Tank designPrepared by :- Moamen Mohamed Hussein Mobile :- +20-01111682604 Email :- [email protected] LinkedIn:- eg.linkedin.com/in/moamenmohamedh eg.linkedin.com/in/moamenmohamedh 1 Tanks eg.linkedin.com/in/moamenmohamedh 2 Classification Open Top Tanks Fixed Roof Tanks Floating Roof Tanks eg.linkedin.com/in/moamenmohamedh 3 The product is open to the atmosphere.linkedin. eg.Open Top Tanks This type of tank has no roof. hence it is an atmospheric tank.com/in/moamenmohamedh 4 . They shall not be used for petroleum product may be used for fire / cooling water. 5.com/in/moamenmohamedh 5 .Fixed Roof Tanks • Atmospheric tank (free vent) • Low pressure tanks (approx.linkedin. 2 Kpa g of internal pressure) • High pressure tanks (approx.6 Kpa g of internal pressure) eg. Fixed Roof Tanks Dome cone eg.linkedin.com/in/moamenmohamedh 6 Supported cone roof eg.linkedin.com/in/moamenmohamedh 7 A supported cone roof tank has a fixed roof in the shape of a cone that is supported by rafters on roof trusses. The trusses are in turn supported by columns resting on the tank bottom. Supported cone roof tanks are used when floating roof tanks are not required or are not more economical. Supported cone roof tanks can be larger in diameter than self- supporting. eg.linkedin.com/in/moamenmohamedh 8 com/in/moamenmohamedh 9 .linkedin. or a "frangible joint". eg. a pressure- actuated vent. vapor pressure changes sufficient to damage the roof or shell may result from daily temperature fluctuations. The weld is designed to fail before any major rupture can occur in the tank’s shell. A frangible joint is a weak welded seam at the roof-to-shell junction. Without proper venting.The supported cone roof tank cannot withstand any significant pressure or vacuum. normal filling and emptying cycles The roof must be equipped with an open vent. Self-Supporting Fixed Roof Tank eg.linkedin.com/in/moamenmohamedh 10 . Self-supporting.com/in/moamenmohamedh 11 .The roof of a self-supporting. fixed roof tanks are practical only where relatively small fixed roof tanks are required.linkedin. fixed roof tank is supported completely from the shell without supplementary structural members. It has same characteristics and usages as the supported cone roof tank eg. A dome-shaped roof can support itself at a larger diameter than a cone-shaped roof. The roof may be either conical or dome. com/in/moamenmohamedh 12 .Floating Roof Tanks eg.linkedin. where the roof floats on the product in an open tank and the roof is open to atmosphere.com/in/moamenmohamedh 13 . External Floating roof eg.linkedin. eg. floating roof tanks should not to be used to store products that tend to boil under atmospheric conditions. usage floating roof tanks must be used to store petroleum products with flash points below 54°C (130°F) or if the flash point is less than 8°C (15°F) higher than the storage temperature.linkedin. Examples of these products are gasoline and naphtha.com/in/moamenmohamedh 14 . linkedin.com/in/moamenmohamedh 15 .Single deck floating roof eg. linkedin.com/in/moamenmohamedh 16 .Single deck floating roof eg. Double Deck Floating Roof eg.com/in/moamenmohamedh 17 .linkedin. com/in/moamenmohamedh 18 . where the roof floats on the product in a fixed roof tank.linkedin. Internal floating roof eg. Fixed Roof with Internal Floating Roof Tank This type of tank is used when the service of an existing fixed roof tank is changed and a floating roof tank should be used for the new service. eg.linkedin. a fixed roof is often added to an existing floating roof tank. This type of tank also may be required when a floating roof tank needs a fixed roof for environmental protection or product quality. The tank is prepared for the new service by adding the internal floating roof inside the existing tank. In this case.com/in/moamenmohamedh 19 . A fixed roof with internal floating roof tank has the same usage as a floating roof tank. linkedin.com/in/moamenmohamedh 20 .Standards for API Storage API 650 Tanks API 653 API 620 eg. com/in/moamenmohamedh 21 . aboveground.5 psig) • Tanks that are non refrigerated • Tanks with design temperatures less than (200°F) • Tanks that store petroleum. eg. design. other liquid products. or water This standard covers material. cylindrical.linkedin. carbon-steel storage tanks. erection. API Standard 650 Welded Steel Tanks for Oil Storage This standard provides the requirements for vertical. and testing. fabrication. This