Weld overlay cladding from A to Z
With technical presentations, end user experiences, practical demonstrations and plenty of time for attendees to pose questions, Polysoude’s VIP days clearly demonstrated the potential of weld overlays for piping components such as valves.
^ What the VIP days are all about: guests are free to talk at length with Polysoude staff who eagerly answer each and every question
Article By David Sear
Visitors were first greeted by Polysoude’s CEO, Mr. Mariner, who explicitly welcomed them to Polysoude’s factory. “We wanted to host the VIP day here so you can see welding processes in action. And as ours is a transparent business you can also witness our products being made and are very welcome to ask questions of anyone you meet, be they a manager or someone working on the shop floor.”
Although Polysoude develops, manufactures and markets a range of equipment using various techniques, including TIG and plasma, Mr. Mariner affirmed that the TIGer process would be at the heart of the show. “We wish also to demonstrate the massive strides we have made in this innovative technology. In just a few short years we have proven ourselves to be the technical leader in this field. Now the basic technology has been proven we continue to innovate. For example, we are now simplifying the equipment, driving down costs for our customers and increasing reliability.“
Mr. Mariner then invited several colleagues to deliver presentations. For example Mr. Penisson talked on ‘Arc & Motion – Weld Overlay Solutions’. He explained that as the TIGer process is two or even three times faster than conventional TIG processes yet offers the same quality, meaning that there are real time savings to be had in many applications. Giving examples he noted that rigs can be used to internally clad risers as well as piping components such as elbows, tees, valves, etc.
“In developing equipment we have looked to standardize components as a way of reducing costs and speeding up deliveries, but at the same time the flexible approach means we can tailor make equipment to meet customers exact needs,” commented Mr. Penisson.” We have also designed a rig that can be easily dismantled and then fits into a standard size container allowing transportation to wherever it may be needed.”
"Extremely versatile, weld overlay cladding can be applied to bores just 20 mm in diameter, to complex shapes and also to large items such as fifteen ton valve bodies!
Rounding off his presentation, he said that TIGer gave excellent overlay quality and was also environmentally-friendly. “Today many people say that TIGer is moreover an eco-friendly technology as it operates without fumes and nor does it require grinding which is also a source of air pollution for workers on the shopfloor.”
Held on the 12th and 13th of December in Nantes, France, Polysoude’s VIP Days attracted over 100 national and international guests – not bad at all for an event put together at short notice and just before the Christmas Holidays. The logic behind the event was to demonstrate the huge potential for weld overlay cladding in various sectors, including valve overlays, and to present a range of technical innovations that would be of interest to fabricators but also to the final customers, such as the valve end users.
Speed and quality
Mr. Mariner then introduced an invited speaker, John Haines, who works as a senior welding engineer with Arc Energy Resources. He kicked off by explaining just how versatile weld overlay cladding can be. “For example you can apply cladding to bores just 20 mm in diameter meaning that it can be applied to very small shapes. But also complex shapes can be clad. Examples I can personally mention include fabricated piping as well as a valve body weighing fifteen tons! The body had been cast in Inconel 625 to which we applied a Hastelloy C276 overlay. Another example includes a valve for flashing steam service, which was made by casting the body in stainless steel and then adding an Ultimet® overlay.”
Having whetted the audience’s appetite by indicating the wide range of cladding materials that might be applied, Mr. Haines did issue a few words of caution. “There are many parameters and issues that you do need to be aware of to get good results when applying weld overlay cladding for special applications. For example, during the welding process iron in the base layer can gravitate into the clad layer. Once you know this it can be taken into account, such as by applying more than one cladding layer.”
Mr. Haines then continued his presentation with slides showing a typical cladding method for Alloy 625 as well as on the benefits of cladding, such as resistance to corrosion, cost effectiveness compared to solid alloys, shorter lead times, reduced component weights, and optimum corrosion properties in key areas. He also gave yet more compelling examples of high integrity work.
Finally he touched on the various weld overlay processes that are universally available, such as TIG, PTA, MIG, SAW and ESW, and compared them to the TIGer process. “Giving an example of a valve we recently overlaid we realised that TIG would have given good quality but been slow and expensive, whilst MIG would have been quicker but the quality would not have been acceptable. We therefore adopted TIGer which performed well in terms of speed and weld quality. An added bonus is that the surface quality is good meaning that less machining is required. This saves money in terms of the wire consumed and also the subsequent machining time and costs.”
Next to take the stage were Willem Konings (Scana) and Peter Jansson (Exotech) who started out by claiming that: “we have produced what we believe to be the longest clad workpieces ever made using Polysoude TWIN TIGer machinery, namely 18-metre-long stress joints!” To explain the background, Mr. Konings indicated that stress joints are important in the offshore industry as they are used to connect risers to platforms. As such, they often have to be able to withstand combinations of fatigue and corrosion resistance.
Taking up the story, Mr. Jansson said that there were many, many challenges that needed to be addressed within a very short timeline. “For example, concerning the lance length of 19 metres, the necessary cable diameters, the need for pre-heating, the large difference in outer diameter, etc. So there were a lot TIGer lance with new functionalities thanks to new CNC software What the VIP days are all about: guests are free to talk at length with Polysoude staff who eagerly answer each and every question The PolyClad TWIN-TIGer system delivers top-quality results of discussions with staff from Polysoude but working together we came up with all the answers.“
Waiting whilst the first workpiece was overlay clad was certainly a tense moment but the test results were more than satisfactory, said Mr. Jansson. “Following application of the dye penetrant – also quite a challenge given the long workpiece length – the inner surface was snow white! So an excellent result all round.”
After a welcome lunch break and networking opportunity guests were then invited to tour the factory floor, where numerous live exhibitions had thoughtfully been arranged. These demonstrated the full potential of the TIG and TIGer processes for weld overlay cladding and also revealed some of the features that are now available. For example, the Polyview WDR video system which enables operators to view welding in real time which would otherwise be hidden. For example, when being performed inside pipes.
In all, Polysoude put together a very informative programme giving an authoritative overview of how overlay clad welding could be applied to various workpieces and so bring benefits to many users in various sectors of industry.
Commented Mr. Konings: “when we were considering a recent project it was clear that there was no existing capacity to clad an 18 metre piece of pipe using a single, uninterrupted process from one end to the other. After some discussion we therefore established a company together with Exotech plus a machining shop in Holland to meet these extreme cladding and machining requirements.”