AUSTRALIAN STANDARD 2885.1 - 2007PIPELINES - GAS AND LIQUID
PETROLEUM
LAUNCH SEMINAR
Pipeline Stress RequirementsVersion1.1
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements
The design task is to carry out sufficient preliminary stress analysis to select a pipe wall thickness for internal pressure design for the transmission pipeline.The pipeline will be buried with a minimum cover to the relevant requirements of the Standard.Most of the buried length will be fully restrained both laterally and longitudinally by the soil. Parts of the buried pipeline will not be fully restrained (i.e. bends) and are treated as being unrestrained.The Study Pipeline internal pressure calculations are for both the buried fully restrained lengths and the buried unrestrained lengths.
STATEMENT OF THE DESIGN PROBLEM
Slide 2
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements
1. Calculate wall thickness for internal pressure design.2. Calculate the relevant components of stress.3. Establish the upper and lower temperature
capabilities of the pipeline (RESTRAINED ONLY).4. Calculate the relevant stress levels in accordance with
the Standard.5. Check that the calculated stress levels are within
allowable limits.
DESIGN TASKS
Slide 3
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements
1. AS 2885 requirements for wall thickness are contained in Section 5.4.
2. The requirements for stress and strain are contained in Section 5.7.
3. The calculation basis for stresses in restrained and unrestrained pipelines is contained in Appendix U.
4. Guidelines for the consideration of combined equivalent stress levels and temperature differentials in RESTRAINED LINES are contained in Appendix W.
REQUIREMENTS OF AS 2885
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AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements
External diameter 406.4 mmDesign factor 0.8Design pressure 15.3 MPaMaterial grade X70SMYS 483 MPaYoung’s modulus 207,000 MPaPoisson’s ratio 0.3Upper design temperature 65oCLower design temperature 0oCClosing temperature 15oCExpansion coefficient 1.17 x 10-5 / oC
PIPELINE PROPERTIES
Slide 5
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements
The limits of stress for restrained parts of the pipeline for stress types that include internal pressure are listed in Table 5.7.8.
These stress types are:
Hoop stress.Sustained stress.Total longitudinal stress.Combined equivalent stress.
PART (A) RESTRAINED
Slide 6
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM Pipeline Stress Requirements - Restrained
YD
DP F
DPtσ2
=
Wall Thickness for Internal Pressure Containment
Reference Clause 5.4.3 – Equation 5.4.3
Slide 7
mmxx
xtP 046.84838.02
4.4063.15==
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM Pipeline Stress Requirements - Restrained
The required wall thickness tW shall be greater than:the wall thickness for internal pressure containment tP.
Therefore tW ≥ 8.046 mm
Round up tW to 8.1 mm
Required Wall Thickness for Pressure ContainmentReference Clause 5.4.2
Slide 8
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM Pipeline Stress Requirements - Restrained
W
DL t
DP2
νσ =
Longitudinal Pressure StressReference Appendix U2.2 – Equation U2(3)
Slide 9
MPaxx
L 1151.82
4.4063.153.0 ==σ
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM Pipeline Stress Requirements - Restrained
essureInternal PrHσ
Hσν
HeatingThermal
compσ
compHT σσνσ −=
THcomp σσνσ −=
Longitudinal Thermal StressReference Appendix W
Slide 10
Ycomp
YYcomp x
σσ
σσσ
4145.0
)1745.0(8.03.0
=
−−=
YT
yY
LTfand
fputtingWFrom
σσ
σσ
1745.0
,)8(5
−=
==
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM Pipeline Stress Requirements - Restrained
Ycomp σσ 4145.0=
Thermal Compressive Stress LimitReference Appendix W5.1.2
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MPaxcomp 2004834145.0 ==σ
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM Pipeline Stress Requirements - Restrained
ασE
compt =Δ
Upper Value of TemperatureReference Appendix U2.3 – Equation U2(4)
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Cot 82
42.2200
==Δ
.max9782151 CT o=+=
MPaandCthenCisTDesign compo
to 12150,651 ==Δ σ
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM Pipeline Stress Requirements - Restrained
MPaxYT 34748310072%72 === σσ
Total Longitudinal Stress LimitReference Table 5.7.8
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AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM Pipeline Stress Requirements - Restrained
SUSTER σσσ −=
Derived Thermal Tensile Stress LimitReference Appendix U2.3 & U2.7 Equations
U2(5) & U2(8)
Slide 14
MPaER 232115347 =−=σ
MPaand EAEREB 232,0 === σσσ
