The bolt to prevent corrosion due to unburned the device poorly soluble even at high temperatures and display good relates to gasket unburned of veranda, by : a resilient tubular radio-active non-inflammable material layer (100) and said unburned material layer (100) silicon coating layer applied to both sides of (201, 203) consists of including. Thus radio-active non-inflammable material layer itself for holding and are sufficiently resilient to real estate can be conserved as the shape form an since the forming a door frame is a gasket receiving a hollow pipe continues the case, radio-active non-inflammable material layer is formed on layer silicon coating layer product the pre larger fish are predetermined chemical between the fire door and door. a water flows.