INTERMEDIATE TUBESHEET CALCULATION · commessa/job n: xx dis./dwg n : xx cliente/client : pag./page : 1 di/of 18 impianto/plant : xx rev. 00 data/date: xx intermediate tubesheet calculation

COMMESSA/Job N: XX DIS./Dwg n : XX

CLIENTE/Client : PAG./Page : 1 DI/of 18

IMPIANTO/Plant : XX REV. 00 DATA/Date: XX

INTERMEDIATE TUBESHEET CALCULATION


XX XX XX XX

REV. DATE DESCRIZIONE EMESSO CONTROLLATO APPROVATO

N° DATE DESCRIPTION ISSUED BY CONTROLLED BY APPROVED BY





1. INTRODUCTION

1.1 SCOPE Scope of the work is the finite element analysis of Intermediate Tube Sheet (ITS) of convection section unit. A complete result element analysis has been developed to investigate the behaviour of tubesheet withstand gravity load, coils weight ad friction loads.

1.2 JOB REFERENCE AND DESIGN CODES REFERENCE DOCUMENTATION

1. Drawings of Process Datasheet [document number: XX]

2. Drawings of ITS [dwg: XX / XX / XX]

DESIGN CODE The design cod is API 560 IV Ed. Agu. 2007 chapter 10. The loads have been assumed according to API 560 Sect. 10.2 in particular tributary length shall be determined in accordance with results and procedures for supporting continuous beams on multiple support. Friction loads shall be based on a friction coefficient of 0.30. MATERIAL SPECIFICATION ITS material have been selected according to reference drawing. According to API 560 Sect. 10.2, the maximum allowable stresses at design temperature shall not exceed the following:

1. DEAD LOAD STRESS: 50% of the average stress required to produce 1% creep in 10000 h 2. DEAD LOAD + FRICTION STRESSES: of the average stress required to produce 1%

creep in 10 000 h 3. For casting the allowable stress value shall be multiplied by 0.8 to determine the required

casting thickness. The allowable stresses at temperature for the material given in “Annex D” of API 560 Code.

1.3 PERFORMANCE OF FEM ANALYSIS In order to perform the Stress analysis of ITS, a FEM Analysis has been executed with the following proprieties:

1. Tetahedral solid elements have been for mesh of ITS 2. A Jacobian 4 point control has been executed 3. Solver Program: Advance Simulation Technology 4. Solver Type: ANSY SOLVER

MESH SETTINGS The mesh sizing and coarseness are specified by following parameters:

1. Average Size: specify the fraction of model’s longest axis between adjacent nodes.





2. Max Turn Angle: specify the maximum angle for arcs 3. Create Curved Mesh Elements: select to create meshes whit curved edges and faces

LOAD AND CONSTRAINT Suitable boundary conditions have been introduced at the interfaces with supports convection section (supports and guides exactly), to allow the real simulation of results. The constraint considered acting on the structure are the follows:

1. SUPPORT CONSTRAINT: surface blocked on the bottom of ITS 2. GUIDE CONSTRAINT: surface locked in the direction normal to the plane of ITS

Figure 1 Typical Support Constraint

Figure 2 Typical Guide Constraint





The loads considered acting on the structure are the follows:

1. CASTING SELF WEIGHT; 2. COIL LOADS, vertical load applied on the lower point of each hole on the tubesheet web; 3. FRICTION LOADS, horizontal load applied on the lower point of each hole on the

tubesheet web; From the above loads the following load conditions has been adopted:

1. CASTING (self weight of steelwork automatically calculated by the program itself. Material density has been assumed equal to r = 8800Kg/m^3 to take into account material added for foundry process as fillets and shrinkage);

2. VERTICAL LOADS (weight of tributary tube length and applied as concentrated loads in correspondence of the contact surface between tube and ITS of each hole on the tubesheet web);

3. FRICTION LOADS (friction action due to tube expanding and applied as concentrated loads in correspondence of the contact surface between tube and ITS of each hole on the tubesheet web);

ACTION ON TUBE SHEET (Ats) in section LOAD CALCULATION is the intensity of the loads for each coil.

