Permanent linear change: the percentage change in length a refractory keeps after being heated to a set temperature and cooled back, tested under ASTM C113 for brick or matching methods for monolithics. Negative values mean shrinkage, which opens joints and cracks; positive values mean growth, which can tighten or crush a lining. Fiber products are rated the same way as linear shrinkage after 24 hours at temperature.
PLC at 1500 is minus 1.5 percent, that castable will pull away from the anchors and open up.
Also heard as
- permanent linear change
- reheat change
- linear shrinkage
Related terms
Expansion joint
Gap deliberately left in a lining so bricks or castable can grow with heat without crushing or lifting.
Bulk density
Mass of a refractory divided by its total volume including pores, a quick check on quality and compaction.
Creep
Slow, permanent deformation of a refractory under steady load at high temperature over hours to years.