Page 221 - Handbook of Structural Steel Connection Design and Details

Welded Joint Design and Production

206 Chapter Three

entry of air into the delivery system. Weld quality can be affected in the
same way as shielding loss. Most field erectors have found it advanta-
geous to utilize the self-shielded process and circumvent all such poten-
tial problems.
Some projects permit multiple welding heads to be simultaneously
operated in the same general vicinity. When this is done, submerged
arc is an ideal choice. Because of the lack of glare and arc flash, an
operator can control multiple arcs that are nearly impossible to con-
trol in a situation where the arc intensity from one torch would make
it difficult to carefully control another. A typical example would be the
use of welding systems that simultaneously make fillet welds on
opposing sides of stiffeners.
The easiest way to control smoke and fumes in the welding environ-
ment is to limit their initial generation. Here, submerged arc is ideal.
Smoke exhaust guns are available for the flux-cored arc-welding
processes. The most effective process for use with these smoke
exhaust guns is FCAW-ss. Because the process is self-shielded, there
is no concern about disruption of the gas shielding.

3.5 Welding Procedures

Within the welding industry, the term welding procedure specification (or
WPS) is used to signify the combination of variables that are to be used
to make a certain weld. The terms welding procedure, or simply proce-
dure, may be used. At a minimum, the WPS consists of the following:

Process (SMAW, FCAW, etc.)
Electrode specification (AWS A5.1, A5.20, etc.)
Electrode classification (E7018, E71T-1, etc.)
5
1
Electrode diameter ( ⁄ 8 in, ⁄ 32 in, etc.)
Electrical characteristics (ac, dc+, dc )
Base metal specification (A36, A572 GR50, etc.)
Minimum preheat and interpass temperature
Welding current (amperage)/wire-feed speed
Arc voltage
Travel speed
Position of welding
Postweld heat treatment
Shielding gas type and flowrate
Joint design details

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