Oil Storage Tank Design - Report Example

Table of contents Introduction………………………………………………………………………… 1 Types of oil storage tanks………………………………………………………….. 1 Fixed cone roof tanks………………………………………………………………. 2 Floating roof tanks…………………………………………………………………..3 Sphere and bullet tanks……………………………………………………………..3 Underground storage tanks…………………………………………………………4 Factors to be considered in the design……………………………………………...4 Metal temperature…………………………………………………………………...4 Pressure………………………………………………………………………………5 Specific gravity of stored liquid……………………………………………………..6 Corrosion allowance…………………………………………………………………6 Other loads…………………………………………………………………………...7 Materials of construction……………………………………………………………8 Types of roofing……………………………………………………………………...8 Spacing……………………………………………………………………………….9 Mechanical design of oil storage tanks…………………………………………….11 Design stress………………………………………………………………………....12 Construction categories and welded joint efficiency……………………………...12 Minimum practical wall thickness…………………………………………………13 Instrumentation……………………………………………………………………..15 Safety concerns……………………………………………………………………...15 Area classification…………………………………………………………………...16 Conclusion…………………………………………………………………………...19 OIL STORAGE TANK DESIGN IN OIL INDUSTRY Introduction Oil storage tanks within the oil industry are of two major types. The first type is the above ground and the underground tanks. Above ground tanks are used in the refining, production, marketing and operations of the pipeline. Underground tanks are normally used in retail service stations for marketing gasoline (Snow 2003 pp. 172).  Oil storage tanks therefore play a very important role in the oil industry. Their design should therefore be done with a lot of care to ensure that they last long and that there will be no losses of oil in the future due to leaking and spills. They should also be designed in a manner that will make maintenance easy. These are some of the factors to consider in the design (Stephenson 2008 pp. 67). In this report the design of oil tanks within the oil industry will be discussed. This report will delve into the factors to consider in the design, the materials of construction, types of roof to be put on the tank, instrumentation, spacing, Mechanical Design among other things. Types of oil storage tanks In the oil industry there is a broad range of tanks used for storage. Depending on the type of tank or the options for mounting, a given measurement solution or tank gauge may prove to be more suitable. Tanks are chosen based on the flash point of the liquid that the tank holds. In refineries, terminals and tank farms that store petroleum based liquids floating roof tanks and above ground tanks with fixed roofs are used. Such tanks operate under very little or no pressure. Storage tanks come in various shapes including horizontal cylindrical, vertical cylindrical, closed top and open top, cone bottom, flat bottom, dish bottom and slope bottom. Huge tanks are normally vertical cylindrical or may have rounded corners transition from vertical side wall to bottom profile so that they can easily withstand the liquid’s hydraulic hydrostatically induced liquid (Swenson, Fenton, Zhi Lu & Baalman1997 pp. 234). Fixed, Cone Roof Tanks Fixed dome or umbrella, cone roof tanks are very common and vessels for bulk oil storage in the oil and gas industry. They mostly have a stair case wrapping around them. Their heights go up to 30 meters and may be 100 meters wide and their main purpose is the storage of liquids whose flash point is high such as heavy oil, fuel oil, diesel oil, kerosene among others. A dome is added at the top to reduce environmental emissions and to give more strength so that the oil can be stored at a higher pressure compared to atmospheric pressure. Tape tank and float gauges may be fixed at grade on the side of the tank or on the roof of the tank (Bjorhovde, Colson, Zandonini 1996 pp. 54). Figure 1; The imkage of a fixed roof oil storage tank (Swenson et al1997 pp. 137) Figure 2; The diagram of tank showing the roof, base and shell (Bjorhovde, Colson & Zandonini 1996 pp. 100) Floating Roof Tanks Certain oil storage tanks must have a storage tank added on the fixed roof. A device for sealing is fixed at the peripheral space between the shell plate and the roof that serves as the device for safety and prevention of pollution by trapping vapor from products with low flash point. Floating roof tanks can be divided into external floating roof tanks (EFR) and internal floating roof tanks (IFR). IFR tanks store liquids that have low flash points. These are cone roof tanks and there is a floating roof within the tank that travels up and down depending on the level of the liquid. EFRs are open on the top side and lack any fixed roof. Because of this they are good for medium flash point liquids such as naphtha, diesel, kerosene, crude oil among others (Yamamoto 1979 pp. 210). Sphere and Bullet Tanks They are normally Cylindrical, flat bottomed, spherical single and double shell storage tanks. They store gases in liquid form with extremely low flash points such as LPG, LNG, ethylene ammonia and butane at temperatures below 100 degrees Celsius or under pressure. Bullet tanks get their name from their characteristic cylindrical shape with flat or round ends. They have a capacity of 5000 to 30 000 gallons fabricated with installation done in a vertical or horizontal manner (Bjorhovde et al 1996 pp. 56). Underground Storage Tanks Underground storage tanks (UST) store petroleum based products and are regulated to avoid the leakage