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ConnectT h e m a g a z i n e o f T W I

Issue 03 2017

TWI has been working with astrospace contractor Airbus Defence and Space to satisfy a European Space Agency (ESA) request to investigate cost-effective manufacturing methods for titanium propellant tanks.

The project investigated the feasibility of using stationary shoulder friction stir welding (SSFSW) techniques for the cylindrical welding of titanium alloys suitable for launch vehicle propellant tanks. The investigations sought to reduce lead times and costs by developing and validating a system required to weld titanium alloys and also to raise the Technology Readiness Level (TRL) of SSFSW of titanium alloys to prototype demonstrator (TRL6) level.

Current manufacturing methods for titanium propellant tanks suffer from extremely high cost and long manufacturing lead times. Material wastage from complicated forging, machining and forming techniques, coupled with electron beam (EB) welding makes propellant tanks one of the most expensive hardware items on a satellite launch programme. While friction stir welding (FSW) is capable of welding high strength high temperature materials such as steel and nickel alloys, by using this modified version of FSW, titanium can also be welded successfully.

The TWI team conducted an extensive review of material and manufacturing processes, with forged and cast titanium both offering the mechanical property requirement.

In August 2016 TWI successfully performed the world’s first full circumferential SSFSW of two 420mm cast titanium cylinders. The test pieces were then subjected to full NDT evaluation and mechanical assessment to confirm joint quality and properties. Later the same year, TWI fabricated and delivered the first one of four SSFSW cast titanium prototype demonstrator (TRL6) propellant tanks to the European Space Agency, with a delighted response from ESA.

The achievement and success of the ESA-TWI-Airbus team was recognised in March 2017, when they were awarded the Raiser 2017 Award (right) for Friction Welding Innovation.

TWI investigates cost-effective manufacturing methods for titanium propellant tanks for the European Space Agency

Stationary shoulder friction stir welded cast titanium demonstrator propellant tank

If you are interested in finding out more about Industrial Membership please contact our Membership team,

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Issue 03 2017

New Industrial Members of TWI

AeroEdge Co LtdJapanSales and manufacturing of aerospace parts.

AMG Al UK LtdUnited KingdomAMG produces highly engineered specialty metal products and advanced vacuum furnace systems.

Ansaldo NESUnited KingdomNuclear engineering and manufacture.

APEMCO SALuxembourgDevelopment and manufacture of atmospheric plasma equipment.

AVIC Manufacturing Technology InstituteChinaAerospace

Cedar Metals LtdUnited KingdomSpecialist consultants in the mining, ore processing, production, fabrication and uses of refractory metals, rare earths and corrosion resistant materials. Plus general powder metallurgical processing and friction stir welding.

City Technology Ltd United KingdomDesign and manufacture of electrochemical gas detection sensors.

ETP Transmission ABSwedenDevelop and manufacture hydraulic hub shaft friction connections.

Integrity NDT EngineeringTurkeyIntegrity NDT specialise in the inspection management of power plant outages and refinery shutdowns ‘turnarounds’.

Mecc.AL srl a Socio UnicoItalyHeat sink and cold plate systems for electronics and telecoms applications.

MIC Group LLCUnited StatesProvider of comprehensive precision machining and electro-mechanical assembly solutions to the most complex of manufacturing challenges.

Mincon International LtdIrelandManufacturer and distributer of precision engineered hard rock drilling tools.

Orbital ATK UK United KingdomDesigns, builds and delivers space, defence and aviation-related systems.

Peter J Douglas Engineering Ltd United KingdomRepair and maintenance of Industrial boilers and auxiliary equipment.

Talga Technologies LtdUnited KingdomGraphene based products and technology development.

Thales Alenia Space S.p.A ItalySpace systems (satellite manufacture).

Sol VoltaicsSol Voltaics

WD Close LtdUnited Kingdom

Qatar Petroleum - Engineering Technical Services Division Qatar

Burgess MarineUnited Kingdom

Selective laser melting training course launchedTWI has announced a new course covering the Fundamentals of Selective Laser Melting (SLM).

The new course has been designed to equip attendees with an appreciation of the Selective Laser Melting process, including the advantages and disadvantages of SLM and the associated equipment and hardware.