standard applies to the following tanks: • Tanks with internal pressures from atmospheric pressure to 17 kPa (ga) (2. and other liquids eg. Low-Pressure Storage Tanks This standard provides the requirements for aboveground tanks with a single vertical-axis-of-revolution.com/in/moamenmohamedh 22 . API Standard 620 Welded. The standard applies to the following tanks: • Tanks with internal pressures greater than 3.linkedin. water.4kPa (ga) (0.5 psig) but not greater than 103kPa (ga) (15 psig) • Tanks with metal temperatures from -168°C to +120°C (-270°F and +250°F) • Tanks that are large enough to require field Erection • Tanks that store liquid or gaseous petroleum products. • Examination and Testing eg. repair.linkedin.com/in/moamenmohamedh 23 . API 653 This standard covers The standard includes the requirements for following sections: inspection. • Suitability for Service alteration and • Inspection reconstruction of API • Considerations for Reconstruction 650 atmospheric storage • Tank Repair and Alteration tanks that have already • Welding been placed in service. com/in/moamenmohamedh 24 . Why floating roof ? floats directly on the product there is no vapour It reduces evaporation space and thus losses and hence eliminating any possibility of flammable reduction in air atmosphere. eg. pollution.linkedin. linkedin.Typical Fitting and Accessories For Floating Roof Roof Seal Fire Fighting System System and Foam Dam Rolling Ladder and Gauger Support Leg Platform Centering and Roof Drain Anti-Rotation System Device Vent – Bleeder Vents eg.com/in/moamenmohamedh 25 . The sealing system has to be flexible enough to allow for any irregularities on the construction of the roof and shell when the roof moves up and down and for any radial or lateral movement of the roof due to wind and seismic.linkedin.com/in/moamenmohamedh 26 . eg. Roof Seal System roof seal is used to prevent the escape of vapour from the rim gap and to minimize the amount of rain water entering the product. com/in/moamenmohamedh 27 .linkedin.types of seals primary seal secondary seal eg. The primary seal its functions are :- • minimize vapour loss . eg.com/in/moamenmohamedh 28 . • centralize the floating roof . Primary seal could be :- • metallic (Mechanical Shoe Seal) • non metallic (Resilient Filled Seal) .linkedin. • Prevent entering snow & rain . linkedin. API 650 recommends The Mechanical Shoe Seal eg.com/in/moamenmohamedh 29 . com/in/moamenmohamedh 30 .linkedin.The Mechanical Shoe Seal Pantograph Hanger Scissor Hanger. eg. com/in/moamenmohamedh 31 .Pantograph Hanger eg.linkedin. linkedin.Roof Seal System eg.com/in/moamenmohamedh 32 . com/in/moamenmohamedh 33 .linkedin.Pantograph Hanger eg. Scissor Hanger eg.com/in/moamenmohamedh 34 .linkedin. it significantly reduces the amount of rainwater entering the tank contents.com/in/moamenmohamedh 35 . Secondary seal it is mounted on top of the primary seal it reduced vapour loss which in turn :- • cost saving. • enhanced safety by protection against rim fires. • Environmental protection with less odour and compliance with the air standards . eg.linkedin. Secondary seal eg.com/in/moamenmohamedh 36 .linkedin. The basic • the material has to be requirement flame retardant.linkedin. of the seal • the ultraviolet resistance material is in which the seal expose to direct sunlight.com/in/moamenmohamedh 37 . Roof Seal Material • the chemical resistance. eg. Roof Seal Material eg.com/in/moamenmohamedh 38 .linkedin. it also provide access room for maintenance personnel. The roof needed to be supported at a certain height above the floor not only that the roof will not foul with any internal accessories that installed at the lowest shell such as heating coil.com/in/moamenmohamedh 39 . mixing propeller. eg.linkedin. Support leg Support leg is the supporting element for the floating roof when the tank is empty where the roof fall to its lowest position. linkedin.Support leg eg.com/in/moamenmohamedh 40 . linkedin. eg. Roof Drain System the roof drains shall be sized and positioned to accommodate the rainfall rate while preventing the roof from accumulate a water level greater then design.com/in/moamenmohamedh 41 . without allowing the roof to tilt excessively or interfere with its operation. linkedin.Roof Drain System eg.com/in/moamenmohamedh 42 . com/in/moamenmohamedh 43 .Articulated Piping System eg.linkedin. com/in/moamenmohamedh 44 .linkedin.Articulated Piping System eg. linkedin. heavy weight to disadvantage the system stress the deck plate wearing of the roof seal.com/in/moamenmohamedh 45 . Complicated installation eg. linkedin.com/in/moamenmohamedh 46 . eg.Flexible Drain Pipe System It consists of only single continuous pipe which expands and contracts with the rise and fall of the floating roof. Full length of the pipe is flexible without any joint. com/in/moamenmohamedh 47 .linkedin.Flexible Drain Pipe System eg. com/in/moamenmohamedh 48 .linkedin. leakage is eliminated features much lighter easy installation Expensive cost eg. A = Q / V . The Drainage (Q)= RH x deck area (m³/hr) 2 ? ∆? 