PYROGENIC PIN

PURPOSE:To prevent a displacement of a wrapping by forming a groove on an outside surface of a cladding tube and by engaging a wrapping wire with the groove. CONSTITUTION:A coil shaped electrical heater 5 is housed in a cladding tube 2 made of a stainless steel or the like, and is insulated by an inorganic insulating material 6 such as a magnesia. On an outer circle of the tube 2, a groove 7 is spirally formed along a contacting line which connects a starting point 1 of a wrapping wire 3 winding to an ending point 11 in order to engage the wire 3 with the groove 7 and to wind the wire 3. At both the starting point 1 of the wire 3 and the ending point 11, both ends of the wire 3 are fixed to the tube 2 by welding or the like.