Figure 3 Typical Dead Load





Figure 4 Typical Dead + Friction Load

FEM RESULTS The numerical model of structure has been full tree-dimension one, studied in the linear elastic range. The FEM Analysis plot the following results:

1. Von Mises Stresses: combination of loads in the main direction of inertia 2. Displacement: combination of displacement

At the end of analysis compare the plot of Von Mises Stresses with the allowable dead load stresses (Sad) and allowable friction stresses (Saf).

2. SUMMARY RESULTS The results, summarize below, are referred to the FEM Analysis.

ALL.

STRESS DEAD LOAD DEAD + FRICTION LOAD

COIL Sa (Mpa) Sad (Mpa) FEM Res.

(Mpa) Safety Factor

Saf (Mpa)

FEM Res. (Mpa)

Safety Factor

XX 3,61 2,89 2,53 0,88 5,78 5,27 0,91





3. INTERMEDIATE TUBE SHEET

ITS MECHANICAL CALCULATION COIL PROCESS COIL XX PROCESS PROCESS GAS F.G. TEMPERATURE INLET 1065 °C F.G. TEMPERATURE OUTLET 980 °C FLUID DENSITY 50 kg/m3

TUBESHEET DESIGN DATA TUBESHEET MATERIAL type= 25Cr 35Ni Nb DESIGN TEMPERATURE T= 1120 °C ALLOWABLE STRESS Sa= 3,61 MPa DEAD LOAD STRESS Sad=(0,8*Sa) 2,89 MPa FRICTION STRESS Saf=(2*Sad) 5,78 MPa CORROSION ALLOWANCE Ca= 1,3 mm

WEIGHTS ACTING ON TUBE SHEET BARE TUBE DESIGN type= 3" SCH 160 NUMBER OF ROWS Nr= 4 PIPE PER ROWS Np= 15 NUMBER OF TUBES Nt=(Nr*Np) 60 BARE TUBE O.D. Dia= 88,9 mm BARE TUBE THICKNESS Th= 11,12 mm BARE TUBE LENGTH Le= 7,32 m LINEAR WEIGHT OF BARE LwT= 21,3 kg/m LINEAR WEIGHT OF BARE (12,5%) LwT0,12=(LwT*12,5%) 23,96 kg/m FINNED TUBES (yes/no) No FINNED HEIGHT Hfi= 0 mm FINNED THICKNESS ThFi= 0 mm N° FINNED N°Fi= 0 n°/m LINEAR WEIGHT OF FINNED LwFi= 0,00 kg/m WEIGHT TUBE UWT=(Le*(LwT0,12+LwFi)) 175,41 kg WEIGHT TUBES WT=(N°*UWT) 10524,33 kg LINEAR WEIGHT OF FLUID Lwf= 0,17 kg/m WEIGHT FLUID ON TUBE UWF=(Le*Lwf) 1,28 kg WEIGHT FLUID WF=(N°*UWF) 76,60 kg WEIGHT BEND UWB= 5.2 kg N° BEND Nbe= 45 WEIGHT BENDS WB=(UWB*Nbe) 234,00 kg WEIGHT ITS (2° Pieces) WITS= 2100,00 kg TOTAL WEIGHTS Tw=(WT+WF+WITS+WB) 12934,93 Kg





COIL GEOMETRICAL DATA

N° TUBESHEET Nts= 2 DISTANCE BETWEEN END SUPPORT L= 7,32 m

DISTANCE BETWEEN INTERMEDIATE SUPPORT L1= 2,44 m

TUBESHEET GEOMETRICAL DATA

TUBESHEET LENGHT ITSLe= 2970 mm DIA HOLE DH= 102 mm DISTANCE ROW DsR= 128,8 mm DISTANCE COLUMN DsC= 161,2 mm DELTA COLUMN DelC=(DsC/2) 80,6 mm DISTANCDE EXTREME HOLE DsHo=(Dsc*(Np-1)) 2337,4 mm DISTANCE I° HOLE DsIHo= 316,3 mm DISTANCE LAST HOLE DsLHo= 316,3 mm





