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The DBNGP runs underground for its entire length. Ten compressor stations are located at approximately 150 kilometre intervals along the length of the pipeline, these stations provide the pressure needed to move the natural gas.
The compressor units are operated remotely from the Transportation Services Control Room in central Perth, with communications to the sites via a supervisory control and data acquisition system or SCADA. Compressor station sites can also be staffed and are used as bases for the pipeline’s maintenance teams.
The pipeline's location is marked by safety signs positioned at regular intervals along the DBNGP Corridor.
Pipeline Construction Standards
The original DBNGP was constructed to meet international standards of engineering and over a quarter of a century later, the foresight shown by those who designed the pipeline is still paying dividends.
An example of this is the Fusion Bonded Epoxy (FBE) coating used in the original construction to prevent the pipeline corroding. This was a controversial decision at the time as it was new technology, but the use of FBE has significantly lessened the need for maintenance due to corrosion compared to other pipelines of the same age. In fact, FBE is still considered the best pipeline protection coating today.
Like all major pieces of infrastructure, the pipeline and its facilities have undergone many upgrades and changes, but the quality of the initial construction has played a key role in the ongoing reliability and performance of the asset.
The DBNGP was constructed in accordance with the Standards Association of Australia Gas Pipeline Code 1697-1981, and more recently, its successor standards AS2885 - 1997 and AS2885 - 2007 Australian Standard 2885-2007 should be consulted when planning and designing works in the vicinity of the pipeline.
Graders and bulldozers are used to clear an area to provide for construction activities. Brush and vegetation is cleared from the work area and stored for respreading after pipeline is laid. Topsoil is then stripped from the work area and stockpiled in windrows for use during rehabilitation.
Steel pipe is trucked to the construction site in sections, each approximately 18 meters long. These are then laid end-to-end next to the trench alignment. The sections are placed on padded bags that are raised on blocks of wood (timber skids), to protect the pipe.
Pipe sections are welded together
Pipeline Fast Facts
- Length: 1489 kilometres
- Diameter: Nominal Size: 650mm, 500mm
- Maximum Allowable Operating Pressure: 8.48 Mpa
- Steel grade: API 5LX 65
- Wall Thickness: 16mm to 4.8mm
- Length: 1252 kilometres
- Diameter: Nominal Size 650mm, 450mm
- Maximum Allowable Operating Pressure: 8.48MPa 10.2 design
- Steel Grade: API 5LX 70
- Wall thickness: 11.7mm to 8.72mm
- Length: 339 kilometres
- Diameter: Nominal Size: 150mm to 500 mm
- Total installed power: 228 MW
- Number of units: 27
- Width: 30 meters reducing to 15 meters south of Wagerup West
- Landowners: 1361 land parcels being occupied by 653 land owners
- Terajoules of gas transported daily : This depends on customers requirements
- One terajoule is enough gas to supply an average home for about 50 years
- The DBNGP is the longest natural gas pipeline in Australia
- The total DBNGP pipeline surface area is approximately 5.9 million square meters which is equivalent to 280 Subiaco Ovals
- The DBNGP stores about 70 million standard cubic meters of gas on average per day. This equates to about 2,700 terajoules of stored gas energy
- The total weight of steel used equates to over 400,000 average family cars
The Pipeline corridor is re-contoured to match surrounding landform and erosion controls constructed where appropriate. Separately stockpiled topsoil is then respread evenly across the corridor and any cleared vegetation placed across the corridor, to assist in soil retention and provision of seed stock.
DBP Expansion Projects
The DBNGP underwent a range of expansion projects under previous ownership structures. However, the most advanced have been undertaken by the current owners, who have invested in three major expansion projects since acquiring the asset, these projects are known as Stage 4, Stage 5A and the most recent, Stage 5B.
These three projects were carried out in direct response to increasing demand for gas in the south-west of WA. The owners worked closely with major gas customers to deliver the capacity required within the timeframes needed to support those customers’ projects. Increasing the gas haulage capacity of the pipeline was crucial in supporting economic growth in WA.
The expansions were designed and built to meet DBP’s contractual obligations. As a result of the expansions, 83% of the pipeline has now been duplicated – effectively creating a second pipeline. This was achieved via a process known as looping. Looping involves installation of pipe lengths parallel to the existing asset. The expansion projects also required upgrade works on the pipeline’s compressor stations, control and communications systems and metering equipment.
The three expansions have increased the capacity of the pipeline by over 300 terajoules per day as well as enhancing the reliability of the pipeline and improving security of supply for customers.
The Stage 4, Stage 5A and Stage 5B expansion projects have seen the pipeline owners inject $1.7 billion into the DBNGP.
In the next 12 months, the final closure and completion of the Defects Liability Period will expire. The works include the:
- Flow testing of all station pipework at design flows
- The completion of the Fortescue River Crossing
- The modifications and completion of traffic and flow management at all stations
- The ongoing environment restoration and subsidence repairs of the Right of Way.