WELDING STAINLESS STEELS IN THE PHARMACEUTICAL & FOOD PROCESSING INDUSTRIES

ESAB’s Cliff Warren and Brian Bowring explain why Tungsten Inert Gas (TIG) welding is ideal for the pharmaceutical and food processing industries

On the face of it welding and the pharmaceutical industry seem to be about as far apart as you can get. Equipment used in the industry is usually highly polished and that bright, highly polished finish does not seem to have much to do with welding.

But in fact, thanks to modern welding processes such as Tig it is possible to achieve a high quality and crevice free finish. In fact, in some circumstances the welder can create such a high quality finish that polishing is kept to a minimum. The weld appearance can be unblemished and high quality that the component can be put straight to work without further processing in some cases.

Tig welding is very suitable for lighter gauge, finer materials. Since a high percentage of the equipment used in food processing comes into this category and generally the finish the industry is looking for has to be extremely good (in a majority of cases it will be polished) hence Tig is often the process of choice.

When you think of welding the image that comes to mind is possibly that of a gas welder. The person with an oxy acetylene blowpipe in one hand that melts the metal with the flame, adding the filler material with the other hand. Substitute the gas torch for a Tig torch with a protective Argon shield and essentially the basic technique is similar but in a much more efficient way.

The efficiency that Tig welding exhibits allows greater weld pool control particularly if Pulsed current is used, that doesn’t mean it is easier or less skilful. Gas and Tig welding are both very skilled processes. In fact there was a saying that a good gas welder generally makes a good Tig welder because a gas welder has to be at ease with the dexterity required. But Tig welding has more benefits over the full range of materials.

Tig can get the job done quicker, though that’s not the prime gain. The real benefits are weld pool control, less distortion, a better finish and no need to use a flux.

Dependent on the service requirements, this cleanliness and smooth profile makes Tig the preferred process when it comes to relatively light and reflective surfaces.

Generally in the pharmaceutical industry, even a very clean Tig weld will be polished so that it appears bright and there are no crevices. However a high percentage of Tig work is good enough to go straight into use as soon as welding is finished.

With Tig if you want to weld autogenously (without filler wire) you can usually do so, particularly with Pulse current, depending on the characteristics of the material / joint.

Welding technology is continually being developed. On the Mig side there are modes of transfer such as Pulse and SuperPulse that helps the welder achieve greater control of the weld pool. The final appearance of SuperPulse can often be similar to Tig.

However Tig still remains the dominant process for the type of welding that is most commonly carried out in the food processing industry.

Orbital Tig offers the benefits of automatic welding. It is particularly beneficial for the welding of tubular applications. This system generally pulses the current and gives a superb weld finish.

When it comes to repair work Tig welding is ideal. It can be used when working in situ no matter whether the application is in the flat, horizontal or vertical position, dependent on the skill of the welder.

Thanks to the development of inverters modern Tig welding sets are highly portable and in many cases are light enough to be comfortably carried by one person and can fit into almost any workspace. Orbital Tig units tend to be a little larger in size.

Mig/Mag (Metal Inert Gas/Metal Active Gas) welding can be used in the food processing and manufacturing industry, especially when it comes to thicker and heavier pieces of construction. When used on these larger structures Mig/Mag welding can achieve a high quality finish.

ESAB is a recognised leader in the welding and cutting industry. From time-honoured processes in welding and cutting to revolutionary technologies in mechanised cutting and automation, ESAB’s filler metals, equipment, and accessories bring solutions to customers around the globe. For more information, visit www.esab.com