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The arts of the trade

The pipefitter trade

The trade involves creating tubular circuits to convey, process, pump and filter fluids or gas required by the production chains of:

  • Electronic components: semi-conductor industry
  • Medicines: pharmaceutical industry
  • Drinks and food: food-processing industry
  • Chemical products: chemical industries
  • Petroleum by-products: petrochemical industry
  • Water, fuel and air: aeronautics industry
  • Steam: energy, nuclear and solar industry
  • Petroleum and gas: gas and petroleum industry

Quality for transporting fluids

The tube is found in a wide variety of industrial sectors. Those named all feature the possibility of conveying sensitive or specific fluids. These fluids therefore require quality installations.
Creating a tubular circuit involves assembling straight tubes with elbows, T-pieces, flanges and valves among other components. In most cases assemblies are welded but crimping by sleeving is also an option, for example. Nevertheless, the welded assembly normally offers equivalent, and frequently superior, characteristics over the material making up the tubes themselves. They are therefore today considered the ideal solution. Different types of welding can be applied depending on the use and above all the characteristics of welded materials: steels, stainless steels, titanium, austenitic steels and tube thicknesses.

The most widely used welding process for stainless steels is TIG - Tungsten Inert Gas - as it controls the bath extremely well and is therefore very suitable for precision welding.

Junctions created in this way are virtually the only places in the installation where problems like leaks, micro-fissures, corrosion and mechanically fragile points can occur. Depending on the significance of the fluid conveyed and also the characteristics of the installation, mainly pressure, the junction points and the welds must be controlled properly at execution as well as in the traceability of welding parameters.

Orbital welding and orbital TIG welding generators

When these welds are created by hand by a welder, he must have the necessary qualifications for the welding process in question (WPQ). Bodies like the Welding Institute, the AFPA (AFPI) professional training associations and many others train welders so that they can obtain these welding qualifications. A welder must retake these qualifications every two years.

When the weld is created automatically by an orbital welding machine, for example, the machine is capable of recording the actual welding parameters at any time and therefore of documenting each weld precisely. The qualification is also in this case necessary but the machine, once calibrated correctly, can repeat very high quality welds. The welder can therefore apply his knowledge to controlling the weld and the welding process.

The preparation of tubes in orbital TIG welding processes therefore takes on huge importance. The welding machine may not take into account tube or alignment defects or over-large tack weld points. The machine is programmed to control the transfer of energy to the welded parts but it cannot anticipate concerns in preparation. Having been trained in this type of welding, the welder will be able to compensate for these faults by interacting with the solder bath in real time.

AXXAIR product range

AXXAIR has therefore made a point since 1997 of offering machines capable of quality preparation and orbital cutting and also square to perfect standard cuts on thin tubes up to 3 mm thick. We also offer bevelling machines for the thicker tubes to enable controlled quality welding.

Our wide range of welding machines is capable of covering the main markets listed above. These machines can create controlled, reproducible and documented welds. This type of weld can undergo the most stringent testing: x-ray inspection.

In less demanding industries, an internal inspection of welds in tubes is enough. An endoscope is normally used for this purpose. This is a remotely steerable camera, used for the most efficient systems to check whether the weld has penetrated 100% over 360° inside the tubes' welded areas and whether the geometry of the inside bead is visually correct (no internal inerting defect, for example, colouration or root porosity). There are other weld inspection methods such as ultrasound inspection machines.

The documentation through acquisition of available data in most orbital welding systems can systematically print the welding parameters required from the system (programme) and also measure the values restored by the material. This acquisition takes place precisely every second at our welding stations. The welds are therefore precisely documented (welding date, welding start time) and the alarms can be displayed (defect detected by the station during the welding process, including operator intervention during welding). This guarantees traceability at each stage in the process.

AXXAIR supports its customers in the global cutting, squaring, bevelling and orbital welding process in over sixty countries worldwide.
We place the emphasis on service in this process, which is increasingly customer-centred. This starts with determining the welding parameters in pre-sale phase including the preparation. We then subsequently train the personnel on the equipment to ensure users are capable of dealing with the applications they will have to manage by themselves.