Innovation and invention

On 12 September 2004, ESAB celebrated its centenary. “The world is now a vastly different place than the one Oscar Kjellberg, ESAB?s founder, knew at the start of the last century,” says Jon Templeman, the company?s CEO.

He explains that at that time heavy steel manufacturing was centred on Europe and North America, whereas today?s production geography is truly global, with new economies in Asia and the emerging markets setting the pace in ship construction and other volume steel fabrication. Over the ensuing period, many new materials and processes have emerged creating many new opportunities for expansion and development.

“The success of our industry, and the way we are best able to serve it, has always been dependent on the active interchange of ideas, applications and experiences between our customers, suppliers, welding institutes and our own engineers,” and “for almost seventy years Svetsaren [the companies welding and cutting journal from which this article was sourced] has been a cornerstone for the encouragement of that interchange.”

A hundred years ago Oscar Kjellberg invented the coated stick electrode in his search for a practical method for repairing leaks in ships? steam boilers. Little would he have realised that his technology would go on to revolutionise metal construction in every branch of industry and serve as the springboard to the development of modern arc welding processes. Unlike many inventors, Oscar Kjellberg had both the vision and drive to pursue his idea commercially and so laid the foundations for ESAB, a leader in welding and cutting.

When 17, Kjellberg was sitting on a bench in the port of Kristinehamn and entered into a conversation with Axel Broström, who had already started to build the shipping empire that would later become the Broström group. Broström is said to have remarked that somebody should invent a process so that the plates forming the hull of a boat could be welded together instead of riveting them. Kjellberg is reputed to have responded: “Surely, that ought not to be impossible!”

Later in 1903, after Kjellberg had completed an impressive theoretical education, very good qualifications and 15 years of practical experience, mainly gained from work onboard steamships ? he had the opportunity to work as a technical officer on one of the biggest ships of that time ? an easy choice for most.

But instead he rented a small workshop near to the Masthuggskajen quay in Gothenburg, where he began his welding experiments. He was aware of previous attempts at electrical welding, and had encountered craftsmen who could solder and weld using contemporary methods.

Importantly, he was fully aware of the two major failings of existing welding processes, which were that the welded joint was not of the same quality as the parent metal, resulting in it being more brittle and porous. And, secondly that not all welding positions could be tackled successfully ? overhead welding at the time for example, was virtually impossible. For welding to become the universal method of repair he needed to solve these major difficulties.

Strengths

One of his strengths was his own practical experience of the problems with which a chief engineer on a steamship had to grapple. Marine boilers were riveted and, without exception, they began to leak after a time. This resulted in a loss of pressure and a reduction in power from the engine. Therefore, the leaks had to be sealed as quickly as possible. Normal practice was to force a wedge-shaped nail, followed by flax and hemp, into the leaking joint, which was an extremely difficult task under the worst conditions imaginable. The boiler also had to be cooled down so that workers could effect repairs and sometimes leaks would occur on the underside of the boiler, making access even more difficult.

Although principles of electrical welding were well known, and explained in over 300 patents the existing methodology was not capable of providing a workable solution for boiler repairs. Kjellberg, working in his experimental workshop, set himself the task of developing a complete solution comprising both the method and the equipment that was needed.

By 1904, he had already developed the theoretical basis for what became his major contribution to electrical welding ? the coated or covered electrode and he was soon given the opportunity to demonstrate his improved methods and new electrodes.

He was given the chance to repair a Swedish warship that had frozen and cracked and the result was so good that both shipping companies and industrial concerns took an interest.

Kjellberg set up a new company called Elektriska Svetsnings Aktiebolaget on 12 September 1904, although the abbreviation ESAB was used from the beginning. The company included a professor from Chalmers University of Technology and a chief engineer from Lindholmens Mekaniska Verkstad in Gothenburg on the company?s board of directors as well as Kjellberg as managing director.

Big breakthrough

The big breakthrough came with the invention that was granted a patent on 29 June 1907.

The patent is called “Procedure for electric welding including the electrode intended for this purpose.” Its revolutionary property was that Kjellberg had coated the welding electrode with non-conductive material, which gave many advantages. Firstly, the coating generated a protective gas (CO2 ) when it melted, which prevented the formation of iron oxides in the hot melt and it became possible to weld longer pieces, up to a whole electrode length, without needing to interrupt the welding. Welding could therefore be more continuous. Moreover the patent described how to build up a weld with several beads.

Secondly, he formulated a ?recipe? for the coating that melted at exactly the same rate as the welding metal rod, which allowed a crater to form at the tip of the weld electrode. This crater directed the flow of molten metal and after many experiments with different coating compositions he was able to find one that enabled overhead welding.

Big ambitions

Early activities were concentrated in Gothenburg, where ESAB offered repair facilities from a barge in the port. However, Kjellberg had ambitions that ESAB should establish workshops in large ports all over the world and by 1911, the company had sufficient capital to set up its first wholly-owned foreign subsidiary.

The UK was the foremost industrial and maritime nation at this time and ESAB already had some licence holders in England. However, it took a year before the Anglo-Swedish Electric Welding Co. – as the subsidiary was called – could be formed. Two years later a second foreign subsidiary was established in Belgium and, at the same time, a very extensive contract was signed with Mitsubishi Zosen Kaisha in Japan.

