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58 Tube Products International November 2015
Polysoude SAS – France
through use of the same type of equipment, from continuous
manufacturing of spooled tubing to final umbilical construction
and subsequent connection. All welding procedures are
transposable and ensure traceability. Polysoude safeguards
the methodology by harmonising welding procedure
development.
Polysoude offshore welding solutions
Polysoude has been a TIG (tungsten inert gas) welding
specialist since 1992. In 99 per cent of applications relating to
umbilical cable production, the cold wire TIG process is used.
However, it has been demonstrated that a clear gain in terms
of productivity and quality can be achieved with hot wire TIG
installations, depending on the diameter-to-thickness ratio. As
the energy input required to melt the wire is lower, the ferrite
rate is also lower than is the case with cold wire technology.
The materials used can also result in a number of constraints
that are all successfully handled by Polysoude. For example,
duplex and super-duplex steels can lose their mechanical
and physical properties as the ferrite content increases. The
energy level must therefore be kept as low as possible to
ensure the lowest ferrite level. Polysoude equipment is fully
compliant to manage such requirements.
Hyper-duplex offers good weldability with a high level of
austenite reformation in the heat-affected zone. This produces
a weld seam with good hardness and excellent mechanical
and corrosion resistance.
Hot wire TIG welding principle
Productivity level between cold wire/hot wire processes
Cold wire TIG welding principle
A specific filler wire is required to guarantee optimum
mechanical strength and corrosion resistance properties.
TIG welding is strongly recommended, and the welding
procedure must include a heat input of 0.2 to 1kJ/mm and
an interpass temperature not exceeding 100°C. Argon, either
pure or with a nitrogen or helium content, must be used as the
shielding gas. Pre- and post-heating are not necessary.
References
Sandvik: Umbilical tubing in Super-Duplex and Hyper-Duplex steel –
Sandvik Materials Technology
Nexans Norway AS: Polysoude interview in 2010 with Truls Nordahl,
welding manager, Halden (Norway) and photographs
Technip: photograph and information from website www.technip.
com, and article published in L’Usine Nouvelle on 29 May 2014, www.
Aker Solutions: photographs and information from website www.
Oceaneering: information from video
oceanmedia/subseaproducts/multiflex-pc-fullvideo.html