Trainees will also learn about the end-to-end manufacturing process chain, including metal powders, component design and optimisation, derivation of SLM process parameters, post processing, cost issues and the certification and validation of SLM components. There will also be a focus on safety and certification. The course will not only cover Selective Laser Melting, but also give an overview of other additive manufacturing techniques.

This three-day course is launching this September (26-28 September) at the TWI Yorkshire office in Rotherham, with another course on 21-23 November.

There are also plans to launch a one-day introductory course and a longer five-day version including theory and practice of SLM.

For more information please contact us.

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January/February 2014

New manufacturing process developed at TWI reinforces Hayter’s winning positionHayter Ltd called upon TWI to assist with the development of a plastic roller for a number of its lawn mowing machines.

The roller, which consists of a roller body and cap and made from glass-filled polypropylene (PP), cannot be manufactured in one piece.

In response, a team of engineers at TWI investigated the use of a 20 KHz ultrasonic welding machine to attach the PP can to the PP roller body.

The team designed a bespoke 20KHz sonotrode and holding nest for welding the two parts before beginning a series of trials. Once sample welds on a number of rollers had been completed, the team was also able to check weld quality using X-ray computed tomography.

Following the successful trials, Hayter is now using the technique in production, with the reinforced polymer rear roller delivering strength, rigidity and resistance to chemical fertilisers and corrosion.

Hayter Ltd kindly donated a Harrier 41 Pro lawnmower to TWI, which can be seen in the atrium at TWI Cambridge.

Issue 03 2017

War at sea: the battle against corrosion and fatigueJob Knowledge 144

Introduction

Corrosion: nature’s great destroyer – and the bane of any offshore operator’s business.

In 2016, NACE International released its report on global corrosion, ‘International Measures of Prevention, Application and Economics of Corrosion Technology (IMPACT)’. Put together over two years, the study came to some staggering conclusions about the price of corrosion and the room for improvement when it comes to preventing it.

IMPACT estimated the annual global cost of corrosion to be $2.5 trillion: equivalent to almost 3.5 per cent of global GDP and only a few hundred billion dollars short of the UK’s entire annual domestic output.

By implementing best-practice corrosion protection, the study said this cost could be reduced by up to a third, or between $375 and $875 billion. With such huge amounts of money at stake, it’s little wonder that companies around the world are investing so heavily in developing more effective corrosion protection strategies.

What is corrosion?

Corrosion is a complex phenomenon that can occur in a variety of ways but, essentially, it is the dissolution of metal due to a chemical reaction with its environment. The metal loses electrons through an electrolyte, such as seawater, as it breaks down at an atomic level.

Some metals corrode more readily than others but, under the right conditions, even the most chemically inert metals can corrode. This even applies to the noble metals such as gold, silver and platinum and can be seen in tarnish, in which corrosion creates a dull outer layer on objects made from silver.

Corrosion can be a problem in air, but it is a far more significant issue in seawater. Here the process is initiated by the presence of oxygen and greatly exacerbated by the prevalence of chloride, which makes the seawater an excellent conductor.

Taking one for the team: cathodic

protection

At sea, the primary form of corrosion mitigation is cathodic protection. Typically this involves the use of a galvanic or “sacrificial” anode: a piece of metal connected to the structure requiring protection and made from a more electrochemically active material.

Connected together, the structure under protection and the sacrificial piece of metal form an electrochemical cell. The structure serves as the cathode, while the sacrificial metal serves as the anode.

Because in corrosion it is the anode from which electrons are lost, the structure – the cathode – is thereby protected from deterioration. The galvanic anode corrodes in its place, disintegrating in the process and sacrificing itself to protect the structure.

These galvanic anodes are made from aluminium, zinc or magnesium and usually take the form of plates or blocks. By definition they require periodic replacement and, with the costs of doing so not insignificant, more cost effective means of corrosion protection remain in high demand.

Cathodic protection systems are often used together with a protective barrier coating on the main structure, which reduces its exposure to the seawater and effectively reduces the size of the electrochemical cell’s cathode. A

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January/February 2014Issue 03 2017

smaller cathode allows a smaller sacrificial anode, which means less material and reduced cost.

A different approach: combining the

coating and the anode

With barrier coatings providing one aspect of corrosion mitigation and cathodic protection another, one potential way to improve the two approaches’ cost-effectiveness is to combine them into a single function.

