Coating Types, Failure Modes, Inspection Criteria Flashcards
__________ Many coatings use water and a thinner or diluents. The major concern is preventing freezing during shipping and storage. Failures are normally from not curing caused by the water evaporating too rapidly due to excessive heat on the surface or excessive air flow over the surface. Pay attention to surface temperature if heat is expected, particularly to the tops of structures in full sunlight.
A. Water-Borne Inorganic Zinc
B. Water-Borne Coatings
C. Moisture-Cured Urethane
B. Water-Borne Coatings
__________ This coating is convertible. It cures by water evaporation and absorbing carbon dioxide from the atmosphere. The cure may take days. It is a good pre construction primer if applied at .75mil. Failures are failure to cure by overcoating to soon and mud cracking this is caused from applying an excessively thick coating typically over 5 mils. Ensure coating is fully cured before overcoating or packaging.
A. Water-Borne Inorganic Zinc
B. Water-Borne Coatings
C. Moisture-Cured Urethane
A. Water-Borne Inorganic Zinc
__________ This coating is convertible. It cures by both solvent evaporation and a chemical reaction from absorbing moisture from hte surrounding atmosphere. May take several days to cure. These can be used as preconstruction primeres but must be applied at only .75mils. Failures are from not curing caused by overcoating too soon and mud cracking caused by an excessively thick application typically over 5 mils. Ensure they are fully cured prior to packaging and overcoating.
A. Solvent-Borne Inorganic Zinc
B. Water-Borne Coatings
C. Moisture-Cured Urethane
A. Solvent-Borne Inorganic Zinc
__________ This coating is convertible. These are high temperature materials applied over IOZ or applied directly over steel. They use a 2 step process to cure. First they cure like any solvenet evaporation material. They do not reach a full cure until they are properly heated. Most heating is done in service and increases incrementally over a period of time. Failures are from improper heat cure cycle.
A. Zinc-Rich Epoxy
B. Polyester/Vinyl Ester Coatings
C. Silocone Coatings
C. Silicone Coatings
__________ This coating is convertible. It cure by chemically induced polymerization. Most widely used in industrial/marine coatings. Failures include failure to cure by improper mixing, too short induction, or temperature too high or too low, cracking caused by thick coats, pinholes from thins coats, sagging from applying too thick overthinning, or too long pot life, delamination fro previous coats from exceeding the overcoat window, contaminated surface, or applying over amine blush, chalking from UV exposure or other radiation. Inspector needs to check if properly mixed, environmental conditions especially dew point and check WFT/DFT. Some specifications may require this coating to be applied over damp, oil contaminated surfaces or underwater.
A. Zinc-Rich Epoxy
B. Epoxy Two-Component Coatings
C. Solvent-Borne Inorganic Zinc Coatings
B. Epoxy Two-Component Coatings
__________ This coating is convertible. It has powdered zinc added to it. It is supplied as a 2 component material with zinc already added or a 3 component material. Similar failures as epoxy. Use this material as a primer only. Inspector needs to ensure it is mixed properly, that the material is continuously agitated.
A. Zinc-Rich Epoxy
B. Polyester
C. Siloxanes
A. Zinc-Rich Epoxy
__________ This coating is convertible. It is used in special situations when a chemical or abrasion-resistant coating is required. A high degree of surface preparation is normally required. Failures are failure to cure, blister from contaminated surface, wicking if fiberglass is used. Hardness may be required to ensure properly cured.
A. Two-Component Thin Film urethane Coatings
B. Polyester/Vinyl Ester Coatings
C. Silocone Coatings
B. Polyester/Vinyl Ester Coatings
__________ This coating is convertible. It cures from moisure. They are used in areas of high humidity where other materials generally cannot be used. They are frequently single package materials but must be applied in strict accordance with the owner’s and manufacturer’s requirements. Failures include failure to cure from low humidity, blisters, and delamination from conctaminated surface. Watch humidity during the cure cycle. Can not flood coating with water but may mist the area.
A. Water-Borne Inorganic Zinc
B. Water-Borne Coatings
C. Moisture-Cured Urethane
C. Moisture-Cured Urethane
__________ This coating is convertible. Most commonly used as topcoats over epoxies due to their good to excellent UV resistance. They are available in many different colors. Failures include delamination due to application after the overcoat window, color and gloss differences from using different batcheds of materials, DFT is not consistent, or using 2 or more application techniques in adjoining surfaces, blushing from moisture on the surace during htre cure, and failure to cure if thinner containing moisure is added during application.
