Alloy 800H is commonly used for pigtails and header tubes in the outlet piping systems of steam reformer furnaces. Two kinds of damages may occur in the pigtails under high operating temperature and pressure. One is caused due to insufficient maintenance, and the other is creep damage due to internal pressure. As an example of former, cracking occurs in weldment of pigtails and headers. Improper lifting load of hangers arose bending stress at stress concentration portion, and it promoted creep damage. Nevertheless, life of pigtails would be consumed by creep damage due to internal pressure. Measuring the change in outer diameter (OD) is a useful technique for assessing the remaining life of pigtails. In this paper, we present damage example cases. Also, the technique for the remaining life assessment of pigtails is presented, which is based on the relation between OD change and life consumption. This relation is provided by the results of National Institute for Materials Science (NIMS) Creep Data Sheet of Alloy 800H tubes.

Subject
High temperature oxidation, Materials, Internal pressure, Tubes, Creep damage, Stress, Furnaces, Creep, Maintenance, Steam, Alloys, Lifting, Damage
Keywords:
Steam Reformer Furnace, Pigtail, Heat Resistant Alloy, Alloy 800H, Creep Damage, Remaining Life, Outer Diameter Measurement
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2018
Association for Materials Protection and Performance (AMPP)
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