ANALYSIS OF EXTERNAL LOADS ON BURIED PIPE (Based on ALA - Guidlines for the design of Buried steel pipe)
Project
: 13404
Pipeline : 6" Jet fuel pipeline
FLOODED
1.) EARTH LOAD Total dry unit weight,
r =
NON-FLOODED
1
120
LB/FT^3
3 18.86 kN/m
Height of backfill above pipe, C =
59.06
INCH
1.50 m
unit weight of water ,
62.4
LB/FT^3
3 9.81 kN/m
59.06
INCH
1.50 m
rw =
height of water above pipe, Water buoyancy factor,
hw = Rw =
0.67
= Earth Load,Pv
(1-0.33(hw/C) rw.hw+Rw.r.C
=
4.88
=
PSI
2.) LIVE LOAD Concentrated load at the surface above pipe, Ps = offset distance from pipe to line of application of surface load d = Impact factor,
F' =
Pressure Transmitted to pipe,
Pp = =
18000
lb
0
inch
1.15 F'*3Ps/(2*π*C2[1+(d/C)2]2.5) 2.83 PSI
3.) OVALITY Pipe Outside Diameter,
D=
6.625 INCH
Bedding constant,
K (~0.1) =
0.1
thickness of pipe, thicknes of liner,
t = tL =
0.280 INCH
thicknes of coating ,
tc =
0.1063 INCH
0 INCH
Pressure on pipe due to load, P =
dy/D =
1.5
E` =
500 PSI
Youngs modulus of pipe, modulus of elasticity of liner,
E= EL =
29000000 PSI
modulus of elasticity of coating, Ec=
113000 PSI
0 PSI
7.71 PSI
Equi. pipe wall stiffness, (EI)eq = Ovality ,
Deflection lag factor, D1(~1.0 -1.5) = Modulus of sol reaction,
53016.52 (D1.K.P)/((EI)eq/R^3 + 0.061 E') 0.001 INCH 0.15%
Ovality percentage =
Check Ovality <3%
OK
Generally in steel pipelines, buckling typically occurs when the ovality reached 20%, however as per API RP-1102 recommends to limit cross section ovality to 3%
4.) RING BUCKLING PRESSURE FS= factor of safety Factor of safety, FS Empirical coeff of elastic support, B'=
2.5 1/(1+4e^(-0.065C/D)) 0.309
Critical Ring buckling Pressure Qrb=
(1/FS)*sqrt(32.Rw.B'.E'.(ET)eq/D^3)) 310.64 PSI
Notes:1.) The surface loads are assumed to be acting as a point load 2.) The analysis is carried out for empty condition of pipe
2.5 for C/D=>2 3 for (C/D)<2
Track Crossing Calculation-Uncased (as per API 1102) PROJECT: 13404 PIPELINE: 6" Jet Fuel Pipeline Initial Design information Pipe and operational characteristics: Outside Diameter, D (inches) Design/Oper. Pressure, p (bar g) Line Pipe Steel Grade Specified min. yield strength, SMYS (psi) Design Factor, F Allowable Design Factor, Fa Longitudinal joint Factor, E Temperature derating Factor T Design Wall Thickness, t (mm) Corrossion Allownace, c (mm) Corroded Wall Thickness, tw (mm) Installation Temp Deg C Maximum operating Temp Deg C Installation and Site Characteristics Depth H (Meters) Bored diameter, Bd Soil Type Modulus of soil reaction, E' (ksi) Resilient modulus, Er (ksi) Unit Weight of soil, Lamda , lbs/in³ Type of Longitudinal Weld Design Wheel Load from axle, Ps/t (kips) Pavement type (Flexible / No Pavement / Rigid) Ap (Area of Tire Contact)sq.m = Critical Axle Configuration Other Steel Properties Young's modulus, Es Poisson's ratio, Vs Coefficient of Thermal Expansion mm/mm/deg C