of petroleum and ground water contamination. In some countries they applicable at automobile fuel filling stations. They also occur in military bases, tank farms and air ports. They are made form steel, glass fiber or aluminum and are normally made with double walls and shaped like bullets and buried in the ground (Bjorhovde et al 1996 pp. 107) Factors to be considered in the design In the design of tanks for storage of oil a number of factors need to be considered. These are metal temperature, specific gravity of oil, pressure, corrosion allowance, other loads and settlement. Metal temperature According to Snow (2003 pp. 172) the metal temperature of the components of a tank for oil storage is known from the operating requirements of the liquid stored in it and from the ambient temperature at the location of the tank. Process engineers determine the requirements and conditions for operation of the liquid stored in the tank. The design of the tank should take into consideration the both the lowest and highest temperatures that the tank may be exposed. Maximum operating temperature to be considered in the design of the tank and the design metal temperature should be the lowest temperature to be considered in tank design. Maximum operating temperature is the one to determine allowable stress used for the design of the components of storage tanks. Allowable stress for every material is normally constant in all temperatures until it gets to 93 degree Celsius. However allowable stress for all materials falls for temperatures over 93°C. The metal temperature of the material used in the design has a big influence on the selection of the material for the tank. If the design metal temperature that has been specified is bigger than necessary based on particular tank applications there could be a brittle fracture on the tank. Design metal temperature relies on ambient conditions for many of the storage tanks (Snow 2003 pp. 190).  Pressure Internal pressure that the tank will operate at is the determining factor of the standards to be followed in the design of the tank and the other components associated to it. The national standards for oil storage tanks should be followed. The internal operating pressure should be determined by the process engineers with consideration of the operating requirements of the liquid to be stored. If the specification of operating pressure is not done correctly then the storage tank design will definitely not be right. Depending on actual pressure magnitude the error in specification could lead to too thin roof and shell or nozzles that lack reinforcement for the pressure to be applied. This error could have consequences such as ductile fracture of the components of the tank or permanent deformations (Yamamoto 1979 pp. 341). Specific gravity of the stored liquid Specific gravity with the liquid depth both determines the liquid’s hydrostatic pressure. The total hydrostatic pressure at any particular elevation in a tank should be considered when determining the real tank shell thickness. Storage tanks are designed for specific gravity of water since water is filled in the tanks for purposes of testing after construction. If the specific capacity of the oil to be stored in the tank is more than that of water or 1 then the tank should be designed for a specific gravity that is higher (Stephenson 2008 pp. 111). Corrosion allowance Storage tank components can have the metal wearing off because of corrosion resulting from the action of the liquid stored in the tank. For compensation purposes of the metal lost, a corrosion allowance could be added to the thickness of the metal to provide strength. The corrosion allowance tends to offset any deterioration of the components of the storage tank when in use. Where necessary the corrosion allowance should be added to the shell required thickness that has been calculated, structural members and internal components that could be used to give support to the fixed roof (Swenson et al1997 pp. 32). A corrosion allowance must not be added to the roof or bottom thickness. Corrosion can at times take place on the outside of the tank shell or roof. Corrosion of this type occurs when there is poor local drainage or the paint system on the outside has deteriorated. Corrosion allowance should not be added to the thickness of the metal because of external corrosion. If the shell of a storage tank corrodes in the course of operation and the corrosion allowance was not specified properly the stress within the shell can increase beyond the allowable stress. When it becomes extreme there can be a permanent deformation in the shell where a hole may develop through it incase it is too thin and this may lead to a ductile fracture (Swenson et al1997 pp. 37-40). Other loads According to Bjorhovde et al (1996 pp. 134) it is also important to consider other loads apart from pressure in the design of an oil storage tank. These loads include earthquakes, wind, loads imposed through connected piping systems as well as other attachments on nozzles and the accumulation of rainwater on external floating roofs. Tanks should be checked to ensure that they are stable enough to overcome overturning moments resulting from the pressure of wind. A tank shell could lose its shape if it is not properly designed for the wind velocity that could be area of its location. When the shell loses its round shape the result could be the binding of floating roofs or cracks may form in the welds of the shell. Requirements for overturning moments are important