Creep Rupture of a Hydrogen Production Reformer Outlet Header of Nickel Base Alloy and Preventive Measures to Reduce Downtime

摘要

Hydrogen gas is in demand in the petroleum refinery for hydro processing. The steam methane reformer is widely used in the oil industry to produce hydrogen gas (H_2). Wrought and cast super-alloys for high temperature service applications, such as reformer tubes and outlet pigtails header, have become refinery and petrochemical industry standard since 1970s. Usually, even after the intended design life (100,000 hours), creep failure is less common in reformer outlet header than catalyst tubes. On-stream isolation by nipping is a commonly used maintenance practice in the event of reformer catalyst tube rupture to sustain H_2 production. The failure of an outlet header can result not only in a plant shutdown, but will also take a longer time to put back into service. In this paper, an incidence of a UNS N08810 header that failed by creep at multiple locations after approx. 210,000 hours in service will be described. This paper investigates the mode of failure, the current practice of non destructive testing methods to monitor the onset & progressive growth of creep degradation, risk-based inspection approach and proactive measures to minimize downtime of production.