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Describe Passivation ANSWERV V Passivation is the formation of a protective oxide film on the surface reducing its chemical activity and its ability to corrode. Describe the following factors and how they affect corrosion: ANSWERV V * Oxygen: Oxygen increases the rate of corrosion. + Temperature: Corrosion usually accelerated with increasing temperature * Chemical Salts: Increase the rate of corrosion by increasing the efficiency of the electrolyte. + Humidity (or Wetness): The wetter the environment, the more corrosion is likely to occur. « Pollutants and Acid Gases: Acid rain, chemical byproducts and chlorides all promote corrosion. Two broad categories of corrosion can be described as: ANSWERV V General Localized Describe Galvanic Corrosion ANSWER¥V ¥V Galvanic corrosion is an electrochemical action of two dissimilar metals in the presence of an electrolyte and an electron conductive path, which occurs when dissimilar metals come into contact. Describe Cathodic Protection ANSWERV/¥ Cathodic protection is the reduction or elimination of corrosion by making the structure to be protected a cathode by means of an impressed current or attachment to a galvanic anode. The two primary types of cathodic protection are: ANSWERV V Impressed Current Galvanic (Sacrificial) Impressed current power sources include: ANSWERV V Rectified commercial power Solar cells Generators Fuel cells Wind-powered cells Thermoelectric cells Describe Cathodic Disbondment ANS WER¥V V Cathodic disbondment is the separation of the coating from the surface through hydroxyl (OH-) formation due to increased (made more negative) potential. The principal component of mild carbon steel is ANSWERV¥ A. Iron (Fe) The formation of a thin surface layer on metals, whether an oxide, carbonate, or other compound, that slows the rate of the corrosion process is called? ANSWERV ¥ D. Passivation Which is the part of a corrosion cell where metal dissolves? ANSWERV V A. Anode Which of these elements is likely to accelerate corrosion on a steel structure? ANSWERV V¥ A. Salts C. High temperatures D. Pollutants Describe air turns (air changes): ANSWERV ¥ « The air turnover principle eliminates air stratification, or layering, in large open spaces by recirculating the hot air that becomes trapped in the higher spaces + The number of times it does this per hour is called air turns. At and below what relative humidity does corrosion virtually cease? ANSWERV V 0.4 Describe two ways to reduce the relative humidity of the boundary layer: ANSWERV V + Increase the surface temperature « Reduce moisture content by dehumidification. Types of dehumidification equipment include: ANSWERY ¥ « Refrigeration and desiccant Describe several benefits of dehumidification: ANSWERV V « Dries the air. Lowers the dew point. Permits blasting the entire surface. Holds the blast with dry air. Helps in cleaning the surface. Holds the surface during coating application. You are the coating inspector on a project with dehumidification provided by a Totaling bed type dehumidifier. The silica gel has become contaminated. What do you expect to happen. with the silica gel? ANSWERV ¥ D. It can no longer adsorb moisture What effect does the rotating bed dehumidifier have on the treated ambient air? ANSWERV ¥ B. It is heated and the humidity decreases Some gencral basic centrifugal blast setups include: ANS WERV JV Tumbling Mill Multi Table Plain Table Swing Table Custom designed systems Centrifugal blasting conveyor systems are commonly used for cleaning of: ANS WERV 4 Plate Rolled structural shapes Large trusses Girders Portable centrifugal blasting systems can be used on: ANSWERV ¥ Ship decks, hull sides, and bottoms Storage tanks Concrete floors Highways and bridge decks Generally centrifugal blast systems are composed of the following elements: ANSWERV / Centrifugal abrasive throwing wheel The blast cabinet (or enclosure) In fixed systems, some type of material handling system Abrasive recycling system A dust collector and vent-pipe system Abrasives The efficiency of the centrifugal blast wheel(s) depends on several factors. ANS WERV 4 Abrasive operating mix the steel. Monitor the speed of the line. Inspect the steel as it leaves the production line In a centrifugal blast operation, the degree of cleanliness is determined primarily by ANSWERVV B. Speed of travel Which of the following are advantages of portable centrifugal blast cleaning? ANSWERV¥ A. Can be used for multiple substrates B. Dust can be collected for disposal D. Abrasives can be recycled Which of the following are abrasives that can be used in centrifugal blast units? ANSWERV V A. Steel shot/grit B. Glass beads C. Garnet D. Walnut shells The WJ-1 (visual cleanliness) is comparable to which abrasive blast cleaning standard: ANSWERV Vv ISO SA 3 A general description of