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Back to Media and Events £19.5m project launched for Port Talbot engineering centre 11th International FSW Symposium 2016 – Call for Papers 2013-07-creepimage-inspecting-creep-damage-in-critical-power-plant-components 2015-05-contributions-invited-for-uk-strategy-for-additive-manufacturing 2015-10-cswip-employer-specific-ndt-in-compliance-with-iso-9712 2016-09-cutting-edge-technology-for-nuclear-decommissioning 2017-08-david-williams-ieng-mweldi-an-engineering-inspiration A career in welding inspection A forum to share knowledge and exchange manufacturing ideas Accelerated Innovation Programmes launch at TWI ActFast: Real-time fibre-optic monitoring for laser welding Additive manufactured medical implants to enter mainstream Additive manufacturing guidelines will support industry adoption Additive Manufacturing UK Strategy update available for download Addressing advances in laser additive manufacturing Advanced electron beam facilities meet advanced industrial challenges Advanced ultrasonic full matrix capture inspection software launched Advisory group promote novel NDT methods in aerospace African company approaches TWI for plastics welding training AILU awards recognise TWI laser technology innovators Alan Taylor to represent TWI at international conference Apprentice welder wins medallion at WorldSkills 2015 Armourers & Brasiers' awards open for entries Art exhibition leads to new method of laser metal deposition Asbestos detection made easier and more reliable ASME issues White Paper on auditing of welding Audit shows TWI as integral to innovation Aviation Industry Corporation of China collaborates with TWI AWFTE to hold first all-day forum at TWI Back to work with TWI's 2018 'Business Resolutions' BeamAssure™ – electron beam welding quality assurance tool Best practice for nuclear construction industry welding Best young welders' teams from throughout Europe will compete BIS Chief Scientist and Director of Innovation visit TWI Blended learning gets results for Spanish NDT students Boccard UK engineers receive plastic welding training from TWI Brazilian student sees advantage of blended learning course BS 7910:2013 - Assessing flaws in metallic structures BS 7910:2013 receives first amendment Budding engineers join Structural integrity project Call for papers: 12th International FSW Symposium Call for papers: International Ocean and Polar Engineering Conference Celebrating success - spotlight on young engineers Centre of excellence created for the next industrial revolution CII and TWI awareness seminar in composites technology Coatings and surface engineering: addressing the needs of industry Cold spray experts launch all-round introduction course Combatting ice and erosion in extreme low temperatures - EIROS Combining Cathodic Protection with Aluminium Coatings CROWN project commended for offshore wind corrosion work Depositing silicon carbide coatings by thermal spraying Designed for future growth: TWI celebrates construction milestone Developing technology to reuse industrial waste heat Digital Twin Technology to monitor offshore assets Digital twin technology wins environmental business award Dr Melissa Riley presents paper at international conference Dr Melissa Riley represents TWI at international conference Effective operation of undersea well control valve stacks eLearning package for CSWIP 3.1 Welding Inspector launched Engineering laboratory marks new era of R&D at TWI Engineers develop chewing machine to test denture adhesives Entrepreneur tours TWI Technology Centre (Wales) Entry is now open for SkillWeld 2016 Evolution of ageing management Exploring opportunities with friction stir welding of steels Extending Aircraft Life Using Cold Spray Technology Familiarisation Course to EN ISO 3834 Fibre delivered laser beam cutting optimisation First MPhil student graduates from NSIRC Franco-British Symposium on Composite Materials Friction stir welding – joining the future of industry Friction stir welding and Japanese jewellery Friction stir welding of high performance steels Gammax IIS, Bury St Edmunds, employs Weldspec and Welderqual Gareth Hurrell wins Advanced Engineering Apprentice Award Gathering of experts at 2016 NSIRC Annual Conference Government funds £10 million technology hub in Teesside Graduates visit TWI to capitalise on Industrial Membership Has your PCN NDT Certification been voided? TWI Can Help… Her Royal Highness The Princess Royal opens new laboratories at TWI Highlighting women in engineering: Ángela Angulo High-pressure hydrogen testing at TWI Hot Gas and Extrusion Welding Appreciation: a new course from TWI Ice-repellant coating for aerospace and energy industries Industry benefits of composites microwave processing Innovation Centres at TWI deliver progress for industry Innovation ensures thermoplastic storage tank integrity International FSW Symposium technical programme available INTRAPID produces rapid in-line laser AM inspection systems Introducing the TWI Virtual Academy: studying on your own terms Investigating geothermal coatings for the future of renewable energy Investigating real-time testing and monitoring of pipelines Investigating the use of lasers for nuclear decommissioning Irish Rail calls TWI for bespoke visual inspection training Joint industry project to develop mobile rail head repair solution Laser research drives greater take-up of cutting technology Laser scanner