS3 CS4 CS5 CS6 CS7 CS8 CS9 CS10
LogZ(Ohms/cm2
Coating System"CS1-10 and Cleaning Methods A-D"
EIS Log Z (Ohms/cm2)
Pass

44. Cycling Test: ResultsCycling Test: Results

45. Cycling Test: Results
0
5
10
15
20
25
30
35
40
A B C D A B C D A B C D A B C D A B C D A B C D A B C D A B C D
CS1 CS2 CS3 CS4 CS5 CS6 CS7 CS8 CS9 CS10
DFTmils
Coating Systems"CS1-10 and Cleaning MethodsA-D"
DFT mils Before and afterthe CyclingTest
DFT (mils) Pre-test DFT (mils) Post-test
Cycling Test: Results

46. 0
1
2
3
4
5
6
A B C D A B C D A B C D A B C D A B C D A B C D A B C D A B C D
CS1 CS2 CS3 CS4 CS5 CS6 CS7 CS8 CS9 CS10
Undercreepmm
Coating System"CS1-10 and Cleaning Methods A-D"
Undercreep(mm)
Cycling Test: Results
CS1
Epoxy
Mastic
(Aluminum-
pigmented
high-solids
mastic
Cycloaliphati
c Amine
Epoxy
CS2
Polymeric
Epoxy
Amine/
Epoxy
Mastic/
Cycloalipha
tic Amine
Epoxy
CS3
Solvent Based
Organic Zinc-
Rich
Epoxy/2layers
of Epoxy
Mastic/
Modified
Siloxane
Hybrid
CS4
3 Layers
of Epoxy
Mastic/
Modified
Siloxane
Hybrid
CS5
Surface
Tolerant
Epoxy /
Modified
Epoxy
CS6
2Layers of
Aluminum
Pure Epoxy/
Acrylic
Polysiloxane
CS7
Polyamide
Epoxy
(contain Zn
phosphate)/
High Solids
Glass Flake
Epoxy
CS8
Polyamide
Epoxy
(contain Zn
phosphate)/
High Solids
Glass Flake
Epoxy
CS9
Zinc
Silicate/
Siloxane
Epoxy
CS10
10
Epoxy
Primer/Sealer/
Elastomeric
Pure Polyurea

47. Cycling Test: Checking
Yes
CS5
Surface
Tolerant
Epoxy /
Modified
Epoxy
CS7
Polyamide
Epoxy
(contain Zn
phosphate)
/ High
Solids
Glass Flake
Epoxy
CS8
Polyamide
Epoxy
(contain Zn
phosphate)
/ High
Solids
Glass Flake
Epoxy
CS10
Epoxy
Primer /
Sealer /
Elastomeric
Pure
Polyurea
No
CS1
Epoxy
Mastic
(Aluminum-
pigmented
high-solids
Mastic /
Cycloali-
phatic
Amine
Epoxy
CS2
Polymeric
Epoxy
Amine /
Epoxy
Mastic /
Cycloali-
phatic
Amine
Epoxy
CS3
Solvent
Based
Organic
Zinc-Rich
Epoxy /
2 layers
Epoxy
Mastic/
Modified
Siloxane
Hybrid
CS4
3 Layers of
Epoxy
Mastic /
Modified
Siloxane
Hybrid
CS6
2 Layers of
Aluminum
Pure
Epoxy /
Acrylic
Polysilo-
xane
CS9
Zinc Silicate
/ Siloxane
Epoxy

48. Summary: Supplier 1
Coating System Cleaning Methods
Cycling Test Results
Color
Change
Checking
Undercreep
(mm) rating
CS1
Cleaning Method A Slight None 0.4 9
Cleaning Method B Slight None 0.1 9
Cleaning Method C Slight None 0.5 9
CS2 Cleaning Method D Slight None 3.1 5
CS3
Cleaning Method A None None 0 10
Cleaning Method B None None 0 10
Cleaning Method C None None 0 10
CS4 Cleaning Method D None None 1.8 7
 For all four coating systems no significant change in DFT, no blistering, no rusting,
no cracking and no checking
 Slight change in color and loss of gloss for CS1 and CS2
 CS2 and CS4 showed tendency to undercreep
 Results indicate that effective surface cleaning and blasting is required for better
coating utilizing epoxy mastic as a first coat
 Loss of gloss is due to use of the modified siloxane hybrid as a top coat

