Incoloy 800HT Weldolet Integrity in Hot Collector: Replica Testing Insights

In this paper, the integrity assessment of Primary Reformer’s hot collector weldolet in the fertilizer plant was conducted. It aims to discuss the findings of the relevant weldolet weldments which include dye penetrant test ultrasonic test, in-situ field metallography (replication), hardness measurements and rectification measures. The first step of the steam reforming process takes place in the Primary Reformer, where preheated hydrocarbon and steam mixture is passed downwards through vertical tubes containing catalyst. The hot gas that exited from the catalyst tubes is termed reformed gas and will enter two headers, namely hot and cold collectors. From then, the reformed gas will transform into raw ammonia synthesis gas after undergoing several processes. The facility was commissioned in 2006 and is still in operation. During the Plant Turnaround in 2022, the Primary Reformer’s hot collector weldolet component is categorised as high nickel content material, commercially known as Incoloy 800HT, was detected with circumferential crack at several locations. The operating temperature of the weldolet is 8110C. The observed damage mechanism of the crack was “Aged Phenomenon”. However, at four locations of the weldments, further dye penetrant test (DPT) and metallurgical testing using replica test had observed sigma phase microstructure which is related to sigma phase embrittlement (SPE) without any creep cavity observed. Finally, both occurrences were reported and reviewed.