LOAD CALCULATION TOTAL FORCE TWF=(Tw*9,81) 126.892 N DISTRIBUTED LOAD Dlo=(Tw/L) 17.335 N/m

Dead Load Friction Load

REACTION ON END TUBESHEET 1 ReaETS1=(L1*Dlo*4/10) 16.919 5.076 N REACTION ON TUBESHEET 1 ReaITS1=(L1*Dlo*11/10) 46.527 13.958 N REACTION ON TUBESHEET 2 ReaITS2=(L1*Dlo*11/10) 46.527 13.958 N REACTION ON END TUBESHEET 2 ReaETS2=(L1*Dlo*4/10) 16.919 5.076 N

Dead Load Friction Load

LOAD ON TUBESHEET LoTs= (MAX ReaITS) 46.527 13.958 N DISTRIBUTED LOAD ON ITS DloTs=(LoTs/DsHo) 19,91 5,97 N/mm REACTION ON TUBESHEET RTs=(LoTs/2) 23.263 6.979 N MAX MOMENT IN L/2 Mmax= 20.952 6.286 Nm MAX SHEAR IN I° HOLE Tmax= 23.263 6.979 N MOMENT IN I° HOLE MIHo= 7.358 2.207 Nm SHEAR IN II HOLE TIIHo= 20.700 6.210 N MOMENT IN II° HOLE MIIHo= 10.189 3.057 Nm





STRESS CALCULATION

TUBESHEET DIMENSIONS L/2 I HOLE II HOLE TUBESHEET HEIGHT H = 551,4 551,4 551,4 mm TUBESHEET WIDTH B = 400 240 280 mm DISTANCE a1= 17,5 17,5 17,5 mm DISTANCE a2 = 151 151 151 mm DISTANCE a3 = 279,8 279,8 279,8 mm DISTANCE a4 = 408,6 408,6 408,6 mm DISTANCE a5 = 539,9 539,9 539,9 mm THICKNESS t1 = 35 35 35 mm THICKNESS t2 = 28 28 28 mm THICKNESS t3 = 0 0 0 mm THICKNESS t4 = 0 0 0 mm THICKNESS t5 = 23 23 23 mm TUBESHEET THICKNESS t6 = 22 55 55 mm RESISTANT AREA Ares = 7643 19107 19107 mm2 NEUTRAL AXIS E = 221 250 246 mm INERTIA X Wx = 8,28E+06 6,19E+06 6,94E+06 mm3 INERTIA Y Wy = 2,29E+06 8,43E+05 1,14E+06 mm3 DEAD LOAD STRESS Sad= 2,89 MPa FRICTION STRESS Saf= 5,78 MPa STRESS RESULTS SIGMA DEAD LOAD sD= 2,53 1,12 1,39 MPa SHEAR DEAD LOAD tD= 0,00 1,22 1,08 MPa

STRESS RESULTS DEAD LOAD sRD = sqrt(sD^2+3*tD^2) 2,53 2,39 2,34 MPa

RATIO sRD / Sad 0,88 0,83 0,81





PASSED DEAD LOAD RATIO < 1 OK OK OK SIGMA FRICTION LOAD sF= 2,54 2,54 2,53 MPa SHEAR FRICTION LOAD tF= 0,00 0,47 0,42 MPa

STRESS RESULTS FRICTION LOAD sRF = sRD + sqrt(sF^2+3*tF^2) 5,67 5,81 5,72 MPa

RATIO sRF / Saf 0,86 0,89 0,87 PASSED DEAD + FRICTION LOAD RATIO < 1 OK OK OK

STRESS ANALYSIS CALCULATION LOAD CONDITION VERTICAL LOAD (y direction) 46.527 N FRICTION LOAD (z direction) 13.958 N GRAVITY LOAD (mass proprieties) 1040 kg

MESH INFO TYPE OF MESH Mesh of solid elements AVARAGE SIZE 0.01 MAX TURN ANGLE 30° CREATED CURVED MESH ELEMENTS Selected MESH QUALITY High ELEMENTS N° 146124 NODES N° 252820 ELEMETS MEDIUM VOLUME 740 mm3

STRESS ANALYSIS RESULTS – dead load The results, summarize below, are referred to dead load combination, according to per API 560.

