Munmorah Gas Pipeline Storage Project

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Jemena’s Munmorah Gas Pipeline supplies and stores gas for the 667 MW Colongra Gas Turbine Station near Newcastle, NSW.  The “linepack” pipeline was the first of its kind in Australia and is also the largest diameter licensed gas pipeline in Australia at 42”.  The project included a pressure regulation station which contains the largest water bath heater in Australia.  GHD provided engineering design from feasibility studies through to detailed design and provided support during construction (by Diona).

The pipeline service is unique as it provides fuel gas for the “peaking” power station which is only brought online during times of peak electricity demand.  While the power station is offline, the pipeline continues to receive gas over a 24 hour period and acts as a storage vessel.  As the instantaneous fuel demands exceed the pipelines capacity to supply gas when the power station comes online, the power station draws down on the stored gas (linepack) in the pipeline over a 3 to 5 hour period.  This allows the Owner freedom to purchase and store gas while the spot price is low and supply it during peak periods when the prices are high, therefore maximizing return.

The unique nature of the pipeline required GHD to adopt an innovative approach to design.  To maximize the storage capacity of the pipeline, two sections of 42” pipe (a combined 9 km) were designed and constructed within a relatively small area of land.  These pipelines were linked to the power station by another 3.6 km of 10” pipeline.

Due to the cyclic nature of the power station operation, the pipeline pressure varies significantly over a 24 hour period.  This introduces fatigue stresses not normally experienced by conventional gas pipelines.  GHD performed extensive fatigue analysis using advanced pipe stress modeling software to test that the pipeline was suitable to operate under the proposed conditions.  As a consequence of the significant pressure variations, operating temperature variations were also a key consideration.  GHD undertook complex hydraulic modeling and process simulations to account for these unusual design parameters in addition to the conventional analysis.

GHD also provided design for the control systems for compression and pressure regulation.  Construction was completed in late 2008.

Hydrocarbons Processing

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Hydrocarbon Processing facilities handle products which are flammable and hazardous and often at elevated pressures and temperatures. We have a direct interest in the various aspects of process hazard management – pipeline risk assessments, HAZOP study, SIL/LOPA study, Consequence Modelling of hazardous incidents (e.g. gas dispersion and thermal radiation). Our activities include the revalidation of previously completed process hazard analysis studies.

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Hydrocarbons Transportation

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Community expectations demand that pipelines and facilities are designed and constructed in such a way that the risk of harm to the public is minimised.  Pipelines projects must also be delivered with minimum impact on the environment and cultural heritage whilst providing a return on investment for pipeline owners.

Pipeline and associated facility design and maintenance are subject to stringent codes and regulatory requirements which aim to achieve safe operation through design life.

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