Prepainted steel for buildings

Transcription

1 Prepainted steel for buildings 1

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3 SSAB has more than 40 years' experience of producing prepainted steel sheet, which has made us into one of the world's leading suppliers. The sheet is produced with absolute focus on the environment and quality. The product itself consists of prepainted steel coils in different colors, perfect for further processing and forming. The material can be shaped into components through profiling, pressing or bending. It can be cut and punched. The color coating can be given different properties in order to suit different applications and environments. Prepainted steel sheet is in many ways an obvious material of the future. CONTENTS: Why choose prepainted steel in buildings? 5 Applications 6 Research and development 9 The material 10 Testing and control of Prelaq 13 Environmental properties 14 Choosing the material 16 Prelaq is easy to process 18 Considerations for detailing and assembly 21 Factors influencing sheet service life 22 Maintenance Well-maintained Prelaq enjoys a long life 24 Handling, storage and transportation 25 Technical support 26 More information about Prelaq 26 The information in this printed leaflet relates to the time of publication and is intended to be a general guide for the use of the product. We reserve the right to make changes as a result of ongoing product development. Stated information and data are not to be taken as guarantees without specific written acknowledgment.

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5 Why choose prepainted sheet in buildings? Prepainted coil coated steel opens up great possibilities for creating beautiful and functional buildings, meeting high environmental and quality requirements. Prelaq is world leading when it comes to sustainable quality products produced with optimal environmental consideration, and holds a world patent for color coating with renewable content from the plant kingdom. The Prelaq product provides many possibilities for variations in shape and color choice, which gives architects and building contractors great freedom. Pre-produced components in Prelaq also mean short construction times and easy handling on the construction site. The steel sheet and paint's good formability means that it can be used in sophisticated forming operations. The development in recent years of roll forming technology makes it possible for architects to design bold buildings almost without limitations. Apart from roll forming, the sheet can be pressed and processed in other ways. Paint systems are available in many color schemes and with different surface appearances. Color coating has several objectives. It gives the sheet an attractive appearance, and also protects it against corrosion. Since there are many different requirements for appearance, environmental condition and processing, Prelaq has many paint systems combined with different steel qualities, which give the product different properties. The combination of zinc and color coating on the steel gives Prelaq its high corrosion resistance. SSAB has many years' experience of producing prepainted sheet. We are building on more than 40 years' knowledge when we choose paint systems and produce our products. Buildings made from Prelaq provide a safe and sustainable climate protection, low maintenance costs and therefore a sound economy. Coil coating is an industrially controlled process like the subsequent manufacturing into components in tailor-made dimensions. This contributes to an intelligent build and shorter construction times. From an environmental perspective, steel is a highly adaptive building material. At the end of its service life, it can be remelted and used for new products. SSAB delivers Prelaq in coils to our customers, who then manufacture components and products out of Prelaq. KulörKArtA Prelaq färgbelagd tunnplåt All the colors can be found in Prelaq's color chart. 5

6 Applications Sheet metal roofing Flat sheet metal roofing dates back to the 19th century and is to a large extent a handicraft. The sheets are joined together by folding. Today, coil coated sheet is used. Flat sheet roofing meets high requirements for functionality, flexibility and appearance, and can also be used on roofs with curved or spherical surfaces. Products for roof drainage Over 90 % of all drainpipes and gutters in Sweden are produced in prepainted steel sheet. The use of effective and easily assembled roof drainage systems manufactured from prepainted steel sheet is also increasing in the rest of Europe. Prelaq steel sheet for gutters and pipes is of a unique quality which makes the sheet easy to form. The result is sustainable products which effectively tolerate the stresses that roof drainage systems are exposed to. Profiled sheet By forming a flat sheet into a linear profile in a roll forming line, it can be given the stiffness and strength needed to bear weight. The profiles can be used in various ways, usually for roof and wall cladding, but also for joists and weight-bearing sheet for large roof spans. Profiled sheet is a major field of application for Prelaq. Steel with standardized strength is used for bearing profiles. 6