First to class

Lloyds Register in London was the first classification company to investigate the possibilities of all- and part welded ships. Trials were carried out at ESAB?s premises in London and the results were highly positive.

Consequently, in 1920, Lloyds approved all-welding as a production method for all types of ship. Shipowners remained skeptical so Oscar Kjellberg commissioned a small floating workshop to be built. ESAB IV was launched on 29 December 1920. It became the world?s first all-welded ship to be classified by Lloyds, and it contributed to dispelling the prejudice of shipowners and shipyards against welded ships. ESAB IV still exists today and forms part of Gothenburg?s Maritime Museum. The first full-welded ship in the UK, the Fullager, was completed in 1920 and sailed for 17 years, sinking in 1937 after a collision.

However, although welding began to be considered as a possible alternative to riveting at the beginning of the 20th century it was fifty to sixty years before riveting was completely superseded. A statement, made in 1960, said: “Riveting is generally regarded as a retrograde step by shipbuilders. It is only used at the owners request.”

There were many reasons for this long period of transition: ship-owners were and still are, traditionally, conservative; riveting worked satisfactorily; weldable steel had to be developed; and the process of producing joints suitable for welding was undefined.

World War II marked the period of significant advance towards general construction of fully welded ships. However, there were still setbacks and some classification societies retained requirements for riveted strakes until after 1950.

However, from the time that riveting declined and welding became the main method of construction, major advances have taken place, in both development of welding techniques and in ship design. For example, the introduction of high tensile steel, low temperature steel (LNG carriers), use of aluminium alloys, stainless steel and duplex steel.

Advanced welding processes

There have been many advances in welding since those early days. When Plasma welding was introduced, it proved to be a much more concentrated and hotter energy source, making it possible to increase welding speed and decrease heat input. Similar advantages applied when laser and electron beam welding were introduced during the 1960?s. Quality and tolerances could be improved beyond what had previously been possible. New materials and combinations of dissimilar metals could be welded. The very narrow beam made it necessary to use mechanised equipment. Robots have been used for resistance welding since 1964. Arc welding robots appeared about 10 years later.

The latest high productivity method is hybrid welding ? where two different processes are combined. Most promising is, perhaps, laser-MIG hybrid welding where very high speed and high penetration are achieved.

Mechanised welding opened up new applications. Narrow gap welding saved time and consumables, and reduced the distortion in the welding of heavy sections. Initially, the MIG process was used, but later also SAW and TIG. Around 1980, ESAB delivered heavy SAW Narrow gap welding equipment to Volgadonsk in the former Soviet Union.

Considerable R&D is invested into laser welding, especially into the laser hybrid MIG process.

Impressive installations are running at Meyer Shipyard in Germany, producing ship panels with stiffeners 20 x 20 metre in size. About 50% of welding seams are made with the Laser Hybrid MIG process. About 850 km has been welded so far.

The main reasons for choosing the hybrid process are:

l Productivity ? higher welding speed.

l More tolerant process ? allows bigger gap than with pure laser welding.

l Lower heat distortion and, hence, much less post work, especially in the shipyard application.

LR is also working closely with Fincantieri and Odense Lindo yards in developing the Hybrid Laser welding process to improve the fit-up in European yards. Originally, laser welding was carried out using a CO2 laser, but this is restricted to simple straight line processes because the beam has to be directed by mirrors. The YAG laser gets around this by directing the beam using a fibre optic cable, but the strength of the laser is considerably less, thus affecting penetration.

Besides CO2 and YAG ? a new type, the Fibre Laser, is attracting a lot of interest. The Southampton Photonics and the Optoelectronics Research Centre (ORC), University of Southampton, UK, has demonstrated over 600W from a single fibre laser.

These results, which the team believes to be the highest powers reported to date with a single fibre gain module, demonstrate that cladding pumped fibre lasers can produce the high powers needed to compete with more traditional laser technology, in applications such as remote welding, by offering high powers which preserve beam quality.

The team led by Dr Johan Nilsson produced over 600W output power at 1090nm from an ytterbium-doped fibre laser (YDFL). Ytterbium-doped fibre lasers are among the most efficient lasers available and it is envisaged that single-fibre, single-mode output powers well in excess of 1kW will be achieved in the not too distant future.

These lasers can then be combined to produce multi-kilowatt solutions with excellent beam quality, efficiency and reliability.

Friction causing a stir

Friction stir welding was patented in 1992 by TWI. The method works very well for aluminium, which can be joined without melting and it produces a very high quality joint. The process does not use consumables and has low energy consumption. Another benefit is low environmental impact. The process is so simple and effective that it must be considered to be one of the 20th century?s most remarkable welding innovations. R&D activities across the world are evaluating FSW and at TWI, where the FSW process was invented, new variants are being studied.

Future trends

“Some general trends in welding are very obvious,” says Klas Weman, ESAB Welding Equipment AB, Laxå, Sweden: “The continuing aim for increased productivity; further mechanisation; and the ongoing search for more effective welding processes. Constructions with reduced weight are achieved by means of new designs and the increased use of high strength steel and aluminium alloys.” A visit to a welding exhibition will show that the development of electronic components, computer technology and digital communication influence the development of the welding equipment.

Weman believes that although new processes such as Hybrid Laser MIG and FSW have been introduced, the traditional TIG, MIG and SAW methods will continue to dominate. n