The use of closed welding heads is the only way to guarantee a high standard for thin walled tubes with small diameters. The reason for this is evident: only a perfect gas protection can avoid the oxidation of the tubes.
Open weld heads are generally used for bigger diameters, where productivity is more important than the quality, or if the accessibility of the tube does not allow the use of a closed welding head.
A great number of industries use closed welding heads
As soon as a perfect and constant quality without any oxidation of the tube is required, the closed welding head will offer an unrivalled finish. This is extremely important for a great number of industries where any irregularity or particle might affect the manufacturing process.
A weld with a tiniest defect will be the weak link of an installation. Remind that a weld with cavities for example can represent the perfect place for microbes or bacteria, resulting in a contamination of the fluids conveyed in the tubes.
This is a real risk factor for food and dairy industries, as well as for pharmaceutical productions, to name just a few.
For other industries, contamination can be caused by particles that have to be avoided. This is especially the case in the semi-conductor industry for example.
But many other industries are concerned, such as the medical or biological applications, the nuclear or aeronautical industry etc.
Closed welding heads: which materials can be welded?
Closed welding heads are perfectly adapted for welding stainless steel, nickel based alloys, titanium and certain carbon steels. Remind that high purity industries mostly use stainless steel (type 304 or 316L) or corrosion resistant alloys.
In the case of welding tubes with wall thicknesses under 3 mm, these operations are realised without wire in butt-welding modus.
Why choose closed weld heads for thin walled tubes?
The particularity of closed welding heads is the optimized gas environment as a neutral atmosphere is created around the tube in order to avoid any oxidation. The pre-gas and the post-gas flow are calibrated and registered in the WPS (Welding Procedure Specification). In this way every new weld can be documented and done with the same constant quality.
These welding heads are equipped with a water or air-cooling equipment enabling an extremely high duty cycle. The clamping jaws of the weld head are adapted for each diameter to be welded, permitting a perfect calibration of the outer diameter of the tube to be welded: an important factor for the “high purity” industries.
And for very small tubes?
If you have to weld thin tubes with a wall thickness of less than 1 mm and a diameter smaller than 17.2 mm (5/8’’), we recommend the use of weld heads with a cassette system: our new Microfit range.
The tubes, flanges, fittings and other accessories are positioned in the corresponding cassettes, adapted for all applications.
Thereafter the welding operates in the same way as a standard closed welding head. The final result will always be optimized and AXXAIR’s standing in this specialised market will allow you an excellent return on investment.