A. Two-Component Thin Film Urethane Coatings
B. Thick Film Polyurethane, Polyureas and Their Hybrids
C. Acrylic Coatings
A. Two-Component Thin Film Urethane Coatings
__________ This coating is convertible. These products are applied by heated plural airless spray. They have a very short pot life. Inspectors must understand how the specialized spray equipment workds and the unique mixing at the tip of the gun. Failures are delamination from improper specification. Polyureas are normally applied over an epoxy primer when used on steel but not required over concrete. Polyurethanes and some polyurea hybrids are commonly applied directly to the steel but sometimes require an epoxy primer on concrete and failure to cure from failure of the equipmnent to heat or pump proper amounts of each material to thte gun or caused by the gun failing to spray both sides in the proper ratio Use standard inspection techniques.
A. Polyester/Vinyl Ester Coatings
B. Allkyds
C. Thick Film Polyurethane, Polyureas and Their Hybrids
C. Thick Film Polyurethane, Polyureas and Their Hybrids
__________ This coating is convertible. These come in single package or a two component material and are normally blended with other resins such as acrylic, epoxy, or polyurethane. Failures include delamination from applying over a non-comparabl product and cracting from improper formula and delamination. Follow standard inspection procedures. Watch for DFT. Make sure each product in the system is applied in its proper order and each product is compatible with each other.
A. Siloxanes
B. Silicone Coatings
C. Vinyl Coatings
A. Siloxanes
__________ This coating is non convertible . It is a single package cured coating. Were once commonly used in both the chemical process industry and the marine industry due to their excellent petro-chemical, water, and UV resistance. Should never be over coated witha a convertible coating such as epoxy mastic. Over coat only with a single package waterborne material or possibly a solvent free chemical cured coating. If a coating containing solvent is applied to a hot surface, the coating will not flow out and cause uneven surface with pinholes and low adhestion. SOlvent entrapments can cause in-service blistering. During application DFT surface temper and overcoat windows should be closely monitored.
A. Vinyl Coatings
B. Bituminous Coatings
C. Chlorinated Rubber Coatings
C. Chlorinated Rubber Coatings
__________ This coating is non-convertible. It has the same issues as chlorinated rubber. These coatings are commonly used in water tanks and as interior linings in water pipes. When used as linings, they are applied in multiple coats with very thin DFTs. They can have solid content as low as 25%. Ventilation is required when using. Common problems are solvent blistering caused by poor ventilation during application, excessive DFT per coat, or failure to follow the recommended recoat window. DFT, sureface temp throughout curing and application, and recoat window.
A. Vinyl Coatings
B. Chlorinated Rubber Coatings
C. Bituminous Coatings
A. Vinyl Coatings
__________ This coating is non-convertible.It commonly blended with other resins because of their excellent resistance to UV degradation. It is also used as the main or singular resin in water borne coatings with very low VOC. When it is used as a singular resin common failures are rom failure to cure and failure to adhere when used as a primer. This is caused by exceeding recommended DFT, applying the material in a hot/windy condition. If the solvent evaporates too quickly from th surface it traps solvent in the lower layers of the film and stops the coalescence process Applying to a hot surface can prevent it from flowing out which prevents adhesion. DFT, surface temp, wind speed, and overcoat windo are necessary inspection points.
A. Allkyds
B Vinyls Coatings
C. Acrylic Coatings
C. Acrylic Coatings
__________ This coating is convertible. It cures by oxygen induced polymerization. It absorbs oxygen from the surrounding atmospere and used the O2 to react with the allkyd molecule in a process called oxidation. Most coomon problem is wrinkling and or soft film caused from applying the coating too thickly. Top surface cures and seals the lower levels of the film from the oxygen. Another problem is putting into service before fully cured. Ensure WFT is taken frequently. Generally any WFT over 3-4 mils in a single coat is too thick. Ensure the coating is fully cured before putting in service.
A. Alykds
B. Bitumious Coatings
C. Vinyl Coatings
A. Alykds