7 Steel roofing tiles Steel roofing tiles are used primarily for residential homes. The roof becomes much lighter compared to, for example, concrete roofing tiles, and is preferential when replacing concrete tiles or tiled roofs. In the same way as profiled sheet, roofing tiles are produced in a roll-forming and press line. This makes it possible to give the sheet an attractive shape. Sandwich panels The use of sandwich panels as wall or ceiling material constitutes an interesting alternative to walls in profiled sheet and miscellaneous prefabrication. Sandwich panels have a core of cellular plastic or mineral wool with a surface layer of steel sheet which is glued on to both sides of the core. Due to the interaction between the core material and the sheet, the unit becomes very strong and can be used as bearing units on large spans. Sandwich panels can be assembled quickly and they provide good heat insulation and air density. Cassettes Cladding sheet cassettes are one of the facade materials with the absolute greatest aesthetic freedom. Prelaq allows you to create a wide range of different expressions, play with different kinds of pattern effects, or emphasize certain parts of the cladding sheet. This is achieved by varying the cassette's width, length and height, and size of the joints between them. 7

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9 Research and development Prelaq products are developed with quality and environmental consideration as constant driving forces. Prelaq GreenCoat are sustainable paint systems with a large proportion of renewable content from the plant kingdom, where SSAB holds a world patent. Prelaq GreenCoat is developed in the tough Nordic climate with extreme temperature variations and extensive periods of wet, which gives the product its exceptional position and guaranteed high quality. Prelaq is constantly developing towards even better quality products with optimal environmental consideration as its primary guide. New products are introduced to the market after thorough testing in true outdoor environments over several years. 9

10 The material Galvanized steel sheet as substrate The core in all Prelaq products is galvanized steel sheet. The steel's mechanical properties are chosen in line with the end product's field of application. For example, structural steel is used in a component that is dimensioned against clearly defined strength demands, see table 1. Soft formable steels are used when the sheet is formed in a demanding way or when the sheet is processed by, for example, a sheet metal worker, see table 2. Zinc coating Zinc coating gives the sheet double protection. It is an effective barrier against oxygen and moisture, and it provides cathodic protection of the steel at cut edges and any damage to the zinc coating. When the sheet is exposed to moisture, a galvanic cell with the steel as cathode and the zinc as anode is formed. The anode sacrifices itself and forms corrosion products which block potential damage. Continued corrosion is hindered and the process ceases. For building purposes, a limited number of thicknesses of zinc coating are used in Prelaq, see table 3. Table 1 Hot-dip galvanized steel material, structural steel corresponding to European standard EN10346 Designation SSAB European standard designation Yield strength, min R p0,2 N/mm 2 Tensile strength, Elongation A80 1 min R m N/mm 2 % min SUB 250 S250GD+Z SUB 280 S280GD+Z SUB 320 S320GD+Z SUB 350 S350GD+Z Designation example: S250GD+Z275 (where Z275 refers to the amount of zinc coating) 1) For t 0.70 mm applies two units lower value. Table 2 Hot dip galvanized steel material, mild steels corresponding to European standard EN Designation SSAB European standard designation Yield strength, min R p0,2 N/mm 2 tensile strength, Elongation A80 1 min R m N/mm 2 % min PLX FAX FAP DX52D+Z FA DX51D+Z ) For t 0.70 mm applies two units lower value. Table 3 Zink coating 2 1 Designation Coating weight g/m Coating thickness per side (approx) μm Z Z ) Metal coating is measured in weight classes and states the total metal amount on both sides of the sheet. Is measured according to the so-called three point test according to EN Table 4 Dimension program 1 Width mm Thickness (mm) ) Thickness and width cannot be combined freely but are instead dependent on the steel grade and running meter weight. 10