3.com/in/moamenmohamedh 49 . Drain Pipe Design 1. ∆? =elevation 5. f = Flow Coefficient . ?=pipe diameter ?= Pipe Length . 4” Schedule 80 ) eg.linkedin. V= f? :1 ? 4. RH (m/hr) ( given) 2. Select the Drain Pipe ( Ex. The Rain Fall. These vent only come to operate when the floating roof landed. Vent – Bleeder Vents Automatic bleeder vents shall be furnished for venting the air to or from the underside of the deck when filling and emptying the tank. This is to prevent overstress of the roof deck or seal membrane.linkedin. and the tank is drained down or being filled. eg.com/in/moamenmohamedh 50 . com/in/moamenmohamedh 51 .linkedin.Vent – Bleeder Vents eg. linkedin.com/in/moamenmohamedh 52 .Vent – Bleeder Vents eg. Vent – Bleeder Vents eg.com/in/moamenmohamedh 53 .linkedin. com/in/moamenmohamedh 54 .linkedin.Vent – Bleeder Vents eg. com/in/moamenmohamedh 55 .Vent – Bleeder Vents eg.linkedin. ?? Design Emptying Rate. ?? eg.linkedin.com/in/moamenmohamedh 56 . Bleeder Vent Design The design data for the venting design is as follow: Design Filling Rate. 86 maximum empty rate. air for each 15.9 ?3 /h of ??1 = ?? / 15. eg.com/in/moamenmohamedh 57 .linkedin.9 *15.The vacuum venting (In-Breathing) The venting capacity for maximum liquid emptying Flow rate of free air for will be 15.86 ?3 /h of free liquid movement. The pressure venting (out-Breathing) The venting capacity for Flow rate of free air for liquid maximum liquid Filling will be 17 movement.com/in/moamenmohamedh 58 .linkedin. ??1 = ?? / 15. ?3 /h of free air for each 15.9 ?3 /h of maximum Filling rate.9 *17 eg. 0.linkedin.com/in/moamenmohamedh 59 .Cross sectional area of vent ? ? ??_?? = Q= maximum flow rate ? 2 ? ∆? ∆P = Pressure different ?= Specific weight of air ??_?? = Cross sectional area of vent k= Discharge Coefficient.62 for circular eg. The upper end of the ladder is attached to the gauger platform by hinged brackets lower end is provided with wheels run on a steel track mounted on a runway structure support off the roof. eg. Rolling Ladder The rolling ladder installed on the floating roof tank to provide safe access onto the floating roof.com/in/moamenmohamedh 60 . The ladder consists of self-levelling treads and it slides along the track as the roof move up and down.linkedin. com/in/moamenmohamedh 61 .linkedin.Rolling Ladder eg. this was called as rim fires.com/in/moamenmohamedh 62 . The main cause of the floating roof rim fires is lighting.linkedin. eg. Most lighting ignited rim fires result from induced charges on the roof and not direct strikes. Fire fighting system is to be designed and installed on the floating roof to fight over and extinguishes the rim fire. Fire Fighting System • Fire on the floating roof tanks are common and it usually happened in the rim space where the vapour escaped. linkedin.com/in/moamenmohamedh 63 .Fire Fighting System eg. The tank design eg.linkedin.com/in/moamenmohamedh 64 . linkedin.com/in/moamenmohamedh 65 .Tank capacities eg. linkedin.com/in/moamenmohamedh 66 .Field Erected Tanks eg. com/in/moamenmohamedh 67 .Material Selection Corrosion Assessment Mechanical stresse eg.linkedin. but it would be more economical to use carbon steel with a corrosion allowance and/or chemical inhibitor treatment.com/in/moamenmohamedh 68 .linkedin. The presence of CO2 infers that carbon steel will have finite life due to the wall thinning.??2 Carbon dioxide dissolves in water and dissociates to Corrosion form weak carbonic acid which causes corrosion on carbon steels . eg. Higher temperatures and pressure increase the corrosion rate . Corrosion resistant alloys (CRA) are used to avoid corrosion at high CO2 contents. a corrosion allowance is practical to accommodate up to 6mm. It is therefore present in liquid hydrocarbon and natural gas deposits.Mercury Mercury (Hg) is a trace component of all fossil fuels.linkedin. water and soil. may transfer into air. Materials unsuitable for hydrocarbon streams in presence of mercury which will result in crack are: Aluminum and Aluminum Alloys Titanium and Titanium Alloys Copper and Copper Alloys Zinc and Zinc Alloys eg.com/in/moamenmohamedh 69 . linkedin.com/in/moamenmohamedh 70 .Material Selection Guide eg. API Standard 650 material groups.com/in/moamenmohamedh 71 . eg.linkedin. com/in/moamenmohamedh 72 .linkedin.The minimum design metal temperature eg. com/in/moamenmohamedh 73 .linkedin.Tank Shell Design Methods one-Foot Method Variable-Design- Point Method Elastic Analysis eg. in mm • H = Design liquid level.A = Corrosion allowance. in mm • ?? = Allowable stress for the design condition. m eg.linkedin.0.3 ? ?? = +C. • For design shell thickness 4.3 m (1 ft) above the bottom of each shell course.A ?? • ?? = Design shell thickness. in Mpa • D = nominal tank diametr.9? ?. one-Foot Method • The 1-foot method calculates the thickness required at design points 0.com/in/moamenmohamedh 74 . in m • G = Design specific gravity of the liquid to be stored • C. NOTE This method is shall not be used for tanks larger than 60 m in diameter.linkedin.com/in/moamenmohamedh 75 . eg. and total material weight .linkedin.com/in/moamenmohamedh 76 . eg.Variable-Design-Point Method This method normally Very complex method provides a reduction in where we use point shell-course thickness with certain equation. This method may only be used when ? 1000 1-foot method is not specified & = ? 6 L = 500 ? ? 0.5 in mm t = bottom-course shell thickness, in mm, eg.linkedin.com/in/moamenmohamedh 77 Elastic Analysis method For tanks where L / H is greater than 1000/6, the selection of shell thickness shall be based on an elastic analysis that shows the calculated circumferential shell stress to be below the allowable stress. eg.linkedin.com/in/moamenmohamedh 78 CIVIL/MECHANICAL LOADS Weight Loads Appurtenance Total Live Loads Pressure Roof Live Earthquake Load Wind Loads eg.linkedin.com/in/moamenmohamedh 79 com/in/moamenmohamedh 80 . which is done using water. Since most petroleum products are lighter than water.1-Weight Loads When designing a tank and its foundation. eg. the design engineer must consider the weight loads which are the weight of the tank and the maximum weight of its contents. the heaviest weight load occurs during hydrostatic testing.linkedin. 1-Weight Loads weight of water weight bottom weight of the weight of shell insulation weight of the weight of any roof appurtenances eg.linkedin.com/in/moamenmohamedh 81 . linkedin. 2-Total Pressure Hydrostatic pressure Vapor pressure wind pressure (will be covered later) eg.com/in/moamenmohamedh 82 . com/in/moamenmohamedh 83 . 3-Roof Live Load the weights of items on the roof that are not a part of the permanent structure. • Personnel • Equipment • Rainwater&dust eg.linkedin. linkedin.com/in/moamenmohamedh 84 .Loading Diagram on a Tank Shell eg. Top Stiffener/ Wind Girder An open-top tank is essentially a vertical cylinder that is open at the top and closed at the bottom.linkedin. eg. or could cause the formation of cracks in shell welds. this cylinder can be forced out-of-round by wind pressure that acts against it. unless adequate stiffness against deformation is provided by the shell alone or by other means.com/in/moamenmohamedh 85 . shell out-of-roundness could prevent free vertical travel of the floating roof. If excessive. linkedin.com/in/moamenmohamedh 86 .Top Stiffener/ Wind Girder eg. com/in/moamenmohamedh 87 .Top Stiffener/ Wind Girder top wind girder are to be provided in an open- top tank to maintain the roundness when the tank is subjected to wind load. The stiffener rings shall be located at or near the top course and outside of the tank shell. eg. The top wind girder must be sized to have a large enough section modulus to provide adequate shell stiffening.linkedin. linkedin.Top Wind Girder selection calculating the minimum required section modulus API-650 contains an equation Selecting a large enough wind girder section API-650 also contains a table eg.com/in/moamenmohamedh 88 . cm³ D = Nominal tank diameter.linkedin.com/in/moamenmohamedh 89 . Minimum required section modulus ? ?2 ? 