Please click the following link to download and install: When you are finished installing, please return to this window and PRESS F5 to view this edition. FMLA Insights is a legal blog operated by Franczek Radelet PC. The blog provides insight and analysis on the Family Medical Leave Act and other medical and leave. Saar, Ferdinand von ¶ Sämtliche Werke 9: Novellen aus Österreich III Leutnant Burda / Seligmann Hirsch / Die Troglodytin / Ginevra / Geschichte eines Wienerkindes. Paint coatings - Steelconstruction. Paint is the most commonly used material to protect steel. Paint systems for steel structures have developed over the years to comply with industrial environmental legislation and in response to demands from bridge and building owners for improved durability performance. Previous five and six coat systems have been replaced by typically three coat alternatives, and the latest formulations have focussed on application in even fewer numbers of coats, but with increasing individual film thickness. Examples of this are epoxy and polyester glass flake coatings that are designed for high build thickness in one or two coat applications, and single coat high build elastomeric urethane coatings, up to 1. The protective paint systems usually consist of primer, undercoat(s) and finish coats. Each coating . The binder is the film forming component in the paint.(c) The solvent. Solvents are used to dissolve the binder and to facilitate application at the paint. Solvents are usually organic liquids or water. The thickness of the 'wet film' can be measured, before the solvent evaporates, using a comb- gauge. As the solvent evaporates, film formation occurs, leaving the binder and pigments on the surface as a 'dry film'. The thickness of the 'dry film' can be measured, usually with an electro- magnetic induction gauge. The relationship between the applied 'wet film' thickness and the final 'dry film' thicknesses (dft) is determined by the percentage volume solids of the paint, i. The most common methods of classifying paints are either by their pigmentation or by their binder type. Each of these inhibitive pigments can be incorporated into a range of binder resins giving for example, zinc phosphate alkyd primers, zinc phosphate epoxy primers, etc. These are described as follows. Its purpose is to wet the surface and to provide good adhesion for subsequently applied coats. For primers applied directly to steel surfaces, these are also usually required to provide corrosion inhibition. There are two basic types of primer. Generally, the thicker the coating the longer the life. Intermediate coats are specially designed to enhance the overall protection and, when highly pigmented, decrease permeability to oxygen and water. The incorporation of laminar pigments, such as micaceous iron oxide (MIO), reduces or delays moisture penetration in humid atmospheres and improves tensile strength. Modern specifications now include inert pigments such as glass flakes to act as laminar pigments. Undercoats must remain compatible with finishing coats when there are unavoidable delays in applying them. Depending on the conditions of exposure, it must also provide the first line of defence against weather and sunlight, open exposure, and condensation. Their function is to build a satisfactory coating thickness at edges and corners where paint has a tendency to contract and thin upon drying. Specifications should indicate the type and number of stripe coats required and state when they are to be applied. Dry film thicknesses are generally checked on the complete paint system, although individual films may be checked separately. Usually, nominal dry film thicknesses are specified but sometimes minimum values are quoted. Values between 8. Wet film thickness (wft) checks may also be required during the application of the coating to check that a subsequent satisfactory dry film thickness will be achieved. They are therefore limited to relatively thin films. Once the film has formed it has limited solvent resistance and usually poor chemical resistance. They can be applied as moderately thick films though retention of solvent in the film can be a problem at the upper end of this range. The formed film remains relatively soft and has poor solvent resistance but good chemical resistance. Bituminous paints also dry by solvent evaporation. They are essentially solutions of either asphaltic bitumen or coal- tar pitch in organic solvents. When these two components are mixed, immediately before use, a chemical reaction occurs. These materials therefore have a limited 'pot life' before which the mixed coating must be applied. The polymerisation reaction continues after the paint has been applied and after the solvent has evaporated to produce a densely cross linked film which can be very hard and has good solvent and chemical resistance. Liquid resins of low viscosity can be used in the formulation thereby avoiding the need for a solvent. Such coatings are referred to as 'solvent less' or 'solvent free' and can be applied as very thick films. May soften in hot conditions. High solvent levels. They are mainly applied to steel plates and sections before fabrication. The main requirements of a prefabrication primer are as follows. The primer should be capable of airless spray application to produce a very thin even coating. Dry film thickness is usually limited between 1. Priming is often done in- line with automatic blast cleaning plant which may be handling plates and/or sections at a pass rate of between 1- 3 metres/minute. The interval between priming and handling is usually of the order of 1- 1. Normal fabrication procedures (e. A welding certificate should be available from the paint manufacturer. Weld fume omitted by the primer must not exceed the appropriate Occupational Exposure Limits. Proprietary primers are tested and certified by the Newcastle Occupational Health Agency. A health and safety certificate should be available from the paint manufacturer. The primer coating should provide adequate protection until either overcoated or placed within a non corrosive environment e. In practice, such periods are rarely met except in the least arduous conditions, e. In aggressive conditions, durability can often be measured in weeks rather than months. Zinc rich and zinc silicate primers provide the highest order of protection of all prefabrication primers. The primed surface, after weathering, should require the minimum of re- preparation for subsequent painting and must be compatible with the intended paint system. Many proprietary prefabrication primers are available but they can be classified under the following main generic types. These primers can be supplied in a single pack or two pack form, the latter providing better durability. They are pigmented with a variety of inhibitive and non- inhibitive pigments. Zinc phosphate epoxy primers are the most frequently encountered and give the best durability within the group. Zinc rich primers produce films which contain about 8. When exposed in either marine or highly industrial environments, zinc epoxy primers are prone to the formation of insoluble white zinc corrosion products which must be removed from the surface before subsequent overcoating. There are currently different categories of zinc silicate primers based upon the binder (organic or inorganic) and the zinc content. Low zinc primers in this group have been developed to improve their weldability and to minimise weld porosity, however their durability is also reduced. The organic silicate primers are the most suitable as prefabrication primers. Brush and roller application are more commonly used for site application, though spraying methods are also used. Nevertheless it has certain advantages over the other methods, e. The paint is atomised into fine droplets and projected onto the surface to be protected where the droplets join together to form a continuous film. The application rates for air spray are quicker than for brushing, or rolling, however paint wastage by overspray is high. The equipment required is much more expensive than for conventional air spraying, because it must withstand the much higher pressures involved. However, the application rates are higher than for air spray with overspray wastage greatly reduced. In this way greater film thickness per application is achieved. These can be more easily controlled under shop conditions than on site. These paints are specifically formulated for application in damp and humid conditions; reference should be made to the manufacturer’s data sheets for details of limiting conditions of application. Industry has recognised this and established a training and certification scheme for paint applicators (ICATS – Industrial Coating Applicator Training Scheme). ICATS registration (or to an equivalent scheme) has subsequently become a mandatory requirement for work on Highways England and Network Rail bridges. The scheme has a mandatory Basic Unit 'Industrial Coating Applicator' that comprises 6 modules. There are also 2 optional specialist modules. ICATS is a registered training scheme that meets the requirements of NHSS 1. A. As with ICATS, this is a registered training scheme that meets the requirements of NHSS 1. A. For corrosion protection of ferrous materials by industrial coatings. UKAS, Issue 3 (9. June 2. 01. 7. Bayliss & D. H. Deacon (2. 00. Steelwork Corrosion Control (2nd edition), Spon Press.
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