Transition Duct Mounting Frame

Overview

The Transition Duct Mounting Frame supports transition ducts as they join the combustor outlet to the turbine inlet. It secures the duct’s geometry, helps align hot gas paths, and absorbs loads from vibration, thermal expansion, and aerodynamic forces. Proper mounting ensures stable operation and minimal leakage or stress.

Materials and Construction

Manufacturers commonly build mounting frames from high-temperature alloys or heat-resistant steels. These materials resist oxidation, creep, and thermal fatigue. Sheet metal components often undergo forging or machining. Sometimes the frame includes backing plates, slots, or adjustable brackets to allow small movement and alignment. Welding or bolting methods must satisfy tight tolerances to avoid deformation or misalignment under load.

Production and Quality Control

Precision in manufacturing is key. First, the frame must be dimensionally accurate so it mates cleanly with both the transition duct and adjacent structures. Tolerances for mounting holes, plates, or support points are held tight. Heat treatment and surface finishing reduce residual stresses. Dimensional inspection, non-destructive testing (e.g. dye-penetrant, ultrasonic or X-ray, depending on material) ensures structural integrity.

Applications and Performance

The mounting frame must manage thermal growth: as the duct heats, it tries to expand. If the frame is too rigid without flexibility, cracks or distortion occur. Also, the frame helps maintain sealing between transition duct flanges and turbine inlet frames. Vibration damping features or flexible joints are often incorporated to reduce stress. Stable alignment contributes to flow efficiency and reduces leakage or flow separation.

Maintenance and Repair

During scheduled overhaul, inspect mounting frame for cracks at welds, distortion in plates or flange faces, and loosening of bolts. Repair may involve straightening, re-welding, or replacing worn bracket parts. Adjustable mounts or slotted plates help in re-aligning ducts when frames shift. Proper refitting ensures that sealing surfaces remain clean and geometry is preserved.