Long, tubular gas cavities, written up as piping or elongated porosity, that form when gas keeps evolving while the weld freezes, so each bubble is drawn out behind the advancing solidification front. It usually traces back to heavy contamination such as oil, primer, galvanizing or wet flux. On radiographs it shows as dark elongated tails, and at the surface it can open as pinholes that run deep into the bead.
Sub arc bead's full of wormholes, that flux got wet, bake it or toss it.
Also heard as
- wormhole porosity
- piping porosity
- worm tracks
Related terms
Porosity
Gas bubbles trapped in weld metal as it freezes, showing as round holes on the surface or on film.
Flux
Material that shields molten metal from air and cleans oxides, as rod coating, wire core, granules or paste.
RT
Radiographic testing: imaging a weld's interior with X-rays or gamma rays on film or a digital detector.
Shielding gas
Gas that protects the arc and molten weld from the surrounding air in GMAW, GTAW and gas-shielded FCAW.