Cavities left by gas that could not escape before the weld solidified. Common causes are lost shielding from wind, leaks or a spatter-clogged nozzle, damp electrodes or flux, and oil, paint, rust or galvanizing on the joint, plus an overly long arc. Codes classify scattered, cluster and linear porosity and limit the size and amount, with elongated piping porosity treated more strictly.
Surface porosity all along that bead, check your gas, I bet the fan's blowing it away.
Porosity only at bead starts points to a damp rod tip or short gas pre-flow; porosity everywhere points to coverage or contamination.
Also heard as
- pores
- gas pores
- blowholes
- pinholes
Related terms
Shielding gas
Gas that protects the arc and molten weld from the surrounding air in GMAW, GTAW and gas-shielded FCAW.
Wormholes
Shop name for elongated gas pores that tunnel through a weld like worm tracks.
RT
Radiographic testing: imaging a weld's interior with X-rays or gamma rays on film or a digital detector.
Discontinuity
Any break in the normal makeup of a weld, such as a pore or inclusion, that becomes a defect only when it exceeds code limits.