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1
Manufacturing Process
Of
Galvanized Steel Frames
2
Introduction
Corrosion and repair of corrosion damage are multi-billion dollar problems. Estimates show
metallic corrosi...
3
Planning and Design
Planning
Planning of this project was started when basic task of the project was received. For setti...
4
was decided to divide the project into phases to make it easy and explanatory. Information
sources concerning the resear...
5
Raw Material
6
Raw Material
The raw material used for manufacturing of self-supported power transmission towers are
steel angle bars. I...
7
Fabrication Process
Introduction
8
The raw material is issued from the storage the next and first operation of manufacturing is
cutting of angle bars that ...
9
Marking and Measurements
When the angle bars are cut in the size then the next process is about markings according to
me...
10
Figure: 6 Steel Frame Cutting Machine
Machining and Drilling
When marking is finished, the material is ready for machin...
11
according to the drawings and some inspection need to perform to check either if the parts
are manufactured according t...
12
Mostly the coolants used in ATL are cutting fluids. In other hand Cutting fluid is a type of
coolant and lubricant desi...
13
Figure: 12 Straightening Machine for keep Steel Frame straight
Figure: 13 CNC Punching Machine Arrangement
14
Galvanizing Process
Introduction
Corrosion and repair of corrosion damage are multi-billion dollar problems. Estimates ...
15
extensively to combat corrosion in major industrial environments including petro-chemical,
transportation, and public u...
16
British galvanizing industry was using 10,000 tons of zinc a year for the protection of steel,
and in 1870, the first g...
17
Figure: 15 Degreasing Tank
Pickling - A dilute solution of hot sulphuric acid or ambient temperature hydrochloric acid
...
18
Figure: 18 Fluxing Tank
Galvanizing
In the true galvanizing step of the process, the material is completely immersed in...
19
Figure: 19 Zink Bath Tank
Rising Tank - This tank consist water. The material is dipped into it for cooking,
cleaning a...
20
ZnO+CO₂ =ZnCO₃
Figure: 21Batch Hot-Dip Galvanizing Process
Figure: 22 Withdrawal of a steel article from the zinc bath
21
Quality Check and Inspection
22
Inspection
The inspection of hot-dip galvanized steel is simple and fast. The two properties of the
coating closely scr...
23
Loading and Tower Erection
24
Loading
In case when quality department is ok with angles, they directly go for loading, than they
dispatched to their ...
25
Application
26
Application of Galvanized Steel
The selection of a steel coating system is an integral part of all engineering design. ...
27
different sections and steel Angles of various sizes and lengths, Hot Dip Galvanized and
fastened with Centrifuged Hot ...
28
Figure: 26 Tower Application of Galvanized Steel
29
Reference
 www.kecrpg.com
 https://en.wikipedia.org/wiki/KEC_International
 www.rpggroup.com/our_business/infrastruc...
30
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Galvanized Steel Manufacturing Process

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Manufacturing process hot-dip galvanization process

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Galvanized Steel Manufacturing Process

  1. 1. 1 Manufacturing Process Of Galvanized Steel Frames
  2. 2. 2 Introduction Corrosion and repair of corrosion damage are multi-billion dollar problems. Estimates show metallic corrosion costs the United States approximately $297 billion annually, or about 3% of the national GDP. Although corrosion is a natural phenomenon, and can never be completely eliminated, utilizing adequate corrosion protection systems in harsh environments can drastically reduce the costs. Hot-dip galvanizing after fabrication is a cost effective, maintenance free corrosion protection system that lasts for decades even in the harshest environments. For more than 100 years, hot-dip galvanized steel has been utilized extensively to combat corrosion in major industrial environments including petro-chemical, transportation, and public utilities. Power grids are being rethought and rebuilt. The fast-growing requirement for transmission capacity is driving the rapid expansion of transmission lines across the World. Transmission infrastructure is being updated at an unprecedented pace. Meeting the challenge of today’s fast-growing demand for quality, reliability and timely delivery requires a unique combination of capability, capacity and experience. Whether the need is transmission structures for the most severe terrains and environments, state-of-the- art advanced design work, dependable tower testing, precision hardware or complete solutions covering the total process from engineering through supply, we have what it takes to get the job done. Flow Chart Figure: 1 Overview of manufacturing of galvanized steel frames
  3. 3. 3 Planning and Design Planning Planning of this project was started when basic task of the project was received. For setting up about the main idea of this project, several meetings were arranged among the team members. The project scopewas defined by discussing the problem and their solutions. It
  4. 4. 4 was decided to divide the project into phases to make it easy and explanatory. Information sources concerning the research topic were analysed and it was decided to start research immediately. Design The Company has in-house design centres with a strong team of over 100 design experts in India and Americas who continuously develop innovative, construction friendly and cost- effective designs. It is equipped with the latest software like PLS Tower, PLS Pole, PLS CADD, AUTOCAD, MICROSTATION, BOCAD and Google Earth. It provides computerized engineering solutions, 3D analysis and design depending on the size and complexity of the project, voltage range, weather condition etc. Figure: 2 Design Department The Company has an unparalleled strength in the design of very complex and large towers with a state of the art in-house Design centre. It has designed Multi circuit, River crossing towers weighing approx. 300 M.T. with the height of more than 150 meters per tower.
