Retrotec USACE - Manual (Page 253)

Appendix D D123
D.7.8.5 Damaged or Missing Refractory (Waste)
Figure D197. Heat treat oven showing inner
refractory bricks.
Refractory or masonry blocks known as bricks are used as the inner lining of
the combustion chamber (Figure D197). They protect furnace and oven outer
steel shell from high temperatures and help insulate the unit. Defi ciencies in
the refractory can result in damage to the furnace and oven and in excessive
heat losses. The internal refractory should be inspected on a yearly basis when
the furnace or oven is shut off—perhaps when it is being cleaned.
D.7.8.6 Openings Used for Charging Too Large for Operation
(Ineffi ciency)
Figure D198. Loading part into a vertical heat
treat furnace.
Figure D199. Small heat treat oven sized for
small loads.