storage tanks with small diameters because the weight of the tank may not be enough to overcome wind load. There could be need for anchor bolts so that the tank does not turn over (Stephenson 2008 pp. 65). The minimum needed thickness for the shell of the tank for the liquid the tank is defined for minus corrosion allowance should be used in determining wind girder requirements for tanks with external floating roofs. Wind girders can prevent tank shell loss of the round shape that could result from wind loads. Seismic loads should also be considered with the applicable seismic zone specified. There could occur a rapture of the tank if its design does not match the required seismic loads. Nozzles should be designed for static liquid loads as well as the loads applied through connected piping. Loads applied by piping connected to the nozzle of a tank put more local stress in the neck of the nozzle, the shell adjacent to it and the attachment weld associated to it. If these additional stresses are very high they can result into formation of weld cracks in the shell or nozzle. It is important to confirm that the loads from the pipe and not too much (Swenson et al1997 pp. 168).  When designing tanks for the storage of oil it is important that relevant standards like the British Standard 4994 (1989) that provides advice on the thickness of the wall, procedures for testing, procedures for quality control, accreditation, design criteria and fabrication of the end product (Stephenson 2008 pp. 119). Materials of construction There are a number of materials from which oil storage tanks can be made from. These materials include mild steel plate, stainless steel, plastic and anodized aluminum. Anodized aluminum and stainless steel are relatively expensive but their costs of maintenance are not high. There are cases in which stainless steel of a thinner gauge can be good to contain the costs of construction. Some designs of mild steel tanks and processes of fabrication need shot or sand blasting added on any of the following materials depending on what kind of product will be stored in that tank. The materials are lanolin based rust preventive, paint that is resistant to oil, exposy resin or plastic coating and aluminum spraying. It is not advisable for galvanized steel to be used for making tanks because of the risks associated with reactions of the additives in the formulated oil. Seams of tanks are riveted or welded. The advantage of using poly tanks or plastic is that they are rust proof and it is possible to see the level of fluid because of the clarity of the materials (Bjorhovde, Colson, Zandonini 1996 pp. 79). Types of roofing There are two major types of roofs for tanks used for oil storage in the oil industry. These are the fixed and floating roofs. Tanks for any given fluid are picked based on the substance’s flash point. Fixed roof tanks are used for storing liquids that have high flash points like oil. This type may have cone roofs that are shaped like a cone, dome roofs where the roof is dome shaped and umbrella shaped roofs. Floating roof tanks are normally divided into external and internal floating roof tanks. Some tanks have both the floating roof and the fixed roof. The floating roof reduces the space for vapor within the liquid since it rises and falls with the liquid. Floating roofs act as a safety requirement and also a measure for prevention of pollution (Swenson et al1997 pp. 89). The floating roof tanks are the ones mostly used in decreasing losses of volatile fluids kept in them. They are used with tanks that are open at the top or they may be fixed inside the fixed roof tanks. They are also used in closed tanks. Figure 4; A tank showing floating roof (Snow 2003 pp. 174)  Spacing The oil storage tank layout and spacing must consider the necessary accessibility for fighting fires and the value of a tank farm to provide a buffer space between the process plant and houses, public roads and other facilities for environmental concerns. The tank should be located in a place that will ensure safety and prevention of accidents from process units. Spacing between tanks and separation distances from boundary lines and the rest of the facilities are very critical. Good roadways need to be provided to be used for approaching the sites where the tanks are especially by fire fighting personnel and equipment. The fire water system must be there to give enough protection from fire to every area of oil storage and facilities for transfer. Bunding and draining the areas around the tanks has to be done in away that makes it easy to control spillage of oil from any tank in order to reduce any more damage to oil tanks and their contents. This should also be able to reduce the possibility of other tanks close by being damaged as well. Storage tanks with flammable liquids need to be located in a manner that spills don’t flow into a process area or a place where it can be ignited (Swenson et al1997 pp. 210). The spacing of a tank with a fixed or floating roof in a group of small tanks is determined by the convenience of construction or maintenance operations. Where there are small and large tanks mixed together, a floating or fixed roof tank should be given a space of a minimum of 10 m. otherwise the spacing is determined by the size of the bigger tanks. Spacing between adjacent individual tanks with fixed roofs which are not small tanks with should be half the larger tank’s diameter but should not exceed 15m (Yamamoto 1979 pp. 56). The spacing between the tank with a fixed or