improves TWI weld analysis services for Members Lasers for decommissioning: the story so far LEP deal launches plans for a new large-scale test facility at TWI Lifting the lid on innovation: exploratory projects at TWI Lord Heseltine opens new TWI technology and training centre Meeting discusses on North Sea oil and gas asset management Meeting reinvigorates Welding Institute's Liverpool branch Mike Russell appointed as TWI Operations Director 'Mind the doors' – New project investigates train door failure Mobile electron beam welds for fabricating large structures ModuLase - combining laser processes for the future of manufacturing MoU between ALFED and TWI enhances collaboration Names of latest Engineering Council registrants published today Nanosecond pulsed laser expands opportunities for project work NDT Voiding of PCN certification from NDT International New benefit for TWI Members: free access to Welding Abstracts journal New building to house TWI's structural integrity expertise New capabilities shown during seminars in China and Japan New centre for Advanced Manufacturing Technologies launched New developments in plastic welding highlighted New eBooks added for Professional and Industrial Members New equipment boosts ultrasonic inspection capability New facility for testing the barrier performance of polymers New fracture testing accreditation New fracture toughness testing standard published New Granta Centre manager guarantees premier conferencing New home and new capabilities for TWI in Middlesbrough New manufacturing process supports Hayter's winning position New project aims to spread the use of additive manufacturing New project to advance laser additive manufacturing New sensor technology for safe shale gas extraction funded New specialist equipment and project to improve tidal energy New TWI article breaks down the changes to ISO 15614-1 New ultrasonic testing courses from the TWI Virtual Academy New version of RiskWISE® released New welding apprenticeship standards receive government approval New Welding of Moulded Plastic Components course New welding procedures CSWIP course launched Nominations now open for The Welding Institute Awards 2018 Novel solution for submersible pumps in oil and gas industry NSIRC invites PhD proposals from leading universities NSIRC to operate from new, expanded facilities at TWI NSIRC welcomes first BP-sponsored PhD student Offering expertise to tackle knife crime epidemic Online tool launched for electromagnetic field assessments Open Day sparks the start of a new era of research for TWI Phased Array Ultrasonic Training – An Innovative Approach Pioneering tests being conducted on bespoke TWI rig Plant Inspection training meets need for competent workers Plant Integrity applies guided wave expertise to handheld device Plant Integrity exhibiting at the IPEIA Conference, Alberta, Canada Plant Integrity exhibits at Middle East Corrosion Conference Plastics welding experts answer your questions at Aquaculture UK 2014 Polyethylene pipeline testing service launches in N. America Polymers expert delivers graphene talk at TWI Preparing students for industry: the Brunel Innovation Centre Progressing graphene as a supercritical fluid barrier Project investigates Powder Metallurgy for astrospace use Project to detect hydrogen attack opens to partners Purpose-built pressure testing facility opens for business at TWI Purpose-built pressure testing facility to be constructed at TWI Quality control project could transform laser welding Reducing impact of air transport using additive manufacturing Registration open for 2017 Structural Integrity Conference Registration open for the UK's national welding competition Registration opens for 11th International FSW Symposium Registration opens for TWI BS EN ISO 15614-1 (2017) training Report examines state of engineering in the UK Richard Dolby / Rolls-Royce Prize launched RJD Engineering gains Factory Production Control system Certification Robotic automated NDT inspection boost for the aerospace industry Rolls-Royce's Martin Boyd discusses the benefits of becoming an IEng Safety warning issued following catastrophic clamp failure Sharc Matter: First -time market access to TWI's VitoNano Technology Showing expertise in corrosion safety, investigation and assessment Simulating real-world conditions for oil and gas research Skills Development Fund Scheme provides extra TWI courses SkillWeld apprentice set for WorldSkills São Paulo 2015 SkillWeld medallist goes on to take gold at EuroSkills 2016 SOCAR and TWI celebrate new competence training partnership STEM Fair workshops inspire next generation Stephen Kinnock MP supports new business initiatives at TWI Wales Strengthening links with Chinese industry Students begin UK's first MSc in Structural Integrity Success for TWI's first blended learning course candidates Successful engineers graduate from EWF/IIW Diploma in Welding 'SUPERSLAB' to meet thicker high-strength steels challenge SurFlow: secure, robust, integrated data transfer through composites Symposium celebrates 25 years of friction stir welding Symposium highlights developments in linear friction welding Taking the next step as a CSWIP Welding Inspector Tate Modern use solvent technology for art restoration Team Romania scoops gold in WeldCup 2015 Technician and STEM Ambassador of the Year awards open Technology tournament inspires young engineers to fly high Teletest business transfers to Eddyfi