Life Assessment of Fired Heater and Boiler or Creep Life Prediction using Physical Properties: OSER and DCPD

Creep failure typically occurs in materials used at high pressures and temperatures, which may diminish the useful life of equipment such as fired tube heaters, boilers, etc. To prevent loss and damage, various calculations based on the power law, such as the Larson-Miller Parameter (LMP), as well as others referred to in codes and standards, were implemented. These also use inspection-based information and rely considerably on expert judgment. The results could be compromised in several of manners, beginning with specimen preparation, inspection results, replicating material microstructures, evaluating replica films, and assessing life spent. To limit the possibility of the foregoing errors, the PTTGC began a research project with KMUTT by Maintenance Technology Center (MTC) to establish a set of life assessment evaluation methodologies. A patent-pending On-Site Extraction Replica (OSER) is introduced to determine the compositions of carbides formed inside the materials during the equipment is in operation, i.e. creep progression. The proportion of Cr and Fe in carbides has been suggested to be related to creep life. However, since the materials would have a limited amount of alloys, carbide formation and alterations would be limited at some point throughout creep life. The Direct Current Potential Drop (DCPD) approach can be utilized as a supplement. It was able to identify both metallurgical and physical changes. As the creep proceeded, microvoids began to form and eventually coalesced into a micro-crack detectable by the DCPD system. As a result, by combining both methods, the creep life of materials used in the equipment could be determined with less deviation due to the reduced dependability of specimen preparation and judgment