  5. 5. 5 Raw Material
  6. 6. 6 Raw Material The raw material used for manufacturing of self-supported power transmission towers are steel angle bars. It can be in different sizes and different profile types i.e. L, V, T-shape and flat angle bars iron net and other sheet metal etc. Steel in normal condition itself is corrosion resistant but for further improvements HDG and paints are applied. Raw material is chosen according to the structural parts, for example most heavy steel angle bars are chosen for the purpose sizes for structural member of power transmission tower. Raw material is directly purchased from the suppliers and as the company has mass production so different suppliers supply raw mater is according to international standards and specifications. Its quality is checked both by suppliers and company itself because in such case of designing tower for the age of 25 years, the tower material must be chosen according to standards. Steel angle bars are directly transported to company storage and they are further sent to machine shop for further processes after quality check. Figure: 3 Raw Material Yard
  7. 7. 7 Fabrication Process Introduction
  8. 8. 8 The raw material is issued from the storage the next and first operation of manufacturing is cutting of angle bars that are done with the presses. Before cutting the angle bars it needed to measure and have to do some marking according to required sizes. There are three presses in the factory which are used to cut different angle bars in different shapes and sizes and then material is sent to machine shop. Manufacturing processes of power transmission towers and the flow of material and products can easily be understood by the following flow chart in fig. Flow chart Figure: 4 Flow Chart of Fabrication Process Raw Material Straightening Cutting Bending Punching Stamping Notching
  9. 9. 9 Marking and Measurements When the angle bars are cut in the size then the next process is about markings according to measurements on it. Different drawings are used for each part and marking is done according to the available drawings. At this stage, as it’s the first and main stage of the manufacturing of telecommunication towers, the workers who do the marking job are well experienced and they do the quality check themselves at same time during marking process. Different tools like scribers, as shown in Figure 11 and different colour of chalks or temporary paints are used for the purpose of marking. Figure: 5 Marking and Measurement by Design Cutting of Material After the raw material is issued from the storage the next and first operation of manufacturing is cutting of angle bars that are done with the presses. Before cutting the angle bars it needed to measure and have to do some marking according to required sizes. There are three presses in the factory which are used to cut different angle bars in different shapes and sizes and then material is sent to machine shop. Presses liken the one presented in Figure 10 that is used for cutting angle bars are either operated hydraulically or then mechanically. They are from 1 to 3 tons in capacity
  10. 10. 10 Figure: 6 Steel Frame Cutting Machine Machining and Drilling When marking is finished, the material is ready for machining processes. For that, the factory has about six drilling machines and different grinding machines. Actually, when the marks are ready and points are located the holes in angle parts need to be done by drilling process that is quite precise. Workers have to be well trained so that they can use exact tools and drill the right sizes of holes because when the tower will go for site for erection then there should not be any play between tower members. That can cause all tower breakage when it’s windy or bad weather like storm etc. Figure: 7 Machining of Steel Frame Technical documentation work need to be done by using Auto Cad in which, the use of part numbers in drawings and different scaling work need to be mention. Work need to be done