Technologies The 50-year view of fracture The Test House Gains UKAS Accreditation For Digital Radiography The Transport Systems Catapult and TWI Announce Partnership The Welding Institute Annual Awards and Dinner 2016 The Welding Institute Annual Awards and Dinner 2017 The Welding Institute Awards 2018 – Applied Technology Award The Welding Institute promoting career development at NECR exhibition Thermal spraying facility opens for industrial research Ties strengthened with Indian industry at UK–India Manufacturing Week TowerPower to reduce costs for offshore wind inspections Training workshop delivered to power company Eskom True Stress-True Strain Tensile Testing to Failure TWI adds to new standard for thermoplastic component joining TWI agreement with AVIC Manufacturing Technology Institute TWI and DNV collaborate to host 'Welding Experts' event TWI and leading university establish new innovation centre TWI and Lloyd's Register launch Fullagar Technologies initiative TWI and Lloyd's Register projects advance take-up of AM TWI and Rolls-Royce team up to develop Welding Engineering Diploma TWI and Teesside University launch Health Innovation Centre TWI announces Technical Open Day in conjunction with WeldCup TWI Arkwright Scholars a step closer to engineering career TWI at Engineering and Construction Recruitment Exhibition TWI attends tribology anniversary reception TWI attends UK-India Manufacturing Week TWI celebrates National Women in Engineering Day TWI CEO Christoph Wiesner awarded OBE TWI Certification chief executive to become president 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Philips Avent's thermoplastic nebulizer to market TWI helps Engineering College meet industry demand for staff TWI helps grow Innovation, Research and Technology sector TWI helps push European car body initiative TWI holds materials workshop at Cambridge sixth-form college TWI holds successful cold spray technology course TWI hosted Innovation Centres continue to grow TWI hosts graduation ceremony for EWF/IIW Diploma engineers TWI hosts successful exploration and production workshop TWI inspection team in high demand at JEC World, Paris TWI joins 'Integral' nuclear waste project TWI lands NDA innovation award for nuclear decommissioning TWI launches course for advanced digital radiography TWI launches new MSc in Engineering Leadership and Management TWI pioneers 'invisible weld' process TWI Pioneers New Dissimilar Weld for European Space Agency TWI plays its part in Working to Engineer a Better World TWI provides fracture toughness training and consultancy in Singapore TWI rewards outstanding undergraduate engineering projects TWI set to exhibit at Offshore Wind Energy 2017 next month TWI set to exhibit at the Farnborough International Airshow TWI set to present at AWS Conference on Plastics Welding and Joining TWI signs Memorandum of Understanding with Saudi Aramco TWI South East Asia commended by Malaysian government TWI supporting the 2016 Royal Institution Christmas Lectures TWI Supports Underwater Laser Cutting Project TWI supports West Suffolk's Outstanding Apprentice of the Year Award TWI Technology Centre Wales secures over €1m through EU programme TWI Technology Fellow given Visiting Professorship at LSBU TWI technology used for ground-breaking SpaceX flight TWI to develop underground storage tank monitoring system TWI to exhibit at 56th Annual British NDT Conference TWI to exhibit at SPE Offshore Europe TWI to launch aerospace inspection software at the Paris Air Show TWI to present at major industry conferences in India TWI to train Environment Agency landfill inspection staff TWI Training success story - Vera Dragoi TWI wins Cambridge Business Weekly Award for International Trade TWI wins RIBA Awards TWI working to progress composites in the automotive industry TWI-led project to reduce costs and improve aircraft efficiency TWI's Dr Philippa Moore: A role model for female engineers TWI's Dr Shiladitya Paul called as guest editor of Coatings journal TWI's flow loop available again after three-year testing UAE seminar demos TWI's unique PolyTest inspection system UK friction stir welding courses see increasing demand UKTI mission to India explores opportunities for UK aerospace sector Ultrasonic imaging climbing robot passes field trials Update on CPD for Welding Institute Professional Members Upgraded surface engineering facilities showcased Vibration-based in-flight composite health monitoring Video series sheds light on studying a PhD with TWI Vince Cable India visit promotes UK business successes Visit Plant Integrity Ltd booth at Corrosion 2016 exhibition Visit TWI at First World Congress on Condition Monitoring Volumetric testing of polyethylene pipe joints with PolyTest Welding Institute Annual Awards 2018 Welding Institute Annual Conference to focus on AM Welding Institute branch promotes welding careers Welding Institute Engineering Council Registrations increase Welding Institute's latest Engineering Council registrants Welding the unweldable: TWI friction stir welds ODS steel WindTwin project to revolutionise wind turbine technology Workshop explores state of play of mooring chain research Workshop to address dissimilar materials joining challenge World's largest linear friction welded component produced World's most precise weld made at TWI Yorkshire MP pays visit to TWI in Rotherham Young welders and metalworkers recognised at WorldSkills UK
16 February 2018

