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Welder’s Handbook
Porosity
Cause
Prevention
Excessive hydrogen, nitrogen, or oxygen in welding atmosphere
Use preheat or increase heat input
High solidification rate
Clean joint faces and adjacent surfaces
Dirty base metal or filler wire
Use specially cleaned and packaged filler wire, and store it in clean area
Improper arc length, welding current, or electrode manipulation
Change welding conditions & techniques
Volatilization of zinc from brass
Use copper-silicon filler metal; reduce heat input Use recommended procedures for baking & storing electrodes; preheat base metal
Excessive moisture in electrode covering or on joint surfaces
High-sulfur base metal
Use electrodes w/ basic slagging reactions
Effects
Porosity causes reduced strength and failures in some cases due to fatigue
Corrective Action
Completely remove porosity from all intermediate weld areas. Grind or carbon arc the affected area until the unacceptable porosity is removed from the weld. Weld repair the affected area, if needed.
Inspection & Standards
Excessive hydrogen, nitrogen, or oxygen in welding atmosphere High solidification rate Dirty base metal or filler wire Improper arc length, welding current, or electrode manipulation
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