Operating a urea plant poses challenges in managing the corrosive environment, especially in the high-pressure synthesis section.
Several mitigation strategies have been developed successfully to minimize severe corrosion and, subsequently, loss of containment scenarios. Nevertheless, loss of containment still occurs occasionally, for instance, due to a tube rupture in a high-pressure urea heat exchanger. The severity of such a mishap will result in the release of a large cloud of toxic ammonia.
Stamicarbon introduced Safurex® stainless steels as the material of construction more than 20 years ago, and to date, the failure rate for a rupture of a single Safurex® heat exchanger tube is less than 10-7. The application of Safurex® steels significantly improves the safety, reliability and availability of critical high-pressure urea equipment. This is also the case when exposed to severe process upset conditions and it offers excellent flexibility in plant operations. This paper presents some case histories to demonstrate this impressive achievement.