[2C01-09] Refinery maintenance(3)

9:30 AM - 9:45 AM JST(12:30 AM - 12:45 AM UTC)Japanese

[2C03] Wall Thinning in the Coke Drum Overhead Piping

○Yuna Onodera¹ (1. Cosmo Oil Co., Ltd.)

Keywords:

Coke drum,PSV inlet piping,Acid dew point corrosion

Wall thinning was identified in PSV inlet piping from the coke drum overhead in a delayed coking unit. The thinning was concentrated on the upper half of a horizontal pipe and fell below the repair criterion, leading to pipe replacement during a scheduled turnaround three months later. The piping is subjected to cyclic operation in which steam is stopped and alternate quench water is injected. During this operation, gas flowing from the drum is cooled by the quench water, forming an acid dew point corrosion environment that is considered to have caused the thinning. This case and its countermeasures are presented.