Manufacturing Process: Analysis and Specification - Coursework Example

Technical Report on Analysis and Specification of the Manufacturing Processing Name Institutional Affiliation Date Table of Contents Summary 3 1.0. Introduction 3 1.1. Rationale of the Report 5 1.2. Aims and Objectives 5 2.0. Summary of Possible Technology to be Used 5 3.0. Comparison of Machining and Casting 6 4.0. Design for Manufacturing Considerations 8 5.0. Detailed Manufacturing Plan 10 6.0. Costing and Pricing 11 7.0. Conclusion 12 References 12 Summary This report aims at providing details on some of the design for manufacture changes that would be made to the valve body. Further, the report gives an outline on how the valve body can be manufactured, the technologies used in the manufacture, the detailed manufacturing plan, costing and pricing, and finally, provides a brief economic analysis necessary for quote preparation by the manufacturing company. 1.0. Introduction A pressure relief valve has been designed to open, to get rid of excess pressure and to reclose, to prevent the excess flow after normal conditions have been met for safety purposes (Ashby, 1999). It should not be confused with pressure safety valves. In pressure safety valves, there is a manual lever to induce the working of the valve when need arises (during emergence conditions). Depending upon the design, it can be used for incompressible or compressible fluids. This device it is the only one that can prevent a catastrophic failure of the system once a state rather condition occurs that shoots the pressure levels to unwanted limits. Overpressure is experienced in the operation of chemical processing plants in many instances. Some of these situations arise from tube rapture, thermal expansions, blockages of fluid carrying pipes, check valve failure and sometimes utility failure. All these can lead to failing of the plant in terms of its operations. It is, therefore, critical to properly design the pressure relief valves in order to curb such incidences from happening (Nesbitt, 2007). From the studies, it has been proved a challenge in determining the required relieving capacity. By ensuring that the pressure in the vessel does not exceed the specified overpressure, it must relief a considerable good amount of the fluid used. It has also been recommended that the outlet of relief valve should be in the open air for the case of high-pressure gas systems (Nesbitt, 2007). If the outlet is connected to piping, it will eventually result to pressure building up in the piping system since the opening of the relief valve will directly contribute to pressure building. And therefore it will make the relief valve not to go back to its initial position when the set pressure is reached. It is recommended that differential relief valves be used in situations that demand placing the valve outlet in the pipes. But again this does not dispute the fact that connecting the relief valves to the outlet pipe system will open as the pressure in exhaust pipe system increases. This will generate undesirable operation conditions. It is used to protect equipment and piping against excessive over-pressure. Its design allows it to open to relieve the excess pressure and then it recloses when normal conditions have been restored. Many of pneumatic, hydraulic and electron systems exist for controlling fluid system changes like pressure, flow and even temperature. All these systems require power for them to run. It could be electricity or from compressed air. But the pressure relief valves should not be limited in their operation in the sense that they should be working at all times more so during power failure situations. 1.1. Rationale of the Report The rationale behind this report is to give insight into all that is required in the manufacture of pressure relief valves. It clearly demonstrates the factors that should be taken into consideration for a quality product that will meet the clients’ expectations. 1.2. Aims and Objectives The main objectives of this report are: To analyse and specify manufacturing requirements for the pressure relief valves. To apply the knowledge base in the manufacturing process and techniques. To identify the best manufacturing method for pressure relief valves. To identify the costing of the manufacturing method used. To establish the design considerations that should be looked unto in the manufacturing of the pressure relief valve. To identify the technologies that has so far been applied in the design of the device. To understand the manufacturing method identified into details. 2.0. Summary of Possible Technology to be Used The technology for manufacturing valves is based on the following steps: 1. Preparation of a flat circular metal plate where each has got a rectangular indentation at its circumference 2. Molding of the plates into the shape of a bowl, for the case of ball valves. 3. Removing of the circular bottom bowl shapes in order to reform a hemi-spherical shape by use of another mold. 4. Welding the pairs of the hemi-spherical shape into a shape of a sphere where each pair is aligned to the opening and the lateral rectangular hole that is through. 5. Trimming and grinding the uneven connection seams 6. Polishing and smoothing the outer surfaces in order to achieve a finished ball valve whose arc and thickness is uniform. 3.0. Comparison of Machining and Casting Casting is an old process of manufacturing. Valves made from this method undergo the very same process but different manufacturing process may be followed thereafter (Coughran, 1996). A good example is when we compare a faucet valve and a copper alloy valve. The two are made from copper alloy as their main material but we realize that the faucet demands further plating and washing processes. Again if we compare a cast steel valve with a cast iron valve, the cast steel valve again it demands cutting oil in the machining process and further it requires cleaning to get rid of the cutting oil. Old even back 6000 years. Basically it involves filling the molds with a molten material. After the material undergoes solidification, it automatically takes the shape of the mold. It is the first manufacturing process in the production of a multi-process manufactured part. However the complicated the design is, the metal casting can be able to, make the device. With this method, intricate parts can be made in a single piece. Careful choosing of techniques and casting parameters will make the method most efficient in production. In machining, a manufactured part is formed to the required shape by the removal of excess material from a work piece through the application of force through a material removal too. However the manufactured material is of lower shear strength. Besides, the high ductility of the polymer material is the reason as to why the removal of material is difficult & machining depends on the removal of material (Ouellet et. al., 2013). Thus, polymers and ceramics have poor machinability. In fact, machining process is more applicable to metals. Machinability does vary among metals; hardened metals present a particular problem, due to very high shear strength. In several circumstances, a metal is machined close to its intended shape before it is hardened. In that manner, the hardened material only has to undergo minimal finishing operations. Since it is a material removal process, wastes are very common. Machining is best for finishing purposes on the manufactured goods. As viewed above, it will be very feasible to produce the valve by the method of casting since it is best for large scale production. The figure bellow illustrates the diagram of a ball valve body in 2D with the plan, front and side views, alongside its 3D shape. 