Design CalCONTENTS:-Sr.No.DESCRIPTIONPAGE1DESIGN DATA32CALCULATIONS FOR MINIMUM SHELL THICKNESS43BOTTOM PLATE DESIGN54INTERMEDIATE WIND GIRDER4.1 AS PER API 650 SEC. 3.9.764.2 VERIFICATION OF UNSTIFFENED SHELL AS PER API 650 App.V.875SUPPORTED CONICAL ROOF5.1 DESIGN OF ROOF PLATE75.2 DESIGN OF ROOF PLATE AS PER API 650 App. V.785.2 DESIGN OF ROOF PLATE WITH STIFFENING75.3 DESIGN OF COMPRESSION RING85.4 DESIGN OF ROOF RAFTERS106COMPRESSION AREA AT ROOF TO SHELL JOINT6.1 DESIGN OF COMPRESSION AREA AS PER API 650 App. F116.2 VERIFICATION OF COMPRESSION AREA AS PER API 650 App.V.7137STABILITY OF TANK AGAINST WIND LOADS7.1)RESISTANCE TO SLIDING138ANCHORAGE FOR UPLIFT LOAD CASES, PER API 650 TABLE 3-21a129ANCHOR CHAIR CALCULATION138FOUNDATION LOADING DATA149VENTING CALCULATIONS1610NOZZLE FLEXIBILITY ANALYSIS AS PER APPENDIX P1911SHELL TO ROOF RAFTER JOINT STRESS ANALYSIS201) DESIGN DATADesign Code:API 650, 10th Edition, Add.4 2005, Appendix FClient's Specs.:32-SAMSS-005, BD-407062 Rev.00CFluid:FIRE / UTILITY / WASH WATER TANKMaterial:SA-516 Gr 70.Density of contentsDL=1004.9kg./m3Specific gravity of contentsG=1.0049Material's yield strengthdy=260MPaAPI 650 Table-3.2Design TemperatureT=71oCInternal PressurePi=0.747Kpa=3.0inch of waterExternal PressurePe=0.245Kpa=1.0inch of waterHigh Liquid LevelHl=8.560mDesign Liquid LevelHL=9.000mWind Exposure (ASCE 7-02)Category CAllowable Design Stress at Design Temp.Sd=173.00MPaAPI 650 Table-3.2Allowable Test Stress for Hydrostatic Test ConditionSt=195.00MPaAPI 650 Table-3.2Corrosion allowanceBottom=3.20mmShell=3.20mmRoof=3.20mmRoof Supporting Structure=3.20mmSlope of Tank Roofq=9.4601 : 6Outside dia. of tankDo=13.516mInside dia of tankDi=13.500mNominal dia. of tankD=13.508m=44.32ftHeight of ShellH=9.000mWeight of roof attachments(platform, handrail, nozzles, etc.)Wr=30.00KNWeight of attachments (pipe clips, nozzles, etc.)Ws=5.00KNWeight of curb AngleWc=6.85KNDesign Wind VelocityV=154Km/hrYield Strength of Steel StructureFy=250M Pa=36.259425KsiLive Load on roofLr=1.2KpaAPI 650 Sec. 3.2.1d2) CALCULATIONS FOR MIN. SHELL THICKNESSCalculations of Shell Thicknesses by Section 3The minimum thickness of shell plate as per section 3.6.3.2, shall be computed using following formula;Design Shell Thickness td =4.9D (HL1 - 0.3)G + CASdHydrostatic Test Thickness tt =4.9D (HL1 - 0.3)StWhere,G = Specific Gravity of fluid to be stored=1.0049D = Nominal dia. of tank=13.508mHL = Design liquid level for course under consideration=9.00mCA = Corrosion allowance on shell=3.20mmE = Weld Joint Efficiency=0.85API 650 App. A.3.41st Shell CourseWidth of 1st courseW1=2.500mDesign height for 1st shell courseHL1=9.076m(Including Equivalent head due to internal pressure)Required Shell Thicknesstd=6.57mmRequired Shell Thicknesstt=3.36mmShell thickness providedt1=8.00mm2nd Shell CourseWidth of 2nd courseW2=2.500mDesign height for 2nd shell courseHL2=6.576mRequired Shell Thicknesstd=5.61mmRequired Shell Thicknesstt=2.13mmShell thickness providedt2=8.00mm(As per Tank General Note 3 of Data Sheet)3rd Shell CourseWidth of 3rd courseW3=1.880mDesign height for 3rd shell courseHL3=4.08mRequired Shell Thicknesstd=4.65mmRequired Shell Thicknesstt=1.28mmShell thickness providedt3=6.00mm4th Shell CourseWidth of 4th courseW4=2.120mIncluding Curb AngleDesign height for 4th. shell courseHL4=2.196mRequired Shell Thicknesstd=3.93mmRequired Shell Thicknesstt=0.64mmShell thickness providedt4=6.00mm5th Shell CourseWidth of 5th courseW5=2.050mDesign height for 5th. shell courseHL5=0.076mRequired Shell Thicknesst5=3.08mmShell thickness providedt5=6.00mmShell Table -1Shell Course #1234Shell width (m)2.5002.5001.8802.000Shell Thickness (mm)8.008.006.006.00Corroded Shell Thk.