floating roof and the top of the inside of the wall of its compound should be equal to not less than one half of the tanks height. Spacing between the tank with a fixed or floating roof and a public fence boundary should be not less than 30 meters. There should be a distance of not less than 15m between the top of the inner side of the wall of the tank compound and a boundary fence (public) or any ignition source that is fixed in its place (Stephenson 2008 pp. 145). A fixed or floating roof tank should be spaced 30m or more from a battery limit of a process plant. Tanks that have a diameter of 10m are categorized as small tanks. Where there are anticipated future changes in tank storage spacing and layout needs to be designed for the case that is most stringent (Snow 2003 pp189). For purposes of accessibility for fire fighting there should be less than two tank rows between adjacent access roads. Those tanks that have fixed roofs floating covers in the inside need to be treated as fixed roof tanks for purposes of spacing. Where there are adjacent fixed roof and floating roof tanks spacing should be done based on the tanks that has the most stringent conditions. In places where there are compressible soils the space between adjacent tanks needs to be enough to prevent too much distortion. They may result from additional settlements on the ground in which the zone of the stressed soil of a single tank is overlapping that of a tank close to it (Swenson et al1997 pp. 234). Mechanical design of oil storage tanks Mechanical design of oil storage tanks should consider a number of factors. These factors include design pressure and design temperature. As far as design pressure is concerned the tank is designed in a manner that it can withstand both maximum external and internal pressure from the oil that will be stored in it. Since the tank is affected by pressure from the oil within it, design pressure is taken as 5 or 10% which is the pressure of the relief device. The tank must be designed to resist maximum differential pressure that could occur in operation. Tank mechanical design is done by mechanical engineers who know the current design practices and design codes and stress analysis methods (Myers 1997 pp. 123). Design temperature is also important in tank design because the strength in metals falls with rising temperature. This means the maximum design stress that can be allowed depends on the temperature of the material. Design temperature for evaluating the design stress is taken to be the material’s maximum working temperature that is used in the prediction of the temperature of the walls (Swenson, Fenton, Zhi Lu, Baalman, 1997 pp. 45). Oil storage tanks are made from high and low carbon alloys, plain carbon steels, other alloys, reinforced plastics and clad plate. When the material is being selected consideration must be made about how suitable the material is for fabrication especially welding and the compatibility of that material with the process environment. The standards and design codes include the lists of acceptable materials based on the appropriate material standards (Swenson, Fenton, Zhi Lu, Baalman, 1997 pp 56) Design stress For purposes of design it is important to decide a suitable value for the maximum allowable stress or nominal design strength acceptable in the construction material. To determine this, the engineer will have to apply a suitable factor of safety or design stress factor. To the maximum stress that the construction material can withstand without failing when subjected to standard test conditions. Design stress factor allows for uncertainties in design methods, material quality, loading and workmanship. If the tank is not expected to be subject to high temperatures design stress must be based on proof stress or yield stress or tensile strength also called ultimate tensile stress of the construction material at design temperature (Myers 1997 pp. 136). Construction categories and welded joint efficiency The welded joint has strength depending on type of joint and welding quality. Non destructive testing or radiography is used to check the soundness of welds. The lower strength of the joint in comparison to the virgin plate is normally allowed for in the design by multiplying allowable design stress for that material to be used by ‘J’ which is the welded joint factor. The joint factor value used in design depends on joint type and amount of radiography that the design code requires. Taking the joint factor as 1.0 means strength of the joint is the same as that of the virgin plate in terms of strength. This can be done through radiographing the whole weld strength, cutting out then remaking the defects if any. When lower joint factors are used in the design radiography costs will be low but the result will be a tank that is thick and heavy and this means the designer should strike a design between fabrication and the costs of inspection against high material costs (Stephenson 2008 pp 78). Minimum practical wall thickness There is a minimum thickness for the wall that is needed to ensure that the storage tank being designed will be strong enough to support its own weight and any other incidental loads without buckling. Generally the thickness of the wall must not be lower than the values in the table below. Included in these values is a corrosion allowance of 2mm (Swenson, Fenton, Zhi Lu, Baalman, 1997). Tank diameter (m) Minimum thickness (mm) 1 5 1 to 2 7 2 to 2.5 9 2.5 to 3.0 10 3.0 to 3.5 12 Figure 5, recommended values for tank diameter