| 摘要 |
PURPOSE:To enable secure shield of piping through a process of using a small amount of gas by providing a pair of expansive body which are able to adhere closely to the inside surface of a piping, an incombustible connecting means which rotatably connects the expansive bodies to each other and a gas discharging means which discharges gas into a piping shield area. CONSTITUTION:A back gas shielding device is composed of a pair of expansive body 2, an incombustible connecting means 3 which rotatably connects the bodies to each other, and a gas discharging means 5 which discharges gas into a piping shield area 4. Each expansive body has a disc-like supporter 6 and a ring-like flexible tube 7. The connecting means consists of a flexible pipe 18 through which gas discharging holes 17 are drilled. The gas discharging means 5 consists of gas supplying means 15, a tube 8 and gas supplying passage to the gas discharging holes 17 through the flexible pipe 18. Therefore a process of using a small amount of gas will do. |