1. Max Von Mises value: 2,53 MPa 2. Max Displacement value: 0.073 mm

The figure show than the Von Mises stresses are less of allowable ones.





Figure 5 Dead Load Analysis: Von Mises Stress

Figure 6 Dead Load Analysis: Von Mises Stress at tubesheet web

Figure 7 Dead Load Analysis: Von Mises Stress at tubesheet top





Figure 8 Dead Load Analysis: Displacement

STRESS ANALYSIS RESULTS – dead + friction load The results, summarize below, are referred to dead plus friction load combinations, according to per API 560.

1. Max Von Mises value: 5,27 MPa 2. Max Displacement value: 0.117 mm

The figure show than the Von Mises stresses are less of allowable ones.

Figure 9 Dead+Friction Load Analysis : Von Mises Stress





Figure 10 Dead+ Friction Load Analysis: Von Mises Stress at tubesheet web

Figure 11 Dead+ Friction Load Analysis: Von Mises Stress at tubesheet top

Figure 12 Dead + Friction Load Analysis: Displacement





CHECK WITH MATERIAL ALLOWABLE STRESSES DEAD LOAD CONDITION Corrected all. Stress for Casting factor (Sad) : 2,89 MPa Evaluated Stress by FEM (SaFEM): 2,53 MPa Safety factor (SaFEM / Sad)= 0.88 Dead load analysis shows that the critical areas are reduced at the bottom of the plate. The critical areas within the limits of tolerance. The complete finite element analysis performed shows that the stress levels are within the allowable ones.

ITS is verified. FRICTION + DEAD LOAD CONDITION Corrected all. Stress for Casting factor (Saf) : 5,78 MPa Evaluated Stress by FEM (SaFEM): 5,27 MPa Safety factor (SaFEM / Saf)= 0.91 Dead plus friction load analysis shows that the critical areas are reduced at the bottom and the top of the plate. The critical areas within the limits of tolerance. The complete finite element analysis performed shows that the stress levels are within the allowable ones.

ITS is verified.





4. SUPPORT MECHANICAL CALCULATION Scope of this section is the mechanical dimension of support for ITS and relative bolts. The figure show the geometric parameters for mechanical dimension.

Figure 13 Support geometrical scheme

ITS SUPPORT SUPPORT CHECK SUPPORT MATERIAL type= 25Cr 35Ni Nb DESIGN TEMPERATURE T = 1035 °C ALLOWABLE STRESS Sa = 7,15 MPa DEAD LOAD STRESS Sad = (Sa*0,8) 5,72 MPa SUPPORT DIMENSIONS SUPPORT HEIGHT h1 = 290 mm SUPPORT WIDTH B = 320 mm SUPPORT HEIGHT h2 = 100 mm DISTANCE a1= 145 mm DISTANCE a2 = 310 mm DISTANCE a3 = 380 mm THICKNESS t1 = 40 mm THICKNESS t2 = 40 mm THICKNESS t3 = 30 mm RESISTANT AREA Ares = 13200 mm2 NEUTRAL AXIS E = 261 mm INERTIA X Wx = 1,38E+06 mm3





SUPPORT LOAD SuL=(RTs*1,3) 30243 N LOAD ARM d= 126 mm MOMENT REACTION MR=(SuL*d) 3810557 Nmm STRESS RESULTS NORMAL STRESS sN= 2,76 MPa SHEAR STRESS tT= 2,29 MPa STRESS RESULTS sR=sqrt( sN^2+3*tT^2) 4,84 MPa RATIO sR / Sad 0,85 PASSED RATIO < 1 OK

