The utility model relates to an is the gas especially given in the power plant equipment field the supporting open space plugging device who uses the maintenance part of steam combined cycle unit. Tocurrent gas steam combined cycle unit opens the part thermal stress damage that stops leading to night, boiler in red -letter day winter in summer and restarts next day chronicly, and season in spring and autumn is long -term stops transport and lead to in the open space metal parts seriously to corrode the scheduling problem, the utility model provides an open space plugging device which comprises a plurality of gasbags that fill the gassing and aerating device, the gasbag includes the cavity bag body of inflation inlet, is equipped with inflation interface on the bag body, aerating deviceincludes the gas -supply pipe of air -blower, butt joint inflation interface and air -blower. The utility model discloses a gasbag and the unit pipeline that can fill the gassing match, and the insideimportant region of shutoff unit to be in order preventing the circulation of air, and fill nitrogen or the maintenance of hot -blast air facilitates for follow -up, effectively reduces each parts internal stress damage of exhaust -heat boiler and prevent metal parts rust and corrosion.