#58541 - 04/09/14 09:37 PM
ASME B31.8 Chap VIII, Hoop stress failure is not recognised
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Member
Registered: 06/03/12
Posts: 45
Loc: India
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Hi,
The code stress summery is as below. Highest Stresses: (MPa ) CodeStress Ratio (%) is 85.2 at Node 10 LOADCASE: 1 (OPE) W+T1+P1+F1 Code Stress: 342.0 Allowable: 401.4 Axial Stress: 157.9 @Node 20 LOADCASE: 3 (OPE) W+T1+P1 Bending Stress: 140.0 @Node 10 LOADCASE: 1 (OPE) W+T1+P1+F1 Torsion Stress: 20.2 @Node 20 LOADCASE: 1 (OPE) W+T1+P1+F1 Hoop Stress: 424.5 @Node 20 LOADCASE: 1 (OPE) W+T1+P1+F1 3D Max Intensity: 342.0 @Node 10 LOADCASE: 1 (OPE) W+T1+P1+F1
Highest code stress ratio is displayed for combined case where allowable is 0.9*446=401.4
My query is
Hoop stress allwable must be 0.72*446=321.12 Then why CAESAR is not recognising the failure in hoop stress. the highest code stress ratio must be 424.5/321.12=1.32
Can anyone pls advice? Also Pls Guide how to enclose/attach file here?
_________________________
Thanks in advance, Regards, Sridhar
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#58549 - 04/10/14 06:38 AM
Re: ASME B31.8 Chap VIII, Hoop stress failure is not recognised
[Re: sridhar]
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Member
Registered: 12/13/99
Posts: 6226
Loc: Houston, Texas, USA
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For B31.8 VIII, there are three Code Stresses and three Allowable Stresses. CAESAR II computes each of these six values and then determines three ratios (hoop/hoop_allowable, longitudinal/longitudinal_allowable, and combined/combined_allowable). The two values that produce the largest ratio are reported in the "Code Stress" and "Allowable Stress" columns.
In the Summary of the report, the values that produce the maximum ratio are (should be reported).
If you can't resolve this, open a Support Request on SmartSupport (formerly eCustomer) and send in you job file.
_________________________
Regards, Richard Ay - Consultant
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#58584 - 04/13/14 10:03 PM
Re: ASME B31.8 Chap VIII, Hoop stress failure is not recognised
[Re: sridhar]
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Member
Registered: 06/03/12
Posts: 45
Loc: India
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Hi I am unable to enclose file. Hence enclosing file inpu here Its simple 2 element file used to verify the problem.
From 10 To 20 DX= -290.000 mm. PIPE Dia= 323.000 mm. Wall= 36.000 mm. Cor= 3.0000 mm. Mill%(-)=12.50 GENERAL T1= 149 C P1= 749.0000 bars Mat= (341)A789 S32750 E= 195,836 Mpa EH1= 186,159 Mpa EH2= 195,836 Mpa EH3= 195,836 Mpa EH4= 195,836 Mpa EH5= 195,836 Mpa EH6= 195,836 Mpa EH7= 195,836 Mpa EH8= 195,836 Mpa EH9= 195,836 Mpa v = .292 Pipe Den=8027.1997070 kg./cu.m. Fluid Den=1150.0000000 kg./cu.m. Insul Thk= .000 mm. RESTRAINTS Node 10 ANC ALLOWABLE STRESSES B31.8 VIII(2007) Sy= 446 MPa Fac= .7200 ----------------------------------------------------------------------------- From 20 To 30 DX= -100.000 mm. FORCES & MOMENTS Node 30 FX1= 200.00 KN. FY1= -50.00 KN. FZ1= 50.00 KN. MX1= 80.01 KN.m. MY1= 100.02 KN.m. MZ1= 200.04 KN.m. FX2= 200.00 KN. FY2= -50.00 KN. FZ2= -50.00 KN. MX2= -80.01 KN.m. MY2= -100.02 KN.m. MZ2= 200.04 KN.m. ALLOWABLE STRESSES B31.8 VIII(2007)
MATERIAL Changes: 10 20 Mat= (341)A789 S32750 E= 195,836 Mpa v = .292 Density= 8,027.1997 kg./cu.m. JOBNAME: C:\DATA\MOHO NORD\CAESAR\FOR CHECK OF HUB\ASME 31.8...\HUB PIPE-C1 (2)
ALLOWABLE STRESS Changes 10 20 B31.8 VIII(2007) Sy= 446 MPa Fac= .7200 20 30 B31.8 VIII(2007)
RESTRAINTS Len MU GAP YIELD Dir NODE TYPE CNODE STIF1 STIF2 FORCE Vectors -------+-------+------+----------+----------+----------+--------------------- 10 ANC .000 .000 .000
FORCES AND MOMENTS 20 30 Node 30 FX1= 200.00 KN. FY1= -50.00 KN. FZ1= 50.00 KN. MX1= 80.01 KN.m. MY1= 100.02 KN.m. MZ1= 200.04 KN.m. FX2= 200.00 KN. FY2= -50.00 KN. FZ2= -50.00 KN. MX2= -80.01 KN.m. MY2= -100.02 KN.m. MZ2= 200.04 KN.m.
