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An Overview of Some Current Processes for the Welding of High Yield Pipe
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Self shielded flux cored arc welding, Figure 2, has the advantages
of shielded metal arc welding with cellulosic electrodes including
high arc force, high penetration and excellent puddle control
when welding with a vertical down progression. In addition,
this process has the advantages of automated processes including
high deposition rates, high travel speeds, high arc on times,
and controlled hydrogen levels. Frequently self shielded is
used over root passes made with shielded metal arc welding.
This is one approach to the welding of X80, where hydrogen cracking
in the parent steel is not a concern for the root pass, but
weld metal hydrogen cracking could be a concern on subsequent
passes.
In shielded metal arc welding shielding is generated by the decomposition of the flux at the arc. In self shielded flux cored arc welding a continuous tubular electrode contains are stabilizers and core materials which will generate shielding when they reach the arc. Both processes work outside under severe weather conditions including temperature extremes and high winds. Likewise, both shielded metal arc welding with cellulosic electrodes and self shielded flux cored arc welding are easily learned by welding operators already skilled in other forms of shielded metal arc welding. For example, one instructor was recently able to train and qualify to API 1104 over ninety welding operators unfamiliar with self shielded flux cored arc welding.
