Galvanized Steel Reinforcement Bars...

Galvanized Steel Reinforcement Bars  Galvanized steel reinforcement bars (also called galvanized steel rebars) are the normal reinforcement steel bars which are coated with a protective layer of zinc (Zn) metal. Zn coating is usually carried out by hot dip galvanizing process. The Zn coating serves as a barrier to the corrosive environment which the rebars are exposed to when embedded in concrete. In addition to the barrier protection, Zn also provides cathodic protection where Zn corrodes preferentially when in contact with unprotected steel. This means that in case of any gap in Zn coating the surface of bare steel is protected by the surrounding Zn. The reaction between steel and molten Zn produces a coating on the steel made up of a series of iron -zinc alloy layers (gamma, delta and zeta) which grow from the steel-zinc interface with a layer of essentially pure Zn (eta) at the outer surface. What distinguishes galvanizing from other types of coatings is that the coating is metallurgically bonded to the steel. It actually becomes an integral part of the steel, as compared to the paints and epoxy coatings which are simply attached to the steel surface by physical bonding. The alloy layers in the coating are harder than the base steel resulting in a coating that is not only firmly adhered to the steel but is tough and hard and can resist abrasion and fairly heavy handling. It also allows the galvanized rebar to be handled, transported and fabricated in the same manner as ordinary steel. A typical galvanized coating structure is shown in Fig 1.  Fig 1 Galvanized coating structure  The first regular use of galvanized coating was done in USA during 1930s. Since then, and especially during the last 25 -30 years, it is being...

Development of Management Skills...

Development of Management Skills  Managers besides managing the work in the organization also manage the employees doing the work. Managers in the workplace, in fact, are the single most important factor in employee engagement, employee motivation, and building a productive workplace. Managers also manage self and personal skills, provide direction, facilitate change, work with people, use resources, and achieve results. (Fig 1) They are keys to the employee’s retention. Development of the management skills is significant for an organization since it builds the skills of the employees so that they can become effective managers and can provide a significant payback.  Fig 1 Functions of a manager  The option of the management development is critical to the effective functioning of the organization. This is because of the power of a manager to impact the organization through his oversight of the work of other employees. Different skills needed from a manager are as follows. Active listening – It means giving full attention to what other people are saying, taking time to understand the points being made, asking questions as appropriate, and not interrupting at inappropriate times. Critical thinking – Under this skill a manager uses logic and reasoning to identify the strengths and weaknesses of alternative solutions, conclusions or approaches to problems. Time management – With time management a manager manages his time and the time of the other employees. Management of personnel resources – It consists of motivating, developing, and directing employees as they work, identifying the best people for the job. Reading comprehension – It means understanding of written sentences and paragraphs in work related documents. Social perceptiveness – Under this skill a manager is aware of the reactions of the other employees and also understanding why they react as they do. Speaking – It...

Secondary Cooling Technology in Continuous Casting Process Jul31

Secondary Cooling Technology in Continuous Casting Process...

Secondary Cooling Technology in Continuous Casting Process  A wide range of steel grades ranging from ultra low carbon (ULC) and low carbon grades to high carbon and different grades of special steels are required to be cast in continuous casting machine (CCM). The casting of these grades is to be achieved while maximizing CCM output. Consistent production of prime quality cast steel product requires increased operational and maintenance flexibility in the CCM for maintaining optimum casting parameters can be maintained. This flexibility is needed both for every element as well as control system of CCM. While the strand is continuously withdrawn at the casting speed, solidification of steel continues beneath the mould through the different zones of cooling having a series of water sprays. The secondary cooling system consists of these different zones, each responsible for a segment of controlled cooling of the solidifying strand as it progresses through the CCM. The sprayed medium is either water or a combination of air and water (mist spray cooling). Mist spray cooling provides the following advantages. Uniform cooling Less water requirement Reduced surface cracking Product quality in a CCM is considerably influenced by temperature variations during strand cooling in secondary cooling zone. Hence secondary cooling zone has a very important function for the maintenance of a correct temperature parameter and is crucial to the quality of the cast steel product. Since the quality of steel depends on the behavior of the surface temperature and the solidification of steel front in time, it is to a large extent defined by the intensity of the water sprays. Improper cooling conditions can have detrimental impact on stress distribution in solidified shell. First of all, overcooling can lead to the formation of cracks. Moreover, there must be a smooth transition...

Fundamental of valves and their types...

Fundamental of valves and their types  Valves are mechanical devices. They are basic elements with which the flow of fluids and pressure within a system can be regulated. They are mainly used to control the direction of fluid flow as well regulate the amount fluid flowing through a particular system or a process. They perform any of the following functions. Starting and stopping or isolating fluid flow. This corresponds to on and off functions. Controlling or varying (throttling) the amount of fluid flow by change of direction or restriction. This corresponds to volume functions. Checking the flow or controlling the direction of fluid flow and preventing backflow. This corresponds to directional functions. Regulating downstream system or process pressure Relieving component or piping over pressure There are many valve designs and types that satisfy one or more of the functions identified above. A multitude of valve types and designs safely accommodate a wide variety of industrial applications. Regardless of type, all valves have the following basic parts: the body, bonnet, trim (internal elements), actuator, and packing. Valves work by creating a partial or complete obstruction in the flow of fluids. The formation of obstruction can be formed manually or by injecting automatic elements in the system. A manual valve is generally controlled by handles, pedals or levers. An automatic valve is generally driven by pressure changes (pneumatic valves), although there can be other versions as well, where they are driven by electrical signals (solenoid valves). Automatic valves are more common nowadays, except for operations which require human judgement. The regulation is accomplished by the varying resistance that the valve introduces into the system as the valve is stroked. As the valve modulates to the closed position the system pressure drop shifts to the valve and...

Interpersonal Relationship at Workplace...

Interpersonal Relationship at Workplace  Human beings need company most when they are afraid, anxious, or unsure of themselves and want to compare their feelings with those of others. Relationships help people to confirm and validate their ideas and feelings as well as to value themselves. Employees like common people are also social animals. They seek the company of others. An employee feels secure when there is a company of a co-employee, and he feels anxious when that co-employee is absent. This desire for human contact can be thought of as a two-pronged need; the need for attachment and the need for affiliation. These are two distinct, yet interrelated needs. Attachment – It is the need to form special close relationships Affiliation – It is the need to be with other people in general – a sense of belonging to a larger group. A strong association between employees working together in the same organization is called interpersonal relationship. Employees must get along well for a positive and healthy work environment at the workplace. An employee spends around eight hours at his workplace and it is practically not possible for him to work all alone. He needs co-employee to talk to and discuss various issues at the workplace. It is a common fact that the productivity increases manifold when employees work together in groups as compared to an individual employee working alone. Interpersonal relationship at workplace is nothing but close relationship between two employees working at the same place. Interpersonal relationships require good effort from the employees to nurture and maintain. A healthy interpersonal relationship gives an employee the most joy and satisfaction. An interpersonal relationship is an association between two or more people that may range from fleeting to enduring. This association may be based...