Page 129 - CITS - Welder - Trade Theory

WELDER - CITS

MODULE 5 : Pipe Welding

Lesson 33 - 43 : Introduction to pipe welding Difference
between plate and pipe welding

Objectives

At the end of this lesson you shall be able to
• describe plate welding
• explain pipe welding
• explain the differences between plate welding and pipe welding.

Introduction to pipe welding

Only high quality pipe welds are acceptable in modern industry because the failure of pipe welds due to poor
quality will not only disrupt the operation of a plant, it can be the cause of a serious accident with the possible loss
of life and property. For this reason, a pipe welder must be thoroughly qualified person in his craft.
To be successful pipe welder and achieve high quality pipe welds, require practice in welding pipe. It cannot be
learned by reading a book alone. However if incorrect techniques are repeated, practices alone will never lead
to successful pipe welding. A pipe welder must have through knowledge on pipe welding in addition to the skill.
When making the weld, the welder is confronted with the following primary tasks:
1 He must prepare to make the weld.
2 He must concentrate his entire attention on the welding operation.

3 In preparing to make the weld, the welder is concerned with the following matters.
i The type of metal to be welded.
ii The selection of correct welding electrodes.
iii The preparation and cleaning the edge or weld joint.
iv The fit up of the pipes to obtain the correct alignment.
After all of the preparations have been made the welder must

1 Give his completed attention to make the sound weld.
2 He must strike the arc and manipulate the electrode correctly in order to deposit a sound bead.
3 He must watch the, molten puddle and make instantaneous adjustment in his welding technique and
4 He must watch and maintain key hole constantly when welding root bead.

Difference between plate and pipe welding

Plate welding: Plate welding is a fusion welding process. It joins plate metals using the combustion of oxygen
and fuel gas. The intense heat that is produced melts and fuses together the edges of the parts to be welded
generally with the help of a filler metal.
Plate welding by gas can be done in two ways. One is leftward welding and the other rightward welding.
All the-position rightward welding is used for all position of welding. (Fig 1) The path travelled by the flame and
the filler rod varies with the welding position. The angles at which the flame and the filler rod are held also vary.

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