Page 75: of Maritime Reporter Magazine (November 2018)

By Danielle Milne, Graduate Mechanical Engineer at Marine Technical Limits (MTL)

Although MTL has a robust oil and gas control measures required to produce an heritage, with formidable experience in acceptable water backed weld. By ? ne the global energy marketplace, it also in- tuning the process and the introduction vests heavily in R&D and undertake rig- of speci? c controls for several variables, orous testing and research from its base MTL was able to conduct successful in Kintore, Aberdeenshire. MTL recog- welding trials which passed all non-de- nises the importance of progression and structive and mechanical testing require- continual improvement for the bene? t ments. MTL achieved this without the of the organisation and its staff. As a introduction of pre-heat and therefore young engineer I’ve been afforded the avoiding additional challenges to the opportunity to see new ways of working process. With the knowledge gained develop from the spark of a good idea through MTL’s extensive water backed through rigorous testing and ? nally to its welding trials, MTL also requali? ed successful deployment in the ? eld. The some of its conventional weld proce- freedom to explore fresh ideas is a com- dures to align its welding consumables pelling opportunity for any ambitious and processes, with all preparation and technician. welding being undertaken in-house at

Innovation does not happen in isola- its premises in Kintore, Aberdeenshire. tion and MTL works closely with clients The quali? cations covered both full pen- to quikly come up with bespoke solu- a harder, more brittle weld that is not ter temperatures below 0°C were used etration butt welds and ? llet welds in a tions to unique problems. considered compliant with welding rules to simulate the lowest temperature that range of positions, again without the use and standards. Therefore, it is not pos- could be encountered offshore during a of pre-heat. These were witnessed and

FPSO Maintenance approved in accordance with an inter- sible to achieve a suitable weld without repair. Throughout these trials, welding

FPSOs have played a key role in ex- variables such as the welding process, nationally recognized welding standard, altering the welding process or introduc- treme offshore areas for many years, and ing pre-heat, a process which is against position, technique, consumable and and in compliance with several Classi? - an FPSO system is one of the most com- cation Society rules. By completing the some Classi? cation Society rules during steel composition, as well as environ- research and trials in-house, MTL was mercially viable concepts for remote or water backed weld procedure quali? ca- mental conditions, were all examined to deep-water oil? eld developments. able to gain a wealth of specialist knowl- tion. understand what impact they would have

Harsh offshore environments, vessel edge of water backed welding along with

A thorough examination of the weld- on weld quality.

motions and production demands can ing process and the speci? c alterations

By completing a full and thorough a clear understanding of a range of weld- put FPSOs under stress. Ineffective in- ing codes. In the pursuit of excellence required was needed to render this tech- schedule of non-destructive and me- and continual development, this allows spection and maintenance regimes not nique feasible. Trials were undertaken chanical testing on each weld, MTL was only negatively impact the safety of the using a bespoke welding test tank con- able to obtain an understanding of the MTL to ensure all of its procedures are asset but can introduce onerous and un- nected to an industrial water chiller unit, variables which affect the weld quality tailored speci? cally to customer’s proj- necessary costs. ect requirements as well as MTL’s core allowing the simulation of the condi- during water backed welding. MTL also

As an FPSO ages, an increasing num- business areas.

tions and ? ow rates found offshore. Wa- identi? ed the speci? c environmental ber of defects can develop in the hull structure and problem areas found below the waterline can be particularly chal- lenging to address. As dry docking may not always be a ? nancially viable option for making repairs below the waterline, alternative methods are sought.

MTL identi? ed that welding a? oat with a water backing, or water backed welding, could be a solution. As it is not a commonly used or well-established welding process, there is limited Clas- si? cation Society code guidance on whether it could be a viable option. But at MTL we empower our team to tackle these challenges, develop ground break-

Come visit us at ing concepts, appraise them through rig-

The WorkBoat Show orous trials and testing, and ultimately deliver them to the market. booth # 1235

In light of this, we have recently under- taken extensive research and in-house welding trials to better understand water

Thrustmaster’s Axial Flow Waterjets range from 130HP to 8600HP and propel backed welding and its associated chal- |G??Gu?I?Žw??OlŽ???O?dSG?A?GEG?sOYGElŽsYlG?IAÐG?GAwuG??u??slS?Ž??

lenges.

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Water backed welding creates more ÐŽYEsOŽY??dS???lwA?lG??AlG?uGl?A?GwAY?IAÐl??GEsY,Ž??lŽY?dG?A??AYE demanding conditions compared to ?G?|sÐGE?slSŽ??uŽÐAuwG?sÐAY?G?|sÐGYGl?Ž?U?ŽYlAÐldS???lwA?lG?IŽ???sÐU conventional welding processes. At AYE?GusAduGAÐÐusÐAOŽY??ÐÐŽ?lA??GuuA?ÐŽwÐGOO|G?AlG?uGlÐ?sÐsYOAYEEGus|G??

the same temperature, the water acts as OwG??

a greater heat sink than air, which sig-

ŽYlAÐl? Jason Hill - Waterjet Sales Manager ????dS???lwA?lG??YGl uA?ŽY?Ssuu?lS???lwA?lG?lG?A??ÐŽwDŽdsuG????????????? ni? cantly increases the cooling rate of the weld. This rapid cooling results in www.marinelink.com 75

MR #11 (74-81).indd 75 MR #11 (74-81).indd 75 11/6/2018 9:22:14 AM11/6/2018 9:22:14 AM