VIS Guides and Initial Conditions
Posted on 15. Mar, 2009 by charles frenzel in NSRP
Use of VIS Guides for Initial Condition
Determine the initial condition of the steel before the flash rust forms.
Initial condition is illustrated as painted or unpainted steel.
Select a photograph that is similar to the initial condition
The inspector and the contractor should be aware that the initial condition of the steel can vary within a short area.
The initial condition is deteriorated paint.
Example of Clean to Bare Substrate and Very Thorough Cleaning with discoloration on right side where the coating was not intact of adhered to the substrate.
There is a very slight yellow hue to the steel on the upper left that is the onset of light flash rust. The condition of the steel under the paint is a mix of Grade D and Grade C.
If the coating is intact, the steel will look close to the original condition. If there is corroded or pitted steel, there often is a very-dark discoloration – gray/brown to black- that cannot be removed by further WJ.
The coatings manufacturers have said that “Analysis shows that this thin film consists mainly of ferric oxide which is an inert material. Because it is tightly adherent, it does not present a serious contamination problem.”
Author’s note- This discoloration has been over coated since 1985 with no apparent effect on subsequent paint performance.