(mm)4.804.802.802.80Shell Weight (KN)65.3665.3636.8639.22Shell Weight (KN)Corroded39.2239.2217.2018.30Total Shell Weight (KN)=206.80KNTotal Shell Wt.(KN) (Corroded)=113.93KNTotal weight of corroded shell + Shell attachments,W'ST=120.78KN3) BOTTOM PLATE DESIGNAs per API 650 Sec. 3.4.1All bottom plates shall have minimum nominal thickness of 6mm, exclusive of any corrosion allowance.Required Bottom Plate Thicknesstb=6+ CAmmtb=9.20mmUsed bottom plate thickness=10.00mmWeight of bottom Plate=11430.3kg=112.13KNWeight of bottom Plate ( Corroded )=7772.6kg=76.25KN3.1) ANNULAR PLATE DESIGN(API 650 Sec. 3.5)Hydrostatic test stress for first shell courseSh=(4.9D (H1 - 0.3)/tsc)=119.97M Pa< 172 M Pa OKIf hydrostatic test stress for first course is less than 172 Mpa,lap welded bottom plates may be used in lieu of butt-welded annular bottom plates.Thickness of annular bottom platetb=10.00mmMax. design liquid levelHL1=9.08mWidth of annular bottom plateWap=215 x tb / (HL1 x G)1/2(between shell ID & lap of bottom plate with annular plate)Required width of annular bottom plateWap=711.91mmWidth of annular bottom plate providedWact=800.0mm4) INTERMEDIATE WIND GIRDER4.1) As per API 650 Sec. 3.9.7The maximum height of the unstiffened shellH1=9.47 t (t / D)3/2 x (190/V)2API 650 Sec.3.9.7.1Where,t = As ordered thickness of top shell course=6.00mmt=As Per Article 3.9.7.1 of 32-SAMSS-005=2.80mmD = Nominal tank diameter=13.508mV = Design wind speed=154.00Km/hrThe maximum height of the unstiffened shellH1=3.81mHeight of transformed ShellTransposed width of each shell courseWtr=W x (tuniform/tactual)5/2API 650 Sec.3.9.7.2Where,W = Actual width of each shell course (mm)tuniform = As ordered thickness of top shell course=6.00mmtactual = As ordered thickness of shell course for which transposed width is being calculated (mm)1st Shell CourseAs ordered thickness of 1st shell courset1=8.00mmActual width of 1st shell courseW1=2500mmTransposed width of 1st shell courseWtr1=1218mm2nd Shell CourseAs ordered thickness of 2nd shell courset2=8.00mmActual width of 2nd shell courseW2=2500mmTransposed width of 2nd shell courseWtr2=1218mm3rd Shell CourseAs ordered thickness of 3rd shell courset3=6.00mmActual width of 3rd shell courseW3=1880mmTransposed width of 3rd shell courseWtr3=1880mm4th Shell CourseAs ordered thickness of 4th shell courset4=6.00mmActual width of 4th shell courseW4=2120mmTransposed width of 4th shell courseWtr4=2120mm5th Shell CourseAs ordered thickness of 5th shell courset4=0.00mmActual width of 4th shell courseW4=2050mmTransposed width of 4th shell courseWtr5=0mmHeight of transformed ShellHtr=Wtr1 + Wtr2 + Wtr3 + Wtr4=6436mm=6.436mAs Htr > H1 Intermediate Wind Girder is RequiredIntermediate Wind GirderThe required minimum section modulus of an intermediate wind girder shall be calculated as follows.Zreq. =D2 H1 x (V/190)2API 650 Sec.3.9.7.617Where: Z = Required minimum section modulus of intermediate wind girder. (cm3)H1 = Vertical distance (m) between the intermediate wind girder and the topangle of the shell =3.218mD = Nominal Tank diameter =13.508mZreq. =22.69cm3From Table 3-20 we provide one angle of 102*76*6 as intermediate wind girder as per fig. 3-20 detail cSection modulus provided =Zpro.