BOLT CHECK BOLT SIZE M= 30 BOLTS TYPE type= ASTM SA193 B8M Cl. 1 BOLTS NUMBER NBo= 4 SECTION AREA Ax= 519 mm2 DESIGN TEMPERATURE T= 538 °C ALLOWABLE STRESS Sa= 77 MPa BOLT DISTANCE dB= 330 mm ACTION ON ONE BOLT ACBo=(SuL/NBo) 7561 N MOMENT REACTION MR = 3810557 Nmm NORMAL FORCE ON ONE BOLT Fa = (MOBo/Db) 5774 N STRESS RESULTS NORMALE STRESS sN= 11,12 MPa SHEAR STRESS tT= 14,57 MPa STRESS RESULTS sR=sqrt( sN^2+3*tT^2) 27,58 MPa RATIO sR / Sa 0,36 PASSED RATIO < 1 OK

ACTION ON ONE BOLT ACBo=(SuL/NBo) 10730 N MOMENT REACTION MR = 5407846 Nmm NORMAL FORCE ON ONE BOLT Fa = (MOBo/Db) 9324 N STRESS RESULTS NORMALE STRESS sN= 17,97 MPa SHEAR STRESS tT= 20,67 MPa STRESS RESULTS sR=sqrt( sN^2+3*tT^2) 40,06 MPa RATIO sR / Sa 0,52 PASSED RATIO < 1 OK





5. GUIDE MECHANICAL CALCULATION Scope of this section is the mechanical dimension of guide for ITS and relative bolts. The figure show the geometric parameters for mechanical dimension.

Figure 14 Guide geometrical scheme

ITS GUIDE GUIDE CHECK SUPPORT MATERIAL type= 25Cr 35Ni Nb DESIGN TEMPERATURE T = 1120 °C ALLOWABLE STRESS Sa = 3,61 MPa DEAD LOAD STRESS Saf = (Sa*0,8*2) 5,78 MPa SUPPORT DIMENSIONS GUIDE HEIGHT h1 = 90 mm GUIDE HEIGHT h2 = 95 mm DISTANCE a1= 45 mm DISTANCE a2 = 105 mm THICKNESS t1 = 35 mm THICKNESS t2 = 30 mm RESISTANT AREA Ares = 4200 mm2 NEUTRAL AXIS E = 74 mm INERTIA X Wy = 1,13E+05 mm3





SUPPORT LOAD GuL=(SuL *0,3/

2) 4536 N LOAD ARM d= 126 mm MOMENT REACTION MR=(GuL*d) 571584 Nmm STRESS RESULTS NORMAL STRESS sN= 5,04 MPa SHEAR STRESS tT= 1,08 MPa STRESS RESULTS sR=sqrt( sN^2+3*tT^2) 5,38 MPa RATIO sR / Saf 0,93 PASSED RATIO < 1 OK

BOLT CHECK BOLT SIZE M= 24 BOLTS TYPE type= ASTM SA193 B8M Cl. 1 BOLTS NUMBER NBo= 2 SECTION AREA Ax= 324 mm2 DESIGN TEMPERATURE T= 538 °C ALLOWABLE STRESS Sa= 77 MPa BOLT DISTANCE dB= 200 mm2 ACTION ON ONE BOLT ACBo=(GuL/Nbo) 2268 N MOMENT REACTION MR = 571584 Nmm NORMAL FORCE ON ONE BOLT Fa = (MOBo/Db) 1429 N STRESS RESULTS NORMALE STRESS sN= 4,41 MPa SHEAR STRESS tT= 7,00 MPa STRESS RESULTS sR=sqrt( sN^2+3*tT^2) 12,90 MPa RATIO sR / Sa 0,17 PASSED RATIO < 1 OK

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INTERMEDIATE TUBESHEET CALCULATION · commessa/job n: xx dis./dwg n : xx cliente/client : pag./page : 1 di/of 18 impianto/plant : xx rev. 00 data/date: xx intermediate tubesheet calculation