2 Z= ( ) 17 190 Z = Minimum required section modulus. including any freeboard provided above the maximum filling height V = design wind speed (3-sec gust). in m. m ?2 = Height of the tank shell. km/h eg. Wind speed eg.linkedin.com/in/moamenmohamedh 90 . linkedin.com/in/moamenmohamedh 91 .Top Stiffener/ Wind Girder eg. Top Stiffener/ Wind Girder eg.com/in/moamenmohamedh 92 .linkedin. com/in/moamenmohamedh 93 .linkedin.Section Moduli of Stiffening-Ring eg. linkedin. In these situations. and tank shell course thicknesses. to resist wind induced shell deformation.com/in/moamenmohamedh 94 . tank diameter. installation of an intermediate wind girder at a location between the top wind girder and the tank bottom reduces the unstiffened length of the shell. Put in simple terms. and is required in order to prevent shell deformation in these cases. the distance between the top wind girder and the tank bottom is too large. eg. Intermediate Wind Girder At some situations just a top wind girder alone will not provide enough shell stiffness for a given combination of tank height. linkedin.com/in/moamenmohamedh 95 .Intermediate Wind Girder The shell of the storage tank is susceptible to buckling under influence of wind and internal vacuum. eg. Intermediate stiffener or wind girder will be provided if necessary. It is essential to analysis the shell to ensure that it is stable under these conditions. especially when in a near empty or empty condition. between the shell intermediate wind girder and top wind girder t = Thickness of the top shell course.linkedin. in m.com/in/moamenmohamedh 96 . km/h eg. mm D = Nonimal tank diameter.47 ? ( )3 ( ) maximum ? ? height of unstiffened H1 = Vertical distance. m V = design wind speed (3-sec gust). The ? 190 3 ?1 = 9. com/in/moamenmohamedh 97 . mm eg. mm ???????? = Thickness of the top shell course. The height ???????? 5 of the ??? = ? ( ) ??????? transformed shell (?2 ) ??? = Transposed width of each shell course. mm ??????? = Thickness of the shell course for which the transpose width is being calculated.linkedin. mm W = Actual width of each shell course. The sum of the transposed width of the courses will be the height of the transformed shell (?2 = ??? ).com/in/moamenmohamedh 98 .linkedin. eg. com/in/moamenmohamedh 99 . eg. If the height of transformed shell is greater than the maximum height of un-stiffened shell. intermediate wind girder is required.linkedin. have approximately the same stiffnesses. It would be incorrect. the lower portion of the tank shell is inherently stiffer than the upper portion of the tank shell. Therefore. to locate the intermediate wind girder at the mid-height between the top wind girder and the tank bottom. however. eg. Because the lower courses are thicker than the upper courses.location of the intermediate wind girder The ideal location of the intermediate wind girder is such that the portions of the tank shell between the intermediate wind girder and the top wind girder. As the tank shell thickness decreases in going from the bottom to the top course.com/in/moamenmohamedh 100 . the upper portion of the tank shell would not be stiffened enough.linkedin. if the intermediate wind girder was located at the mid-height of the shell. and between the intermediate wind girder and the bottom of the tank. linkedin.Overturning Stability against Wind Load eg.com/in/moamenmohamedh 101 . com/in/moamenmohamedh 102 . to determine the stability of the tank with and without anchorage.linkedin.The overturning stability of the tank shall be analyzed against the wind pressure. eg. linkedin.com/in/moamenmohamedh 103 .The wind pressure used in the analysis is given by API 650 ?? = 0.86 kPa (V/190)² wind pressure on the vertical projected areas of cylindrical surface area ?? = 1. eg.44 kPa (V/190)² Uplift pressure on horizontal projected area of conical surface . the tank will be structurally stable without anchorage when the below uplift criteria are meet :- 0.linkedin.5 ?? + 0.4 ??? < (??? + ?? ) /2 eg.6 ?? + ??? < ??? / 1.com/in/moamenmohamedh 104 . linkedin. ?? and ?? is the wind load acting on the roof ?? = Overturning ??? = moment about and shell respectively moment about the the shell-to-bottom and ?? and ?? is the shell-to-bottom joint from design internal height from tank from horizontal plus pressure (Pi) bottom to the roof vertical center and shell center respectively.com/in/moamenmohamedh 105 . ??? = π 2 ? ?? 1 ∗ D ?? = ?? ?? + ?? ?? 