  11. 11. 11 according to the drawings and some inspection need to perform to check either if the parts are manufactured according to drawings or if there are some mistakes. The work needs to be done by workers under the guidance of foremen and some faulty parts have to be fixed under the guidance of concerning supervisor and foremen. A typical drawing of the tower steel part and the drilling machine used for the drilling purpose is shown in the Fig 12 and Fig 13 on the next page. Figure: 8 CNC Punching or Drilling of Steel Frame Coolants are used for the devices to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. For an ideal coolant it should have high thermal capacity, low viscosity, is low-cost, neither causing nor promoting corrosion of the cooling system either in a machine part or cutting tools. Coolant is commonly used in automotive, some temperature-control applications. In industrial processing, heat transfer fluid is used both in high temperature as well as low temperature manufacturing applications. Figure: 9 Types of Notching
  12. 12. 12 Mostly the coolants used in ATL are cutting fluids. In other hand Cutting fluid is a type of coolant and lubricant designed specifically for metal working and machining processes. Different kinds of cutting fluids are used for different purposes i.e. oils, oil-water emulsions, pastes, gels, aerosols (mists), and air or other gases. Cutting fluids may be made from petroleum, animal fats, water and air, or plant oils etc. A good cutting fluid must have the following properties: • A cutting fluid must keep the work piece at a stable temperature. • It must ensure safety for the people handling it and for the environment upon disposal. • It prevents rust and corrosion on cutting tools and machine parts. • It must maximize the life of the cutting tip by lubricating the working edge or tip. Figure: 10 Bending Machine Figure: 11 CNC Punching Machine for generating holes on Steel Frames
  13. 13. 13 Figure: 12 Straightening Machine for keep Steel Frame straight Figure: 13 CNC Punching Machine Arrangement
  14. 14. 14 Galvanizing Process Introduction Corrosion and repair of corrosion damage are multi-billion dollar problems. Estimates show metallic corrosion costs the United States approximately $297 billion annually, or about 3% of the national GDP. Although corrosion is a natural phenomenon, and can never be completely eliminated, utilizing adequate corrosion protection systems in harsh environments can drastically reduce the costs. Hot-dip galvanizing after fabrication is a cost effective, maintenance free corrosion protection system that lasts for decades even in the harshest environments. For more than 100 years, hot-dip galvanized steel has been utilized
  15. 15. 15 extensively to combat corrosion in major industrial environments including petro-chemical, transportation, and public utilities. The zinc of the hot-dip galvanized coating is more corrosion resistant than bare iron and steel. Similar to steel, zinc corrodes when exposed to the atmosphere; however, zinc corrodes at a rate approximately 1/30 of that for steel. Also like steel, zinc corrodes at different rates depending on its environment. Therefore, the performance of hot-dip galvanized steel varies from environment to environment. Environments in which galvanized steel is commonly used include indoor and outdoor atmospheres, the storage of hundreds of different chemicals, in fresh water, sea water, soils, concrete, and conjunction with other metals, treated wood or extreme temperatures. Because of the many years galvanizing has been used for corrosion protection, a wealth of real-world, long-term exposure data on zinc coating performance in a wide variety of environments is available. Because hot-dip galvanized steel is used in so many different applications. Figure: 14 Galvanized Mild Steel Frames History Of Galvanizing The recorded history of galvanizing dates back to 1742 when P.J. Malouin, a French chemist described a method of coating iron by dipping it in molten zinc in a presentation to the French Royal Academy. Thirty years later, Luigi Galvani, galvanizing namesake, discovered more about the electrochemical process that takes place between metals. Galvani’s research was furthered in 1829 when Michael Faraday discovered zinc’s sacrificial action, and in 1836, French engineer Sorel obtained a patent for the early galvanizing process. By 1850, the
