The Overall Manufacturing Cycle of Flange and a Proposed Manufacturing System - Research Paper Example

 1 EXECUTIVE SUMMARY Flanges are the most essential component or part that is being used exclusively in large numbers during a drilling process and even in the production phase of an oil and gas. This report is majorly concerned with the manufacturing and selection of materials, and processes regarding the assembly of flanges and ring gaskets in a well head equipment. Flanges are used to join pipes during drilling as well as in production these are used in two major equipments those are well head equipment and Christmas tree. For integrating pipes assembly flanges are very efficient tools as compare to other processes. By the use of flanges pipes can easily be integrated or disintegrated. For this purpose of easily assembling the pipes, the usage of flanges have superseded all remaining processes of assembly like welding, connectors, and manual fittings. Hence flanges are the most exclusive components that are used for joining and disjoining the pipes. In flanges, ring gaskets are used to seal the annular space between the two mating male and female flanges. In oil and gas sector it is very vital to prevent any leakage because the leakage can result in a disaster of the oil rig platform. Therefore designing of a flange and ring gaskets to seal the meeting of the flanges are vital element for consideration. Thus by the correct selection of material and processes ring gaskets and flange assembly can be assured for proper working so to avoid any big loss. 2 INTRODUCTION Now in this report, it has two products and their assembly; the report will focus for process and material selection for the manufacturing of the two products. These two components are flange and ring gasket. These are used in well head equipments. Now the sizes and dimensions are actually defined by the customer and the type and size of well head equipment used. Well head equipments are the primary equipment used in drilling and production of oil and gas. This equipment is installed at the land of the well. This equipment is used to deliver the hierarchal and over all support to all the drilling and production structures. The major purpose of the equipment is to provide the necessary support to the suspension area as well as the tubing that go deep in to the well. There are other several functions of the well head equipment these includes sealing of the casings, a way for accessing well, attachment of Christmas tree or production valves on the top is only possible through well head equipment. Now the flanges are used to connect different parts of well head, as well as the pipes within the well. The pressure of the mud coming out of well is huge and thus the design specifications of the well head equipment should be accordingly catered. Now the flanges are the integral part of the well head equipment, their design considerations and specifications are vital in manufacturing, any problem in its designing can even maltreat the whole project of oil and gas or can result in severe consequences. 3 DESIGN QUERIES 3.1 Functions Of Components And Equipments So for the flange assembly we need to know few things, the components of the flange assembly and the desired location where these flanges will be used. So for this purpose the following equipments need to be visualized and understood. This flange assembly includes Flange, Ring Gaskets while the other locations where these will be used are Christmas tree and well head equipment. 3.1.1 Flanges: Flanges are comfortable devices used for immediate assembling and disassembling. If ring gaskets or sealing is not used in these flanges then there will be leakage. 3.1.2 Ring Gaskets: These are components that are used for flange assembly in order to seal the flange assembly. Their manufacturing is of high importance and their functional credibility is a major concern. A typical assembly of flange and ring gaskets is shown in this figure. 3.1.3 Well Head Equipment: As discussed earlier in introduction, well head equipment is an assembly of different component; primary purpose is to provide support for drilling strings deep inside the well. Flanges are the essential component of this equipment. It is placed at the surface of the well. 3.1.4 Christmas Tree: Christmas tree is equipment that is mounted just above the well head; this equipment is used for production controlling, production delivering and adding additive chemicals into the mud material. This equipment is also composed of flange assembly and is joined by the well head equipment with a flange assembly. 3.2 Materials For Flange Assembly Components Now, as the flange assembly is to be used in these equipments, here quality and reliability of the flanges are our primary criterion for manufacturing of the component and its assembly. Now the flange assembly’s ring gaskets can be made up of materials like: soft iron, low carbon steel, 304 stainless steel and chromium resistant alloy. The selection of a specific material is identified by API 6A. API 6A is a standard that governs all the manufacturing related to well head and Christmas tree manufacturing. So according to specific hardness one can identify the material of ring gaskets to be used by using API 6A. As far as the flanges are concerned, a detail guide is provided in API 6A to select their material. Usually low alloy steels and martenstic stainless steels with different alloying compositions are used for this purpose. The alloying elements include a long list of carbon manganese, silicon, phosphorous, sulfur, nickel, chromium, molybdenum and vanadium. For the assembly of female and male flange with gaskets an nuts, studs and bolts are used made up of the same material of the flange so to avoid any non uniformity of material that may result in failure. Corrosion is a great challenge for these environments of well head, therefore alloying elements with different proportions are used for this purpose so to avoid corrosion or rusting phenomenon and test and inspection, and overhauling of the equipments after a specific time period on the well is done for the same purpose of avoiding any chance of such failures and ruptures. 