and minimum thickness (Stephenson 2008 pp 57). The designer however needs some specialist data to be able to complete the design. This data includes the function of the tank, process services and materials, design and operating temperature and pressure, construction materials, orientation and dimension, type of heads to be used, connections and opens required and specification for internal fittings (Stephenson 2008 pp 58). Vertical cylindrical tanks, with conical roofs and flat bases are used universally for storing liquids at atmospheric pressure. The size of a tank may vary from tens of cubic meters to hundreds of cubic meters. Hydrostatic pressure of the oil is normally the main load that is considered but there is also the load from wind and snow. The minimum thickness of the wall needed to overcome hydrostatic pressure may be calculated from equations for membrane stress in cylinders. For small tanks there should be a constant thickness of the wall should be used with the calculation done at maximum depth of the liquid. For big tanks the variation expected in hydrostatic pressure with depth is taken by increasing plate thickness in a progressive manner from top to tank bottom. In the construction of tanks plates commonly used are those with widths of 6 feet or 2m (BS 2654 1989 pp. 13). Tanks roofs are designed with supports of steel framework. When the diameter of the tank is massive it is supported on columns. Atmospheric storage tank designers and engineers in the oil industry should consult the British standards BS 2654. Instrumentation Tank Instrumentation and gauging helps in the determining the level of contents in the storage tank at a particular time. Instrumentation for fluids in tanks can be done by the level and flow electronic instrumentation. Continuous measurement of levels and flow is done with this technology although it is only seventeen years old. The major advantage of this kind of technology is that one obtains a level measurement without any consideration of the oil properties. This technology gives very accurate measurements of levels in various applications with differing turbulence, vapors or form over a wide pressure and temperature range. Measurement of the rates of emissions from tanks can be done using Magnetron’s TA2 mass flow meter fro thermal dispersion. The instrument gives an advantage because mass flow measurement can be obtained directly on the rate of flow over a big range of conditions of operation. The technology gives good sensitivity during low floor and this makes it measure low rates of flow and to provide high turn down capabilities. This instrument is easy to install in the piping of the tank and it the flow rate measurement and the totalized flow as well as the indication of the elapsed time to provide total rates of emission within a particular interval of time (Swenson, Fenton, Zhi Lu, Baalman, 1997 pp.51). Safety Concerns The national electric code has standards that need to be followed in the installation of an electrically powered device on tank that that has explosive or flammable liquids and vapors. Third party agencies test the equipment to ensure adherence to standards and that the equipment can be used in hazardous places. When working with instrumentation in places with hazards one needs to consider the definition of the area classification and protection method that is used for meeting the standards (Stephenson 2008 pp 80). Area Classification Area classification can be defined by class referring to the category of material type, division referring to the frequency of hazardous condition taking place, group referring to type of flammable material considering its energy of ignition. Class Type of material Class 1 Vapor, flammable gases, or liquids occur in the air in such quantities that can explode Class II Combustible dust and powder in suspension in the atmosphere enough to explode Class III Flammable fibers in air in quantities that can explode in the atmosphere Figure 6; Class and type of material (BS 2654 1989 pp. 41) Applications within the petroleum industry normally deal almost exclusively in liquids, gases and vapor that are hazardous and they fall in class I. Division Division Frequency of occurrence of hazardous condition Division 1 Hazardous places are where there is continuous or intermittent existence of a hazardous atmosphere under fault or normal conditions of operation. Division 2 Hazardous areas close to division 1 location or place where there is an infrequent existence when there is equipment break down or fault. Figure 7; Division and frequency of hazardous condition occurrence (BS 4494 1987 pp. 19) In the case of oil storage tanks the internal and external conditions around the tank must be considered. The area within the tank falls in division 1 and that outside of the tank can be division 1 or 2 hazardous location. Those tasked with the responsibility of area certification should make the boundary between division two and division 1area (BS 2654 1989 pp. 67).s Group Group classification is a specification of flammable material type with regards to vapor type. Grouping is based on material’s ignition energy. For class I that deals with flammable vapors liquids, the groups are: Group A Atmospheres with acetylene Group B Atmospheres with hydrogen and other hydrocarbons Group C Atmospheres with ethylene and such like vapors Group D Atmospheres with ethane, propane, methane and similar gases Figure 8; Classification of groups and flammable material type (BS 4494 1987 pp. 23) The most