End Of Chapter Study Guides Flashcards
Define corrosion
The deterioration of a metal that results from a reaction in the environment.
What is passivation?
A reduction of the anodic reation rate of an electrode involved in corrosion.
What are the elements of a corrosion cell?
Anode
Cathode
Return path
Electrolyte
Describe what happens at the anode.
Oxidation occurs at anode. Electrons flow away from anode in the external circuit. Corrosion occurs at anode and metal ions enter the solution at the anode.
What is the function of the electrolyte?
The electrolyte must be present to close the loop in the corrosion cell. The corrosion current is carried by ion transport through the electrolyte.
What is the function of the metallic pathway?
Connects the anode to the cathode and allows a passage of electrons from anode to cathode.
What is the galvanic series?
A list of materials in order of their corrosion potentials, with the most active at the top and the least active at the bottom.
The general rules of galvanic corrosion are:
When dissimilar metals are connected, the most active metal corrodes faster while the least active metal corrodes slower.
As the potential difference between the metals increase, the rate of galvanic corrosion increases.
Five factors that affect the rate of corrosion
Oxygen Temperature Chemical salts Humidity Pollutants and Acid Gases
General corrosion is
relativelt uniform loss of material over the entire surface and is a general thinning of affected surface.
Localized corrosion is
Occurs at discrete sites on the metal surface.
List some of the common tools/methods for corrosion control.
Design Inhibitors Material selection Cathodic protection Protective coatings Alteration of the environment
How does NACE define the inspector’s role?
Quality control technician who observes and reports technical aspects of coating project. Observe, test, verify, report.
What is the inspector’s responsibility when it comes to safety on a project?
Safety enforcement is not the inspector’s responsibility. Be knowledgeable of safety violations.
Tests that may need to be conducted during surface preparation and coating operations.
Relative humidity and dew point. surface temperature. surface contaminants. proper abrasive media. cleanliness of abrasive. check air compressor. Air supply to blast hose. Blast nozzle for size and wear. Blasted surface for anchor pattern. Viscosity of coating. Application equipment. DFT of each coat. Surface contaminants.
Documentation/reports that may be required to be maintained on a coatings project.
Daily written report. Inspection logbook. Routine report. Notes from weekly progress meetings. Any reports required by client.
Most important characteristics of a good report?
Objective, accurate, detailed.
What is the inspector’s primary responsibility and what should the inspector not do as it pertains to the specification.
The inspector’s primary responsibility is to VERIFY the specification. The inspector does not make changes to the specification for any reason.
What type of information do you find on a Product Data Sheet?
Manufacturer’s Product Data Sheet answers questions about coating product. Application methods, surface cleanlinesss, parameters, temperatures, curing times.
What type of information do you find on a Safety Data Sheet
Toxicity Health Effects First Aid Reactivity Storage Disposal PPE Spill Handling Procedures
Explain the difference between Quality Assurance and Quality Control
QA - Checks whether the product or service is meeting specified requirements.
QC - Product or service is meeting the requirements of the client.
Identify some defects that can be caused by incorrect temperature applications
Blistering Pin holing Cratering Dry spray Mud cracking
Describe Relative Humidity
A measure of the amount of moisture in the air compared to saturation level.
What is the dew point temperature?
Temperature which moisture begins to form on a steel surface.