Technical Drawings and their Types...

Technical Drawings and their Types Technical drawings are also known as ‘engineering drawings’. They are means of communications and convey technical information of plant and equipment. They describe three-dimensional objects through the medium of two-dimensional paper. The process of producing technical drawings, and the skill of producing those, is often referred to as ‘drafting’. Technical drawing is normally accepted as legal document and is frequently being used for regulatory approvals. Technical drawings are most frequently used to establish engineering requirements. They describe typical applications and minimum content requirements. They are standardized tools of graphical language which avoid verbal exchanges. They are used and understood by the technical personnel speaking different languages and belonging to different countries and cultures. Technical drawings are prepared in such a way that they convey complete information of the plant and equipment clearly and concisely. They often contain more than just a graphic representation of the subject. They also contain dimensions, notes and specifications. Clarity is the essential aspect of the technical drawings. They normally represent two dimension view of the object though some drawings also provide three dimensional views. They are prepared either manually or with the aid of computer. They are generally prepared or printed in standard size of paper. Except a few category of drawings (e.g. process flow diagrams, control diagrams, piping and instruments diagrams, and single line diagrams etc.), all the drawings are normally prepared in plan and different section views usually to the scale in order to provide complete information of the drawing object. Often help of standardized symbols are taken in the drawing for depicting certain equipments or instruments. Those informations which cannot be given in the plan and sections view such as material specification, tolerances, and bill of materials etc. are normally given in a...

Iron and Types of Iron...

Iron and Types of Iron Iron is a chemical element with symbol Fe (from Latin word Ferrum). Its atomic number is 26 and atomic mass is 55.85. It has a melting point of 1538 deg C and boiling point of 2862 deg C. The density of iron is 7.87 grams/cu cm. It is a metal in the first transition series. Like the elements of other group 8 elements (ruthenium and osmium), iron exists in a wide range of oxidation states, ?2 to +6, although +2 and +3 are the most common. Iron as a common metal is mostly confused with other metals such as different types of steels. Iron is by mass the most common element on the earth, forming much of earth’s outer and inner core. It is the fourth most common element and the second most common metal in the earth crust. Steels contain over 95 % Fe. Elemental iron occurs in meteoroids and other low oxygen environments, but is reactive to oxygen and water. Fresh iron surfaces appear lustrous silvery-gray, but oxidize in normal air to give hydrated iron oxides, commonly known as rust. Unlike the metals which form passivating oxide layers, iron oxides occupy more volume than the metal and thus flake off, exposing fresh surfaces for corrosion. Iron objects have been found in Egypt dating from around 3500 BCE (Before Common Era). They contain around 7.5 % nickel, which indicates that they were of meteoric origin. The ancient Hittites of Asia Minor (today’s Turkey) were the first to smelt iron from its ores around 1500 BCE. The ‘Iron Age’ had begun at that time. The first person to explain the various types of iron was René Antoine Ferchault de Réaumur who wrote a book on the subject in 1722. This explained how steel, wrought iron, and cast iron, were to be distinguished by the amount of charcoal (carbon) they contained. The...

Non Coking Coal for Iron Production...

Non Coking Coal for Iron Production A non-coking coal is that coal which when heated in the absence of air leaves a coherent residue. This residue does not possess the physical and chemical properties of the coke and is not suitable for the manufacture of coke. Non coking coal like any other coal is an organic rock (as opposed to most other rocks in the earth’s crust, such as clays and sandstone, which are inorganic). It contains mostly carbon (C), but it also has hydrogen (H2), oxygen (O2), sulphur (S) and nitrogen (N2), as well as some inorganic constituents which are known as ash (minerals) and water (H2O). Coal was formed from prehistoric plants, in marshy environments, some tens or hundreds of millions of years ago. The presence of water restricted the supply of oxygen and allowed thermal and bacterial decomposition of plant material to take place, instead of the completion of the carbon cycle. Under these conditions of anaerobic decay, in the so-called biochemical stage of coal formation, a carbon-rich material called ‘peat’ was formed. In the subsequent geochemical stage, the different time-temperature histories led to the formations of coal of widely differing properties. These formations of coal are lignite (65 % to 72 % carbon), sub-bituminous coal (72 % to 76 % carbon), bituminous coal (76 % to 90 % carbon), and anthracite (90 % to 95 %) carbon. The degree of change undergone by a coal as it matures from peat to anthracite is known as coalification. Coalification has an important bearing on the physical and chemical properties of coal and is referred to as the ‘rank’ of the coal. Ranking is determined by the degree of transformation of the original plant material to carbon. The ranks of coals, from those with...