Robotic waterjetting includes: ANSWERV V Attaches using vacuum, cables, or magnets Vertical, horizontal or overhead surface Controlled by single operator Collects in excess of 95% of the water, removed coatings and rust (waste generated) A typical waterjetting team consists of: ANSWERV ¥ The nozzle operator The pump operator Additional operators or workers Waterjetting is effective for removing: ANSWERY ¥ Surface oil and grease Rust Concrete (shot-crete) spatter Existing coatings Water-soluble contaminants that cannot otherwise be removed by abrasive blasting An underwater unit used to clean barnacles or other micro-organisms for ship hulls or off- shore platform legs. Describe two of the considerations with regards to "back thrust": ANSWERV V/ Causes fatigue Should be no more than 1/3 of operators body weight To ensure a safe work place, before commencing the job, the waterjet team should ensure that! ANSWERV ¥ The work area is properly barricaded Electrical equipment protected from the water. Electrical connections are not allowed to sit in water. All fittings and hoses are in good condition/proper pressure rating Nozzles free of obstructions. System is flushed clean and air removed The dump system and all control systems are operational. Which of the following are Flash Rust designations of waterjetting? ANSWERV V A. No flash rust B. Light C. Moderate D. Heavy When viewing NACE WJ-2/SSPC-SP WJ-2 - Very Thorough Cleaning, the allowable tightly adherent thin coatings that can remain on the surface after preparation is: ANSWERV V B. 5% When using UHP waterjetting with an inhibitor, the steel surface after cleaning will appear ANSWERVY¥ A. Asa dull matte finish Waterjetting can be an effective method for ANSWERV V A. Removing rust B. Cleaning pits D. Removing barnacles As the coating inspector on a high pressure waterjetting project, what safety gear would you expect to see? ANSWERV V A. Metatarsal guard B. Whip lock C. Hose shroud What cleaning method uses water at pressures from 34 to 70 MPa (5,000-10,000 psi)? ANSWERV ¥ C. High-pressure water cleaning You are a new inspector on a UHP waterjetting project. What is the typical distance between the waterjetting tip and surface that you would expeet to see? ANSWERV ¥ B. 2 inches (5 cm) Some of the most common hazards associated with specialized application are: ANSWERV ¥ Fumes and dust inhalation Electrical Shocks Burns Falling objects Explosions Environmental contamination Thermal Spray safety practices for operators include: ANS WERV V Use hoses rated for high pressure. Never clean powder off equipment or clean spray cubicles with compressed air. Do not use compressed air to clean clothing. Do not supply plant compressed air to a breathing apparatus. Which of the following are some of the physical dangers in application of polyester coatings? ANSWERV ¥ B. Central nervous system damage C. Skin and respiratory irritation D. Damage to the eye Brass chills are most commonly associated with which process? ANS WERV¥ ¥ B. Thermal spray remove soluble contaminants and then abrasive blast. In some cases you may find it necessary to abrasive blast a surface then wash it and blast it again, this could be repeated several times, before an acceptable result is achicved. What are antifouling materials used for, and how do they work? ANSWERV ¥ The purpose of antifouling (AF) paints is to either make the hull of the ship so distasteful the larva of the biofouling reject it as a home or they make the hull so slick the larva cannot adhere. The three main types of anti fouling coatings are: ANS WERV V Ablative Self Smoothing Foul Release Name and describe the two main types of fireproofing coatings. ANS WERV / Cementitious - Made of lightweight cement and can be applied several inches thick. Intumescent - A substance that swells or bubbles up as a result of heat exposure, thus increasing in volume, and decreasing in density. What are the best known characteristics of flouropolymer coatings? ANSWERV / Flourpolymer coatings are best known for their non-stick feature and also have excellent chemical and high temperature resistance. Describe the two broad curing categories of powder coatings: ANSWERV / Thermoplastic: materials that soften when heated and return to their original hardness when cooled Thermosetting: materials that harden when heated and retain their hardness when cooled What are the four distinct stages powders pass through when a heat source is applied? ANSWERYV ¥ * The flow stage, which occurs when the particles of powder begin to flow, but are not fully liquid + Wetting stage, which occurs when the particles of powder absorb more heat, fully liquefy, and wet the surface + Gel stage, which occurs when the particles of the powder begin to gel, converting into a solid + Curing stage allows for further changes to take place, permitting the powder to cure