AUSTRALIAN STANDARD 2885.1 - 2007 PIPELINES - GAS … Kempster - AS 288… · AS 2885.1 - 2007...

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



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



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

Slide 4



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



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==


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


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


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

−=

==


Ycomp σσ 4145.0=

Thermal Compressive Stress LimitReference Appendix W5.1.2

Slide 11

MPaxcomp 2004834145.0 ==σ


ασE

compt =Δ

Upper Value of TemperatureReference Appendix U2.3 – Equation U2(4)

Slide 12

Cot 82

42.2200

==Δ

.max9782151 CT o=+=

MPaandCthenCisTDesign compo

to 12150,651 ==Δ σ


MPaxYT 34748310072%72 === σσ

Total Longitudinal Stress LimitReference Table 5.7.8

Slide 13


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


ασE

EAt =Δ

Lower Value of TemperatureReference Appendix U2.3 – Equation U2(4)

Slide 15

Cot 95

42.2232

==Δ

.min8095152 CT o−=−=

MPathenCisTDesign EREAo 36,02 == σσ


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


MPaLSUS 1150 =+=σσ

Sustained StressReference Appendix U2.6 – Equation U2(7)

Slide 17

otherFWLSUS σσσσσ +++=


MPaTensile

ERSUST 15136115:

=+=+= σσσ

Total Longitudinal StressReference Appendix U2.7 – Equation U2(8)

Slide 18

MPaeCompressiv

compSUST 6121115:

−=−=−= σσσ


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)

Slide 19

22TTHHC σσσσσ +−=



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



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

Slide 21


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.



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

Slide 23



W

DL t

DP4

=σ

Longitudinal Pressure StressReference Appendix U3.2 – Equation U3(3)

Slide 24

MPaxx

L 1921.84

4.4063.15==σ



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



Bending StressReference Appendix U3.4 – Equation U3(8)

Slide 26

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.



Direct Axial StressReference Appendix U3.5 – Equation U3(9)

Slide 27

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.



MPaSUS 2640072192 =+++=σ

Sustained StressReference Appendix U3.6 – Equation U3(10)

Slide 28

otherFWLSUS σσσσσ +++=



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



That Completes the Presentation.

Are there any Questions?

Slide 30

AUSTRALIAN STANDARD 2885.1 - 2007 PIPELINES - GAS … Kempster - AS 288… · AS 2885.1 - 2007...

Documents

Transcript of AUSTRALIAN STANDARD 2885.1 - 2007 PIPELINES - GAS … Kempster - AS 288… · AS 2885.1 - 2007...