49. Summary: Supplier 2
Coating System Cleaning Methods
Cycling Test Results
Color
Change
Checking
Undercreep
(mm) rating
CS5
Cleaning Method A Medium Yes 1.7 7
Cleaning Method B Medium Yes 2.5 6
Cleaning Method C Medium Yes 1.6 7
Cleaning Method D Medium Yes 4.6 5
CS6
Cleaning Method A None None 2.3 6
Cleaning Method B None None 2.4 6
Cleaning Method C None None 1.1 7
Cleaning Method D None None 3.3 5
 Similar effect of cleaning on coating performance with no change in DFT, no
blistering, no rusting, no cracking, medium change in color and loss of gloss
 Checking was observed for CS5
 Undercreep observed in all samples but UHP water jetting (Method D) showed
lower resistance to undercreep
 This indicates effective surface cleaning and blasting is required to improve coating
performance with regard to undercreep

50. Summary: Supplier 3
Coating System Cleaning Methods
Cycling Test Results
Color
Change
Checking
Undercreep
(mm) rating
CS7
Cleaning Method A Slight Yes 2.4 6
Cleaning Method B Slight Yes 1.5 7
Cleaning Method C Slight Yes 1.7 7
Cleaning Method D Slight Yes 2.6 6
CS8
Cleaning Method A Slight Yes 1.5 7
Cleaning Method B Slight Yes 2.3 6
Cleaning Method C Slight Yes 2.6 6
Cleaning Method D Slight Yes 4.8 5
 The same coatings but CS8 was applied at a higher DFT (24-25 mils) while CS7 at
14 mils
 Steel substrate cleaned by UHP water jetting (Method D) showed slightly lower
resistance to undercreep
 Similar performance: tendency to undercreep but no change in DFT, no blistering,
no rusting, no cracking, slight change in color, loss of gloss and checking

51. Summary: Supplier 4
Coating System Cleaning Methods
Cycling Test Results
Color
Change
Checking
Undercreep
(mm) rating
CS9
Cleaning Method A None None 0.5 9
Cleaning Method B None None 0.6 8
Cleaning Method C None None 0.8 8
Cleaning Method D None None 0.4 9
 Similar effect of cleaning methods on the coating performance from cycling test
 No change in DFT, no blistering, no rusting and no cracking, no change in color,
no loss of gloss
 Very slight tendency to undercreep (≤ 0.8 mm)
 The only coating which has surface tolerant properties for tarnished substrate
 The inorganic zinc primer has a chemical bond in additional to a physical bond
between the coating and the steel

52. Summary: Supplier 5
Coating System Cleaning Methods
Cycling Test Results
Color
Change
Checking
Undercreep
(mm) rating
CS10
Cleaning Method A None Yes 1.6 7
Cleaning Method B None Yes 0.9 8
Cleaning Method C None Yes 0.9 8
Cleaning Method D None Yes 1.2 7
 All cleaning methods had similar effects on the coating performance
 No change in DFT, no blistering, no rusting, no cracking and no change in color
 Checking and some loss of gloss were noted for all test samples
 Some tendency to undercreep (0.9 - 1.6 mm)

53. Conclusions
 Low salt levels for all methods but UHP wash with no blast before or after
the water jetting resulted in a slightly tarnished substrate due to oxides
formation on steel surface
 Differences in gloss change and degree of checking between coatings
which are surface phenomena and formulation related reactions
 The only significant difference in coatings performance observed for
undercreep
 Most coatings applied after UHP wash showed tendency to undercreep
indicating coating systems sensitivity to substrate preparation
 The chemical treatment included in this study (Cleaning Method C), did
not show any significant positive or negative effect on the performance of
the applied coatings

54. ACKNOWLEDGMENT
The authors would like to thank Chevron
Energy Technology Company in conjunction
with Chevron Gulf of Mexico Business Unit
for their finical and technical support of this
work