  16. 16. 16 British galvanizing industry was using 10,000 tons of zinc a year for the protection of steel, and in 1870, the first galvanizing plant opened in the United States. Today, galvanizing is found in almost every major application and industry where iron or steel is used. Hot-dip galvanized steel has a proven and growing history of success in myriad applications worldwide. How Zinc Protects Steel from Corrosion The reason for the extensive use of hot-dip galvanizing is the two-fold protective nature of the coating. As a barrier coating, it provides a tough, metallurgical bonded zinc coating that completely covers the steel surface and seals the steel from the corrosive action of the environment. Additionally, zinc’s sacrificial behaviour protects the steel, even where damage or a minor discontinuity in the coating occurs. The Hot-Dip Galvanizing Process The hot-dip galvanizing process consists of three basic steps: Surface Preparation, Galvanizing, and Inspection. Surface Preparation Surface preparation is the most important step in the application of any coating. In most instances, incorrect or inadequate surface preparation is the cause of a coating failure before the end of its expected service lifetime. The surface preparation step in the galvanizing process has its own built-in means of quality control because zinc wills not metallurgical react with an unclean steel surface. Any failures or inadequacies in surface preparation will immediately be apparent when the steel is withdrawn from the molten zinc, because the unclean areas will remain uncoated and immediate corrective action must be taken. Surface preparation for galvanizing consists of three steps: Degreasing, Acid pickling, and Fluxing. Degreasing - A hot alkali solution, mild acidic bath, or biological cleaning bath removes organic contaminants such as dirt, paint markings, grease, and oil from the steel surface. Degreasing baths cannot remove epoxies, vinyl, asphalt, or welding slag; thus, these materials must be removed by grit-blasting, sand blasting, or other mechanical means before the steel is sent to the galvanizer.
  17. 17. 17 Figure: 15 Degreasing Tank Pickling - A dilute solution of hot sulphuric acid or ambient temperature hydrochloric acid removes mill scale and iron oxides (rust) from the steel surface. As an alternative to or in conjunction with pickling, this step can also be accomplished using abrasive cleaning, air blasting sand, metallic shot, or grit onto the steel. Figure: 16 Pickling Tank Rinsing Tank - The material is cleaned and cooled by dipping it in water tank because HCL acid sticks on it. Figure: 17 Rinsing Tank Fluxing - The final surface preparation step in the galvanizing process serves two purposes. It removes any remaining oxides and deposits a protective layer onto the steel to prevent any further oxides from forming on the surface prior to galvanizing. Flux is applied in two different ways; wet or dry. In the dry galvanizing process, the steel or iron is dipped or pre-fluxed in an aqueous solution of zinc ammonium chloride. The material is then dried prior to immersion in molten zinc. In the wet galvanizing process, a layer of liquid zinc ammonium chloride is floated on top of the molten zinc. The iron or steel being galvanized passes through the flux on its way into the molten zinc.
  18. 18. 18 Figure: 18 Fluxing Tank Galvanizing In the true galvanizing step of the process, the material is completely immersed in a bath of molten zinc. The bath contains at least 98% pure zinc and is heated to approximately 840 F (449 C). Zinc chemistry is specified by ASTM B 6. While immersed in the kettle, the zinc reacts with the iron in the steel to form a series of zinc/iron intermetallic alloy layers. Once the fabricated items coating growth is complete, they are withdrawn slowly from the galvanizing bath, and the excess zinc is removed by draining, vibrating, and/or centrifuging. The metallurgical reaction will continue after the articles are withdrawn from the bath, as long as the article remains near bath temperature. Articles are cooled either by immersion in a passivation solution or water or by being left in open air. Hot-dip galvanizing is a factory- controlled process performed under any climate conditions. Most brush and spray-applied coatings depend upon proper climate conditions for correct application. Dependence on atmospheric conditions often translates into costly construction delays. The galvanizer’s ability to work in any climate conditions provides a higher degree of assurance of on-time delivery; furthermore, no climate restrictions means galvanizing can be completed quickly and with short lead times. Zink Bath - There is mainly ZN in this bath at 460’c temperature. AL & Lead also present these for surface finishing of material. The material is dipped into it and after Certain time it is raised from it. Thus the Zn coating is made.