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12 Paint systems for different demands Prelaq is used in a whole range of fields of application. By coating the sheet with different paint systems, Prelaq can be adapted to suit different environmental stresses and quality demands. Color coating has been developed over many years together with paint suppliers through laboratory tests and by following-up practical use within construction. Detailed facts about each paint system can be found in specific product leaflets. The paint is applied with rollers Organic coating of zinc-coated sheet takes place in a carefully controlled continuous process. The steel coil is carefully cleaned, chemically pre-treated, and then the paint is applied with a roller in two stages; primer and top coat. The coating is quenched in the oven between the two coats of paint. The sheet can also be coated on both sides with the two layer system. A marking is then applied to the reverse side at the point of paint application, which makes it possible to identify the material at a later date. Property profiles Property profiles show outline information about the technical properties of important areas. A large distance from the center of the diagram shows high values of each property. Table 5 Paint system Paint system Surface Used for Prelaq Nova is a special extra thick variation of polyester coating. It has a structured durable surface due to its incorporation of polymer corn in the top coat. It also has better forming properties than standard polyester. Prelaq Nova is available in two finishes; matt and semigloss. Prelaq Polyester is a smooth coating of polyester. Polyester is a cost-effective system, and is currently the most common paint system for construction sheet. Prelaq Matt Polyester is a matt coating of polyester with a structured surface. Prelaq X-matt is designed to guarantee even better visual similarity between different production times. Prelaq GreenCoat is a structured proof coating with good color retention. Available in both matt and semigloss finishes. Prelaq P 200 is a thick coating of plastisol with embossed surface which has high wear resistance and durability against corrosion. Prelaq P 200 is easy to process and can be bent without restriction. Prelaq PVDF is a smooth coating. The paint has excellent color fastness and PVDF is therefore often used where highest demands are placed on the paint retaining the same appearance over a very long period of time. Prelaq PVDF can be delivered with a protective film to protect the surface from damage during transportation and assembly. Prelaq reverse side coating consists as standard of a coating based on epoxy. It is adapted for bonding purposes. structure smooth structure structure structure embossed smooth Prelaq Nova is used for flat sheet roofing, profiled sheet, steel roofing tiles, roofing drainage and cladding sheet. Prelaq Polyester is primarily used for profiled sheet with associated flashings, and is suitable for roofs and cladding sheet with normal demands. Prelaq Matt Polyester is specially suited to steel roofing tiles. Prelaq X-matt is used for steel tiles which are supplied in smaller sizes for the do-it-yourself market. Prelaq GreenCoat is used for flat sheet roofing and accessories as well as profiled sheets. Prelaq P 200 is primarily used for cladding sheet and flashings in corrosion-exposed environments, and also in close proximity to the sea. Not to be used in central and southern Europe. Prelaq PVDF is primarily used for cladding sheet with highest demands on color resistance. Not to be used near the sea. Prelaq reverse side coating is used on the reverse of the sheet. This paint system has lower demands for corrosion protection and durability against mechanical impacts than other paint systems. The reverse of the sheet can be coated with other paint systems on request. 12

13 Outdoor exposure in coastal environments. Testing and control of Prelaq Standardized methods are used to test prepainted sheet. In order to control the paint's outdoor resistance and the sheet's corrosion protection, the material is exposed to the toughest environments imaginable. The material is primarily tested at Bohus Malmön, far out in the salty North Sea, and in Florida where it is exposed to extremely strong sunlight. Each roll of Prelaq material is tested according to the following properties: Thickness of the color film Adhesion Color Gloss Bendability Demands and testing methods are in accordance with European standard EN Tests of the steel material is carried out in order to document its mechanical properties. Quality controls mean that we follow national and international standards and approvals. SSAB has been certified as evidence that the company works with a quality system which is in line with the standard SS-ISO Our sheet is stamped so that it can be identified. 13

14 Environmental properties The lifecycle of steel Steel plays an important role for social development, and is an essential material within many fields of application. Iron and steel have always been recycled, and therefore constitute a natural part of the modern environmental and recycling society. Iron is a so-called essential metal, i.e. a metal that is important for sustaining mankind's functions. Iron and steel do not emit any substances that are harmful to the environment or health. Ore mining ~6 months ~1 10 years ~5 50 years Blast furnace for pig iron Recycling of scrap Electrosteel furnace Production of steel Recycling of steel Use of steel ~80 years years Steel converter Production of sheet, strip, bars, profiles, tubes, wire and powder Working construction and engineering industry years 14

