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Elastic Bending Radius Calculation of PIPELINES.pdf
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Input Data:Pipeline Diameter D = 168.3 mmDesign Pressure P = 23.0 Mpa
Installation Temperature Ti = 21 Deg C
Max. Design Temperature (U/G) T2 = 85 Deg CMin. Design Temperature (U/G) T1 = 4 Deg CSMYS of linepipe material S = 241 MPaYoungs modulus of pipe E = 207000 MPa
Steel expansion co‐efficient α = 0.0000116 mm /m / oCPoisson/s ratio = 0.3Corrosion Allowance CA = 3.0 mmPipeline Deisgn factor f = 0.72Joint efficiency factor e = 1.0Temperature derating factor T = 1Min. Required Thickness(incl. CA) tmin = 11.15 mm
Selected wall thickness (incl. CA) ts = 14.27 mm
Selected wall thickness without CA t = 11.27 mm
Restrained Pipe Stress Calculation
Hoop stress Sh = PD / 2t
Sh = 171.73469 MPa
Longitudinal Stress due to Internal Pessure SP = ShSP = 51.520408 MPa
Thermal stress (Compressive) Stc = Eα (Ti ‐ T2) = ‐153.6768 MPa
Thermal stress (Tensile) Stt = Eα (Ti ‐ T1) = 40.8204 MPa
Longitudi. stress (fully restrained) SLC = (Sh‐P)+Eα (T2‐ Ti) = ‐109.06 Mpa
SLt = Sh‐P)+Eα (T1‐ Ti) = 85.44 Mpa
Allowable equivalent stress SAE = 0.9 x S x T
SAE = 216.9 MPa
Bending Stress based on Von mises Equivalent stress Criteria
Seq= (SL2‐SLSH+SH
2) 0.9ST (As per ASME B 31.8/ASME B 31.4)
SL = {SH±SH2‐4(SH
2‐(0.9ST)2)]}/2
SL1 = 243.75 MpaSL2 = ‐72.01 Mpa
Max. value of Net Longitudinal Stress, SL = ‐72.01 Mpa
Allowable Bending Stress values
SB1 = SL‐SLc SB3 352.80
SB1 = 37.04 Mpa
SB2 = SL‐SLt SB4 158.31
SB2 = ‐157.45 Mpa
Maximum Allowable Bending Stress |SB| = 37.044018 Mpa
Minimum Allowable Elastic bend radiusAllowable Bending Stress SB = 37.04 Mpa
Min. Allowable Bending Radius R = ED/2SB= 470.23 m = 2794 D
Value > 0.9ST
Value<=0.9ST