Destruction of a monolithic lining during dry-out when water turns to steam faster than it can escape, building pressure inside the dense, low-permeability castable until chunks blow off, sometimes with enough force to hurt people. Low-cement castables, thick sections, heavy water addition and fast heat-up all raise the risk. Proper curing, burnout fibers, vent holes and a slow schedule with holds near the boiling point and the cement dehydration range prevent it.
Ramped too fast through 200 C and got explosive spalling, half the ladle bottom is lying in the preheater.
Stay away from the openings of any castable lining going through its first heat, especially between about 150 and 350 C.
Also heard as
- steam spalling
- explosive failure
- blow-out
Related terms
Dry-out
Controlled first heat-up of a new monolithic lining to drive off water without cracking or spalling.
Burnout fibers
Plastic fibers mixed into castables that melt during dry-out, leaving channels for steam to escape.
Low-cement castable
Dense castable with 1 to 2.5 percent lime from cement, using micro-fines and dispersants for strength and low porosity.
Cure
To hold freshly placed castable moist and at moderate temperature so its cement can fully hydrate.