15 Hot-dip galvanized sheet from an environmental perspective Zinc, in the same way as iron, differs however from other metals in that they are both of great importance to our existence. People, animals and plants need zinc in order to survive. One of the best ways of protecting steel against rust is to coat the steel with a thin layer of zinc. Depending on the thickness of the layer, rust protection can last from just a few years to over 100 years. Zinc is used on our substrate of galvanized sheet in order to give a corrosion-protective metal coat. Galvanized sheet can be smelted over again and is 100% recyclable. Zinc is found in the smoke dust formed during the smelting process. Zinc is recycled from the collected dust. Coil coated sheet from an environmental perspective More than 99% of solvent emissions are taken advantage of in coil coating. Energy from the burning of solvents is recycled and is returned to the paint-drying process. Surplus heat is sent via the municipality's district heating network to heat our homes. The closed processes that we use for coating the steel are, from an environmental perspective, in most cases, superior to the methods used within the engineering industry. Prepainted steel sheet is very light in relation to its bearing and covering capabilities, which makes it easy to build with and transport, and is therefore energy saving. With the right product choice and maintenance, its service life becomes very long, which is positive from the perspective of resource use. If the sheet cannot be reused, it is easy to recycle by smelting again. Environmental impact in steel-sheet production SSAB has been actively working with environmental efforts for many years. It covers work with raw materials, residual products, chemicals, risk analyses, and measures to limit emissions into the air and water, energy management, etc. Processes and products are developed with regard for the environment and from a lifecycle perspective. Environmental product declarations/building product declarations Prelaq's properties are described from an environment perspective in our environment product descriptions 15

16 Choosing a material Each field of application has an optimum combination of steel, zinc coating and organic coating. Factors to consider when choosing organic coating and substrate Type of end product Expectations on appearance and long-term color retention Degree of processing (forming) Degree of exposure to mechanical impact Corrosive impact Sun and heat Future maintenance Static strength of the product. Table 6 contains our general recommendations for some typical fields of application. Table 6 Fields of application and material recommendations The field of application Organic coating Zinc coating Steel quality 2 Profiled sheet for roofs Steel roofing tiles Profiled sheet for walls Sandwich panels Prelaq Nova Prelaq Polyester Prelaq GreenCoat Prelaq Nova Prelaq Polyester Prelaq Matt Polyester Prelaq GreenCoat Prelaq GreenCoat Mica Prelaq Nova Prelaq Polyester Prelaq GreenCoat Prelaq PVDF Prelaq Nova Prelaq GreenCoat Prelaq PVDF Z 275 SUB 250 SUB 350 Z 275 SUB 250 SUB 350 Z 275 SUB 250 SUB 350 Z 275 SUB 250 SUB 350 Sheet metal roofing Prelaq GreenCoat Z350 PLX Cladding sheet cassettes Prelaq Nova Prelaq GreenCoat Prelaq PVDF Z275 Roof drainage products Prelaq Nova DS Z 275 FAX, PLX Flashings Same as connecting material. Z 275 FA, FAP FA 1. Coated on both sides of the sheet 2. See also table 1 and 2, page

17 Color and gloss The color, surface gloss and color coating's durability play the most important role in a building's appearance. The color scheme must not only suit the house, but also allow it to blend into its surroundings. Color variations between different deliveries are measured in Cielabunits. One Cielab unit is normally the highest permitted color variation from our reference. Some paint systems are more sensitive than others to color variations. These include metallic colors and Matt polyester. For these paints systems, it is best to aim to have the same production batch for a roof or cladding sheet surface, as well as ensure that the sheet is positioned so that stamped arrows on the reverse of the sheet all point in the same direction. 17