INPUT UNITS USED...
UNITS= SKULD NOM/SCH INPUT= ON LENGTH inches x 25.400 = mm. FORCE pounds x 0.004 = KN. MASS(dynamics) pounds x 0.454 = kg. MOMENTS(INPUT) inch-pounds x 0.000 = KN.m. MOMENTS(OUTPUT) inch-pounds x 0.000 = KN.m. STRESS lbs./sq.in. x 0.007 = MPa TEMP. SCALE degrees F. x 0.556 = C PRESSURE psig x 0.069 = bars ELASTIC MODULUS lbs./sq.in. x 0.007 = Mpa PIPE DENSITY lbs./cu.in. x 27680.000 = kg./cu.m. INSULATION DENS. lbs./cu.in. x 27680.000 = kg./cu.m. FLUID DENSITY lbs./cu.in. x 27680.000 = kg./cu.m. TRANSL. STIF lbs./in. x 0.175 = N./mm. ROTATIONAL STIF in.lb./deg. x 0.113 = N.m./deg UNIFORM LOAD lb./in. x 0.175 = N./mm. G LOAD g's x 1.000 = g's WIND LOAD lbs./sq.in. x 6894.757 = N./sq.m. ELEVATION inches x 0.025 = m. COMPOUND LENGTH inches x 25.400 = mm. DIAMETER inches x 25.400 = mm. WALL THICKNESS inches x 25.400 = mm.
SETUP FILE PARAMETERS ------------------------------------------------------------------------------ CONNECT GEOMETRY THRU CNODES = YES MIN ALLOWED BEND ANGLE = 0.100000 MAX ALLOWED BEND ANGLE = 95.0000 BEND LENGTH ATTACHMENT PERCENT = 1.00000 MIN ANGLE TO ADJACENT BEND PT = 0.500000 LOOP CLOSURE TOLERANCE = 25.4000 mm. THERMAL BOWING HORZ TOLERANCE = 0.100000E-03 AUTO NODE NUMBER INCREMENT= 10.0000 Z AXIS UP= NO USE PRESSURE STIFFENING = DEFAULT ALPHA TOLERANCE = 0.500000E-01 RESLD-FORCE = NO HGR DEF RESWGT STIF = 0.175120E+12 N./mm. DECOMP SNG TOL = 0.100000E+11 BEND AXIAL SHAPE = YES FRICT STIF = 175120. N./mm. FRICT NORM FORCE VAR = 0.150000 FRICT ANGLE VAR = 15.0000 FRICT SLIDE MULT = 1.00000 ROD TOLERANCE = 1.00000 ROD INC = 2.00000 INCORE NUMERICAL CHECK = NO OUTCORE NUMERICAL CHECK = NO DEFAULT TRANS RESTRAINT STIFF= 0.175120E+12 N./mm. DEFAULT ROT RESTRAINT STIFF= 0.112980E+12 N.m./deg IGNORE SPRING HANGER STIFFNESS = NO MISSING MASS ZPA = EXTRACTED MIN WALL MILL TOLERANCE = 12.5000 WRC-107 VERSION = MAR 79 1B1/2B1 WRC-107 INTERPOLATION = LAST VALUE DEFAULT AMBIENT TEMPERATURE= 25.5035 C BOURDON PRESSURE= NONE COEFFICIENT OF FRICTION (MU) = 0.000000 INCLUDE SPRG STIF IN HGR OPE = NO INCLUDE INSULATION IN HYDROTEST = YES REDUCED INTERSECTION = B31.1(POST1980) USE WRC329 NO NO REDUCED SIF FOR RFT AND WLT NO B31.1 REDUCED Z FIX = YES CLASS 1 BRANCH FLEX NO ALL STRESS CASES CORRODED = YES ADD TORSION IN SL STRESS = DEFAULT ADD F/A IN STRESS = DEFAULT OCCASIONAL LOAD FACTOR = 1.00000 DEFAULT CODE = B31.8(ch 8) B31.3 SUS CASE SIF FACTOR = 1.00000 ALLOW USERS BEND SIF = NO USE SCHNEIDER NO YIELD CRITERION STRESS = MAX 3D SHEAR USE PD/4T NO BASE HOOP STRESS ON ? = OD EN13480 USE IN OUTPLANE SIFS= NO LIBERAL EXPANSION ALLOWABLE= NO B31.3 SEC 319.2.3C SAXIAL= NO B31.3 WELDING/CONTOUR TEE ISB16.9 FALSE PRESSURE VARIATION IN EXP CASE= DEFAULT IMPLEMENT B313 APP-P YES IMPLEMENT B313 CODE CASE 178 NO IGNORE B31.1/B31.3 Wc FACTOR= NO USE FRP SIF = YES USE FRP FLEX = YES BS 7159 Pressure Stiffening= Design Strain FRP Property Data File= CAESAR.FRP FRP Emod (axial) = 22064.0 Mpa FRP Ratio Gmod/Emod (axial) = 0.250000 FRP Ea/Eh*Vh/a = 0.152730 FRP Laminate Type = THREE FRP Alpha = 21.5983 C FRP Density = 1660.80 kg./cu.m. EXCLUDE f2 FROM UKOOA BENDING = NO
EXECUTION CONTROL PARAMETERS
Rigid/ExpJt Print Flag ..... 1.000 Bourdon Option ............. 1.000 Loop Closure Flag .......... 1.000 Thermal Bowing Delta Temp .. .000 C Liberal Allowable Flag ..... .000 Uniform Load Option ........ .000
Ambient Temperature ........ 4.000 C Plastic (FRP) Alpha ........ 21.598 Plastic (FRP) GMOD/EMODa ... .250 Plastic (FRP) Laminate Type. 3.000 Eqn Optimizer .............. .000 Node Selection ............. .000 Eqn Ordering ............... .000 Collins .................... .000 Degree Determination ....... .000 User Eqn Control ........... .000
COORDINATE REPORT /--------------------(mm.)----------------------/ NODE X Y Z 10 .000 .000 .000 20 -290.000 .000 .000 30 -390.000 .000 .000
_________________________
Thanks in advance, Regards, Sridhar
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#58625 - 04/15/14 03:13 PM
