INTRODUCTION to welding:
Welding is a process of permanently fixing metal parts by applying heat (fusion welding) or pressure (pressure welding or forging) or both (resistance welding). Both ferrous metals (steel, cast iron) and non-ferrous metals (such as brass, copper and alloys) can be joined by welding.
Welding is cheaper, stronger, easier and faster than riveting. The various types of welding process are
The. Gas welding
B. Arc welding
I. Metal Arc Welding (MAW)
ii. Gas Metal Arc Welding (GMAW)
iii. Submerged Arc Welding (SAW)
4. Tungsten Inert Gas (TIG) Welding
v. Metal Inert Gas (MIG) Welding
w. Forge Welding
d. Resistance welding
It is. Thermal welding
f. High energy welding
Welded joints are broadly classified into
The. Butt joint b. Lap joint c. Corner or fillet joint d. T-joint e. Edge joint
SYMBOLIC REPRESENTATION OF WELDING
The standard welding symbol is given below.
Arrow line and reference line
The position of the arrow line relative to the weld has no special significance. The side of the joint on which the arrow line is drawn is called the “arrow side”. The side of the joint away from the arrow line is called the “other side”. The reference line has importance on the weld side. If the welding symbol is placed BELOW the reference line, welding must be done on the “ARROW SIDE”. If the welding symbol is placed ABOVE the reference line, welding must be done on the “OTHER SIDE”. If the welding symbol is placed ABOVE and BELOW the reference line, welding must be done on both the “ARROW AND OTHER SIDES”
soldagem_symbol_description IMAGE SOURCE: Welding UniverseBasic Welding Symbol
The basic symbols recommended by the Bureau of Indian Standards (BIS) to specify the type of welding are shown in fig.
welding symbol Weld size
The weld size is the height of the isosceles triangle in the case of fillet welds. In other cases, the size will be the minimum distance from the bottom surface of penetration.
Finish and contour symbol
Contour symbols are
The. Flat (level)
B. Convex
w. Concave
Finish welds, except cleaning, shall be indicated by finish symbols.
Chipping – C, Grinding – G, Machining – M
finish counter symbol Welded and unwelded length
Weld length means that it is the length to be welded once, after this step equal to the unwelded length it is not welded and this process continues for the entire length of the side.
Weld all around
If the weld is made all around the joint, a circle must be placed at the point connecting the arrow and the reference line.
Welding on site
When some of the welds (welded structures) need to be done on site during assembly. They must be drawn by a filled circle at the point connecting the arrow and the reference line.