TWI’s decades of experience in materials joining and engineering processes for industry has seen innovation and problem-solving across all areas of manufacturing, fabrication and integrity management. Included in this body of work is TWI’s expertise in assessing and mitigating failures as a result of corrosion, such as with pipelines for the oil and gas industry.

One example of this saw TWI called by the Kuwait Oil Corporation to find the root cause of failure in a critical high-pressure wet sour service gas pipeline. The pipeline had suffered several leaks, including one due to a crack along a spiral weld, however repair uncovered severe internal corrosion which caused the pipeline to be decommissioned. TWI was called to undertake a failure investigation, but initial tests found that the pipe material had been correctly selected and the outside of the pipeline was in good condition, indicative of effective coating and cathodic protection.

However, the inside of the pipeline showed severe pitting in the bottom of the pipe alongside a spiral weld failure. Phased Array Ultrasonic Testing showed that the cracking originated internally and was longer on the inside than on the outside. This internal corrosion had been caused by the presence of water, CO2 and H2S gases, in addition it was found that a weld misalignment had resulted in roof-topping of the spiral weld, which increased the in-service stresses, while regular pipeline shutdowns added a small amount of cyclic loading. While none of these factors would have created the problems on their own, when combined they were enough to cause the cracking. TWI determined that increased localised stress at the spiral weld along with corrosion due to a severe sour service environment caused the cracking. As a result, the Kuwait Oil Corporation replaced their pipeline with a seamless sour service pipe rated to the correct level of H2S and water cut. You can find out more about this incident of failure along the spiral welds in this gas pipeline here.

