PURPOSE: To provide a backing material for one side welding which is composed to permit formation of penetration beads having an excellent shape and uniformity by using glass fibers having different compsns. in forming the central part and both sides of an inorg. fiber layer placed on a refractory material layer.
CONSTITUTION: A backing material for one side welding is formed of a solid refractory material layer 1 and an inorg. fiber layer. The central part 2b in the longitudinal direction forming penetration beads near the part right under the groove of objects to be welded in said inorg. fiber layer is formed of glass fibers contg. 40W70wt% SiO2, 5W25% ZrO2, 7W25% Na2O and K2O and ≤0.8% Al2O3. Both sides in the longitudinal direction thereof are formed of glass fibers contg. 40W70% SiO, 10W30% Al2O3, and 7W25% CaO and MgO. Penetration beads having excellent smoothness and uniformity are obtd. by using such backing material without snaking and undercut.
ASADA IKUO
MIYAHARA SATORU
ABE HITOSHI
