Developing a WPS requires extensive knowledge of the TIG welding procedures, the orbital equipment, the material as well as the welding processes. There is no room for error since a WPS describes by its definition a certified weld that is to be applied in serial welding.
The relevant parameters in both manual and automated TIG welding
Travel speed (in mm/min)
A reminder: The advancing speed needs to take the heat input into account.
Current type (alternating or direct) and polarity
The polarity plays a key role when it comes to deposition rates and weld penetration.Please refer to the AWS (American Welding Society) for more information.
Welding current (in Amperes)
This parameter is essential because the amperage has a direct influence on the energy supply. An experienced welder or an outside expert can help finding the proper current setting.
Voltage (in Volts)
Since tension control depends on the distance of the welder’s hand to the workpiece, it is impossible to be consistent in manual welding. In semi-automated welding, the tension remains the same throughout the entire weld. Just as with the welding current, knowledge and welding experience is of use when setting the voltage. Feel free to reach out to us for help.
Type and diameter of the filler wire
The filler wire must be perfectly compatible with the base materials in aspects of metallurgy, physics and chemistry and needs to be selected prior to the development of a WPS. If filler wire is used, it must be appointed to the relevant passes and welding processes.
Wire feeding speed
In semi-automated and automated welding, once again the experience of the welder or the advice of an expert is crucial in regard to the speed of the wire feeding.
The type and flow rate of the gas
The right choice of gas flow is what makes the difference between an experienced welder and a beginner. This value – together with the purging technique – ultimately determines whether the weld will show signs of oxidation or not.
Types of tubes to weld
Whether you are welding tubes or tube sheets, the types of products (tubes and filler material) must be precisely specified, leaving no room for doubt when applying the WPS. The classification of tubes is done through American standards (ASME/ASTM) or ISO. It is strongly advised to check ISO/TR 20172 and ISO/TR 20173.
Be clear and precise in aspects such as for example diameters. For instance, it is not recommended to weld a 15,2mm tube with a WPS that only specifies a tube diameter of 15,0mm.
Joints and bevels
The type of joint is nothing more than an indication for the welder, but nonetheless its importance is not to be underestimated. Depending on the application, it is difficult to precisely indicate the exact number of passes in a welding configuration. It is therefore necessary to define a maximum amount of passes to be carried out. Of course, the shape of the joint with information on the width of the gap, the surface quality and the angle is a necessary indication. With regard to the preliminary bevel preparation, simply indicate the type of preparation (grinding, …).
This list is far from being exhaustive but it should serve as a general overview. Aspects such as the type of electrode, the angle of the torch, the preheat, the type of welding (butt welding or welding with filler wire) etc. should always be considered as well.
Nevertheless, it is this high degree of precision that will enable you to weld with optimum quality. If you need advice on how to develop your WPS, our experts are happy to help. Click here to request a free call back.