GT Outlet / HRSG Inlet Cycling Joint (Hot Casing)
Externally Insulated Ducts (Hot Casings)
DEKOMTE has many designs for hot casing exhaust systems of gas turbine systems. In order to establish a suitable design of casing, support, stiffeners and expansion joint, the stress calculations and fatigue of materials must be considered. Most significant in the calculation process is the cycling and types of starts that a plant will run.
The temperature gradient of the casing to the fabric clamping area will create high stresses, increasing fatigue and reducing life. Square ducts can have more serious problems with the corner regions due to high stresses.
In many plants the failure and replacement of fabric expansion joints is considered a normal and routine maintenance. With weld repairs to steel parts, adjacent stiffeners and duct cracks and regular outage activity.
DEKOMTE has more than two decades of experience in designing two shift, high cycling expansion joint systems. The goal is a complete solution which encompasses the whole scope of duct, frame, adjacent insulation and expansion joint to give a lifetime maintenance free solution.
Expansion joint design issues:
- Steel frame design
- Fabric and bolster
- Fixing system
Short term solution:
- Weld repairs to frame and duct
- Regular replacement of fabric
- External insulation
Long term solution:
- New steel part arrangement
- Improved duct interface
- New external insulation
- New fabric and bolster design
- New fixing and convector design