Session: 21-08 Field Service and Modernization

Paper Number: 101082

101082 - Laser Welding in Steam Turbine Rotor Recondition 

Steam turbine rotor is the main equipment in thermal and combined cycle power plants. In forced shutdown, damages in terms of rubbing, scratches and cracks could be located on journals and thrust collars. As a result, repairing work plays a significant role to refurbish the rotor back to service at which dimensions, run outs and residual unbalances must be in acceptance criteria without vibration problems. In addition, very tight dimensional accuracy has to be required after reconditioning. In the past, rotor repair has been using conventional welding processes for instance Submerged Arc Welding (SAW), Gas Metal Arc Welding (GMAW) and Gas Tungsten Arc Welding (GTAW) from which high deposit rate and large volume of weld have been the priority. For different point of view, Workshop and Spare Parts Division of Electricity Generating Authority of Thailand (EGAT), the maintenance unit responsible for repairing power plants’ parts, has been initiating laser welding with manual wire feeding system contributing low heat input in rotor refurbishment process to reduce residual stress and the risk of rotor bow after welding. In this paper, the case study in laser welding for steam turbine rotor was represented. The results showed that no indications examined by liquid penetrant test were found. The maximum radial run out of the rotor did not exceed the value from the as received condition. The residual mass unbalance after low speed balancing was minimized corresponding the acceptance criteria with the quality grade ISO 1940.

Presenting Author: Isarawit Chaopanich Electricity Generating Authority of Thailand

Presenting Author Biography: - Ph.D. in Industrial Engineering from Chulalongkorn University
- Qualification Engineer in Industrial Engineering of Thailand
- Experiences
- Repairing and manufacturing power plant parts
- Laser welding
- Balancing
- Rotor machining
- Valve repair: Built up and Hard surfacing
- Grinding

Authors:

Isarawit Chaopanich Electricity Generating Authority of Thailand
Jitti Buapoon Electricity Generating Authority of Thailand
Vissaruud Preebut Electricity Generating Authority of Thailand
Arpaporn Nararak Electricity Generating Authority of Thailand