Fire following vapour explosion at a plant making titanium sponge due to design errors: A vapour explosion, followed by a fire, occurred at a drier in a plant making titanium sponge. When titanium containing water was put into the drier, it came to contact with the edge of the protecting tube of the inside thermometer, generating sparks which ignited the titanium sponge. The red-hot titanium sponge melted the drier to leak out, and reacted with water spilled from the fractured drier, producing hydrogen gas. This led to the vapour explosion scattering titanium, which ignited the nearby products of titanium.