Pipeline design in high consequence areas Compliance with AS 2885 in an area subject to encroachment

PIPELINE DESIGN IN HIGH CONSEQUENCE AREAS General principles Specific requirements Application of principles & requirements

GENERAL PRINCIPLES 0.2 BASIS OF THE AS 2885 SERIES OF STANDARDS The fundamental principles …are as follows: (a) … ensure the safety of the community, protection of the environment and security of supply. (b) … designed and constructed to have sufficient strength, ductility and toughness to withstand all planned and accidental loads … during … operation. etc.

GENERAL PRINCIPLES Appendix G ALARP Costs disproportionate to benefits What else can I do? Why haven’t I done it?

DESIGN Specific requirements 4.7 SPECIAL PROVISIONS FOR HIGH CONSEQUENCE AREAS 4.7.1 General Locations …where special provisions are necessary to limit the consequence of pipeline failure on the community or the environment. For gas pipelines, the consequence is likely to result from ignition of the fluid released. For oil pipelines the environmental consequence may be dominant.

DESIGN Specific requirements 4.7.2 No rupture Residential (T1), High Density (T2) Industrial (I), Heavy Industry (HI) and Special (S) Design such that rupture is not a credible failure mode. Either: The hoop stress does not exceed 30% of SMYS or; (b) Critical defect length at MAOP is not less than 150% of the axial length of the largest equivalent defect produced by the threats identified in that location. Definitions of T1 etc are in 4.3 CLASSIFICATION OF LOCATIONS

DESIGN Specific requirements 4.7.3 Maximum discharge rate All Locations Consideration shall be given to … limiting the maximum discharge rate.. High Consequence Locations .. jet fires or vapour cloud fires … maximum allowable discharge rate shall be determined and shall be approved. Flammable gases, HVPLs & liquids with flash point < 20°C … maximum allowable discharge rate shall not exceed 10 GJ.s-1 in Residential, Industrial and Sensitive locations or 1 GJ.s-1 in High Density locations. .

DESIGN Application of principles & requirements X80 pipe with 0.8 design factor City gate with 15.3 MPa upstream and 10.2 MPa downstream Minimum pressure thickness, 10.2 MPa 4.7 mm Minimum pressure thickness, 15.3 MPa 7.1 mm Reasonable penetration resistance (B=1) 8.4 mm Absolute penetration resistance (B=1.3) 11.0 mm No rupture, 10.2 MPa 8.4 mm No rupture, 15.3 MPa 11.0 mm Rural areas upstream of city gate 7.1 mm Rural areas downstream of city gate (if any) 4.7 mm Elsewhere downstream of city gate 8.4 mm T2 or sensitive areas 11.0 mm

DESIGN Application of principles & requirements T1 DOWNSTREAM OF CITY GATE (10.2 MPa, 8.4 mm) No Rupture OK ? Energy Release Rate Maximum credible hole size? Excavator (B=1) ? Borer????? Release rate? < 10 GJ.s-1?

Energy Release Rates (GJ.s-1) 1 MPa 2 MPa 3 MPa 5 MPa 7 MPa 10 MPa 25 mm 0.05 0.09 0.14 0.23 0.32 0.46 50 mm 0.18 0.37 0.55 0.92 1.29 1.85 100 mm 0.74 1.48 2.22 3.69 5.17 7.39 150 mm 1.66 3.32 4.99 8.31 11.63 16.62 250 mm 4.62 9.23 13.85 23.08 32.31 46.16

DESIGN Application of principles & requirements T2 DOWNSTREAM OF CITY GATE (10.2 MPa, 11.0 mm) No Rupture OK Energy Release Rate Maximum credible hole size? Excavator (B=1.3) – N/A Borer????? Release rate? < 1 GJ.s-1?

Compliance with AS 2885 in an area subject to encroachment General principles - unchanged Specific requirements Application of principles & requirements

ENCROACHMENT Specific requirements 4.7.4 Change of Location Class If location becomes Residential, High Density, Industrial, Heavy Industry or Sensitive , must Do safety assessment Implement additional measures Demonstrate risk of rupture is ALARP. Must consider MAOP reduction Pipe replacement Pipeline relocation Modification of land use Extra physical and procedural measures Must demonstrate Cost of alternative is grossly disproportionate to the benefit.

ENCROACHMENT Application of principles & requirements R2 DOWNSTREAM OF CITY GATE CHANGES TO T1 No Rupture ? NOT OK (Wall is 4.7 mm, need 8.4mm for no rupture at 10.2 MPa) Risk of Rupture ALARP? (a) Reduce MAOP? (b) Replace pipe? (c) Relocate Pipe? (d) Modify land use? (e) Improve protection measures?

ENCROACHMENT Application of principles & requirements Highett Gasworks 2.8 MPa assets below ground Courthouse under construction Land adjacent to regulator pits to be used for medium rise residential development

ENCROACHMENT Application of principles & requirements Melbourne Docklands Former West Melbourne Gasworks 2.8 MPa assets above and below ground MAOP maintained Some assets relocated Remaining assets buried Notification zone around regulator pits Restrictions on building and other uses

QUESTIONS?