Types Of Joints - Linde BOC Smootharc Advance MIG 425R Operating Manual

46 BOC Smootharc Advance III MIG 425R & 555R Operating manual
Butt Welding
Face Reinforcement
Root Face
Electrode Angle
The angle which the electrode makes with the work is important to ensure a
smooth, even transfer of metal. The recommended angles
for use in the various welding positions are covered later.
Correct Travel Speed
The electrode should be moved along in the direction of the joint being
welded at a speed that will give the size of run required. At the same time
the electrode is fed downwards to keep the correct arc length at all times.
As a guide for general applications the table below gives recommended run
lengths for the downhand position.
Correct travel speed for normal welding applications varies between
approximately 125–375 mm per minute, depending on electrode size, size of
run required and the amperage used.
Excessive travel speeds lead to poor fusion, lack of penetration, etc. Whilst
too slow a rate of travel will frequently lead to arc instability, slag inclusions
and poor mechanical properties.
Run Length per Electrode – BOC Smootharc 13
Electrode Electrode
Size (mm) Length (mm)
4.0 350
3.2 350
2.5 350
Correct Work Preparation
The method of preparation of components to be welded will depend on
equipment available and relative costs. Methods may include sawing,
punching, shearing, lathe cut-offs, flame cutting and others. In all cases
Electrode Angle for 1st and 2nd Layers
Weld Face
Layers
Root Gap
Layers
Run Length (mm)
Minimum Maximum
175 300
125 225
100 225
Layers
Electrode Angle for Subsequent Layers
Weld Beads
Layers
Weld Beads
edges should be prepared for the joints that suit the application. The
following section describes the various joint types and areas of application.

12.5 Types of Joints

Butt Welds
A butt weld is a weld made between two plates so as to give continuity of
section. Close attention must be paid to detail in a butt weld to ensure that
the maximum strength of the weld is developed. Failure to properly prepare
the edges may lead to the production of faulty welds, as correct manipulation
of the electrode is impeded.
Two terms relating to the preparation of butt welds require explanation at this
stage. They are:
→ Root Face: the proportion of the prepared edge
that has not been bevelled.
→ Root Gap: the separation between root
faces of the parts to be joined.
Various types of butt welds are in common use and their suitability for
different thickness of steel are described as follows:
Square Butt Weld
The edges are not prepared but
are separated slightly to allow fusion through the full thickness
of the steel. Suitable for plate up
to 6 mm in thickness.
Single 'V' Butt Weld
This is commonly used for plate up to 16 mm in thickness and on
metal of greater thickness where access
is available from only one side.
Weld Beads
Weld Beads
Electrode
Weld Pool
Slag
Weld Metal
Direction Of Welding
A