This is where thermally sprayed aluminium (TSA) comes in. In this process, microscopic droplets of molten aluminium are fired at very high speed onto a substrate – such as a steel wind turbine foundation pile – where they bond with the underlying structure and with each other, creating a high-integrity barrier that doubles up as a “distributed” anode should any of the underlying steel become exposed to the seawater.

Aluminium is a perfect material to serve as a protective barrier, as it possesses the extraordinary ability to repair itself. As soon as it corrodes, an impermeable oxide layer forms on its surface, protecting the underlying metal from further corrosion. Should the metal beneath become exposed, an oxide layer will quickly form to plug the gap. A TSA barrier may remain effective for up to 50 years at sea, with minimal maintenance costs. There are big savings to be made here: one company’s decision to

replace its conventional paint and sacrificial anode corrosion protection system with TSA for two offshore turbine foundation piles is expected to lead to savings of approximately 30 per cent.

Built to withstand the ocean swell

Corrosion isn’t the only destructive power marine structures must resist: they must also endure the relentless assault of the movement of the sea. With the typical wave frequency being approximately once every five seconds, over the course of 20 years a structure at sea must withstand more than 126 million cycles. Even if the loads involved are relatively low, that represents a tremendous amount of fatigue damage. Structures exposed to such environments experience fatigue – material deterioration in response to repeated loads. Marine structures are designed and built with high fatigue resistance in mind-and design codes such as BS EN ISO 19902 and DNVGL RP-C203 stipulate in detail the standards they must meet.

These codes take into account the impact of aqueous corrosion: structures exposed to seawater are subjected to an environmental reduction factor of three compared to structures in air. This means, under free corrosion conditions, a structure would achieve a fatigue design life in seawater just one third of the duration it would have in air.

The next step: proving the fatigue

performance of TSA-coated parts

In the interests of safety, design standards understandably tend towards conservatism. However, with the emergence of more effective corrosion protection techniques, there may be cause to relax some of these design requirements.

Much information already exists on fatigue performance. Likewise, the effect of TSA on corrosion has been widely investigated. However, the fatigue performance of TSA-coated welded joints has not been properly explored and doing so could yield scientific data that would make the savings inherent in using TSA for corrosion protection even more significant.

Such data could underpin revisions to design codes and support TSA gaining international acceptance as an alternative to conventional corrosion protection systems, leading to lower material usage, lower maintenance requirements and lower costs.

For more information, please contact us.

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Armourers Alumni EventThe Worshipful Company of Armourers & Brasiers is a City of London livery company dating back to 1322. Through its charity, the Armourers and Brasiers’ Gauntlet Trust, it supports education and research in materials science and metallurgy through award schemes that recognise outstanding individual achievements in engineering.

In partnership with The Welding Institute, the trust offers a range of prizes for outstanding PhD, BEng/BSc and MSc students and the STEM (science, technology, engineering and maths) Ambassador of the Year, as well as travel awards to enable students to attend events in relation to their degrees. Cash prizes of £1000, £750 and £500 are being offered to the winners.

Earlier this year, TWI’s Joanna Nicholas and Marian Bourebrab both attended an Armourers alumni event, where Joanna gave a short speech about welding and its challenges in the industry.

TWI Technology Fellow Alan Taylor honoured with Visiting Professorship at London South Bank UniversityTWI Technology Fellow, Dr Alan Taylor has been honoured with a visiting professorship at London South Bank University. The professorship, in Advanced Functional Materials, was awarded to him in March 2017 and is allied to the Advanced Resins and Coatings Technology Innovation Centre (ARCTIC).

Alan’s role is to provide technical leadership and oversee ARCTIC’s work in materials-by-design as they strive to become a World Centre of Excellence in Advanced Functional Materials. This involves the creation of a bottom-up nanotechnology capability to develop next generation materials for unmet needs in a variety of industrial and commercial sectors; a notable target is super-repellent coatings with sufficient durability to survive real-world environments.

A first paper from the Innovation Centre has already been published in relation to this work and two projects are already in place, with one PhD student from South Bank University assisting and another student set to follow suit in September.

With a multitude of potential applications, Alan’s work looks set to revolutionise numerous industries and commercial settings.