6 19.6 API 5L Gr. B 35000 0.72 0.72 1 1 7.11 0 7.11 13 65
= Barg = psi
168.3 mm 284.3
1.960 Mpa 240 MPa
mm mm mm C C
1.5 m 168.3 mm Loose Sand & Gravel 0.5 ksi = 5 ksi = 0.070 lbs/in³ = SMLS 17.8125 = Rigid 0.053 m² Single
30000000 psi 0.3 0.0000117
4.92 feet
3.4 MPa 34 MPa 1926 Kg/m³ 79.23 KN
206842.772 MPa
Check Allowable Barlow Stress Equation 8a, (Shi=p.D/2.tw) less than or equal to FxExTxSMYS p= 1.96 MPa D= 168.3 mm tw= 7.11 mm F= 0.72 E= 1 SMYS= 240 MPa T= 1 Shi (Barlow) Barlow Criteria fulfilled (Shi less than F.E.T.SMYS) Circumferential Stress Due to Earth Load tw/D E' From Figure 3 of API RP1102, KHe Dia of earth surrounding the pipeline Bd H/Bd From Figure 4 of API RP1102, Factor Be = Bd /D = From Figure 5 of API RP1102 Factor Ee = Unit Weight of Soil Lamda SHe from Equation 1 of API RP1102, (SHe=KHe.Be.Ee.Lamda .D)
23.197 OK
< or =
0.0422 3.4 800 168.3 mm 8.91 1.300 1.00 0.820 1926 kg/m³ 2.71 MPa
172.80 MPa
2711 KPa
Page 2/6
Impact Factor Fi and Applied Design Surface Pressure, w Fi from Figure 7 & Sect 4.7.2.2.2 Ap (Area of Tire Contact)sq.m =
1.50 0.05295796 m² 1496.09 KPa
w = Pt/Ap lbs/in2 Cyclic Circumferential Delta SHh From Fig 14 of API RP1102, for tw/D and Er values KHh = From Fig 15 of API RP1102, GHh = From Table 2 of API RP1102, R = From Table 2 of API RP1102, L = From Equation 5 of API RP1102, Delta SHh = KHh.GHh.R.L.Fi.w
8.00 1.30 1.10 1.00 25.67 MPa
25673 KPa
Cyclic Longitudinal Delta SLh From Fig 16 of API RP1102, for tw/D and Er values KLh = From Fig 17 of API RP1102, GLh = From Eqn 6 of API RP1102, Delta SLh =KLh.GLh.R.L.Fi.w
9.00 1.550 34.44 MPa
34436 KPa
Circumferential Stress Due to Internal Pressure From Eqn 7 of API RP1102, SHi =p(D-tw)/2.tw
22.22 MPa
22217 KPa
Principle Stresses S1, S2, & S3 From Eqn 9 of API RP1102, Circumferential S1 =SHe+Delta SHh+Shi From Eqn 10 of API RP1102, Longitudinal S2 = From Eqn 11 of API RP1102, Radial S3 = -p = -MAOP From Equation 12, Page 2, Seff =
50.60 -83.93 -1.96 117.43
Check Allowable Effective Stress Total effective stress in pipeline, Seff not to exceed SMYSxFa SMYS x Fa
172.80 MPa
IF Seff is Equal or Less Than (SMYS x F) then Crossing is
MPa MPa MPa MPa
S1-S2 S2-S3 S3-S1
OK
134.53 MPa -81.97 MPa -52.56 MPa
67.96%
Check Fatigue F = 0.72 SFG
From Table 3 of API RP 1102 Delta SLh = SFG x F =
=
12000 psi
=
82.74 MPa
34.44 MPa 59.57 MPa Girth Welds Delta SLh < = SFG x F
Girth Welds OK for Fatigue
Longitudinal welds F = 0.72 SFL = From Table 3 of API RP 1102 21000 psi = 144.79 MPa Delta SHh shall be less than or equal to SFL x F Delta SHh = 25.67 MPa SFL x F = 104.25 MPa Longitudinal welds Delta SHh < = SFL X F Longitudinal Welds OK for Fatigue
