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Economics Index
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Economics Index
Abtracts:The Cost of Corrosion to the U.S. EconomyBridge Structures:Cost Model of Bridge Structures:Bridge Structures:Cost
Effective Alternative Methods for Steel Bridge Paint System Maintenance Cost Model:Excel Model of Cost-Based
Workbook
Cost Effective Alternative Methods for Steel Bridge Paint System Maintenance FHWA Contract DTFH61-97-C-00026 "Cost Effective Alternative Methods for Steel Bridge Paint System Maintenance" Several technical reports, introductory presentation, and an interactive Excel based cost model workbook Compares thermal adhesive metal stripping of edges and metallizing to the conventional three coat paint system. The individual reports must be read carefully as some of the project were just spot removal: others were full removal and economics are based on the specific projects. Summary results- Spot Cleaning
Rapid Deployment- for less than 50,000 sq. feet and fast turnaround All coating system applied in one 10 hour period.
Full Removal
Comparison of Grit, Grit _ Admixture to reduce hazardous waste, and Girt + liquid pretreatment to soften/remove paint
Torbo ® blasting involves mixing water and abrasive in a pressurized blast pot to produce a slurry material. This slurry material is forced through the blast hose to the nozzle using compressed air, similar to the method used to move dry abrasive through hoses in conventional abrasive blasting operations. However, the Torbo® system allows the blast operator to control the following directly at the nozzle: abrasive mixture quantity, air pressure and nozzle on/off. The composition of the slurry is typically 80% abrasive to 20% water. The use of this slurry media reduces airborne dust, which could possibly reduce the containment requirements compared to dry abrasive blasting. Torbo® can be used for complete coating removal or spot repair scenarios. The Torbo® Wet Abrasive Blasting System will impart a profile on steel. The depth of the profile is dependent on the size and type of abrasive used as well as the air pressure. Depending on the type of abrasive media, spent abrasive maybe reused without filtering or cleaning. A wide variety of abrasives may be used such as sand, plastic, glass, slag, bicarbonates and other manmade abrasives.Download this document: AC10010 Abrasive Injected Water Blasting The Abrasive Injected Water Blasting (AIWB) process involves introducing an abrasive into a high pressure water stream where it is delivered to the surface to be blasted. The abrasive is introduced into the stream immediately prior to the exit-nozzle of the gun. This combination of high-pressure water and abrasive prepare the substrate while minimizing the airborne particulate matter. AIWB will impart a profile on the substrate and is capable of cleaning to an SSPC-SP-5, though flash rusting may occur. The depth of the profile is dependent on the type and size of abrasive used. This equipment is useful in spot repair requirements for highway structures where localized corrosion and/or damaged paint areas require repair. While performing the spot repair requirements, AIWB is also capable of feathering transition areas of intact paint, which surround areas prepared to bare metal. In addition, the surrounding areas of intact paint are sweep-blast to remove delaminated coating. AIWB is an effective tool for removing weakly adherent coatings and surface rust, though hand tools and power tools are often used to increase productivity while clean areas of heavy packed, rust and scale.Download this document: AC10011
Admixtures of Abrasives and Liquid Pretreatments Costs for hazardous waste disposal are more than double that of non-hazardous waste disposal costs.1 This, combined with the liability involved with hazardous waste disposal has brought other options to the forefront in the bridge painting industry. Two relatively new solutions to the hazardous waste problem in bridge painting are the use of admixture blended abrasives and liquid applied pretreatments. The admixture is a fine, dry material that is blended with the abrasive used. The liquid pretreatment is a liquid material that is sprayed on the painted surface at a specified thickness, allowed to dry, then blasted off with the underlying lead-based paint. These products are intended to reduce the amount of leachable lead in the waste produced during blasting operations as indicated by the Toxic Characteristic Leaching Procedure (TCLP) test. Each user of these products must perform the correct testing to determine if the waste is hazardous. It is important to note that lead is still present when these products are used and that the requirements for environmental containment and Personal Protection Equipment (PPE) required are not reduced.Download this document: AC10012 The ElectroStrip™ process causes coating delamination from a steel-substrate by applying DC current to a painted metal substrate. An electrolyte is contained in a liquid-absorbent material to which a counter electrode is attached. This apparatus, often combined with a liner, is attached to the painted metal surface (typically steel) with magnets. To facilitate current flow, the existing coating surface is scored prior to attaching the apparatus. A DC voltage of 8 to 10 volts is applied for ˝ to 2 hours. After electrochemical treatment, the ElectroPad™ is removed and paint fragments are recovered. No particles become airborne. Up to 160 ft2 of ElectroPad™ can be energized simultaneously using an 8000 Amp rectifier.Download this document: AC10013 Field metallizing highway bridges Metallizing is a type of thermal spray coating (TSC) that produces a durable metal coating. The TSC metal typically applied to steel structures such as highway bridges is either pure zinc or a zinc/aluminum alloy. A feed wire of the TSC metal is heated to a molten state by flame or electric arc and propelled by air spray onto a surface. The metal solidifies upon contact with the substrate to form a durable metallic coating. Prior to TSC application on bridges, the surfaces are cleaned thoroughly using abrasive blasting. The corrosion protection performance of metallizing is well proven. 