Over 35 Years of Providing Metallurgical Analysis

Life Assessment

Creep is permanent plastic deformation at temperatures and stresses below the metal’s defined yield point on the stress-strain curve. Boiler tube materials have a maximum operating temperature defined by the manufacturer. Differences between the actual operating temperature and the expected design temperature can significantly shorten the life of affected tubes. Three major factors contribute to unexpectedly high tube-metal temperatures during boiler operation: Internal oxide scale growth; loss of wall thickness due to oxidation, corrosion, and erosion; and higher operating temperatures. In the normal service life of a Superheater, failure usually occurs by a creep or stress-rupture mechanism. DNFM takes a comprehensive look at your sample and the environment in which it operates in order to evaluate the remaining useful life of pressure parts.

Life assessment includes the following engineering services:

Microstructural characterization
Oxide scale thickness measurements
Dimensional and hardness measurements
Estimation of operating temperature and design temperature
Calculation of operating stresses
Larson-Miller Parameter (LMP) evaluation
Plotting the operating stresses and LMP on pre-defined curves

For tube sampling guidelines click here

For more information email us at contact@davidnfrench.com or speak with us directly at 502-955-9847.