Page 3/6
ANALYSIS OF EXTERNAL LOADS ON BURIED PIPE (Based on ALA - Guidlines for the design of Buried steel pipe)
Project
: 13404
Pipeline : 3" Jet fuel pipeline
FLOODED
1.) EARTH LOAD Total dry unit weight,
r =
NON-FLOODED
1
120
LB/FT^3
3 18.86 kN/m
Height of backfill above pipe, C =
59.06
INCH
1.50 m
unit weight of water ,
62.4
LB/FT^3
3 9.81 kN/m
59.06
INCH
1.50 m
rw =
height of water above pipe, Water buoyancy factor,
hw = Rw =
0.67
= Earth Load,Pv
(1-0.33(hw/C) rw.hw+Rw.r.C
=
4.88
=
PSI
2.) LIVE LOAD Concentrated load at the surface above pipe, Ps = offset distance from pipe to line of application of surface load d = Impact factor,
F' =
Pressure Transmitted to pipe,
Pp = =
18000
lb
0
inch
1.15 F'*3Ps/(2*π*C2[1+(d/C)2]2.5) 2.83 PSI
3.) OVALITY Pipe Outside Diameter,
D=
3.5 INCH
Deflection lag factor, D1(~1.0 -1.5) =
1.5
0.1
Modulus of sol reaction,
E` =
500 PSI
Youngs modulus of pipe, modulus of elasticity of liner,
E= EL =
29000000 PSI
modulus of elasticity of coating, Ec=
113000 PSI
Bedding constant,
K (~0.1) =
thickness of pipe, thicknes of liner,
t = tL =
0.216 INCH
thicknes of coating ,
tc =
0.984 INCH
0 INCH
Pressure on pipe due to load, P =
7.71 PSI
Equi. pipe wall stiffness, (EI)eq = Ovality ,
dy/D =
0 PSI
33380.52 (D1.K.P)/((EI)eq/R^3 + 0.061 E') 0.001 INCH 0.12%
Ovality percentage =
Check Ovality <3%
OK
Generally in steel pipelines, buckling typically occurs when the ovality reached 20%, however as per API RP-1102 recommends to limit cross section ovality to 3%
4.) RING BUCKLING PRESSURE FS= factor of safety Factor of safety, FS Empirical coeff of elastic support, B'=
2.5 1/(1+4e^(-0.065C/D)) 0.428
Critical Ring buckling Pressure Qrb=
(1/FS)*sqrt(32.Rw.B'.E'.(ET)eq/D^3)) 756.12 PSI
Notes:1.) The surface loads are assumed to be acting as a point load 2.) The analysis is carried out for empty condition of pipe
2.5 for C/D=>2 3 for (C/D)<2
Track Crossing Calculation-Uncased (as per API 1102) PROJECT: 13404 PIPELINE: 3" Jet Fuel Pipeline Initial Design information Pipe and operational characteristics: Outside Diameter, D (inches) Design/Oper. Pressure, p (bar g) Line Pipe Steel Grade Specified min. yield strength, SMYS (psi) Design Factor, F Allowable Design Factor, Fa Longitudinal joint Factor, E Temperature derating Factor T Design Wall Thickness, t (mm) Corrossion Allownace, c (mm) Corroded Wall Thickness, tw (mm) Installation Temp Deg C Maximum operating Temp Deg C Installation and Site Characteristics Depth H (Meters) Bored diameter, Bd Soil Type Modulus of soil reaction, E' (ksi) Resilient modulus, Er (ksi) Unit Weight of soil, Lamda , lbs/in³ Type of Longitudinal Weld Design Wheel Load from axle, Ps/t (kips) Pavement type (Flexible / No Pavement / Rigid) Ap (Area of Tire Contact)sq.m = Critical Axle Configuration Other Steel Properties Young's modulus, Es Poisson's ratio, Vs Coefficient of Thermal Expansion mm/mm/deg C
