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Challenges of welding Duplex

Here at Daver Steels we work with duplex on a daily basis and understand the challenges when welding duplex grades.  We have a dedicated team of welders which have undergone testing according to ISO 9606-1 (WQTC) working under ISO 15614-1 (WPQR).  The welding team work to welding procedures (WPS) unique to them for each project.

Having welded duplex, I understand it’s not the easiest of materials to weld.  I understand that some welders want to turn up the volts but don’t realise that by increasing voltage they will spread the arc and reduce penetration.  The main area of concern with all stainless steels is the effect of increasing the heat input.  If you exceed the 1.5kJ/mm recommendation, then there is a danger of sensitisation.  The weld may look perfect but it’s corrosion resistant properties will be seriously reduced.  Our team weld in accordance with ISO 5817, which is a standard for quality levels of imperfections and the NSSS (National Structural Steelwork Specification) for building construction.  Having good weldability is key as for all projects that Daver Steels undertake, so we understand that the welding team require the best consumables and equipment.

We have been welding duplex grades for many years and have extensive knowledge of working with the duplex family.  Daver Steels holds over 55 WPQR’S, which 8 of them are for the duplex family – From Single sided V butts, Double bevel T-butt and Fillet welds, Product form for pipe and plate.  This enables Daver Steels to have wide range of approvals for undertaking duplex projects.

The choice of filler metal for the project featured in the film we have recently made with ESAB, was the Exaton 22.8.3 LSi.

It was chosen for the added silicon, which in practice gives you a more stable arc and better fluidity, and will make the day of the welder that little bit easier.  We put some samples together to send away for Destructive Testing as we were completely new to using this Exaton filler.  The results gave us excellent mechanical properties.  

With the Exaton 22.8.3 LSi filler we found that the welders had a more productive day. It provided better weldability because of the weld pool having better fluidity and a good stable arc.  We also found that the pass rate on the NDT was much higher than the norm.  Again, this helped with productivity as there is less re-work time.  The welding team can carry on laying the welds, keeping Daver Steels keep on track with the deadlines for a project.

Daver Steels were invited to be featured in this promotional film commissioned by ESAB, who came into the factory to film in June. The film has been made for ESAB’s social channels to be shown later in the year. You can watch it here. Many thanks to the all team!

Darren Spalding – Daver Steels RWC (EXC 3)