Welding variable procedure for GTAW

Welding variable procedure for Gas tungsten arc welding (GTAW).

Variables:-

Variable is a situation, number, or quantity that can vary or be varied. There are so many welding variables for the gas tungsten arc welding (GTAW), that affect the weld quality.

All the necessary parameters like joint, base metal, filler metal, preheat post-weld heat treatment, positions, electric characteristics, technique, in all these parameters there is a number of variables, like that ampere, volt, travel speed, filler metal, shielding gas, deposited weld metal chemical compositions ('A' number), material characteristics and similarity such as chemical compositions and weldability and mechanical properties (P number), the grouping of filler metal characteristics (F-number), etc.

There are three types of variables that are used in (You can also click for know about) welding procedure specification (WPS).

1. Essential variables.

2. Non-essential variables.

3. Supplementary variables.

For more details about variables please click this link Variables and their types.

GTAW variables

Content which is used in welding procedure specification:-

* Joint.

* Base metal.

* Filler metal

* Position.

* Preheat.

* Gas.

* PWHT (Post weld heat treatment.

* Electrical characteristics.

* Technique.

1. Essential variable for gas tungsten arc welding:- 

Here take an example of essential variables for Gas tungsten arc welding, When it will be changed then need to be requalification of welding procedure specification (WPS) for Gas tungsten arc welding.

Note:- Content that is used in Welding procedure specification the same for all three variables.

1.1 Joint:-

* There are no essential variables for Gas tungsten arc welding in the joint.

1.2 Base metal:-

* Thickness qualified range.

* Change in P number qualified.

1.3 Filler metal:-

* Change in F-number.

* Change in A-number.

* Addition or deletion of filler metal.

* Change in filler metal product form.

* Change in weld metal thickness "t".

1.4 Position:-

* There are no essential variables for Gas tungsten arc welding in the Position.

1.5 Preheat:-

* Decreases greater than (>) 55 degrees centigrade.

1.6 Post weld heat treatment (PWHT):_

* Change in PWHT.

* Change in base metal thickness "T".

1.7 Gas:-

* Change in single, Mixture, or percentage.

* Deletion of backing or compound.

* Change in shielded and trailing.

1.8 Electrical characteristics:-

* There are no essential variables for Gas tungsten arc welding in the electrical characteristics.

1.9 Technique:-

* Change in close to our chamber.

* Use of thermal processes.

2. Non-essential variable for Gas tungsten arc welding.

When it will be changed then not need to be requalified of  Welding procedure specification (WPS) for Gas tungsten arc welding.

2.1 Joint:-

* Change in groove design.

* Addition of backing.

* Addition and deletion of retainers.

2.2 Base metal:-

* Change in size.

2.3 Filler metal:-

* Addition and deletion of consumable of the insert.

* Change in classification.

* Addition or deletion of flux.

2.4 Positions:-

* Change in position.

* Change in forehand and backhand vertical welding.

2.5 Preheat:-

* There are no non-essential variables for Tungsten arc welding in the preheat.

2.6 Post weld heat treatment (PWHT):-

* There are no non-essential variables for Tungsten arc welding in the PWHT.

2.7 Gas:-

* Addition or deletion of trail or compound.

* Change in flow rate.

* Addition and deletion or change in breaking flow.

2.8 Electrical characteristics:-

* Addition or deletion of pulsing current.

* Change in current or polarity.

* Change in the tungsten electrode.

* Change in the current (I) and Voltage (E) range.

2.9 Technique:-

* Change in string or wave.

* Change in orifice cup or nozzle size.

* Change in method of cleaning.

* Changer in the method of black gauging.

* Change in oscillation.

* Change in multi to single-pass/ side.

* Change in single to multiple electrodes.

* Change in electrode spacing.

* Change in manual or automatic.

* Addition or deletion of peening.

3. Supplementary essential variable for Gas tungsten arc welding.

It is a condition when toughness properties are required, that time supplementary variables, work as essential variables. then needs to be requalification of WPS.

3.1 Joint:-

* There are no supplementary essential variables for Gas tungsten arc welding in the joint.

3.2 Base metal:-

* Change in the group number.

* Thickness limit.

3.3 Filler Metals:-

* Change in Qualification.

3.4 Positions:-

* Change in positions.

3.5 Preheat:-

* Increase greater (>) 55-degree centigrade (IP).

3.6 PWHT (Post weld heat treatment):-

* Change in PWHT (Thickness to thickness range).

3.7 Gas:-

* There are no supplementary essential variables for Gas tungsten arc welding in the Gas.

3.8 Electrical characteristics:-

* Increase heat input.

* Change in current and polarity.

3.9 Technique:-

* Change in multiple to single-pass/side.

* Change in single to multiple electrodes.

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