Personal Protective Equipment for Safety of Employees...

Personal Protective Equipment for Safety of Employees Personal protective equipment (PPE) is the equipment or a device which is intended to be worn or otherwise used by an employee at work and which protects the employee against one or more risks arising from the operation to the employee’s safety or health. It includes any addition or accessory to the equipment designed to meet a similar objective. It protects the employee from hazards and any harmful conditions (existing and potential) which may result in injury, illness, or possibly fatal injury. PPE can be an item worn on the body, such as gloves, or a device, such as a protective shield or barrier. Besides face shields, safety glasses, helmets, and safety shoes, personal protective equipment also includes a variety of devices and garments such as goggles, coveralls, gloves, vests, earplugs, and respirators. Examples of some of the personal protective equipments are given in Fig 1. Fig 1 Examples of personal protective equipments PPE is an important means of preventing work injuries. Ideally, the best approach is to maintain a safe work environment and eliminate any potential hazards. PPE is only to be relied upon as a last line of defense in places where it is not practicable to control the hazards at source. PPE is designed to protect the employee from serious workplace injuries or illnesses resulting from contact with chemical, radiological, physical, electrical, mechanical, or other workplace hazards. It is one of the ways to protect employees. However, it does not eliminate or reduce the hazard. It only places a barrier between the employee and the hazard. If the PPE fails or is not used, then the employee is not protected from the hazard. The use of PPE generally implies working in a potentially hazardous...

Ferrous Scrap and its Collection and Recycling...

Ferrous Scrap and its Collection and Recycling Ferrous scrap also referred to as, iron and steel scrap, or simply scrap comes from end of life products (old or obsolete scrap) as well as scrap generated from the manufacturing process (new, prime or prompt scrap). It is metal that contains iron. Iron and steel scrap can be processed and re-melted repeatedly to form new products. Due to the value of metal in the ferrous scrap, it is recycled or reused wherever it is possible.  In fact, ferrous scrap is being recycled long before current awareness of environmental concerns started. Ferrous scrap is generated during the production of iron and steel, fabrication or manufacture of iron and steel products, or when the product made of iron and steel reaches its end of life. Due to the high value of the metal, the ferrous scrap is largely being recovered. Given the chemical and physical properties of the material, iron and steel produced from ferrous scrap can, in almost all applications, compete with primary iron and steel produced from ore. However the amount of scrap collected and finally recovered depends on many factors, such as the collection system, the possibility and techniques used for the collection, etc. as well as a variety of legislation. The main sources for ferrous scrap are those products, for which iron and steel is the main constituent. These are namely, vehicles (including ships and rail coaches and wagons), products of construction, machinery, electrical and electronic equipment, and packaging etc. There is a difference between carbon steel scrap and stainless steel scrap since the carbon steel differs from stainless steel by composition and treatment. Carbon steel scrap is mainly used for the production of steel in induction furnace (IF), electric arc furnace (EAF) and partly...

Defects in Thermo Mechanical Processing of Metals...

Defects in Thermo Mechanical Processing of Metals  Thermo mechanical processing of materials is a technique designed to improve the mechanical properties by controlling the hot-deformation process. This was originally designed to produce the required external shape of the product. Controlled rolling, controlled-cooling and direct-quenching are typical examples of thermo mechanical processing. Such processing saves energy in the manufacture of steel by minimizing or even eliminating the heat treatment after hot-deformation, thus increasing the productivity for high grade steels. It normally requires a change in alloy design and often reduces the productivity of the hot deformation process itself, but at the same time makes it possible to reduce the total amount of alloying additions and to improve weldability, while sometimes producing new and beneficial characteristics in the steel. Thermo mechanical processing is the sophisticated combination of well-defined deformation operations and well-defined heat treatment in a single production stage to control the microstructure of the material being formed. It produces materials with the desired external qualities (dimensions, shape and surface quality) and acceptable mechanical properties. The process is normally considered as the final stage in the production of steels. Thermo mechanical process defects are usually focused on individual forming technique. The defects generally range from mostly macroscopic ‘form and fracture’ related defects to defects related to strain localizations, as well as imperfections related to microstructure.  The defects in case of thermo mechanical processing have two possible origins namely (i) process related, and/or (ii) metallurgical. The first one is usually related fully to the practices of the thermo mechanical processes including the forming techniques and the heat treatment, while the metallurgical origin defects can range from the starting solidification structure to structural developments during thermo mechanical process. It is difficult to establish a clear demarcation between the...