  19. 19. 19 Figure: 19 Zink Bath Tank Rising Tank - This tank consist water. The material is dipped into it for cooking, cleaning after Zn coating. Figure: 20 Rising Tank During the actual galvanizing step of the process,the material is completely immersed in a bath of molten zinc. The bath chemistry is specified by ASTM B6, and requires at least 98% pure zinc maintained at approximately 840 F (449 C). While immersed in the kettle, the zinc reacts with the iron in the steel to form a series of zinc/iron intermetallic alloy layers. Once the fabricated items’ coating growth is complete, they are withdrawn slowly form the galvanizing bath, and the excess zinc is removed by draining, vibrating, and/or centrifuging. The metallurgical reaction will continue after the articles are withdrawn from the bath, as long as the article remains near bath temperature. Articles are cooled either by immersion in a passivation solution or water or by being left in open air. Temperature of molten bath is around 860°F (460°C). Zn+O₂ =ZnO
  20. 20. 20 ZnO+CO₂ =ZnCO₃ Figure: 21Batch Hot-Dip Galvanizing Process Figure: 22 Withdrawal of a steel article from the zinc bath
  21. 21. 21 Quality Check and Inspection
  22. 22. 22 Inspection The inspection of hot-dip galvanized steel is simple and fast. The two properties of the coating closely scrutinized are coating appearance and coating thickness. A variety of simple physical and laboratory tests may be performed to determine thickness, uniformity, adherence, and appearance. Products are galvanized according to long-established, accepted, and approved standards of ASTM, the Canadian Standards Association (CSA), the International Organization for Standardization (ISO), and the American Association of State Highway and Transportation Officials (AASHTO). These standards cover everything from minimum required coating thicknesses for various categories of galvanized items to the composition of the zinc metal used in the process. The inspection process for galvanized items also requires minimal labour. This is important because the inspection process required assuring the quality of many brush- and spray-applied coatings is highly labour-intensive and requires expensive skilled labour. Once a job has been delivered and accepted at the galvanizer’s plant, there is one point of responsibility for ensuring the material leaves the plant properly galvanized. That point of responsibility is the galvanizer. Figure: 23 Inspection of Zinc Coating The last process after HDG and before sending it to storage is quality check and final inspection where all the galvanized parts of tower are finally inspected by QC department. In the final inspection zinc coated parts are inspected and it is made sure that there is not any faults i.e. blowholes, porosity, black spots and missed zinc coated places because it is necessary to galvanize parts in proper way. Otherwise there can be rusting and corrosion with the passage of time. Zinc coating thickness is important to consider in point because of cost and safety factors. For checking zinc coating thickness, a special tool, positector is used. Thickness of zinc varies from 2 µmm to 1 mm, depending on the part and size of the tower member. Electronic magnetic gages (e.g. PosiTector 6000 F Series, PosiTest DFT Ferrous) come in many shapes and sizes. They commonly use a constant pressure probe to provide consistent readings that are not influenced by different operators. Readings are shown on a liquid crystal display (LCD).
