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AUSTRALIAN WELDING | JUNE 2016
Welding Challenges of the
Collins Class Submarines
Daniel Miller is the Principal Structural Engineer at ASC, and is responsible for the technical integrity of engineering direction for in-service support and major dockings holding technical authority delegation in structural and material domains on the Collins Class Submarines for the Royal Australian Navy. Daniel graduated from Monash University in 1996, with a Bachelor of Engineering (Civil) specialising in Structural Engineering. In 1998, he completed a post graduate diploma in Materials, Welding and Joining at the University of Adelaide.
INSIDE THE INDUSTRY: IIW 2016
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Established in 1985 as Australian Submarine Corporation, ASC was chosen in 1987 as the prime contractor for the design, manufacture, and delivery of the Royal Australian Navy’s fleet of six Collins Class submarines. At the conclusion of their construction in 2003, ASC commenced a 25-year contract with Defence Materiel Organisation for the ongoing repair, maintenance and design upgrades of the submarines. Today, ASC is Australia’s largest specialised defence shipbuilding organisation, with unparalleled naval design and engineering resources, and over 2,600 permanent personnel across three facilities in South Australia and Western Australia.
Daniel Miller, Principal Structural Engineer at ASC, presented at the IIW International Conference on the topic of Welding Challenges of the Collins Class Submarines. Construction The construction of the Collins Class submarines was an unprecedented feat of engineering, design and logistics in Australia. The project required specification, integration and installation of equipment and material from over 150 major contractors and hundreds of smaller suppliers. Over 500 welders were employed by ASC throughout the build, who performed approximately 34km of weld for each of the vessels. Despite the vast amount of weld required during the construction of the Collins Class submarines (between 1987 and 2003), the weld defect rate was less than 1%. Over 33,000 drawings and 5,000 work orders were produced before construction of the Collins Class submarines could begin. Once work started, each submarine took 2.5 million man hours to assemble, with the first submarine completed within three years and eight months. Pressure Hull Steel The Collins pressure hull is a microalloyed QT steel with a low carbon content (to reduce the carbon equivalent). The steel was derived from Kockums and Royal Australian Navy requirements, based on MILS-16216J for HY100, with some additional requirements:
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Impact tests (Charpy V at low temperature) Elongation minimum Dynamic tear tests (at lower temperature) Explosion bulge tests
In-Service Maintenance In 2003, ASC signed a multi-billion Through Life Support agreement with Defence Materiel Organisation for ongoing design enhancements, maintenance and support of the Collins Class submarines, until the end of their operational lives. The initial duration of the agreement was 15 years, with two five-year options to extend. In 2012, ASC signed a new In Service Support Contract (ISSC), a new performance-based contract to replace the Through Life Support agreement. Under this contract, ASC is charged with maintaining and sustaining the operational capability afforded to Australia by the Collins Class submarines. The objective of all in-service maintenance undertaken by ASC is to improve the level of availability of the Collins Class; and to significantly reduce planned maintenance, thereby reducing associated costs from $36 million to $24 million. Daniel described some of the inwater and docked maintenance services that ASC has performed. These services have included a circumferential hull cut (to enable the removal and service of the main motor), and a main generator room hull cut (to remove and refurbish the V8 turbo-charged generator sets).
Both of these maintenance procedures involved careful planning, particularly in terms of balancing the hull once it was cut in half—a specially designed cradle was constructed to ensure the stability of the vessel at all times. Similarly, the pre-heat welding processes and non-destructive testing and validation of weld quality, once the motor and generators were back in position, were extremely rigorous. All welding maintenance work carried out on the Collins Class submarines is subject to rigorous non-destructive testing and validation, with industry best- practice results, including: • 100% visual inspection • 100% magnetic particle inspection • 100% penetrant inspection • 100% ultrasonic inspection • 10 - 100% x-ray inspection Future Technologies: TIP-TIG TIP-TIG is a hybrid welding process, based on Gas Tungsten Arc welding. TIP-TIG can provide high quality, high deposition rates with low heat input values, consistently delivering high quality metallurgical results on a number of alloys. According to Daniel, ASC has had great success in recent times with this new technology, particularly in terms of increasing productivity and lowering costs during inonel clad welding refurbishment. As such, it comes as no surprise that ASC is currently qualifying the process for use in pressure hull welding.