3.3 Proposed Processes For Flange Assembly Components There may be several processes for the manufacturing of a flange and a ring gasket. For ring gaskets we have following suggested methods: Forging Casting Piercing tubes or pipes API 6A defines the processes as well to manufacture the ring gaskets. Well these are the alternatives any of these can be used for the purpose of manufacturing flanges’ ring gaskets. Similarly for flanges it we can use following processes all having their own advantages and disadvantages: Forming process for flange Machining processes on a disk Casting In the discussion of process selection, the best optimum process to manufacture the components will be discussed. 4 DESIGN SPECIFICATIONS Design specifications are provided by the customer itself. The oil and gas production companies are the clients for the manufacturing of flange assembly, they will define the maximum pressure rating, maximum temperature rating, hardness requirement, environmental chemicals, sizes of the components they need. On account of which other design specifications, nut diameter, bolt diameter, threads, ring gaskets, flanges types and other criterions will be selected. The selection is based on the detailed API 6A, where all sizes tables for each component of a flange is defined, moreover material requirement can also be specified from there. API 6A provides explanation for all flanges, ring gaskets, studs, nuts and bolts. Table 4 and table 5 of API 6A specifies the material rating of the required flange when pressure rating is defined by the customer. For example the pressure rating is 207 MPA then the flange material designation is 75K, on which we can find the yield strength, the tensile strength from table 5 as for 75k it is 517 MPA material yield strength, and 655 MPA tensile strength and other physical requirements of the material can be well understood from these tables. Both the two tables are discussed in other section material selection. 5 MATERIAL SELECTION Now as for the material selection of ring gaskets section 5.5 of API 6A tells us about the following table, in which we can see that maximum hardness rating is there. Because ring gaskets play their part on sealing areas where these are permanently indented hence hardness is the criterion for selection. So the client specifies the maximum hardness value which is usually proposed more than the operating value. API 6A enables us to identify the material of ring gasket directly. When we come to flange materials, pressure rating is the factor to decide the material type or gradation. Table 4 API 6A reveals us that on different pressure ratings there are different gradation of materials. This gradation is noted for the purpose to study material properties from API 6A. As we have got the material gradation from table 4, we will use this gradation to specify the material properties. These material properties can help in directly selecting a material fulfilling such property. For example 60K is our material designation then the table shows us that yield strength is 414 MPA and other physical quantities can also be found on the same. Through table 8 we can select the alloying elements or material composition by just a specific designation of material. It is again not necessary to use any material composition fulfilling the material properties specified by table 5 can be used. 6 MATERIAL SELECTION TABLES Ring gasket materials as discussed earlier can be found out easily. The below table is formed with the help of API 6A. The under table under section 5.5 and table under section 8.7.3 of API 6A are merged together, only the hardness values are taken in HBW instead of HRB in the following table: Where CRA stands for corrosion resistant alloy, this column is left for customer choice in API 6A. Through the above table of API 6A material specification for ring gasket will not be a problem for engineers. The details of Flanges’ material can be selected from the following table after analyzing all before parameters of material selection. This table not only tells the material but also the type of flange that will be used for the specific yield value or HBW value. Connections Material Min. Yield/Min. HBW 6B Weld Neck Flanges Carbon Steel 45K/140 Integral Flanges and Hubs Low Alloy Steel, or 410 Martinsitic Stainless Steel 60K/174, 75K/197 6BX Weld Neck Flanges Low Alloy Steel 60K/174, 75K/197 7 PROCESS SELECTION In the early section, we discussed the process selection for manufacturing components like ring gasket and flange. Here we will discuss the best optimum process for our usage in this specific perspective of well head and Christmas tree. 7.1 Ring Gaskets Process Selection For ring gaskets we have following suggested and alternative methods: Forging Casting Piercing tubes or pipes Piercing tubes or pipes and forging are not our option because it is not defined in AI 6A because of the fact that piercing dies for every time changed designed flange is not possible. It is because a die is used for batch processing, here orders are specialized not even batch hence every product is unique is some aspects. So every time we have to cater the die manufacturing cost, it will be an extra expense. Piercing tubes or pipes are valid where there is batch production and mass production of ring gaskets. On the other hand if we go for centrifugal casting, it is the only method API 6A endorse. Centrifugal casting is highly precise and accurate as compare to other castings, more over the horizontal and vertical axes machines for centrifugal castings can be programmed for various changes in the design of ring gaskets, hence with minor change in program a new design of ring gasket as demanded by the customer can be produced. The part produced by centrifugal casting require little machining, so it is affordable. Further the melting of the material for ring gaskets should be highly controlled. This same molten metal is fed into centrifugal casting. Therefore ring gaskets molten metal should be uniform in crystal structure to avoid any sort of future damage that can result due to material impurities. There are other heat treatment processes that should be done with the ring gaskets to add more strength and reliability to their functions. It can be treated with normalizing, annealing or any other. This is incompliance