4.0. Design for Manufacturing Considerations Since the complexity of the device is directly related to its reliability, it is significant that designing the device be made as simple as possible. The design parameters need to be carefully looked unto for the proper working of the pressure relief valve. According to Matthews (2004), the materials used have to be compatible with the range of other viscous material. It should accommodate from ordinary air, water and even to the most corrosive fluid. It should be ensured that it is open at a set pressure, flow a specified rate of capacity at a certain limit of pressure and closes when the system returns to the required level. Another consideration in the design of this device is to ensure tight shut off. This is because the device experiences varying conditions and pressure for a considerable longer period. Evaluation of back pressure should not be overlooked. Its design also should ensure that it works even in power failure conditions. It is, therefore, significant that the material selection should posses enough strength that can withstand the temperature and the pressure of the system fluid. This material should be resistant to chemical attack by the fluid and the exposed environmental conditions. The bearing properties should be keenly selected especially for parts that have guiding surfaces. The tight shut off is taken into account by achieving a fine finish on the seating surfaces of the nozzle and the disc itself. Improper design can lead to failure of a stop valve to close, uncontrolled chemical reactions, fire outbreak, pump failure, control system failure and so forth. Therefore the combination of all these effects of improper design can be used to determine the required capacity. If multiple valves are used, then the required capacity that is determined from the combination of these worst conditions should be much less than the total relieving capacity of the valves used. Finally it will also factor in the rates of expansion that are caused by temperature of mating parts. 5.0. Detailed Manufacturing Plan The manufacturing of pressure relief valves basically comprises the following processes; casting, cleaning of casted pieces, mechanizing, coating and the testing (Baumeister, Sadegh & Avallone, 2007). The process of casting is a general term for each process of core molding, mold assembly, mold assembly, core insertion, pouring and shake out. The quality of these processes determines the final product quality. Therefore, casting forms an essential part in the process of manufacturing of valves. Phenol resin are used in Class I Designated Chemical Substances used in the casting process as binder for molding/core sand, acetaldehyde, xylene, phenol and formaldehyde contained in the furan resin. However they are disposed off as binder residue. A large mass of sand is used in the process of casting but most of it is recycled. The waste which cannot be recycled is disposed off. However we have only very little wastes hence no particular problems experienced. . In the cleaning process, the casted pieces are thoroughly cleaned for the next process which is mechanization (Taiwan, 2000). In this step the different pieces are joined together to form one complex device known as the valve. A lot of keen is needed here since making of any slight mistake will lead to the poor working of the valve in the sense that it can result even to system failure. An example is when joining the facets that are not smooth. It will lead to leakages. The mechanization process is critical in the entire casting method. Monitoring should be done ensuring even minor mistakes are not committed (Hellemans, 2009). After the mechanization, the device is coated with the specified paint. The purpose for doing this is to improve its desired life by providing a layer that will prevent the direct contact of the device surface to the surrounding environmental changes. To be most precise it prevents the valve from rusting and also reacting with the fluid that it will be in contact with. The last process is testing to ensure it is effective and whether the required efficiency has been attained. After the attainment of the set efficiency, the material is ready for packing. 6.0. Costing and Pricing A number of items are taken into consideration when machining a pressure relief valve. These include the cost of material, the mechanizing cost, the cost of machining, the cost of coating and labor cost. The Table below shows the unit cost incurred in manufacturing a unit pressure relief valve. Item Unit Cost in $ Material Cost 200 Mechanizing cost 8 Machining Cost 9 Coating Cost 10 Labour 7 Total Cost 234 7.0. Conclusion In the manufacture of pressure relief valves, it has been realized the design consideration should not be carelessly dealt with. Since this will lead to problems in the working of the device. Complications arise in the operation process of the device as mentioned above hence proper designing and the use of casting method are key to quality pressure relief valves. References Top of Form Top of Form ASHBY, M. F. (1999). Materials selection in mechanical design. Oxford, OX, Butterworth-Heinemann.Bottom of Form Top of Form BAUMEISTER, T., SADEGH, A. M., & AVALLONE, E. A. (2007). Marks' standard handbook for mechanical engineers.Bottom of Form Bottom of Form Top of Form COUGHRAN, M. (1996). Performance influences in globe control valves. Bottom of Form Top of Form HELLEMANS, M. (2009). The safety relief valve handbook design & use of process safety valves to ASME & international codes and standards. Amsterdam, Butterworth-Heinemann. http://www.books24x7.com/marc.asp?bookid=37846. Top of Form MATTHEWS, C. (2004). A quick guide to pressure relief valves(PRVs).London, Professional Engineering Pub. Bottom of Form Bottom of Form Top of Form NESBITT, B. (2007). Handbook of valves and actuators. Oxford, Butterworth-Heinemann. http://www.engineeringvillage.com/controller/servlet/OpenURL?genre=book&isbn=9781856174947. Bottom of Form Top of Form OUELLET, T., TOUGAS, B., MARIN, G., & JACOB, O. (2013). Titanium Cast Valves Repair with GTAW Process. MATERIALS SCIENCE AND TECHNOLOGY -ASSOCIATION FOR IRON AND STEEL TECHNOLOGY-. 2, 1179-1186. Bottom of Form Top of Form TAIWAN JING JI YAN JIU SUO. (2000). Pumps, compressors, taps and valves manufacturing. Taipei, Taiwan, Taiwan Institute of Economic Research. http://0-search.ebscohost.com.emu.londonmet.ac.uk/direct.asp?db=bth&jid=BLL0&scope=site. Bottom of Form Read More

