Investigation on corrosion failure of $\mathrm{Cr}$–$\mathrm{Mo}$ P11 grade pipe in primary section of a superheated steam generation system

This paper presents failure analysis of corroded steam pipes ($\mathrm{Cr}$–$\mathrm{Mo}$, P11 grade) at ammonia production plant. The corrosion and deposition morphologies are characterized using scanning electron microscopy. In addition, elemental composition analysis of deposited corrosion products is carried out using energy dispersive X-ray. This study clearly indicates the sensitivity of P11 grade steel pipe to intensive oxidation in steam generation systems with improper implementation of deoxygenating processes. Furthermore, this pipe grade and oxide layer on its surface is susceptible to cracking at the presence of high-level thermal stresses.