Sting-out is the term used to describe the presence of combustion flames coming out of the
forehearth. Sting-out can be from the combustion and cooling flues or may even be found coming
from the peephole blocks, between the mantle or zone block clearance area or from cracks in the
forehearth superstructure.
The lubricants from the mould doping process condense on the forehearth structure where with
time they build a dangerous potential fire hazard. Cleaning of the forehearth superstructure steel
to remove this flammable layer of oils should be part of the forehearth general maintenance
program. Unfortunately, in most cases this is not done. Excessive sting-out can cause these oil
layers to catch fire. The forehearth platform is not an often visited site so any fire that starts can
do considerable damage before it is discovered.
Sting-out can also damage forehearth equipment leading to expense and forehearth control and
disruption problems. Thermocouples and pyrometers and their associated cabling are particularly
prone to damage by sting-out.