4 2 eg. com/in/moamenmohamedh 106 .linkedin. ??? = Moment about the shell-to- ?? = Moment bottom joint from ? about the shell-to- the weight of the ??? = *??? bottom joint from shell and roof 2 liquid weight supported by the shell eg. Seismic design eg.com/in/moamenmohamedh 107 .linkedin. linkedin.com/in/moamenmohamedh 108 .seismic design Overturning Stability Maximum base shear Freeboard required eg. linkedin.com/in/moamenmohamedh 109 .eg. seismic load The vibration of liquid filled tanks subject to seismic loading depends on the inertia of the liquid and on the interaction effects between the liquid and the tank shell.linkedin.com/in/moamenmohamedh 110 . eg. linkedin.Response modes impulsive convective eg.com/in/moamenmohamedh 111 . linkedin. eg. It experiences the same accelerations as the earthquake.com/in/moamenmohamedh 112 . • The part of the liquid in the lower The part of the tank which moves with impulsive the tank & foundation as though it component were a solid. impulsive pressure eg.com/in/moamenmohamedh 113 .linkedin. com/in/moamenmohamedh 114 . eg.linkedin. It has a much component longer natural frequency time than the impulsive portion. • the part of the liquid in the upper The part of the tank which is free to form convective waves or to slosh. com/in/moamenmohamedh 115 .Convective pressure eg.linkedin. Spring mass model eg.linkedin.com/in/moamenmohamedh 116 eg.linkedin.com/in/moamenmohamedh 117 eg.linkedin.com/in/moamenmohamedh 118 eg. However. impulsive and convective pressure distributions are likely to change. no study is available to quantify effect of such obstructions on impulsive and convective pressures. impulsive pressure will increase and connective pressure will decrease.linkedin.NOTE Sometimes. vertical columns and shaft are present inside the tank. These elements cause obstruction to sloshing motion of liquid.com/in/moamenmohamedh 119 . In the presence of such obstructions. At present. it is reasonable to expect that due to presence of such obstructions. eg.com/in/moamenmohamedh 120 . Seismic overturning stability The seismic overturning moment at the base of the tank shall be the SRSS summation of the impulsive and convective components.linkedin. ?? 2 • ?? = Impulsive response coefficient • ?? = Convective response coefficient • ?? = Effective impulsive liquid weight • ?? = Total weight of the tank shell • ?? = Total weight of fixed tank roof • ?? = Effective convective liquid weight • ?? Height from the bottom of the tank shell to impulsive force • ?? =Height from the bottom of the tank shell to the shell’s center • ?? = Height from the bottom of the tank shell to the roof • ?? = Height from the bottom of the tank shell to the convective force eg.M= ?? ?? . ?? 2+ ?? . ?? +?? . ?? +?? .com/in/moamenmohamedh 121 . ?? .linkedin. 2 sec & 5% damped ? = importance factor ??? = Response Modification Factor eg.?? = Impulsive response coefficient ??? .com/in/moamenmohamedh 122 .linkedin. ? ?? = ??? ??? = Design spectral response acceleration at 0. linkedin. IMPORTANCE FACTOR Occupancy category ? I or II 1 III 1.5 eg.25 IV 1.com/in/moamenmohamedh 123 . Response Modification Factors Anchorage System ??? ??? Self-anchored 3.5 2 Mechanically - anchored 4 2 Factors used for force reduction eg.linkedin.com/in/moamenmohamedh 124 ? tanh 0.866 ? ?? = .?? (total liquid weight) 0.866 ? 0.367 ? ?? = 0.23 ?? tanh( ) ? ? 3.67 ? cosh( );1 ?? = 1 − 3.67? ? 3.67? .D ?? = 0 .375 H sinh ? ? eg.linkedin.com/in/moamenmohamedh 125 Base Shear Force Base shear is defined as the SRSS combination of the impulsive and convective components V = ?? 2 + ?? 2 ?? = ?? ?? + ?? + ?? + ?? ?? = ?? ?? eg.linkedin.com/in/moamenmohamedh 126 N ?? = Total weight of fixed tank roof including framing. N ?? = Total weight of the tank shell. N ?? = Total weight of the tank bottom.?? = Effective impulsive portion of liquid weight. N eg. N ?? = Effective convective (sloshing) portion of liquid weight. any permanent attachments and 10% of the roof design snow load.com/in/moamenmohamedh 127 . knuckles.linkedin. Anchorage requirement The anchorage requirement is checked by the Anchorage Ratio.0. ??? J= ?2 ?? 1.linkedin.com/in/moamenmohamedh 128 .4 ???? eg. it will determine whether the tank can be self-anchored or mechanically anchored. J.4?? :?? − 0. Anchorage requirement Anchorage Ratio Criteria No calculated uplifted ? ≤ 0.54 Tank is not stable eg. Tank is uplifting.com/in/moamenmohamedh 129 .785 < ? ≤1. Tank is self anchored.785 The tank is self-anchored.54 requirements.linkedin. ? > 1. check shell compression 0. 0.9 ?? ?? ?? ? ?? = Min.linkedin.