Variation of Pipeline Licence WA-11-PL (John Brookes (Cth))

Item

Item Description

Details

1

Outside diameter of pipe and riser

457.2 mm (18 in)

2

Wall thickness of pipe inclusive of riser (only for carbon steel)

15.9 mm (0.6 in) (KP21.2 to KP48.1 and pipeline riser);

17.5 mm (0.7 in) (KP48.1 to KP53.9);

15.9 mm (0.6 in) (KP53.9 to KP54.4) pipeline repair spools

3

Length

33.2 km (approximate)

4

Design life

20 years (approximate)

10 years for replacement spool installed as part of the John Brookes Replacement Project completed Q1 2023

5

Pipeline Material

Carbon Steel

6

Pipeline and Riser Steel Grade

DNV-OS-F101 Grade 450

7

Pipeline Specification

DNV-OS-F101 High Frequency Weld

8

Minimum yield strength of pipe steel

450 MPa (65,267.0 psi) Specified Minimum Yield Strength (SMYS)

9

Maximum Allowable Operating Pressure

13.75 MPag (1,994.3 psi)

10

Design Capacity

Maximum design flowrate of 260 MMscf/d

11

Characteristics of substance proposed to be conveyed

Wet gas (approximate 85.5% methane saturated with water at reservoir conditions)

12

General plans and descriptions of pump stations, tank stations or valve stations and their equipment

• Subsea isolation valve located adjacent to
  John Brookes platform, which is provided with dropped object protection frame and
  1 electrical cable and 1 hydraulic pack

13

General plans and descriptions of pipeline repair

2015 Replacement Project

• The inclusion of a 520 m (1,706 ft) (nominal) length comprising straight spools and tie-in spools to form a cooling spool downstream of the Subsea Isolation Valve as the replacement for the existing Carbon Steel pipeline
• Straight spools American National Standards Institute (ANSI) flange jointed (Weld Neck/swivel-ring pairs) as 4 lengths (nominally 46 m (150.9 ft) long), externally coated with Thermally Sprayed Aluminium (TSA)
• Tie-in spools ANSI flange jointed (WN/swivel-ring pairs) as varying lengths, externally coated with TSA
• Straight spools, tie-in spools and flanges corrosion-resistant alloy (CRA) (Inconel 625) clad internally
• Straight and tie-in spools stabilised by gravity anchors
• Cooling spool cathodic protection by sacrificial anodes affixed to the gravity anchors and cable connected to the straight and tie-in spools
• Straight and tie-in spool welded joints TSA coated
• Subsea Isolation Valve structural modification to accommodate the new spool configuration
• Downstream tie-in of the cooling spool via mechanical connector
• Removal of the existing Ring Pair Corrosion Monitoring (RPCM) probe and dummy spool immediately downstream of the Subsea Isolation Valve
• Installation of a retrievable temperature data logger in the vicinity of the mechanical connector.

2023 Tie-In Spool Replacement

• Replacement of the tie-in spool directly upstream of the Subsea Isolation Valve
• Tie-in spool ANSI flange jointed (WN/swivel-ring pair) and externally coated with TSA
• Tie-in spool and flanges corrosion-resistant alloy (CRA) (Inconel 625) clad internally
• Tie-in spool cathodic protection by sacrificial anodes affixed to the existing gravity anchor

14

General plans and description of pigging facilities

Provision for offshore pig launcher located at the platform and an onshore pig receiver at Varanus Island