Distinction between Weld Symbol and Welding Symbol

The weld symbol indicates the type of weld and, when used, is a part of the welding symbol.

Weld Symbol: Weld symbols shall be as shown in figure below. The symbols shall be drawn “on” the reference line (for illustrative purposes shown dashed)

547

Weld symbol

Welding Symbol: The welding symbol consists of several elements (see Figure). Only the reference line and arrow are required elements. Additional elements may be included to convey specific welding information. Alternatively, welding information may be conveyed by other means such as by drawing notes or details, specifications, standards, codes, or other drawings which eliminates the need to include the corresponding elements in the welding symbol. All elements, when used, shall have specific locations within the welding symbol as shown in figure below.

568

Welding symbol

Example showing welding symbol with weld symbol is shown below.

123456

Reference: AWS A2.4 literature

Keep reading, happy welding

Thank you,

KP Bhatt

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Fluid Flow in Arc

The driving force for the fluid flow in the arc is the electromagnetic force or Lorentz force.

F = J x B

Where J is the current density with its vector in the direction of the electric current flows. B is the magnetic flux vector.

This Lorentz force affects the shape of the arc (depending on the electrode tip geometry) and hence influences in the shape of the weld pool.

The electric current tends to be perpendicular to the electrode tip surface and the work piece surface and induces a magnetic field. Both electric current and magnetic field produce downward and inward forces, which push the ionic gas to impinge on the work piece surface and turn outward along the work piece surface. More of downward movement in the sharp electrode tip, producing a bell shaped arc, and less downward movement in the flat electrode tip, producing a more constricted arc.

1212

Downward and inward momentums due to electric current and magnetic field cause different fluid flow in sharp and flat electrode tips. Downward momentum is stronger in the sharp electrode tip than in the flat electrode tip.

Capture2

Flat tip electrode

Capture1

Sharp tip electrode

Reference: Suranaree University of Technology- literature

Keep reading, happy welding

Thank you,

KP Bhatt