Technical note Stress corrosion cracking of ammonia receiver tank

Abstract

A 900 t/day capacity installation, used for recycling of ammonia to a urea plant, with two ammonia streams and four receiver tanks, failed after 3 years in service. The vessels were of the cylindrical bullet type, made of SA 516 grade 70 carbon steel. Of the four receiver tanks, only one suffered stress corrosion cracking, caused by incomplete mixing of the 0·2% water required by the process parameters. The vessel was operated at ambient temperature and a pressure of 1·765 x 10⁶ Pa; the design pressure of the vessel was 2·256 × 10⁶ Pa.