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM Pipeline Stress Requirements - Restrained
ασE
EAt =Δ
Lower Value of TemperatureReference Appendix U2.3 – Equation U2(4)
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Cot 95
42.2232
==Δ
.min8095152 CT o−=−=
MPathenCisTDesign EREAo 36,02 == σσ
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM Pipeline Stress Requirements - Restrained
W
DH t
DP2
=σ
Hoop Stress for Pressure ContainmentReference Appendix U2.1 – Equation U2(1)
Slide 16
MPaxx
H 3841.82
4.4063.15==σ
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM Pipeline Stress Requirements - Restrained
MPaLSUS 1150 =+=σσ
Sustained StressReference Appendix U2.6 – Equation U2(7)
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otherFWLSUS σσσσσ +++=
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM Pipeline Stress Requirements - Restrained
MPaTensile
ERSUST 15136115:
=+=+= σσσ
Total Longitudinal StressReference Appendix U2.7 – Equation U2(8)
Slide 18
MPaeCompressiv
compSUST 6121115:
−=−=−= σσσ
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM Pipeline Stress Requirements - Restrained
MPaxTensile C 335151)151384(384: 22 =+−=σ
MPaxeCompressiv C 387)6())6(384(384: 22 =−+−−=σ
Combined Equivalent StressReference Appendix U2.9 – Equation U2(15)
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22TTHHC σσσσσ +−=
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements
Stress Summary for Restrained Lines
Slide 20
Stress Type (Limit)
ValueMPa
LimitMPa
% Allowable
Hoop(FD σY)
384 386 99
Sustained(54% σY)
115 260 44
Total Long(72% σY)
151/-6 347 44/2
Combined(90% σY)
335/387 434 77/89
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements
The limits of stress for unrestrained parts of the pipeline for stress types that include internal pressure are also listed in Table 5.7.8.
These stress types are:
Hoop stress.Sustained stress.
PART (B) UNRESTRAINED
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AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements - Unrestrained
Wall Thickness for Internal Pressure Containment
Reference Clause 5.4.3 – Equation 5.4(2)
Slide 22
The equation covers both restrained and unrestrained lines.
Therefore use the previously calculated value of wall thickness of 8.046 mm.
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements - Unrestrained
The required wall thickness for internal pressure containment tP is the same for both restrained and unrestrained lines.
Therefore tW = 8.1 mm as before.
Required Wall Thickness for Pressure ContainmentReference Clause 5.4.2
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AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements - Unrestrained
W
DL t
DP4
=σ
Longitudinal Pressure StressReference Appendix U3.2 – Equation U3(3)
Slide 24
MPaxx
L 1921.84
4.4063.15==σ
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements - Unrestrained
W
DH t
DP2
=σ
Hoop Stress for Pressure ContainmentReference Appendix U3.1 – Equation U3(1)
Slide 25
MPaxx
H 3841.82
4.4063.15==σ
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements - Unrestrained
Bending StressReference Appendix U3.4 – Equation U3(8)
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Consider a ninety degree 5D buried bend in 8.1 mm thickness subject only to internal pressure in sandy soil with a 90% Proctor compaction density.
Pipe stress analysis software gives the following bending moment at the mid point of the bend:
Bending moment 43,770 N.m
Stress Intensification Factor 1.63.
From which the bending stress σW = 72 MPa.
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements - Unrestrained
Direct Axial StressReference Appendix U3.5 – Equation U3(9)
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From the same analysis the pipe stress analysis software gave the following axial force at the mid point of the bend:
Direct axial force 217,000 N
From which the axial stress σF =21 MPa.
As this is not an externally applied axial pressure force the stress need not be included in the sustained stress calculation.
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements - Unrestrained
MPaSUS 2640072192 =+++=σ
Sustained StressReference Appendix U3.6 – Equation U3(10)
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otherFWLSUS σσσσσ +++=
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements
Stress Summary for Unrestrained Lines
Slide 29
Stress Type (Limit)
ValueMPa
LimitMPa
% Allowable
Hoop(FD σY)
384 386 99
Sustained(54% σY)
264 260 102
AS 2885.1 - 2007PIPELINES - GAS AND LIQUID PETROLEUM
Pipeline Stress Requirements
That Completes the Presentation.
Are there any Questions?
Slide 30
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