Here, Mr Lei Jin, Managing Director of Bao Australia Pty Ltd, a wholly-owned entity of Baosteel, speaks to The Australian Pipeliner about the design specifications and construction aspects of the pipeline.
QGC Pty Limited, the wholly-owned Australian subsidiary of BG Group, is developing coal seam gas (CSG) in the Surat Basin of southern Queensland for domestic and export markets through its Queensland Curtis LNG (QCLNG) Project.
The LNG plant is located on Curtis Island, near Gladstone, Queensland. CSG is being extracted from several production areas and transported by an approximately 196 km DN1,050 gathering pipeline to the export pipeline receipt point, located in the vicinity of Miles. The DN1,050 export pipeline is approximately 344 km long and will transport gas to the LNG plant at Gladstone.Article continues below…
The basis of the design – why the pipeline is the largest onshore gas transmission pipeline built in Australia
The size of the pipeline was dictated by the need to supply 190 PJ/a of CSG for two LNG trains under free flow, with a maximum allowable operating pressure of 10.2 MPa, and provision for addition of compression to supply a possible third train in the future. These requirements led to the choice of a diameter of DN1,050 with a wall thickness of 14.1 mm, 18.0 mm, and 23.5 mm for operation at a principal design factor of 80 per cent specified minimum yield strength for X70 line pipe.
Although there have been some short lengths of DN1,050 pipeline constructed in Australia, the previous largest long-distance onshore gas transmission pipeline built in Australia was the 864 mm diameter Moomba to Sydney Pipeline, which was built in the 1970s.
The total quantity of pipe ordered was 550 km allowing for 340 km of export pipeline with the balance for the collection header. The total tonnage was 207,690 t.
Why did QGC select Baosteel as the sole supplier?
Following a competitive tender and a careful technical bid evaluation process, the pipe order was placed with Howa Trading Co. Ltd, a wholly-owned subsidiary of Baoshan Iron & Steel Co Ltd (Baosteel) of the People’s Republic of China. This was the first major export of high-strength longitudinal seam submerged arc-welded (LSAW) pipe outside of China by any Chinese company, and is the largest order of line pipe by Baosteel for a single pipeline project.
Prior to the award of the project, QGC required the development of an agreed project- and contract-specific manufacturing procedure specification (MPS), covering steel making, plate rolling, pipe making, and coating and lining. This process allowed the purchaser to have confidence and certainty in the agreement rather than relying upon pre-production negotiations following the award of the contract, when the purchaser has reduced leverage.
Baosteel provided a detailed project-specific MPS at bid stage, and this document evolved further through pre-production and manufacturing procedure qualification. Together with highly detailed inspection and test plans, the MPS is central to the specification, inspection and quality-control processes of both parties. The development of the MPS was especially helpful in assisting mutual understanding in a new relationship involving different cultures.
Manufacturing procedure qualification testing (MPQT), including a range of special tests such as longitudinal tensile tests, fracture propagation and initiation transition temperature tests and full-scale burst tests were carried out on each of the three wall thicknesses in both the as-manufactured and as-coated condition before the commencement of production.
Key aspects of the specification that Baosteel agreed to meet included a low value of yield-to-tensile ratio on round bar (unflattened) tensile tests, the conduct of full-scale pressure tests to measure yield strength and burst pressure before and after coating to assess the degree of strain ageing caused in the fusion-bonded epoxy coating process, and the performance of field weldability tests.
The MPQT process demonstrated to QGC and other stakeholders that the Baosteel pipe is equal to or better than best practice in all respects and provided assurance that construction and operation risks were addressed and mitigated to low or negligible levels consistent with the requirements of AS2885.
Baoshan Iron & Steel Co., Ltd (Baosteel) is the largest and most advanced integrated steel company in China. By means of leveraging comprehensive advantages such as good faith, talents, innovation, management, and technology, Baosteel said that it is also recognised as a world-leading steel company by the global steel market. According to World Steel Dynamics, the company ranks as number three in the world in terms of comprehensive competency.
Baosteel specialises in producing high-tech and high value-added steel products. It has become the main steel supplier to the automobile, household appliance, energy, shipbuilding, pressure vessel and container industries in China. Baosteel also exports its products to over forty countries and regions including Australia, Japan, South Korea, the United States and the European Union.
Baosteel’s steel pipe industry includes a large range of tubular products including medium-diameter high-frequency-welded pipe, and large-diameter longitudinal submerged arc-welded pipe.
Baosteel’s line pipe capability
Baosteel has the capacity to supply cold expanded LSAW pipe from 508 mm to 1,422 mm diameter in grades up to X80, and has undertaken successful manufacturing trials on grade X100. Sour service steels have been supplied on grades up to X65. The steel-making facilities are state-of-the-art and can achieve extremely low sulphur steels with excellent weldability.
During the last two decades, Baosteel has produced 7.4 MMt of pipeline products. In order to develop pipeline products, Baosteel has built state-of-the-art facilities such as a 5 m wide heavy plate rolling mill, an HFW (ERW) mill and a UOE mill in quick succession. This has helped to achieve multi-varieties of products such as coils, plates and pipes.
Baosteel also has a complete and consistent quality-assurance system, which enables the implementation of the client’s requirements within Baosteel’s internal quality-control system and the achievement of high-quality and fully traceable product identity.
Success on the pipeline
The success of the QGC project did not happen by chance. From first learning about the project, until the final shipment arrived in Brisbane in the fourth quarter of 2011, Baosteel established a dedicated project team to work with QGC to achieve full compliance with the project requirements. Baosteel is dedicated to the provision of customer responsive service and the supply of fit-for-purpose product, not only in technical issues but also in commercial terms.
The delivery arrangement of 60 km per month with 30 km safety stock always ensured that the whole project remained on track, and Baosteel also provided a quick response as soon as project quantity variations arose as further project design proceeded.
In overall terms, the project was a major challenge for Baosteel and gave rise to many requirements that had not been encountered by the company previously. At the same time this challenge was undertaken in the face of competition from world-class first-tier pipe mills from Europe, Japan and elsewhere.
Some of the specification requirements in areas such as steel cleanliness, and pipe toughness and strength properties were unusually onerous, and this added to the challenge.
Nevertheless, now that delivery has been completed and a substantial portion of the pipeline has been welded, lowered in, and back-filled, the company is able to say that all of the challenges have been met.