common are groups C and D which raise a big concern because they apply to vapors emanating from oil storage. Temperature Code The last consideration in instrumentation of oil tanks is the heat that the instrument generates. Any instrument must be classified for a particular surface temperature that can be reached by the device in fault and normal conditions. In order to apply an instrument properly in a hazardous place it is important that the maximum surface temperature of the instrument should less compared to the auto ignition temperature for potential vapor or gases that the equipment could come in contact with. For one to apply any instrument properly in a place that is hazardous, maximum device surface temperature should be lower compared to the auto ignition temperature of potential vapor or gases that the device may be in contact with (Swenson, Fenton, Zhi Lu, Baalman, 1997 pp. 213). In application of an instrument in an area that is hazardous the designer must also check the protection method so that it meets the area classification. There are methods of protection in use which are explosion proof, non incentive suitable for division 2 locations, intrinsically safe, suitable for division 2 and 1 areas. In explosion proof, items are made in a way that the enclosure can have an explosion but propagation of the flame to the outside will be prevented. An explosion can take place but it remains within the enclosure that has been made to resist the developing pressure in case of an explosion. The enclosure walls should therefore be thick to contain the explosive force. The internal pressure of an explosion is dependent on the ignited vapor or gas. Explosion proof designs need very strong enclosure common in petroleum processing (Weld 1952 pp. 200). Intrinsically safe is that method used to ensure that the quantity of energy present in the instrument is not high enough to ignite the air and vapor mixture. The energy going into the instrument is normally limited through an intrinsically safe barrier situated in an area that is not hazardous. This reduces the current and voltage getting into the instrument. The power allowed to an intrinsically safe instrument is 24 VDC. Current needed ranges from 4 to 20mA. Intrinsically safe designs are not dependent on the design of the enclosure although many instruments make use of the enclosure for the intrinsically safe design and explosion proof (Stephenson 2008 pp114). The non incentive technique is appropriate only in the division 2 locations in which hazardous conditions occur when the conditions are upset. To get anon incentive approval the electricity circuit must be unable to ignite an atmosphere that is explosive. There should be no sparking or arcing components. This approval operates where hazardous conditions occur in fault conditions but not in normal operations. This protection method is however cheaper to install when compared to installation with explosion proof requirements (Weld 1952 pp. 213). Conclusion In conclusion, the design of oil storage tanks has been discussed in this report. The factors to consider in the design, materials used in the construction of the tanks, types of roof, instrumentation, mechanical design and spacing among other things have been examined in detail. Tanks come in various type and the major types are the fixed roof and the floating roof tanks. Other categories include sphere and bullet tanks and underground storage tanks. When designing a tank, the engineer must consider the pressure, metal temperature, specific gravity of the stored liquid, corrosion allowance and other loads. Materials for construction of tanks include mild steel plate, stainless steel, plastic and anodized aluminum. Mechanical design of the tanks must consider design stress, construction categories and welded joint efficiency and minimum practical thickness of the wall. In instrumentation the installation of the instruments must put into consideration the safety concerns, area classification, division, group, temperature code among other things. In the mechanical design and the general design of any oil storage tank it is important to consider the standards and code guiding the oil industry in such matters. In the UK various codes and standards exist and some of them have been cited in this report. Since oil is a flammable liquid, engineers and designers must be sensitive to all requirements in the process of designing these tanks to avoid accidents. Bibliography Bjorhovde R., Colson A., Zandonini R. (1996) Connections in Steel Structures Three; Elsevier BS 2654 (1989), Specification for the manufacture of welded non-refrigerated storage tanks for the petroleum industry. BS 4494 (1987) Specification for vessels and tanks in reinforced plastics BS CP 5500 (2003) Specification for un fired fusion welded pressure vessels. BS EN 13445, Unfired pressure vessels Myers, P. E. (1997) Above Ground Storage Tanks (McGraw-Hill). Snow A. D. (2003) Plant Engineers reference book; Butterworth-Heinemann Swenson D., Fenton D., Zhi Lu A. G., Baalman J., (1997) Evaluation of  Design Criteria for Oil Storage Tanks with Frangible roof joints, Diane Publishing Stephenson J.  (2008) Above ground Oil Storage Tanks: More Complete Facility Data Diane Publishing Weld I. (1952) Handbook for Welded Structural Steel Work, 4th ed. (The Institute of Welding) Yamamoto S. (1979) Structural analysis and seismic design of oil storage tanks; Civil & Applied Mechanics Research Department, Chiyoda Chemical Engineering & Construction Company Read More