Excessive root penetration forming drops or spikes on the inside of a pipe, like icicles. Besides restricting flow and snagging pigs and debris, they often sit beside burn-throughs and can break loose into the system. Codes limit internal reinforcement, commonly to around 1/8 inch, and icicles are ground off where reachable or cut out.
Borescope shows icicles all along the bottom of the root, you're hanging in the gap too long.
Also heard as
- grapes
- excess penetration
- drop-through
Related terms
Burn-through
A hole melted through the root of a weld where the molten metal fell out.
Root pass
The first weld pass in a joint, laid at the root, which sets the quality of everything above it.
Suck-back
Shop name for a concave root on pipe, where the inside of the weld sits below the pipe wall.
Root opening
The gap between members at the root of a joint, set during fit-up before welding.