Submerged Arc Welding (SAW) Process
The submerged arc welding process, which was originally developed by the Linde - Union Carbide Company, is commonly used in beam, boom, tractor, and multi-head type rigs. Unlike the open arc welding process, SAW is performed beneath a protective blanket of flux. This means that the arc is constantly covered or submerged by the flux, thereby eliminating any exposed arc radiation and the need for welding screens.
How the SAW Process Works
Submerged arc welding may be fully automatic or semi-automatic. The arc is flat and is maintained between the end of a bare wire electrode and the weld. The electrode is constantly fed into the arc as it is melted. In the automatic version of SAW, this is achieved by a set of rollers driven by a controlled motor to ensure that the wire is fed into the arc at a speed rate that is equivalent to the rate at which the electrode is melted. The arc length remains constant as a result.
A layer of granular flux provides a protective cover beneath which the welding occurs. The blanket is created as some of the flux becomes molten. The remainder of the flux is recovered and reused, unless it has become contaminated.
Guns Used in Automatic Sub-Arc Welding
In automatic submerged arc welding, there are three types of guns that are generally used. These include the side flux delivery gun, the deep groove gun, and the concentrated flux delivery gun.
The concentrated flux delivery gun deposits the flux around the wire. With both the side flux delivery gun and the deep groove gun, the flux is fed from an overhead gravity hopper to the gun’s flux shut-off assembly.
The type of gun chosen for a certain job may be dependent upon the joint design and/or the welding operator’s preference.
Variables of the SAW Process
There are some key variables of the submerged arc welding process. These variables include:
- The arc voltage
- The wire feed speed
- Travel speed
- Contact tip to work (CTTW) or electrode stick-out (ESO)
- Polarity and current type (may be either AC or DC), as well as variable balance AC current
Variations of Submerged Arc Welding