13 Mar MAINSTREAM PRESENTATION 2011
HRSG AND HIGH ENERGY PIPING WELD REPAIRS AND INSPECTIONS IN COMBINED CYCLE POWER PLANTS.
Auckland, New Zealand.
Co-Presentation: Anita Zunker, PEI & Grant Teesdale, Contact Energy
An early phase weld inspection program at Contact Energy revealed day one weld defects and in-service defects in high energy piping systems comprised of P91 and 304H materials. As a result of these inspections a number of weld repairs were undertaken and a more comprehensive inspection program developed.
Recent experience with P91 fabrication and troubleshooting of quality issues (soft spots, hard weld metal, poor PWHT controls) and rework during the construction of a new combined cycle power plant led to the development of more stringent P91 handling procedures. Contact Energy has refined its procedures, which have been applied in several areas of rework in P91 components in HRSG’s and high energy piping systems at its two combined cycle power plants.
Key take-away points:
1. The importance of understanding the real condition of your plant. Until baseline inspections are carried out the plant condition is only an assumption.
2. Managing risk. A weld inspection programme in a power plant can only ever have a sampling approach due to the high number of welds. Programmes need to be developed to adequately sample the areas of risk.
3. The higher the quality of the works (repair or original construction) the longer the life of the equipment. Develop contractors to work with upgraded material handling procedures and with higher QA expectations.