with API 6A. 7.2 Flanges Process Selection For the manufacturing of flanges, we got following alternative methods as discussed in the earlier section: Forming process for flange Machining processes on a disk Casting There are few problems and limitations if we go on forming process for flange, this is because flanges will fracture soon, and the forming process will take the help of plastic deformation to give the required shape of the flange. The material will be under the effect of stresses and hence the stresses can be trapped therefore the material when it will be working might rupture. The other reason is the same, for every new type of flange a new die is required which is too costly. On the other hand if we go CNC programmed machining, this is a good process in the long term. The process is flexible for any change and the resultant strength required can be achieved with high surface finish and timely product. Centrifugal Casting is not recommendable for this process it is because flanges have different features which cannot be achieved through centrifugal casting, hence programmed machining is compulsory. Why not use CNG programmed machining from the inception?? Definitely both in terms of cost and process reliability CNC programming is the best option for manufacturing a flange. The orders that clients make every time is neither exactly similar, not these are entirely different. This means that group technology should be implemented in such manufacturing facility. Every type of flanges is associated with part classification and coding scheme. For every order a part family is to be selected which suits the order best. A part family should be grouped on similar designing features, so that a new order can be easily designed on the basis of existing part family design. Few alterations will be enough and the soft version of the design is then to be programmed automatically through CNC, and then the resultant part is produced in just the nick of time. There should be a composite part for each part family that contains all the complex features of all the parts in part family. This composite part is actually to be modified with the help of CAD software available with the CNC. This how an optimum proposal of manufacturing plans for above assembly of flange can be designed. The assembly of the two mating flanges is simple. A nut, bolt and stud are required. The spacing area is filled with the ring gasket while the flanges are joined with the help of nuts, studs and bolts on all the required areas of the flange. The flange assembly looks like as ring gaskets sandwiched between two male and female flanges. 8 RELATED STANDARDS The old standard that governs the manufacturing of flange assembly in well head equipments was ISO 10423, which was last updated in 2003. The modified and most updated standard is API 6A or ANSI 6A standard. This standard is especially for the purpose manufacturing and producing well head equipments and Christmas tree. The whole report is therefore based on the above standard of API 6A that proposed a detail guide of all the manufacturing ins and outs for the flange assembly which we analyzed. The standard even provides the details of even the little components of flange assembly like nuts, bolts and studs for assembling purposes. API 6A can also be called as an updated version of ISO 10423, because API 6A is also authenticated by ISO as well as other international standards. Professional service companies are getting API 6A certification to gain confidence of their customers. Hence when we talk about the manufacturing of a flange assembly in a specific environment of well head it is very unusual that we don’t take into account API 6A license. Therefore whole of our report is related and conformed to API 6A. 9 CONCLUSION The report explicitly identifies the general processes and material selection criterion in conformance with the standards for the manufacturing and production of a flange assembly. It not only focuses on material selection of a specific type of flange assembly, but it provides an extensive outlook of the overall manufacturing process for any type of flange assembly with different design. For this purpose the incorporation of relevant standard is tried to be done at every step whether its process selection, material selection, material selection tables, design specifications, or any other things. The extensive nature of the analysis will make it easy for the reader to understand the overall manufacturing cycle of flange and a proposed manufacturing system can work best in given alternatives. This analysis will give a good idea of the flange assembly manufacturing and also the mode where, how and in what domains should the operations be carried out in order to achieve proper and great results. The service sector in oil and gas is one of the booming sectors, without this sector production of oil and gas is not possible, and therefore flanges are also the necessary part of production of oil and gas, hence the report focuses a crucial economic component manufacturing that has got immense market demand and importance. APPENDICES TABLE EXTRACTED FROM API 6A TABLE EXTRACTED FROM API 6A TABLE EXTRACTED FROM API 6A TABLE EXTRACTED FROM API 6A 11 BIBLIOGRAPHIES: American Petroleum Institute. API Composite List. API. [Online] Available from: http://compositelist.api.org/. [Accessed: 25 December 2010] API (2004) 6A Specification for Wellhead and Christmas Tree Equipment. Northwest Washington, API. API. API 2010 Publications Programs and Services. s.l.: API, 2010. Baker, Ron. A Primer of Oilwell Drilling. 6th edition: Amazon Publishers. Nayyar, Mohinder. (1999). Piping Handbook. New York : McGraw-Hill, 1999. ISBN 0070471061 Pakistan, Department of Industrial and manufacturing (2010) Feasibility Study Of A Manufacturing Facility To Develop API 6a License IMD NEDUET KARACHI. Rabia, H. (1985). Oilwell drilling engineering : principles and practice . London: Graham and Trotman, 1985. ISBN / 0860106616 William C. Lyons (1996) Hand book of petroleum and natural gas engineering Houstan, Texas Gulf publishing company. William C. Lyons Gary J Plisga (2005) Standard Hand book of petroleum and natural gas engineering Houston, Texas, Gulf professional publishing. Read More