Abstract

Contamination of blast cleaned steel surfaces prior to application of protective coatings leads to premature coating failure resulting from corrosion. It has become common practice to include a salt contamination test prior to the application of the first coat to ensure the required cleanliness.

One simple and quick method for this test is the Saturated Filter Paper Method for extracting the salts from the surface with a conductivity meter to assess the resulting sample to determine the concentration of the soluble salts. This method is described in SSPC(1) Guide 15.

Testing using this method has shown that soluble salts, particularly sodium chloride crystals, do not spread evenly over a surface and therefore the area tested and the number of tests in a given area are significant in determining if the blasted surface is clean in respect of soluble salts.

This paper will discuss the advantages inherent in the saturated paper method compared to other extraction methods and describe how the soluble salt contamination over a significant area can be determined. Reference will be made to the possibility of developing a reference test surface doped with a known concentration of sodium chloride so that the accuracy of testing can be verified.

Keywords:
materials and corrosion, riser corrosion, pipeline corrosion, subsurface corrosion, corrosion inhibition, oilfield chemistry, concentration, publication division, well integrity, filter paper method
Subjects:
Production Chemistry, Metallurgy and Biology, Pipelines, Flowlines and Risers, Information Management and Systems, Materials and corrosion, Well Integrity, Subsurface corrosion (tubing, casing, completion equipment, conductor), Corrosion inhibition and management (including H2S and CO2)
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2015. NACE International
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