18 Prelaq is easy to process Prepainted sheet is formed primarily through bending or roll forming. Trimming takes place by cutting or slitting the sheet. It is important that all tools used during processing are clean and have smooth surfaces. Do not process prepainted material after cold rolled or galvanized sheet without cleaning the tools. Radii when roll forming and bending are to be adapted in line with the selected material's bending properties. As large a radius as possible should be aimed for during tool construction. This allows flexible material choice, forming at lower temperatures without damage, and a low risk for micro cracks in the coating layer. It is always an advantage to form sheet at room temperature. Roll forming During roll forming a flat strip is fed into a roll forming mill. Here it is formed after a number of stages into a profile by rolls gradually forming the sheet. Roll forming is particularly effective for forming long profiles. The operation goes quickly and gives good measuring precision. It is also gentle on the color coating. Each set of tools for roll forming is designed for a material with a certain thickness and specific elastoplastic properties. This means that settings should be adapted to suit the steel grade used in order to avoid any tolerance issues with the profile being formed. Water-soluble lubricants can be used during roll forming, but not lubricants that contain solvents or substances that are harmful to the color coating. Pressing Pressing is a common method used in the production of components in Prelaq. The paint surface has a slightly smooth surface which means that it can often be formed without additional lubrication. The material can be deep pressed which in practice gives a combination of pull and stretch pressing. Formability is improved with lower strength which is why mild steels are often used, for example, PLX. Bending Bending can take place in a press brake or bending machine. In the process, the outside of the sheet is stretched, while the inside is angled. Stretching increases as the bending radius decreases. Basic requirements for successful bending of prepainted sheet in a press brake: Tools must be clean, in good condition, and without sharp angles and pointed edges. The latter applies in particular to the upper part of the V in a V-die. When bending Prelaq PVDF, Prelaq Nova and Prelaq Polyester protective tape or plastic film should be used on the tools. V-shaped dies to avoid damage to the color coating. Knife set so that it does not reach right down to the bottom of the die. When the sheet is bent 180 (turnover) care must be taken so that the coating is not damaged during the final compression. Ensure that the sheet is bent with a radius of 1 3 mm so that the selected paint system and steel material can handle the bending without cracking. A soft material between the sheet and tools reduces the risk of damage. 18

19 Cutting When cutting Prelaq with thick coating, it is an advantage if the cut takes place on the reverse of the sheet. The cut edges that arise are then hidden and protected in color coating. Take care to remove the chips, so that they do not get caught in the paint layer. All cutting should take place at right angles to the sheet surface. Appropriate interplay between the cut steel, punch and die can vary between 6 12% of the substrate's thickness depending, among other things, on the strength of the material. Ensure that the cutting edge is always sharp. Cutting with blunt cutting edges increases the risk of edge corrosion. Slitting Edge trimming and slitting to narrow strips takes place with a pair of pulleys with blades. The blades are assembled in the desired number on parallel axes. The quality of the blades and the interplay between the pulleys is controlled by the material to be slit. The following guidelines can be used for the horizontal interplay: Working material Rm < 450 N/mm 2, interplay approximately 6% of thickness. Working material Rm > 450 N/mm 2, interplay approximately 8% of thickness. Trimming Do not trim prepainted sheet with a grinding wheel. It increases the risk of edge corrosion at the trimmed edge. The grind spray also causes damage to the coating and produces rusty grindings. However, a nibbling machine can be used for trimming. 19

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21 Considerations for detailing and assembly It is not only the environment that influences the service life of Prelaq. Detailing and how the sheet is processed and handled is of great importance for the sheet's power of resistance against external impacts. Flashings and sheet edges Avoid open sheet edges where water drops can collect. Open sheet edges should be covered where possible. Joined flashings should either be covered or folded together. Ensure that the lower end of profiled sheet is well ventilated. Hide cut edges that arise when nibbling. Extra protection of cut edges in corrosive environments Profiled sheet on roofs with low pitch (< 6 degrees) in harsh environments has an increased risk of edge corrosion in the sheet's cross joins. Corrosion protection on cut edges on small pitches is significantly improved if the edge is painted after assembly. A downward bend to a water spout in the lower open sheet end decreases the risk of edge corrosion in harsh environments. The sheet's fastener Profiled sheet used as an external surface layer is fastened with screws. The fastener should have at least the same service life as the sheet, which in most cases means choosing a fastener in authentic stainless steel. The surface that the sheet is screwed onto is not to allow depressions to form around the fastener, where water could collect. Fastener suppliers provide detailed instructions about their products. Harsh environments Sheet should not be stored or assembled near damp and corrosive materials. Seek advice from SSAB if Prelaq will be used in, for example, a permanently damp environment, areas where the sheet is exposed to strong cleaning agents, or in premises with animal husbandry. If a more precious metal than zinc comes in contact with the zinc coating, corrosion damage to the sheet may arise. Design details so that water containing copper does not run over the prepainted sheet. Water with copper content may, for example, come from drainpipes, copper window sills or copper pipes. Roof surfaces and pitch The roofing sheet should be of a certain pitch to allow rain water to freely run off all surfaces. Increasing concentrations of pollutants collect over time in water that is left to stand, which can damage the paint layer in the long run. The base of the long strip roofing must be so stable that depressions with collected water do not occur when smaller areas of the sheet are put under pressure. The roof should preferably have a pitch of at least 6 degrees. Rails Roofing sheet cannot be mounted directly on impregnated wooden rails. Place strips of roofing underlayment between the rails and sheet. Seek advice from SSAB when Prelaq is to be mounted on impregnated wooden rails. Assembly without damage to coating During assembly, it is important not to unnecessarily cause damage to the sheet. An intact paint layer increases the service life of the sheet. Note that certain coatings can be delivered with a peel-off protective film. Clean the sheet surface Remove borings, nibbling chips and rivet splinters from the sheet surface. Remaining metal residue leads to discoloration and corrosion in the long term. 21