This is not the only incident that TWI has investigated on behalf of the Kuwait Oil Company, as internal blistering on a 20” diameter cross-country pipeline created the need for a fitness-for-service assessment. In this instance, TWI was sent a 200mm long specimen of the longitudinally-welded damaged pipe along with an undamaged spirally welded section from the same pipeline. Both destructive and non-destructive tests were undertaken on the pipes in order to determine material property and identify the cause and extent of the damage. The results of these tests would allow the Kuwait Oil Company to undertake in-line inspections to assess the fitness-for-service of their pipeline as a whole. Tests included ultrasonic testing, magnetic particle inspection, tensile, hardness, and toughness tests, together with chemical analysis and metallography. Meanwhile, the operating history of the pipe revealed that laminations and blistering had created failure in 1976 and that the pipe had briefly been used to transport seawater for fire-fighting following the Gulf War of 1991.

An inspection report from 1981 was assessed, although it was unclear whether recommendations for repair had been actioned at that time, while in-line inspection found internal corrosion damage was almost entirely absent from the 7km of spiral welded pipe but was widespread in the long-seam welded pipe that comprised the rest of the pipeline. Test results showed that the long-seam pipe contained hydrogen induced cracking and blistering alongside internal corrosion, leading to the conclusion that the spiral welded pipe had been installed later. However, the long-seam pipe had failed due to the transport of a sour product, most likely before the 1976 failure, while the transport of seawater in 1991 had little effect, if any. Since the Kuwait Oil Company confirmed that the future operating pressure of the pipeline would be very low, TWI was able to recommend an alternative revalidation methodology for the pipeline, based on a hydrostatic proof test. This saved significantly on the cost of inspection and repair, while ensuring the continued safety and integrity of the pipeline. You can find out more about this pipeline fitness-for-service case here.

It is not just in the case of failure that TWI is called to assist, as demonstrated by a case involving Single Buoy Moorings (SBM) of Monaco. SBM had been tasked with designing and building an offshore floating production, storage and offloading (FPSO) vessel to be used off the coast of NW Australia. However, during the pipework welding, high hardness values were discovered in the weld zones for the duplex stainless steel rigid arm and riser piping. As these hardness values were outside the design requirements, the welds were sent to TWI for evaluation.

Simulated environment tests were done using slow strain rate (SSR) tensile testing and four-point bent beam tests at elevated temperature and pressure in a hot, sour brine solution. These tests showed that while there were high hardness values related to the strain induced by welding, these were unlikely to be a problem during service, meaning that the welds were passed as fit for purpose. You can find out more about this duplex stainless steel riser fitness-for-service work here.

Another case involving deepwater risers saw TWI carry out a series of detailed engineering critical assessments (ECA) on steel catenary risers ahead of installation in an oil and gas field. The risers were constructed from C-Mn steel with alloy 625 cladding in critical locations and there were a variety of pipe geometries due to different service requirements. TWI was asked to determine the maximum initial allowable flaw sizes that would ensure the integrity of the risers through installation and operation while also taking account of possible fatigue loading, sour service and internal corrosion during operation. The structural integrity of the risers is critical, considering the high pressure flammable fluids they can contain and the proximity to the platform which may be manned. They also need to be able to withstand a variety of loads, both static and cyclic, including internal pressure, self-weight, fatigue loading and loading from ocean currents, and to a range of environmental degradation mechanisms, including external and internal corrosion, and environmentally assisted cracking (particularly in the presence of sour fluids, i.e. those containing hydrogen sulphide).

TWI examined the structural integrity of the girth welds as they are subject to cyclic (fatigue) loading and cannot usually be inspected once installed. Careful examination of the quality of materials, welding and inspection, along with the ECA to look into the relationship between flaw size, materials and loading can ensure that flaws will not grow large enough to lead to failure of the riser during its design life. These calculations were carried out using BS 7910, backed up by validation data to assess the integrity of the project. You can find out more about this project to ensure the structural integrity of deepwater risers here.

TWI is holding a related Sour Corrosion Training Course – providing information on performance and testing materials in sour service. The course will provide an excellent introduction for engineers looking to develop their knowledge in this area.

Experts from TWI will also be at the world’s largest corrosion conference and exposition when we attend NACE International’s event in Phoenix, Arizona from 15-19 April, 2018.

You can find out more about TWI’s work with aggressive environment testing here, or, please contact us for more information.

Spiral Weld Crack in Oil Pipeline

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