In an industrial boiler room, two boilers (5 & 6) were connected to the same metal chimney. Following the breakdown of one of the boilers, it was decided to disconnect the corresponding smoke flue. The operations were carried out in compliance with the manufacturer specifications. However, a major deformation appeared on the 3rd and 4th shell with the risk of the chimney collapsing. The train traffic was stopped for 8 hours on a railway line passing through the site during the indispensable temporary slinging of the chimney and its support by a 200 tonne crane.