22 Factors that influence the sheet's service life Ambient environment The environment surrounding a building influences the paint coat. Several factors determine the length of time it takes before the paint is broken down. The four most important factors are: Ultraviolet radiation from the sun, intensity and time. Heat. Amount of rain and total time the surface layer is exposed to moisture (wet time). Degree of pollutants in the atmosphere. Sheet surfaces in so-called rain shadows, where the rain does not reach to rinse away pollutants, are more exposed to corrosion than other surfaces. Marine atmosphere. Coastal regions also have the added effect of saline air. It effects all surfaces on a building. We define a marine environment as being up to one kilometer from the coast. The geographic location is of great significance to the amount of sunlight and heat that the paint coat is exposed to. There are restrictions when it comes to product choice for buildings in Central Europe and lower latitudes. Solar radiation heats up the sheet, which contributes to the break down of the paint coat. Sheet covering on insulated base surfaces becomes hotter than on those without insulation, since the insulated base surface reduces the ability to conduct the heat away. Roofs and walls detailing Roof surfaces are exposed to the harshest stresses from the environment, in particular roofs with a small pitch. Roofs are exposed to strong sunshine, moisture, dirt and often with people walking on them and other mechanical impacts. Roofs with a significant amount of people walking on top should have walkways. Defects in detailing can intensify the effects of the environmental impacts described above. Maintenance In order to prevent time and environment from having unnecessarily better chances of causing damage to the sheet, it is important to avoid damages to the surface layer, both during and after building work. Tools or flashings that are dropped by mistake can cause small damages to the paint coat. These should be touched up with paint. Material selection Incorrect material selection shortens the sheet's service life, and results in a more maintenanceintensive building. UV radiation and heat are the most important factors for the service life of the paint coat for plastisol coating Prelaq P 200. Therefore, the position of the sheet surface in relation to the sun's radiation is of great significance. Areas of water close to the building can intensify the sun's radiation by being reflected on the water surface. 22

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24 Maintenance Well-maintained Prelaq enjoys a long life With regular maintenance a sheet roof can last years or more. There are Swedish buildings with sheet roofing from 1832 where the sheet is still in good condition thanks to regular control and maintenance. Two different measures of service life are normally used for the surface layer of prepainted sheet; aesthetic and functional. Aesthetic useful life is the measure of time taken for a paint layer to change to such an extent that the appearance no longer meets the demands placed. The extent to which a color change is considered acceptable for sheet covering depends on who is judging it and on which building the sheet is placed. In some cases, the aesthetic useful life limit is the point when the color starts to peel. The choice of color influences the aesthetic useful life. Light and dark colors have, for example, different characteristics. Choosing Prelaq's tested standard colors comes with a guarantee that the paint meets all demands placed. The lifespan also depends on whether the material is used as a wall or roof, roof pitch, sun direction and whether it is an inland or coastal environment. It is also important to consider the environmental impact from local factory emissions, traffic and oil burning when estimating the service life of the paint coat. An undamaged surface layer in normal environmental conditions can expect an aesthetic useful life of at least 20 years for Prelaq PVDF, 30 years for Prelaq GreenCoat, and 25 years for Prelaq Nova, Prelaq Polyester and Prelaq P 200. The functional service life is up to the point when the sheet can no longer protect the building's load-bearing structure or underlying insulation. The time varies greatly depending on the coating used on the sheet, the type and thickness of zinc coating and, most importantly, in which environment the sheet is used. Inspection and maintenance With regular control and maintenance, prepainted sheet is given the right conditions for a long service life. Inspection of the sheet surface should take place at least once a year. In most cases, maintenance is confined to cleaning the sheet a few times during its service life, especially in dirty environments. Often rain is enough to keep the sheet clean. Sheet that is in a so-called rain shadow, where rain is not able to rinse dirt away, should be checked extra carefully. Contact SSAB for practical advice. Advice is also summarized in the printed leaflet Inspection and maintenance of prepainted sheet. Repainting Depending on the requirements placed on a building with sheet, it may be necessary to renew the surface layer. This can be done by replacing the sheet or by painting over the surface layer. An appropriate time for painting over can be determined through regular inspections of the paint coat. Painting should take place before the existing paint coat has lost its adhesion to the sheet material. An appropriate time for repainting should preferably be assessed by an expert. Standard time for repainting varies depending on environmental impacts and selected paint system. See more information under service life on the previous page. Extra care must be taken when painting over plastisol coating. In this case, guidance from an experienced person is recommended so as to assess whether it can be repainted. Paints for repainting are available from several different manufacturers and systems in the market. 24

