Abstract: Pipe insulation for water cooled support piping in a reheating furnace comprising refractory semicircular, pivotal complementary sleeves having wire reinforcement embedded in the sleeve refractory material and wherein the wire may be prestretched and located on the inner surface of the refractory insulation to directly contact, metal-to-metal, the outer surface of the cooling pipe. The reinforcing reticulations of the wire are at an angle to the longitudinal axis of the refractory sleeve. They enable stressing of the wire reinforcement simply by turning nuts of J-bolts, eliminating the requirement for welding of the reinforcing wire to the pipe. Longitudinal shoulders on the refractory protect the bolts from the effect of heat of the slab. The construction is such that tightening of the bolts and stressing of the reinforcing wire will cause no relative movement between the wire and refractory insulation.