1. Specification Components Consideration of Variables
Learning Objectives
Specification Components
Consideration of Variables

2. Abrasive Blast Cleaning Standards
SSPC-SP 7/NACE 4 *
SSPC-SP 14/NACE 8 *
SSPC-SP 6/NACE 3 *
SSPC-SP 10/NACE 2 *
SSPC-SP 5/NACE 1 *
SSPC-SP 16
* In addition, Wet Abrasive Blast (WAB) Standards have been developed.

3. SSPC-SP10/NACE No. 2, Near-White Blast Cleaning
Requires removal of all loosely and tightly adhering mill scale, rust and paint from the surface
Staining from rust, paint and mill scale permitted but must not exceed 5% of each 9 square inches of prepared surface

4. SSPC SP10
Rust-Back occurs when freshly cleaned steel is exposed to moisture, contamination, or a corrosive atmosphere. The time interval between blast cleaning and rust-back varies greatly from one environment to another. Under mild ambient conditions, if chemical contamination is not present, it is best to blast clean and coat a surface on the same day. Severe conditions may require a more expeditions coating application to avoid contamination from fallout. Chemical contamination should be removed prior to coating.

5. SSPC SP10 (WAB)
Flash Rust is an oxidation product that forms as a wetted carbon steel substrate dries. Flash rust is an additional consideration when a carbon steel substrate is subjected to WAB cleaning.
No flash rust: A carbon steel surface that, when viewed without magnification , exhibits no visible flash rust.
Light (L) flash rusted surface: A carbon steel surface that, when viewed without magnification, exhibits small quantities of a rust layer through which the carbon steel substrate may be observed. The rust or discoloration may be evenly distributed or present in patches, but it is tightly adherent and not easily removed by lightly wiping with a cloth.
Moderate (M) flash rusted surface: A carbon steel surface that, when viewed without magnification, exhibits a layer or rust that obscures the original carbon steel surface. The rust layer may be evenly distributed or present in patches, but it is reasonably well adherent and leaves light marks on a cloth that is lightly wiped over the surface.
Heavy (H) flash rusted surface: A carbon steel surface that, when viewed without magnification, exhibits a layer of heavy rust that hides the original carbon steel surface completely. The rust may be evenly distributed or present in patched, but it is loosely adherent, easily comes off, and leaves significant marks on a cloth that is lightly wiped over the surface.

6. Sampling, Detecting and Removing Soluble Salt Contamination
Contaminants include chloride, ferrous ions, sulfates and nitrates
Deposited onto surfaces while structure is in service
Deposited during transportation of new steel overseas
Soluble in water
More difficult to remove from rough or pitted surfaces
Pressure washing or water jetting using clean water

7. Sampling, Detecting and Removing Soluble Salt Contamination
Proprietary salt removal-enhancing solutions available
If salts are not detected and adequately removed they can become trapped beneath a newly installed coating system
Consequences: osmotic blistering, underfilm corrosion, and premature coating failure
Recycled abrasive may
become contaminated

8. Salt Testing Methods
Specifications may require testing of surfaces for soluble salt contamination
Two steps:
Extraction
Analysis

9. Salt Testing Methods Methods of Extraction: Latex patch/cell
Surface swabbing
Latex patch/cell
Latex sleeve
Saturated contact pad
Magnetic cell
Filter paper saturation

11. Salt Testing Methods Methods of analysis: Chloride ion test strips
Drop titration
Chloride ion detection tubes
Conductivity meter
Ferrous ion test strips (not shown)
Nitrate ion test strips (not shown)
Sulfate ion meter (not shown)

13. Tolerable Levels of Soluble Salt Contamination
No industry standard
Dependent on the service environment & coating system
Atmospheric exposure = higher tolerance
Immersion service = lower tolerance
The project specification must indicate the maximum quantity of soluble salts that can remain on the surface and be safely coated over

14. Abrasives Two broad categories
Expendable – used once and then discarded
Recyclable – breakdown rate slow, allows them to be used multiple times

15. Expendable Abrasives Mineral (occur naturally) Silica sand Garnet
Staurolite
Recycled glass
Agricultural Abrasives

16. Recyclable Abrasives Steel grit (angular) Aluminum oxide (angular)
Steel shot (rounded)
Slag (not naturally generated). By-products of other industries processed into abrasives)
Copper slag
Nickel slag
Coal slag

17. Recyclable Abrasives SSPC AB1 Specific Gravity Hardness
Weight Change on Ignition
Water Soluble Contaminates
Moisture Content
Oil Content
Crystalline Silica Content
Surface Profile
Particle Size Distribution

18. Cleanliness Specifications for Metallic Abrasives
SSPC AB 2
SSPC AB 3

19. Specifications for Metallic Abrasives
SSPC AB 2
Cleanliness of recycled metallic abrasives
“Indirect” requirement of SSPC abrasive blast cleaning standards (if abrasive is recycled)
Testing for conformance
Non-abrasive residue*
Lead content (laboratory only)
Water soluble contaminants*
Oil content*
* Can be verified in the field

20. Specifications for Metallic Abrasives
SSPC AB 3
Standard addresses unused abrasive
Abrasive cleanliness sections of AB 3 are an “indirect” requirement of SSPC abrasive blast cleaning standards
Categorizes by Class
Class 1: Steel
Class 2: Iron
Testing for conformance
Abrasive size
Specific Gravity
Chemical composition
Hardness
Durability
Cleanliness*
Conductivity*
* Can be verified in the field

21. Measurement of Ambient Conditions Prior to Final Surface Preparation
No min or max air or surface temperature restrictions
No relative humidity restriction
If air temperature and relative humidity cause moisture from the air to condense on the surface, the surface may flash rust
Verify that the temperature of the surface is at least 5°F higher than the dew point temperature

22. Surface Preparation/Primer Application Window
Specification may dictate a maximum time period between final surface preparation and primer application
4 – 8 hours, same shift, may be addressed in the specificaion
Inspector verifies primer application to prepared surfaces within allowable “window”
If surface rusting is evident, the surfaces must be re-prepared to achieve the specified level of cleanliness (independent of elapsed time)
Dehumidification equipment can extend the holding of the blast longer

23. Variables
Weather
Rain
Fog
Cold Temperatures

24. Variables
Location
Rivers
Lakes
Streams
Oceans
Mountains

25. Variables Proximity to the ground Substrate is close to the ground
Cribbing

26. Variables Tank effluent in the tank
Containment (could create internal micro climates due to poor design)
Abrasive selection
Reusable vs. expendable

27. Variables Containment and dehumidification equipment
Inhibitors – Products that “hold blast”
Require coating manufacturer approval in writing

28. Goal End Result One size does not fit all and the need to: Investigate
Proper Planning
Material
Equipment
Schedule
Location
Weather Patterns
End Result
Project meets the contract documents

29. Chemical Plant Project
Furnace Description
6 Story Box
Approximately 14,000 sq. ft. of shell
Multiple paint systems
Ambient and high temperature paint systems
Stack
Approximately 90’ x 12’ diameter – 3,500 sq. ft.
Decks
Approximately 8 ft. wide with railing, stairs and ladders – 7,000 sq. ft.
Ambient paint system

30. Chemical Plant Project
Blower
Approximately 2,500 sq. ft.
Ambient paint system
Miscellaneous pipe, equipment inside of containment
Approximately 5,000 sq. ft.
Multiple paint systems
Ambient and high temperature paint systems
Total – Approximately 35,000 sq. ft.