25 Handling, storage and transport Prepainted strip products are a quality product, but must be handled correctly. Moisture, dents or any other impact can destroy all or parts of the sheet roll or sheet batch. The following simple rules help you to avoid damage to the sheet. Moisture free Prepainted and metal coated sheet should be protected against moisture when stored. Storage indoors in dry premises with an even temperature is optimum. Rapid temperature variations can cause condensation. The sheet should therefore be kept far from doors that open and close often. If moisture collects between the sheets, these should be taken off and air dried. Profiled sheet that is stored outdoors should be covered, but kept well ventilated. Lifting It is unsuitable to lift prepainted sheet with chains or cables. If a forklift truck is used it should have protection on its forks to prevent indentation damage in the sheet. A lifting device should not have sharp edges and it should have the same diameter as the inside of the roll. Edge protection should be used when lifting with a sling. The sheet should be carefully lifted out of the sheet batch, and not be pulled. This avoids any unnecessary scratches. Preferably use pneumatic or magnetic lifting devices. If the sheet is stored under high pressure, a so-called gloss transfer can arise. This disappears again if the sheet is heated up to C. Roofs and walls often reach these temperatures in the summer. Storage Cut-to-length sheet is stored with interlayers of wood, which are placed directly on top of each other. Lateral displacement can distort the sheet. Coils are stored lying on a rubber mat in a steel stand. Transportation Prepainted sheet should be transported covered and well protected from moisture. Packs of sheet, which are transported through different climate zones, will be exposed to different temperatures and weather conditions during transportation. There is therefore a significant risk that condensation will form within the pack of sheet and cause corrosion. Corrosion can also occur if the profiled sheet is packed without space in between. It is an advantage if the sheet can be stacked with a space between each piece, for example, some type of string or band. The sheet can alternatively be supplied with protective film and special reverse side coating. Once the sheet arrives at the work site, it should be unpacked immediately and separated. Packaging Prelaq can be delivered with different packaging in accordance with specific descriptions. 25

26 Technical support Knowledge Service Center is an important part of our offer to the customer. Our experts in different areas are at your disposal if help is needed regarding material selection and other technical questions. You can easily contact us on More information about Prelaq The marketing department for prepainted products are happy to help with additional information. Further information about Prelaq can be found on our website Other printed material about Prelaq can be ordered from SSAB. Courses and seminars are included as part of our business activity for customers and other interested parties who want to familiarize themselves with our experience and increase their knowledge about steel sheet. 26

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28 SSAB is a global leader in value added, high strength steel. SSAB offers products developed in close cooperation with its customers to reach a stronger, lighter and more sustainable world. SSAB has employees in over 45 countries and operates production facilities in Sweden and the US. SSAB is listed on the NASDAQ OMX Nordic Exchange, Stockholm. For more information, contact us or visit 517en-Prepainted sheet steel for buildings. V Confetti. Österbergs. SSAB Borlänge T +46 (0) F +46 (0) prelaqinfo@ssab.com