1. Comparison of the structure of special compensator and general compensator for gas: First of all, there's no countercurrent in the gaseous medium, there's no accumulation, and that solves the problem of condensing the gaseous chloride ions into a liquid. Second, because there is no accumulation, the chloride ion content will not increase. This virtually eliminates the possibility of corrosion of working bellows. Third, because the inverse bellows and working bellows between the existence of thermal insulation layer, will not form liquid chloride ion will not corrosion bellows. 2, because the gas compensator has the reverse structure, even if the condensation acid formed by stopping for maintenance stays on the surface of the reverse structure, with the temperature rise and high-speed flow of hot gas after driving away; This is also a crucial advantage. Iii. Due to the existence of the reverse structure, even if the reverse bellows are corroded for a long time, the damaged part will appear. However, the relative concentration of chlorine ions in the damaged part is also small or even lower than the critical concentration of corrosion. Product name: reverse structure corrugated expansion joint Product: N: dn800-dn3000 pressure range: 0.1-2.5mpa compensator with inverse structure consists of a compensating bellows with two ends connected with a noose respectively and a guide tube set on the inner side of the compensating bellows connected with a noose on the corresponding side. An inverted bellows is set at the other end of the guide tube and the connection between the two ends and the corresponding side of the end: By setting up the inverse bellows in the compensator, the direct contact between the conveying mass and the compensating bellows is blocked, and the direct corrosion of the compensating bellows by the medium is avoided, so the service life of the compensator is effectively increased.