Many of pneumatic, hydraulic and electron systems exist for controlling fluid system changes like pressure, flow and even temperature. All these systems require power for them to run. It could be electricity or from compressed air. But the pressure relief valves should not be limited in their operation in the sense that they should be working at all times more so during power failure situations. 1.1. Rationale of the Report The rationale behind this report is to give insight into all that is required in the manufacture of pressure relief valves.

It clearly demonstrates the factors that should be taken into consideration for a quality product that will meet the clients’ expectations. 1.2. Aims and Objectives The main objectives of this report are: To analyse and specify manufacturing requirements for the pressure relief valves. To apply the knowledge base in the manufacturing process and techniques. To identify the best manufacturing method for pressure relief valves. To identify the costing of the manufacturing method used. To establish the design considerations that should be looked unto in the manufacturing of the pressure relief valve.

To identify the technologies that has so far been applied in the design of the device. To understand the manufacturing method identified into details. 2.0. Summary of Possible Technology to be Used The technology for manufacturing valves is based on the following steps: 1. Preparation of a flat circular metal plate where each has got a rectangular indentation at its circumference 2. Molding of the plates into the shape of a bowl, for the case of ball valves. 3. Removing of the circular bottom bowl shapes in order to reform a hemi-spherical shape by use of another mold. 4. Welding the pairs of the hemi-spherical shape into a shape of a sphere where each pair is aligned to the opening and the lateral rectangular hole that is through. 5. Trimming and grinding the uneven connection seams 6.

Polishing and smoothing the outer surfaces in order to achieve a finished ball valve whose arc and thickness is uniform. 3.0. Comparison of Machining and Casting Casting is an old process of manufacturing. Valves made from this method undergo the very same process but different manufacturing process may be followed thereafter (Coughran, 1996). A good example is when we compare a faucet valve and a copper alloy valve. The two are made from copper alloy as their main material but we realize that the faucet demands further plating and washing processes.

Again if we compare a cast steel valve with a cast iron valve, the cast steel valve again it demands cutting oil in the machining process and further it requires cleaning to get rid of the cutting oil. Old even back 6000 years. Basically it involves filling the molds with a molten material. After the material undergoes solidification, it automatically takes the shape of the mold. It is the first manufacturing process in the production of a multi-process manufactured part. However the complicated the design is, the metal casting can be able to, make the device.

With this method, intricate parts can be made in a single piece. Careful choosing of techniques and casting parameters will make the method most efficient in production. In machining, a manufactured part is formed to the required shape by the removal of excess material from a work piece through the application of force through a material removal too. However the manufactured material is of lower shear strength. Besides, the high ductility of the polymer material is the reason as to why the removal of material is difficult & machining depends on the removal of material (Ouellet et. al., 2013).

Thus, polymers and ceramics have poor machinability. In fact, machining process is more applicable to metals. Machinability does vary among metals; hardened metals present a particular problem, due to very high shear strength. In several circumstances, a metal is machined close to its intended shape before it is hardened.

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