Has the Critical Art of Surface Preparation for Pipe Coating Been Forgotten?
This article will examine the key features of surface preparation; identify and resolve problem areas; show how to achieve the right result consistently, cost-effectively, and more easily; and dispel misconceptions and even some traditional beliefs about surface preparation that may be the root cause of some of the problems seen recently.
Measuring Surface Salts – Conductivity vs Ion Specific
Testing and identifying residual surface salts is an integral part of proper surface preparation; their removal is pivotal to the long-term performance of industrial coatings. Consequential risk reduction translates to lower life-cycle costs. Two commercial field methods are discussed to provide the user guidance on the method most suited to identifying the presence of salts where salt contamination is suspected.
Monetizing the Risk of Coating Failure
Coatings can fail because of soluble salt contamination remaining on the substrate after surface preparation. This article discusses methods of salt removal and the importance of good surface preparation specifications. A case history reveals the possible costs of a coating failure from salt contamination
Pipeline Coatings by Revie page 6
Recent R&D on pipeline coatings is discussed, and the main R&D issues at this time in the area of pipeline coatings are identified.
Pipeline Corrosion Protection by Guan page 17
Corrosion protection by coatings for water and wastewater pipelines is the implementation of a well-balanced cycle of four equally important elements: specifying and using a proper coating system, proper surface preparation for the coating system, proper application of the coating system, and quality inspection of the coating system. This paper discusses the details of this concept, together with a comprehensive review on various coating systems and different surface preparation requirements for steel, ductile iron, and concrete pipes in water and wastewater applications.
Salts 101 – Part 1
What are salts; Where do they come from; How do they cause coating failure; How do they cause corrosion; How to test for and remove them.
Standardization of Wash Water
This article provides information on wash water quality, establishes levels of wash water quality, provides methods for testing and the interpretation of results, and discusses the inclusion of wash water quality in specifications.
Not all “water-soluble” salts may be removed by water washing because various salts adsorb on the steel surface. If a surface salt analysis indicates salts, extra surface preparation in addition to traditional cleaning is necessary to ensure good coating performance.
Surface Prep Chemicals – Salt Removal or Passivation
Surface preparation methods and standards are under a lot of scrutiny and are subject to significant revisions because of premature coating failures. Nonvisible surface salts have been considered a leading cause of these failures. Cost-effective chemical removal using products with the proper chemical functionality is summarized.
The Impact of Corrosion Inducing Salts
Corrosion and passivation are naturally occurring phenomena on metal surfaces. A passive film, or grain boundary, consisting of reaction products of metal oxide or other compounds, will form on the metal surface and separates the metal form from its environment, slowing the rate of reaction. These products are slightly alkaline to neutral in pH. The acidic environment and atmosphere and consequential contamination of metallic surfaces with salts will reverse the formation of the naturally protective surface boundary layer, exposing the surface to aggressive electrochemical corrosion induced by the salts.