  23. 23. 23 Loading and Tower Erection
  24. 24. 24 Loading In case when quality department is ok with angles, they directly go for loading, than they dispatched to their desired location. Tower Erection The last operation after manufacturing is erection of simply supported towers. When the towers are transported to site, the foundation of tower is ready before the tower structure is unloaded. The foundation of the part is constructed by company's civil engineers who make the foundation ready two weeks before the erection of tower. The foundation consists of concrete and works as base of tower. Heavy cranes and different fork lifters are used for the handling the tower members. As they are heavy in weight, it is not possible to lift them easily. Different pulleys are used too during the erection of power transmission towers and safety precautions are adapted for the safe work. Different tools are used step by step for the quality work and it takes about a week to completely erect a 60 meter high telecommunication tower. The lower joints and legs of the tower are fitted with the foundation with anchor rods and bolts. And then whole tower is fitted upward by starting from foundation. Some heavy working cranes are used for that purpose and of course some fitters and workers under supervision. It takes about a week to erect one tower and the rest of the telecom devices are fitted later by client's own engineers. When erection of mechanical structure of telecommunication tower is finished then different power transmission companies install the power transmission unit along with the tower. For that they use a control room (processing unit), antennas and some cables for the purpose of communication. The whole tower from its erection to the final working takes about a month. Figure: 24 Tower Erections
  25. 25. 25 Application
  26. 26. 26 Application of Galvanized Steel The selection of a steel coating system is an integral part of all engineering design. The main consideration for the engineer in the selection of the most suitable corrosion protection system would be the performance of a steel coating and the economics of the application of the steel coating system. There is no other corrosion protection system that could match the performance and economics of hot dip galvanizing. POWER GENERATION AND POWER TRANSMISSION In the building of a power station for power generation, steel is a major construction material. Galvanized steel is used in platforms, equipment buildings, stairs and handrails. In the area of fuel supply to the main power generating plants galvanized steel conveyor systems are common in a coal fired power station. Cooling water, water reticulation and fire protections systems consume huge amounts of galvanized steel in the form of piping and it fittings. As for power transmission every piece of steel in a transmission tower is completely galvanized from the main steel frame, every piece of bolt and nut used to fasten the angles together to the cable support systems are completely galvanized. They are now many transmission towers that are also painted with special paint system for identification purposes. INFRASTRUCTURE DEVELOPMENT Government of many countries now invest and spent huge part of their budgets in improving the infrastructure such as road highways and expressways, railways, Light Rail Transport system (LRT) and Mass rapid Transportation system (MRT) , Port terminals and airport facilities. These projects consume huge amounts of exposed steel and as such hot dip galvanizing is the preferred corrosion protection system. As for other developments such as schools, hospitals, community halls and other public places galvanized steel are mainly in galvanized products such as galvanized water tanks for fire protections systems, street lights, safety barriers and road and drain covers. Hot dip galvanized reinforcement steel was only used in critical construction areas such as coastal or marine concrete structures. In the last decade the use of hot dip galvanized reinforcement steel increased with the rapid expansion of the road, highways and expressways. Steel rods and strips for reinforced earth (RE) walls and soil nails are always hot dip galvanized. Guardrails, crash cushions, decorative street lights, high masts, pedestrian overhead bridges, noise barriers, parapet handrails are some of the other products that are corrosion protected with hot dip galvanizing TELECOMMUNICATION TOWERS Telecommunication steel towers are difficult structures to maintain considering its location which normally are difficult to access since it is situated on hills slopes and on top of mountains. For easy installation these Steel Towers are fabricated from Steel Tubes in
  27. 27. 27 different sections and steel Angles of various sizes and lengths, Hot Dip Galvanized and fastened with Centrifuged Hot Dip Galvanized Bolts, Nuts and Washers. These 3 Leg Telecommunication Towers are 100% Hot Dip Galvanized and Duplex coated for long term corrosion protection and aerial Identification. BUILDING AND CONSTRUCTION The Twin Tower in Kuala Lumpur and the Kuala Lumpur Tower are prestigious projects in Malaysia. For durability most steel are Hot Dip Galvanized and Duplex coated. Commonly found in the open areas are Forged Welded Gratings hot dip Galvanized, Garden Lighting Poles Hot Dip Galvanized and Children Play Stations all Hot Dip Galvanized and Duplex Coated. Figure: 25 Tower Transmissions and Telecom Tower Application of Galvanized Steel Figure: 26 Industries and Building Application of Galvanized Steel
  28. 28. 28 Figure: 26 Tower Application of Galvanized Steel
  29. 29. 29 Reference  www.kecrpg.com  https://en.wikipedia.org/wiki/KEC_International  www.rpggroup.com/our_business/infrastructure/kec_international.aspx  www.theseus.fi/bitstream/handle/10024/41511/Ishtiaq_Muhammad.pdf?sequence =1  https://en.wikipedia.org/wiki/Hot-dip_galvanization  https://en.wikipedia.org/wiki/Galvanization  www.steeldoor.org/res/SDI_112.pdf  www.galvanizingasia.com/pdfs/page9-25.pdf  www.buzzle.com/articles/use-of-galvanized-steel.htm  Google Images galvanizedsteelapplication  www.azom.com/article.aspx?ArticleID=2629
  30. 30. 30 Thank You

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