Metallurgical Replication of a High Pressure

High-Temperature Steam Line

Environment
Steam header, exposure to elevated temperatures of 750°F and pressures of 400 psi.

Material
ASTM A-53 grade B carbon steel pipe.

Service Life
More than 60 years.

Findings
Metallurgical replication of the high-temperature, high-pressure steam header that had been exposed to over six decades of service indicated that the header had come to the end of its safe service life. The microstructure indicated a primarily soft and weak ferrite matrix with -5 percent fraction pearlite. High-temperature damage from over 60 years of elevated temperature service is shown by the presence of iron carbide particles which precipitated along grain boundaries from decomposed pearlite lamellae within the grains. Recommendations were made to have the steam header and adjacent piping replaced.