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Case Study: Reducing the costs of offshore windHenry Begg - Senior Project Leader – Surface Engineering

7th IIW Welding Research and Collaboration Colloquium

The 7th IIW Welding Research and Collaboration Colloquium will be held at TWI Ltd, near Cambridge, UK on 19-20 September 2017.

The event will bring together representatives from local and global industry and research to exchange ideas and establish cooperative networks for future communication and development.

To register please visit the website.

TWI is actively engaging with industry stakeholders, including wind farm developers, foundation fabricators and coating suppliers, to initiate the development of novel corrosion protection solutions based on Thermally Sprayed Aluminium (TSA) that have the potential to reduce the cost of offshore wind.

TWI has established itself as a world leader in the understanding and application of metallised coatings for the corrosion protection of offshore structures, having run a number of joint industry projects, primarily on behalf of TWI’s oil and gas sector members.

TSA is used extensively in the oil and gas industry on offshore platforms and in pipeline applications, and TWI now has a wealth of industrially relevant knowledge on the performance of such coatings that it is bringing to the renewable energy sector.

Offshore wind is growing at an extraordinary pace, with industry reports estimating that over the past five years an offshore wind foundation has been installed every 40 hours. In 2016 alone, 338 new turbines were grid-connected in Europe and €18.2bn worth of projects reached a final investment decision. With the technology and the market maturing, the cost of offshore wind is steadily decreasing and may soon draw level with traditional power generation.

Replacing conventional corrosion protection, based on paint and sacrificial anodes, with a single coating of TSA, provides a high reliability coating that requires less frequent maintenance and repair and also reduces the cost of manufacturing foundations.

While often seen as an expensive coating option, TSA can offer significant savings during fabrication as there is no need for sacrificial anodes, secondary steelwork, or extended curing times for multiple coatings of paint. Despite the potential cost savings offered through the use of TSA, to date, the offshore wind sector has been reluctant to implement new coatings due to uncertainties surrounding performance in certain settings unique to offshore wind foundations.

TWI is currently working with a consortium of stakeholders in the offshore wind sector and was awarded a £1.2m project by Innovate UK to address the barriers to the adoption of TSA and introduce a potentially radical new corrosion protection design into the industry.

TWI’s subsidiary, The Test House has been awarded UKAS (United Kingdom Accreditation Service) Accreditation for its digital radiography services, becoming one of just three facilities to have this award in the UK.

Digital radiography is the latest area of non-destructive testing (NDT) for The Test House to gain this award. The Test House is now also able to offer expert witness verification in digital radiography NDT carried out under the scope of this accreditation.

UKAS accreditation ensures inspection repeatability and adheres to agreed inspection tolerance limits, with all results reported to UKAS standards. Not only does this award offer the Test House further credibility, but also opens up the potential for work from new clients who will only accept UKAS accredited services.

UKAS is a regular assessment that helps improve efficiency and quality by regularly reviewing the whole inspection process, including equipment maintenance and calibration, the goods inwards/outwards process, inspection reporting and management.

Offering services to investigate weld failures and materials qualification, amongst others, this latest award firmly places the TWI facility among the best in the UK for digital radiography.

For more information, please contact us.

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January/February 2014

Connect is the quarterly magazine of TWIPhotographySimon Condie Production Kim Barratt Graphic Design Craig Carter Copyright © TWI Ltd 2017

Articles may be reprinted with permission from TWI. This publication is also available in alternative formats. To request a copy please contact marketing@twi.co.uk

The Test House gains UKAS accreditation for digital radiography

Is the voiding of PCN NDT certification affecting you? TWI can help...Individuals and companies have been affected by the recent voiding of PCN certification from NDT International. The withdrawal of these certificates may threaten your employment or prevent companies from delivering manufactured products. TWI is making resources available to support those affected.

TWI is offering fully-approved PCN examinations, according to the PCN guidelines for those who have been affected.

TWI also provides CSWIP examinations for those companies and individuals who would prefer to gain CSWIP NDT certificates (CSWIP NDT certificates are in full accordance with ISO 9712 requirements and accredited by UKAS for international recognition, www.cswip.com).

TWI’s classroom-based refresher training and eLearning packages (PAUT, ToFD, UT) will ensure that candidates are well prepared to take the examination.

For more information, please contact us.

Issue 03 2017