The usual practice for inspection of metallic FCCU expansion bellows, others than visual inspection are: PT (liquid dye penetrant) inspection to look for cracking, Routine checks for metallurgical condition, in-situ metallography/replication could possibly reveal microstructure changes as polietionic acid attack or sigma phase embrittlement, Thermographs to detect high temperature hot spots. PERIODIC INSERVICE INSPECTION 1. Immediately after placing the system in operation, a visual inspection should be conducted to insure that the expansion joints in the manner for which they were designed are absorbing the thermal expansion. 2. The bellows should be inspected for evidence of unanticipated vibration. 3. A program of periodic inspection should be planned and conducted throughout the operating life of the system. The frequency of these inspections should be determined by the service and environmental conditions involved. Such inspections can pinpoint the more obvious potential problems such as external corrosion, loosening of threaded fasteners, and deterioration of anchors, guides and other hardware. It must be under stood that this inspection programme, without any other backup information cannot give evidence of damage due to fatigue, stress corrosion or general internal corrosion. These can be the cause of sudden failures and generally occur without any visual or audible warning. 4. When any inspection reveals evidence of malfunction, damage or deterioration, this should be reviewed by competent design authority for resolution. Additionally, any changes in the system operating conditions such as pressure, temperature, movement, flow, velocity, etc that may adversely affect the expansion joint should be reported to, and evaluated by, a competent design authority. "At what age and number of shutdowns does worldwide practice accept that FCCU bellows should be replaced"? What are others practice on Inspection of FCCU Gimbal expansion bellows? Luis Marques