Page 91 - CITS - Welder - Trade Theory

WELDER - CITS

Rightward welding technique:
It is an oxy-acetylene gas welding technique, in which the welding is begun at the left hand edge of the welding
job and it proceeds towards the right. This technique was developed to assist the production Work on thick steel
plates (Above 5mm) so as to produce economic welds of good quality. It is also called backward or back hand
technique. the following are its features. (Fig 1)

Fig 1 Fig 2

Welding is commenced at the left hand edge of the job and it proceeds to the right. The blowpipe is held at an
angle of 40° - 50° with the welding line. The filler rod is held at an angle of 30° - 40° with the welding line. The
filler rod follows the welding blowpipe. The welding flame is directed towards the deposited weld metal.The filler
rod is given a rotational or circular loop motion in the forward direction. The blowpipe moves back in a straight
line steadily towards the right. This technique generates more heat for fusion, which makes it economical for thick
steel plate welding.
For butt joints the edges are prepared as shown in Fig 2. The table given below gives the details for welding mild
steel by rightward welding technique for Butt joints.
Application:
This technique is used for the welding of steel above 5mm thickness and ‘LINDE’ WELDING PROCESS of sheet
pipes.
Advantage:
Less cost per length run of the weld due to less bevel angle, less filler rod being used, and increased speed.
Welds are made much faster. It is easy to control the distortion due to less expansion and contraction of a smaller
volume of molten metal. The flame being directed towards the deposited metal, is allowed to cool slowly and
uniformly. Greater annealing action of the flame on the weld metal as it is always directed towards the deposited
metal during welding. We can have a better view of the molten pool giving a better control of the weld which
results in more penetration. The oxidation effect on the motion metal is minimized as the reducing zone of the
flame provides continuous coverage.

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CITS : C G & M - Welder - Lesson 14-26 CITS : C G & M - Welder - Lesson 14-26