(1 .?? = Weight of tank shell & portion of roof supported by shell ? ?? = π?? + ??? (Roof load acting on shell) ???? = Uplift due to product pressure ?? = Resisting force of annulus = 7.4 ?? ) ?? Vertical earthquake acceleration coefficient (given or ) ???? eg.com/in/moamenmohamedh 130 . specified yield strength of bottom annulus ?? = Effective specific gravity including vertical seismic effect ?? ?? = G. com/in/moamenmohamedh 131 .linkedin.Response parameter eg. linkedin.com/in/moamenmohamedh 132 .Shell Compression The maximum shell longitudinal compression stress at the bottom of the shell 1.5? eg.5 ? ? 2.4?? + ?2 1000 ?? The shell compression stress has to be less than the allowable stress ?? 83 ?? ?? = + 7.273 ??? 1 ?? = ?? 1 + 0. linkedin.com/in/moamenmohamedh 133 .273 ??? ??? = − ?? 1 − 0.?? eg.4?? + ???? ?2 ??? < 0.8 ?? ( Bolt allowable tensile strength) ?. Anchorage Design the design uplift load on the anchor bolts due to the seismic is determined 1. linkedin.Freeboard eg.com/in/moamenmohamedh 134 . 578 ?? = 1.com/in/moamenmohamedh 135 . ?? ?? 2 ??1 ?? = ??? 0. ?? . ?? = 0.5 .8 ? Convective (Sloshing) Period 3.5 ? ?? 4 .68? tanh ? eg.linkedin. ?? ?? = 2. linkedin.Response parameter eg.com/in/moamenmohamedh 136 . 2sec 1.Mapped MCE spectral response acceleration ?? ?1 5% 5% damped damped period of period of 0.linkedin.com/in/moamenmohamedh 137 .0 sec eg. Mapped MCE spectral response acceleration eg.com/in/moamenmohamedh 138 .linkedin. eg. Foundation In the early phases of tank foundation engineering.linkedin.com/in/moamenmohamedh 139 . • Condition and settlement of similar equipment in nearby areas. several types of information should be considered and evaluated: • Site conditions like pore water pressures and dewatering quantities. eg. In addition. and potential settlement.com/in/moamenmohamedh 140 . These are determined from soil borings. Foundation design usually begins with specifications provided in the soils report. soil bearing capacity. one of the most important bits of information available to the tank foundation designer is the experience with similar structures available from a soils engineer familiar with the area. the advantages of having these reports available are substantial. load tests and laboratory testing. Soil investigations Although many tanks have been built without the soils reports.linkedin. The soils report addresses subsurface conditions. Important Elements to Consider in Foundation Design The final elevation of the tank bottom is important because the tank shell may sit in moist conditions This results in accelerated corrosion or pitting and a reduced tank bottom life.com/in/moamenmohamedh 141 .linkedin. Tanks should be designed to be at least 8 to 12 in above the surrounding grade level eg. Use of a material which contains mineral salts or is contaminated with organic matter that can decompose. The solution is to use appropriate backfill.com/in/moamenmohamedh 142 . it should be cleaned and washed to minimize the presence of saIts and minerals. When a granular material such as sand is used. induce microbial corrosion.linkedin. eg. or turn acidic can accelerate underside corrosion. Since typical tanks require less than 1 ft of submergence to float off of the foundation. the most likely cause of this is the rainfall.linkedin.com/in/moamenmohamedh 143 .Another consideration for setting tank foundations is the possibility of buoyancy of the tank due to submergence in water. the probability of this happening while the tanks are empty . eg. This pattern prevents and minimizes intrusion of rainwater from the outside periphery of the tank bottom. A typical slope of 1 to 2 in per 10 ft of horizontal run is used.com/in/moamenmohamedh 144 . eg. Foundation profile Cone up This is the most common profile.linkedin. it is slightly more complex for the shell construction to accommodate this pattern.linkedin. However. and an internal sump is usually included here for water bottom removal. Planar sloped bottom. the bottom is constructed as a plane but it is tilted to one side. eg. For small tanks it is not worthwhile to provide a sloped bottom for services where water removal is not required. Plane flat bottom.Cone down. it is easier to construct.com/in/moamenmohamedh 145 . The bottom slopes toward the center of the tank. The rate of slope is the same as for a cone-up tank. It is also not necessary to use sloped bottom tanks. linkedin. Foundation