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Tag: Materials of Construction

Introducing ammonia flow-induced corrosion

In recent years, extensive and severe internal attack has been observed of carbon steel equipment and lines in aqua ammonia service at several Yara manufacturing sites across the globe. In all cases, the damage has a distinct flow-accelerated corrosion (FAC) signature which challenges the current understanding of FAC. All features typically observed for this kind of damage mechanism, that seem to be specific to the NH3 recovery section of ammonia plant, are reported. Upgrading the material of construction for this unit, will solve this failure mode, but a leak would potentially generate health and safety problem for the release of ammonia.

Methods to mitigate metal dusting in syngas production

Industrial plants using synthesis gas at elevated temperatures risk metal dusting attack on the equipment, which are typically made of steels or Ni-based alloys. Parameters which impact the metal dusting risk are discussed and factors affecting the material selection and processing are described. One important focus is surface preparation, showing that grinding (40 grit) improves the metal dusting resistance compared to glass bead blasting and brushing. The surface treatment outweighs the impact of welds or the manufacturing route.