=50.2cm3(Including shell participating width & corroded thickness of 2.8mm)As Apov.>Areq. The Intermediate Wind Girder Is Ok4.2) Verification of Unstiffened Shell As per API 650 App.V.8For an Unstiffened Tank Shell subjected to external pressure, elastic buckling will occur if the following criteria is satisfied;(D/tsmin)0.75[(Htr/D)(Fy/E)0.5] 0.00675API 650 App.V.8.1.1Where,E = Modulus of Elasticity of the Roof Plate Material =197,534.80MpaASME Section II-D(Table TM-1)tsmin = minimum thickness of thinnest shell course (mm)=6.00mm(Including corrosion allowance)External Shell Stiffeners is Not Required0.0317690.006750Since section 8.1.1 is satisfied, Therefore Tank must comply with the following section;Total design external pressure (Ps);Ps = the greater of Pe or W+0.4PeAPI 650 App.V.3.1Where,W - maximum wind pressure =0.0000333x V2 x Kg x KhKg =wind gust factor =1.1Kh =wind height factor =1.1W=0.956KpaPe=0.245KpaW+0.4Pe=1.054KpaTherefore;Ps=1.054KpaMaximum design external pressure;Ps 5.70mmSince tpro.> 5.7mm, Shell stiffeners is Not Required5) Design of Roof Plate5.1) Supported Conical RoofMinimum roof plate thicknesstR=D x Tr/2.2API 650 Sec.3.10.5.14.8 SinqWhere,Tr = Greater of load combinations (e)(1) and (e)(2) as per App. RCombination i,P1 = DL + (Lr or S) + 0.4 PeAPI 650 App. R (e)(1)Combination ii,P2 = DL + Pe + 0.4 (Lr or S)API 650 App. R (e)(2)Where,Dead Load of the roof,DL=0.981kPaLive Load on the roof,Lr=1.200kPaExternal Pressure,Pe=0.245kPaSnow Load,S=0.000kPaP1=2.279kPaP2=1.706kPaTr=2.279kPa(Max. of P1 & P2)API 650 Sec. 3.10.5tR=17.43mm 5 mmtR + C.A.=20.63mmAs per API Sec. 3.10.5.1 the Maximum thickness for self supported roof is 12.5mm (excluding corrosion allowance)but due to high value of calculated roof thickness, it is proposed to provide supported roof.Used thickness =10.00mm5.2) Self Supported Conical Roof with External Pressure as per API 650 App.V.7tc=83D x Pr/1.72 E tRAPI 650 App.V.7.2.1SinqMinimum roof plate thicknesstc=17.668mm 5 mmtc + C.A.=20.87mmRoof Plate Thickness tprov=10.00mm(Including Corrosion Allowance)Roof developed radiusRr=6.85mRoof developed AreaAr=147.5m2Weight of Roof=114.72KNWeight of Roof (corroded)=77.22KNRoof is designed as a supported cone roof. The system of rafters is provided to support the roof plate. The rafters aresupported at tank shell and load is transferred to tank periphery.Maximum Spacing of Rafters at Outer Ring=0.6 * =1.88mAPI 650 3.10.4.4Maximum No. of Rafters RequiredN= x D/0.6 X =22.515.2) Design of Roof Plate and Stiffening Member( Brownell & Young - 4.3b)Roof plate shall be designed as continuous beam with uniform load comprising of roof live load and self weight of roof plate.The maximum unsupported span of roof plate is equal to the spacing of stiffeners at tank outer dia.Number of Rafters N2 =24.00Roof Plate Span l=1.77m=69.7inch(Maximum spacing of Rafters at tank outer dia)Roof plate thickness tr=6.80mm=0.2677165354inch(corroded plate thickness)Assumed Plate