completely Describe the advantages and disadvantages of plural component airless spray over single piston airless spray system: ANSWERV V Advantages: Accurate mixing of materials without human element Ability to spray very thick solvent free materials without thinner The ability to spray materials with very short pot life Disadvantages: Cost is much higher than cost of single piston pump Higher education requirement for the mechanic High voltage clectricity is required for the heaters Applicator's job more difficult with multiple hoses Which of the following components are contained in powder coatings? ANSWERV Vv A. Pigments C. Resin/binder D. Flow control additives You are the inspector on a project that requires coating the internal of 4 inch (10 cm) diameter piping. The owner asks for an example of an application process for coating the internals, What would be the best choice? ANSWERV ¥ B. Centrifugal spray The benefits of electrostatic spray application over conventional spray are ANSWERV / A. Produces somewhat thicker coatings on sharp edges C. Transfer efficiency improved Coating materials that soften when heated and return to their original hardness when cooled are known as ANSWERV ¥ D. Thermoplastic materials Two major classes of rubber: ANSWERV V Natural + Derived from latex obtained from Hevea trees and is coagulated with acetic or formic acid * Unsaturated hydrocarbon known as polyisoprene Synthetic + any one of a group of manmade elastomers with one or more of the properties of natural rubber What is vulcanization? ANSWERV V Vulcanization is a physicochemical (physical and chemical) change resulting from the cross-linking of the unsaturated hydrocarbon chain of natural rubber (polyisoprene) with sulfur, and the application of heat. Three factors affect the properties of the vulcanizate (vulcanized product): ANS WERV V + Percentage of sulfur and accelerator used + Temperature of the curing process + Time of cure Methods used to cure (vulcanize) rubber are: ANSWERV ¥ « Autoclave (vulcanizer) cure + Internal steam cure + Atmospheric steam cure (also called exhaust steam cure) + Hot-water cure + Chemical cure The three categories of Natural Rubber are: ANS WERV V ° Soft + Semi-hard « Hard Describe a "tri-ply" lining. ANSWERV V A "tri-ply" lining construction is used to form a sandwich which is semi-hard, or hard, rubber between two layers of soft rubber. Some various types of synthetic rubber are: ANSWERV ¥ « Butyl Rubber * Neoprene Rubber + Nitrile Rubber * Chlorobutyl Rubber + Flame spraying Which are the most common curing methods for a field applied natural rubber lining project? ANSWER¥V ¥ D. Atmospheric steam or internal steam Which component cross links with the natural rubber giving a physicochemical change that makes the rubber harder? ANSWERV ¥ D. Sulfur Typically polymeric sheet materials are ANSWERV V B. Thermoplastic C. Heat welded together at seams D. Primed with a suitable adhesive The Standards Engineering Society (SES) describes a standard as: ANSWERVV A document that applies collectively to codes, specifications, recommended practices, classifications, test methods, and guides, which have been prepared by a standards developing organization or group, and published in accordance with established procedures. Describe the difference between voluntary and mandatory standards: ANSWERV / Voluntary standards are standards established generally by private-sector bodies and that are available for use by any person or organization, private or government. A mandatory standard is a standard that requircs compliance because of a government statute or regulation, an organization internal policy, or contractual requirement. Explain the difference between a National Standards Body (NSB) and Standards Developing Organization (SDO): ANSWER ¥ National Standards Body (NSB) Used to refer to the one-per-country standardization organization which is that country's membership to International Organization for Standardization (ISO). Standards Developing Organization (SDO) Refers to the thousands of industry or sector-based standards organizations that develop and publish industry specific standards. Name and define the three NACE standards classifications. ANSWERV V ¢ Standard Practice (SP) « Test Method (TM) + Materials Requirement (MR) The formal process in which a standard is changed or updated is ANSWERV ¥ B. Change control You will inspect a project in 6 months’ time where the requirements of a consensus standard is being interpreted differently by the various parties. What would be the best course of action to resolve the matter? ANS WERV ¥ B. Request interpretation from the originating organization The standards produced by NACE International are considered to be ANSWERV ¥ D. Consensus standards Some of the properties of Concrete are ANS WERV V « Extremely durable. + Inorganic. + Hard. 
