The construction of the 42 inch Colongra Lateral Pipeline brought a range of challenges from the procurement of suitable equipment worldwide, to welding operations and programming to meet tight construction deadlines.

Jemena Site Manager Craig Fuller said “The project presented considerable challenges. We were very happy with the positive way Jemena and Diona worked together to meet these challenges with minimal cost and time impact.”

The 9 km project required the same commitment to setup as it normally would for a pipeline much longer in length. Diona said that it adapted to this challenge in the most cost effective way for the client.

The terrain was typical of semi-urban pipeline, with a strict defined easement of widths ranging from 5 m to 60 m. The ground conditions ranged from rock to swamp and construction involved a bored crossing of the Pacific Highway as well as a number of other vital infrastructure crossings.

With the weight of the pipe being up to 9.2 t for each 12 m length and with wall thicknesses of up to 30 mm it was necessary to construct the pipeline using a tie-in method requiring multi-pipe strings being lifted into place. Diona acquired additional suitable equipment and included in-house modifications to make lifting the pipe safe and effective for welding purposes. Procurement of a 48 inch bending machine was required to bend the heavy walled pipe.

To meet construction deadlines, the welding of the pipe introduced a combination of automatic and semi-automatic welding systems to the project. The equipment had to deliver high metal deposit along with a high quality weld in a X70 high carbon pipe to meet strict defect criteria. In addition to high-end welding equipment, Diona provided a range of heating equipment including induction coils to provide fast pre-heating of the heavy walled pipe. An ergonomic environment was developed to ensure quick setup times and a comfortable working environment for welders resulting in greater productivity.

Dewatering and earthworks were carried out as a priority to ensure that the ground was stable enough to take the heavy construction equipment needed to install the pipe. Diona has a range of earth works equipment which was used for this task.

Careful planning of string lengths was required to meet the challenge of installing the looped pipe, which required three and four pipes to be laid in parallel within a 30 m easement in addition to three loops of induction bends to bend the pipeline through 180 degrees. Other work included installation of a 27 t valve.

Construction of the pipeline was completed in December, with testing in January and commissioning scheduled for completion by the end of the first quarter in 2009.

Managing Director of Diona John O’Connor said “The job has gone extremely well, especially considering all the engineering and construction challenges there were in the beginning. Our thanks go to all involved in the project; it is all the people who make a project a success.”