The Preheat Calculator

  1. Enter Arc Energy.  Arc energy is the heat produced by the welding arc, it is equal to the welding current times the welding voltage divided by the travel speed.  The actual current and voltage should be measured during welding along with the travel speed in mm/sec. 

  3. Select welding Process.  The heat input is the arc energy going into the parent metal. It is calculated by multiplying the Arc energy by an efficiency factor specific to the welding process.

  5. Enter Carbon Equivalent.  The CE must be based on the IIW formula shown below.  The program will calculate it for you if the base metal composition is known.

  7. Select Hydrogen Scale.  Diffusible hydrogen content is split into 5 groups:-
  8.                            A,          >   15 ml/100g     No hydrogen control!
                               B,   10  <    15 ml/100g 
                               C,    5   <    10 ml/100g 
                               D,    3   <    5  ml/100g 
                               E,         <    3   ml/100g 

    MMA using Rutile or Cellulose covered electrodes use scale A. MMA using Basic coated electrodes is capable of up to scale D if the electrodes are baked and stored in accordance with the makers recommendations.  MIG/MAG  Normally scale C, but if the welding wire is clean scale D is possible.  TIG welding scale D.  Scale E requires special consideration.

  9. Enter the combined thickness of the joint.  Consider the thickness of all paths taking heat from the weld. For example:- The combined thickness for a butt weld between two plates of the same thickness will be twice the base metal thickness, for a T fillet weld three times the thickness.

  10. When all data has been correctly entered click the calculate preheat button.

Got To The Pre-Heat Calculator

Main Page
Page last updated 18 July 2001