Appendix E
Wall Thickness Calculation Report
08-GHD-02-0006 - Arrow Energy Major Pipelines - Initial Safety Management Study
Client: Arrow Energy CALCULATION
Project: ABP
Calculation Title: Wall Thickness Requirement for Job
Internal
No: Pressure
41-24306
1. Introduction
Arrow Energy (the Principal), is proposing to develop a pipeline network in central eastern Queensland
that will deliver coal seam gas from its gas fields in the Bowen and Surat Basins to a proposed LNG
facility to be located on Curtis Island near Gladstone. The proposed network will be approximately
1,200km long and will incorporate scraper stations and intermediate mainline valves.
A pipeline licence has been granted for the major part of the proposed pipeline from the Surat Basin,
however an environment impact assessment of the initial 100km at the start of this pipeline, to the Kogan
North Central Gas Processing Facility near Dalby in south-eastern Queensland, is required.
No part of the proposed pipeline from the Bowen Basin has yet been assessed and this preliminary
engineering is associated with the full extent of approx. 610km of pipeline length, the subject of a
separate report.
The ABP system will consist of a DN800 (32”), Class 600 buried steel pipeline.
This calculation also reflects a possible future upgrade of the ABP system to a DN1050 (42") pipe
diameter.
This calculation only considers the internal pressure containment requirements. It is for preliminary
design purposes only.
The design parameters are:
DN800
DN1050 (possible upgrade)
API 5L X70
MAOP/Design Pressure 10.2 MPa(g)
Design Temperature: -10 to 60°C (assumed)
2. Design Basis and Scope
The basis for performing this calculation is in accordance with AS 2885.1-2007 Section 5.4.2, which
requires numerous design, operation and constructability issues to investigated and (where applicable)
wall thickness values to be calculated. The wall thickness shall be the greatest of the values calculated.
This calculation determines the pipeline wall thickness for the above mentioned project, taking into
consideration internal pressure only.
The further requirements of AS2885.1 are covered in separate calculations.
3. Assumptions
3.1 Code Related Inputs
3.1.1 Specified Minimum Yield Strength
API Grade SMYS (MPa) UTS (MPa)
X 70 485 565(minimum)
Page 1 of 3
Client: Arrow Energy CALCULATION
Project: ABP
Calculation Title: Wall Thickness Requirement for Job
Internal
No: Pressure
41-24306
3.1.2 Design Factor
The maximum allowable design factors are:
0.80 - general
0.67 - for pipeline assemblies and facilities
3.1.3 Gas Temperature
Where the pipeline design temperature is above 65°C the yield stress of the pipe steel shall be de-rated
in line with AS2885.1 3.4.3 – Strength De-rating. The reduction in yield strength shall be 0.07%/°C by
which the design temperature exceeds 23°C.
It is assumed that the maximum pipeline temperature is 60°C. Therefore strength de-rating is not
required as per AS2885.1.
3.2 Design Basis Inputs
3.2.1 Additional Allowances
The gas flowing through the pipeline is assumed to be 'Sales Gas' quality. Consequently the gas is
deemed to be 'Non-Corrosive'. Therefore, the pipeline will have a corrosion allowance of 0 mm.
3.2.2 Pressure Class & Pressure
The pipeline has a Design Pressure of 10.2 MPa.
4. Calculation Procedure
4.1 Internal Pressure
The pipeline wall thickness is calculated using the Barlow formula for internal pressure, using Equation
5.4.3 from AS 2885.1.
= Pressure (MAOP)
= Design Factor
=
2× = Yield Strength
= Outside Diameter
= Wall Thickness
5. Calculation Results
5.1 Internal Pressure
The minimum wall thickness for internal pressure is tabled below both pipe diameters with the associated
design factors.
DN OD MAOP Design Minimum Wall
DN Grade Thickness (mm)
(in) (mm) (MPa) Factor
General 800 32 813 10.2 X 70 0.80 10.69
Pipeline
800 32 813 10.2 X 70 0.67 12.76
Assemblies
Page 2 of 3
Client: Arrow Energy CALCULATION
Project: ABP
Calculation Title: Wall Thickness Requirement for Job
Internal
No: Pressure
41-24306
DN DN OD MAOP Design Minimum Wall
Grade Thickness (mm)
upgrade (in) (mm) (MPa) Factor
General 1050 42 1067 10.2 X 70 0.80 14.03
Pipeline
1050 42 1067 10.2 X 70 0.67 16.75
Assemblies
6. Conclusion
Each location class requires the following minimum wall thickness to meet only the internal pressure
design requirement. Results are rounded up to the nearest 0.1 mm.
All locations require a minimum wall thickness of 10.7 mm for DN800 or 14.1 mm for DN1050.
Pipeline Assemblies and facilities require a minimum wall thickness of 12.8 mm for DN800 or
16.8 mm for DN1050.
Page 3 of 3