Re: ASME B31.8 Chap VIII, Hoop stress failure is not recognised
[Re: sridhar]
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Member
Registered: 12/13/99
Posts: 6226
Loc: Houston, Texas, USA
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Submit the job through SmartSupport, please. This must be assinged an incident number and tracked.
_________________________
Regards, Richard Ay - Consultant
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#67881 - 12/11/16 11:12 PM
Re: ASME B31.8 Chap VIII, Hoop stress failure is not recognised
[Re: sridhar]
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Member
Registered: 06/03/12
Posts: 45
Loc: India
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Hi I am facing a new problem using ASME B31.8 Chapter VIII code.
When Defined hydro case the Factor entered in field is 0.72.
In code stress failure criteria. It takes allowable stress as 1*SMYS However expected it should take 0.72*SMYS value entered in field.
In code no such reference is found that It must take factor 1.
Now i do not understand how to explain client.
As wall thickness is calculated with 0.72 for hydro case and it came as governing wall thickness (Higher between case of Design temprature and the Hydro case),. Pls help me with quick reply on this, preferable reference section from ASME B31.8 code. so that proper reply can be sent to the client.
_________________________
Thanks in advance, Regards, Sridhar
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#67891 - 12/13/16 05:02 AM
Re: ASME B31.8 Chap VIII, Hoop stress failure is not recognised
[Re: sridhar]
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Member
Registered: 06/03/12
Posts: 45
Loc: India
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Hi Richard Ay,
Can you please answer this query.
_________________________
Thanks in advance, Regards, Sridhar
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#67896 - 12/13/16 10:03 PM
Re: ASME B31.8 Chap VIII, Hoop stress failure is not recognised
[Re: sridhar]
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Member
Registered: 12/13/99
Posts: 6226
Loc: Houston, Texas, USA
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We really need to see your input file. Please open a Support Request on Smart Support and submit the file(s).
_________________________
Regards, Richard Ay - Consultant
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#67954 - 12/22/16 04:39 AM
Re: ASME B31.8 Chap VIII, Hoop stress failure is not recognised
[Re: sridhar]
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Member
Registered: 06/03/12
Posts: 45
Loc: India
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How can i upload the file on the smart support? can you share the website address and advice the procedure to upload?
_________________________
Thanks in advance, Regards, Sridhar
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#67966 - 12/22/16 11:32 AM
Re: ASME B31.8 Chap VIII, Hoop stress failure is not recognised
[Re: sridhar]
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Member
Registered: 12/13/99
Posts: 6226
Loc: Houston, Texas, USA
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Send an email to: " Loren dot brown at intergraph dot com" and ask for the link and registration details.
_________________________
Regards, Richard Ay - Consultant
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#67968 - 12/22/16 02:00 PM
Re: ASME B31.8 Chap VIII, Hoop stress failure is not recognised
[Re: sridhar]
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Member
Registered: 06/03/12
Posts: 45
Loc: India
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Hi Loren is out of office . Pls send me access to smart drive
Hide quoted text
On 23 Dec 2016 1:28 a.m., "Brown, Loren A" wrote: I am currently out of the office and will return on January 3 2017. For critical support issues, please contact ppmcrm@intergraph.com
_________________________
Thanks in advance, Regards, Sridhar
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