width b=1inchDesign Live Load Lr=1.20KN/m26.8511719224147.4618249305Self Wt. of roof plate Wr=0.78KN/m2Design load for roof plate shall be comprising of roof live load and the total dead load acting on the roof.Roof Plate Design Load wp = Lr + Wr=1.98KN/m2=0.29psiAssuming width of roof plate 1 inch and calculating the bending moment for strip if roof plate 1 inch wide.Roof Plate Span l=69.7inchDesign load/ length w = wp x b=0.29lbs/inchBending Moment At Mid SpanMc=wl2=58.035lbs inch24Bending Moment At SupportsMs=wl2=116.07lbs inch12Section modulus of PlateZp=b tr2/6=0.012in3Allowable Bending StressFb =0.6 x Fy=22625.8812psi( As per API 650)Allowable Bending Moment M allowFb x Zp=270.3lbs inchMallow>Ms Thickness Is OkTherefore Plate Thickness Provided=6.80+CA=10.00mm(Including Corrosion Allowance)5.3) Design of Compression RingFig- 2 : Central Compression Ring Loading DiagramLive Load on roof Lr =1.2KN/m2X=0.8110295262Load of roof plate Dr =1.04KN/m2(including weight of rafters & accessories)x=6.8430616271g = Lr + Dr =2.24KN/m2(udl due to roof plate and live load)X-x=6.0320321009Radius of tank R =6.75mRadius of central compression ringR2 =0.80mSpan of RafterLs =6.03mSelf weight of Rafter=25.30Kg/mTotal weight of Rafter=3662.6Kg=35.93KNTotal weight of Rafter corroded=2444.8Kg=23.98KNTotal weight of Rafter/area=0.24KN/m2Weight of Raftergr =0.248KN/mWeight of Central RingWr =2.76KNNumber of rafterN2 =24.00Height of Roof at centerh =1.12mRadius of tank - radius of compression ring =R1 =5.95mg1=2pRg=3.959KN/mN2g2=2pR2g=0.469KN/mN2Calculation of load transferred at joint of stiffener and central ringWa = P1 + P2Weight of Central Ring ,Wr per stiffenerP1=Wr=0.115KNNLoad transferred to central ring by rafters,P2 =g2 x R2=0.38KNWa =P1 + P2 =0.49KNg0 = gr + g2=0.72KN/mg3 = g1 - g2=3.49KN/mConsidering the equilibrium and taking Moments about point A.Ha = Wa x R1 +(g0 x R1) R1/2 + g3 (R1/2) ( R1/3)hHa =32.19KNRadial Load transferred to ring through stiffeners, Ha =32.19KN =7.24KipsNumber of Stiffeners Supported on central Ring, N2 =24Radius of central compression ring, R2 =0.8m =2.624ftMoment transferred to ring, M =Ha R2 ( cot 180 - N2 ) =2 N2 pM=0.41Kip ft=0.562KN mThrust T = Ha Cot 180 =27Kips=122.25KN2 N2Fig -3 : Central Compression RingPROPERTIES OF COMPRESSION RING (Corroded)b1 =200A1= b1h1 =1360mm2A1y1 =4624mm2h1 =6.8A2= b2h2 =3400mm2A2y2 =850000mm2b2 =6.8A3= b3h3 =1496mm2A3y3 =164560mm2h2 =500Location of Centroid ( See Fig)b3 =6.8C = A1y1 + A2y2 +A3y3 =162.91mmh3 =220AMoment of Inertiay1=3.4I = b1h13 + A1 (C-y1)2 +b2 h23 +A2(C-y2)2 + b3 h33 + A3 (C-y3)2y2=250121212y3=110I =141451394.828985mm4A =6256mm2 =0.00626m2Section Modulus =Z = I / (h2 - C) =419628.8mm3=0.0004196288m3fb = M =1340.28KN/m2ZAllowable Bending Stress Fb = 0.6 Fy =150000KN/m2fc = T =19541.63KN/m2AAllowable Compression Stress Fc = 0.5 Fy =125000KN/m2f b +fc =0.17FbFcAs fb/Fb+fc/FcAmin, Therefore used Curb Angle is satisfactory6.1) Tank Design As Per Appendix FUplift on Tank as per F.1.2Corroded Roof ThicknesstR=6.80mmNominal dia. of tank (Di + Shell thick)D=13.508mArea of tankAt=p x R2=143m2Internal design pressure of tankPi=0.747kPaTotal upward lifting force acting on roofFR=Pi x At=107kNWeight of roof (corroded)WR=77.22kN107>77.22Weight of shell, roof and attached framingD'L=224.75kN107