Foundation Types WITHOUT A RINGWALL WITH A CONCRETE RINGWALL WITH A CRUSHED STONE RINGWALL eg.com/in/moamenmohamedh 146 . Not settle excessively at the perimeter due to the weight of the shell wall. Provide adequate drainage. eg.linkedin.foundation should accomplish the following: Provide a stable plane for the support of the tank.com/in/moamenmohamedh 147 . Limit overall settlement of the tank grade to values compatible with the allowances used in the design of the connecting piping. linkedin.com/in/moamenmohamedh 148 .FOUNDATIONS WITHOUT A RINGWALL eg. a concrete ring wall foundation should be used. eg. When there is some doubt whether a foundation will be able to carry the shell load directly.linkedin.com/in/moamenmohamedh 149 .FOUNDATIONS WITH A CONCRETE RINGWALL Large tanks and tanks with heavy or tall shells and/or self-supported roofs impose a substantial load on the foundation under the shell. eg. It minimizes moisture under the tank.com/in/moamenmohamedh 150 . It provides a level.linkedin. Advantages It provides better distribution of the concentrated load of the shell to produce a more nearly uniform soil loading under the tank. it is capable of preserving its contour during construction. It retains the fill under the tank bottom and prevents loss of material as a result of erosion. solid starting plane for construction of the shell. com/in/moamenmohamedh 151 .linkedin.FOUNDATIONS WITH A CONCRETE RINGWALL eg. welded vertical tanks can be erected satisfactorily in several ways.linkedin. erector contractors normally have a particular method. TANK CONSTRUCTION Just as most of the construction task.com/in/moamenmohamedh 152 . eg. which they have adopted as the result of experience. linkedin.com/in/moamenmohamedh 153 .eg. eg.linkedin.com/in/moamenmohamedh 154 . eg.linkedin.com/in/moamenmohamedh 155 . eg.com/in/moamenmohamedh 156 .linkedin. Tank Testing eg.com/in/moamenmohamedh 157 .linkedin. Tank Bottom Testing After welding of the bottom plates has been completed. The test is preferably be made as soon as possible after welding of the bottom but before any surface coating is applied. eg.com/in/moamenmohamedh 158 . The bottom plates has to be tested before water is put into the tank for hydrostatic testing. This can be done by using a vacuum box. which enables any leaks in the seams to be positively located by visual examination.linkedin. all welds will be tested to ensure that the tank bottom is free from leaks. linkedin.com/in/moamenmohamedh 159 .vacuum box eg. it also tested the foundation for its capability of taking the filled tank load.linkedin. The water test not only to ensure no leakage of the tank. Settlement will also be measured during the water testing.com/in/moamenmohamedh 160 . The tank will be filled up with water to its design level. eg. Tank Shell Testing The tank shells should be water tested/ hydro tested after completion of the wind girder. • However sea water contains very high chlorine and it would cause corrosion to the tank. never dewatering from the Manway or the clean out door. the tank venting were not designed for emptying in such big opening. Hydro/ Water Test • Water is always an issue on construction site to fill up and test the huge tank.linkedin. • The materials selected were not designed for the sea water.com/in/moamenmohamedh 161 . for cost saving purpose. • Some contractor who has limited knowledge on the tank and material properties. • After the water test. they would use sea water as water medium to perform the water test. eg. for all the weld seams and joints has to be liquid-tight.linkedin. they will be inspected and tested in a more careful way.com/in/moamenmohamedh 162 . eg. Floating Roof Testing The floating roof has to be liquid- tight in order for it to function safely and effectively. • Centre Deck The weld seams of the centre deck plates should be controlled on liquid-tightness by the vacuum box method.com/in/moamenmohamedh 163 .linkedin.5 bar. and during the flotation test. • Roof Drain The roof drain pipe systems for the floating roof will be tested with water to a pressure of 3. the roof drains should be kept open and observed for leakage of tank contents into the drain lines. eg. Myers eg. References Design. Construction and Operation of the Floating Roof Tank Submitted by Kuan Siew Yeng API 650: Welded Steel Tanks for Oil Storage Aboveground Storage Tanks Philip E.com/in/moamenmohamedh 164 .linkedin.