1,2 It is widely accepted across different industries and guidelines are available for the specification and implementation of metallizing.3,4 In spite of its apparent advantages, metallizing has seen limited exposure in the highway bridge maintenance market. Likely reasons for this have included a relatively high initial cost and a lack of familiarity and experience with metallizing among bridge painting contractors. This report will highlight the history of metallizing on highway bridges, point out the criteria and issues affecting the acceptance of this technology, and detail data from a recent site visit to a highway bridge metallizing project.Download this document: AC10014
Application of an aluminum-based foil material to a substrate Corrofoil 1 is a novel coatings concept involving the application of an aluminum-based foil material to the substrate. The foil is supplied with a self-adhesive backing and is recommended for application over primed steel. A topcoat is recommended over the foil to promote aesthetics and UV durability of the system. The tape coating was tested in a series of accelerated and outdoor exposure tests in comparison to a moisture cured polyurethane coating system. The testing included ASTM B117 salt fog, scratch adhesion, water vapor transmission, and outdoor weathering exposure at a marine exposure location. Analysis of the testing included evaluating the cost of the tape coating in comparison to traditional three-coat wet-applied coating systems in conjunction with the performance data obtained from the various tests.Download this document: AC10015 Mobilizing rapid equipment deployment On many highway overpasses, bridge painting is an inconvenience to the travelling public as well as a safety hazard. Therefore, a concept called "Rapid DeploymentSM" has been developed to reduce these inconveniences and hazards. The main objective of the concept is to mobilize all equipment to the site, blast and paint, and incrementally demobilize all equipment from the site; all in one over-night working shift. Generally, Rapid DeploymentSM would be used on highway overpasses where the structural steel is easily accessible, using a lift truck or other form of mobile modular containment, from the roadway below. Rapid DeploymentSM requires a significant array of equipment that is in good condition and a knowledgeable contractor with skilled workers. The Rapid DeploymentSM method utilized a Recyclable Steel Grit Rig1, a truck for the paint equipment, modular containment, a dust collector, and an air compressor. All of these pieces of equipment must remain mobile, either self-propelled or connected to a truck.Download this document: AC10016 Removing Lead Based Paint Using Recycled Steel Grit Abrasive blasting is one of the oldest and most popular surface preparation methods used in the bridge painting industry. Abrasive blasting uses high-pressure air to propel an abrasive to a substrate with the intent of removing any old coatings, mill scale and rust. Traditionally, once the abrasive media has been used to prepare a surface the combination of used media and paint are collected and treated as waste. Recyclable Steel Grit (RSG) blasting is very similar to expendable abrasive blasting except that instead of simply discarding the abrasive waste, it is recycled several times through specialized machinery that separates the paint, mill scale and rust from the reusable steel grit. The steel abrasive is reused until it breaks down into a sufficient size to be removed with the waste from the recycler. Most RSG equipment setups consist of a blast pot, recovery vacuum, recycler unit, and air compressor. Each piece of equipment can be purchased separately or collectively mounted on a trailer.Download this document: AC10017 Removing Lead Based Paints with Waterjetting Waterjetting (WJ) is the process by which high-pressure (HP) (10,000 to 25,000 psi) or ultrahigh-pressure (UHP) (25,000 or greater psi) water is used to prepare a surface for coating. Waterjetting can be used to remove existing coating, rust, surface oil and grease, and water-soluble surface contaminants.1 The water is propelled through a single nozzle or multiple nozzles on a rotating head. Rotating heads are used to better distribute the amount of energy transferred to the surface. Waterjetting is used in many industries to remove coatings and prepare surfaces for painting. Currently, the technology is gaining popularity or well accepted in the marine industry, petrochemical industry and the transportation sector (highway bridges).Download this document: AC10018 Excel Model of Cost-Based Workbook Download this document: AC10019 Cost Model Examples Download this document: AC10020 Cost Model User Guide Download this document: AC10021 A 1975
benchmark study by Battelle-NBS calculated the cost of corrosion to be $70
billion per year, which was 4.2 percent of the nation's gross national product
(GNP).
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