3 19.6 API 5L Gr. B 35000 0.72 0.72 1 1 5.49 0 5.49 13 65
= Barg = 284.3
88.9 mm
psi
240 MPa
1.960 Mpa
mm mm mm C C
1.5 m 88.9 mm Loose Sand & Gravel 0.5 ksi = 5 ksi = 0.070 lbs/in³ = SMLS 17.8125 = Rigid 0.053 m² Single
30000000 psi 0.3 0.0000117
4.92 feet
3.4 MPa 34 MPa 1926 Kg/m³ 79.23 KN
206843 MPa
Check Allowable Barlow Stress Equation 8a, (Shi=p.D/2.tw) less than or equal to FxExTxSMYS p= 1.96 MPa D= 88.9 mm tw= 5.49 mm F= 0.72 E= 1 SMYS= 240 MPa T= 1 Shi (Barlow) Barlow Criteria fulfilled (Shi less than F.E.T.SMYS) Circumferential Stress Due to Earth Load tw/D E' From Figure 3 of API RP1102, KHe Dia of earth surrounding the pipeline Bd H/Bd From Figure 4 of API RP1102, Factor Be = Bd /D = From Figure 5 of API RP1102 Factor Ee = Unit Weight of Soil Lamda SHe from Equation 1 of API RP1102, (SHe=KHe.Be.Ee.Lamda .D)
15.869 OK
< or =
0.0618 3.4 400 88.9 mm 16.87 1.350 1.00 0.820 1926 kg/m³ 0.74 MPa
172.80 MPa
744 KPa
Page 5/6
Impact Factor Fi and Applied Design Surface Pressure, w Fi from Figure 7 & Sect 4.7.2.2.2 Ap (Area of Tire Contact)sq.m =
1.50 0.05295796 m² 1496.09 KPa
w = Pt/Ap lbs/in2 Cyclic Circumferential Delta SHh From Fig 14 of API RP1102, for tw/D and Er values KHh = From Fig 15 of API RP1102, GHh = From Table 2 of API RP1102, R = From Table 2 of API RP1102, L = From Equation 5 of API RP1102, Delta SHh = KHh.GHh.R.L.Fi.w
4.25 1.45 1.10 1.00 15.21 MPa
15212 KPa
Cyclic Longitudinal Delta SLh From Fig 16 of API RP1102, for tw/D and Er values KLh = From Fig 17 of API RP1102, GLh = From Eqn 6 of API RP1102, Delta SLh =KLh.GLh.R.L.Fi.w
7.50 2.100 38.88 MPa
38880 KPa
Circumferential Stress Due to Internal Pressure From Eqn 7 of API RP1102, SHi =p(D-tw)/2.tw
14.89 MPa
14889 KPa
Principle Stresses S1, S2, & S3 From Eqn 9 of API RP1102, Circumferential S1 =SHe+Delta SHh+Shi From Eqn 10 of API RP1102, Longitudinal S2 = From Eqn 11 of API RP1102, Radial S3 = -p = -MAOP From Equation 12, Page 2, Seff =
30.85 -82.27 -1.96 100.80
Check Allowable Effective Stress Total effective stress in pipeline, Seff not to exceed SMYSxFa SMYS x Fa
172.80 MPa
IF Seff is Equal or Less Than (SMYS x F) then Crossing is
MPa MPa MPa MPa
S1-S2 S2-S3 S3-S1
OK
113.12 MPa -80.31 MPa -32.81 MPa
58.33%
Check Fatigue F = 0.72 SFG
From Table 3 of API RP 1102 Delta SLh = SFG x F =
=
12000 psi
=
82.74 MPa
38.88 MPa 59.57 MPa Girth Welds Delta SLh < = SFG x F
Girth Welds OK for Fatigue
Longitudinal welds F = 0.72 SFL = From Table 3 of API RP 1102 21000 psi = 144.79 MPa Delta SHh shall be less than or equal to SFL x F Delta SHh = 15.21 MPa SFL x F = 104.25 MPa Longitudinal welds Delta SHh < = SFL X F Longitudinal Welds OK for Fatigue
Page 6/6
