FAQ: What Are The Essential Variables In Welding?

In most of welding process, The P number, F number, A number PWHT, thickness (out of specified range) are essential variable.

What are the nine essential variables of welding?

joints, base metals, filler metals, positions, preheat, PWHT, gas etc. (including ranges, if any) under which the welding process must be performed. These parameters are known as variables (as per ASME Section IX).

What are the 4 variables of welding?

There are so many welding variables that influence a weld’s quality; the variables are amps, volts, travel speed, filler metal, shielding gas, base material, etc.

Is welding process essential variable?

Section QW-401: general Note that a change from one welding process to another welding process is an essential variable and requires requalification.

What are supplementary essential variables in welding?

The code defines it as “Supplementary essential variables are conditions in which a change will affect the toughness properties of the joint, heat-affected zone, or base material “. The supplementary essential variable becomes an essential variable when welding procedure qualification requires impact testing.

What are essential variables?

Essential variables are those that will affect the mechanical or metallurgical properties of a weldment. If they are changed outside their qualified range a new procedure has to be qualified. The essential variables will be determined by the code that is being used so you do not need to guess what they are.

What are essential and non essential variables in welding?

Welding variables that are critical to making acceptable welds are categorized as essential variables. Welding variables that do not have a profound influence on the mechanical properties of the weld or those that are associated with the skills of the welder are categorized as nonessential variables.

What are the five essential variables of welding?

In order to have a good weld profile, we have to consider a the 5 essentials variables of welding which are: Current setting, Length of arc, Angle of electrode, Speed Of travel and Selection of Electrode.

What are the different essential variables which must be considered in performing welding operations?

The essential variables are detailed in the relevant specification but include material type, welding process, thickness range and sometimes welding position.

Is backing an essential variable?

For welder qualification, backing is invariably classed as an essential variable. This is because being able to produce a sound weld root using backing does not demonstrate he has skill required to make a sound weld without backing.

Is Rod size an essential variable?

10. QW-404.6 A change in the nominal size of the electrode or electrodes specified in the WPS. But electrode size will not affect mechanical properties. Having this in mind, it is just natural that it is a non-essential variable that you may want to control anyways.

What is essential variable PQR?

When the test is made the values for essential variables, such as wire feed speed/amperage, voltage, travel speed, shielding gas mixture, shielding gas flow, polarity, etc. are all recorded in the procedure qualification record (PQR). If that procedure passes the tests then the procedure is qualified.

What is the difference between PQR and WPS?

WPS is welding procedure specification whereas PQR is procedure specification record. These are some of the significant and mandatory documents especially to ensure that the welds comply with the rules.

What are non essential variables in WPS?

Normally, joint design, filler metal diameter, the minor change in the electrical characteristics, welding positions, welding technique (some of them) are nonessential variable in welding procedure specification..

What are P numbers in welding?

To reduce the number of welding procedure qualifications that are required, P-Numbers (shortened to P-No) are assigned to base metals according to the characteristics of the material, such as composition, weldability, brazeability and mechanical properties.

What is a no in welding?

A number gives a similar chemical composition in a “as weld” condition. The A number is essential variable in most of welding process in ASME Code Section IX. The Table QW-442 in ASME Code Section IX provides the list of A number. The filler metal and deposited weld metal have different chemical compositions.