The charge heater in a crude distillation unit was designed with castable refractory on all side walls and roof casing plates of the radiation and convection sections. The heater was performing satisfactorily since commissioning in 1988 until 2010.
In February 2010, hot spots and small perforations were observed on the radiation roof casing plates. The perforations were caused by the oxidation of carbon steel casing plate due to the damage in refractory lining. The extent of refractory damage and oxidation of radiation roof casing plate kept on increasing to about 42ft2 (3.9m2) on the western side and 80ft2 (7.4m2) on the eastern side of the heater.
To continue safe operation of the heater and to avoid unplanned unit shutdowns, on-stream replacement of oxidized casing plates and refractory spraying was carried out. This was a unique and challenging job, but averted an unplanned shutdown of the crude unit, and resulted in considerable savings to the company. During M&I shutdown of the crude unit in October 2011, the whole radiation roof was replaced with new casing plates and body soluble fiber as insulating material.
This paper describes the complete work scope and sequence of activities carried out, as well as the health and safety precautions taken during the on-stream repair work. This paper also discusses the lessons learnt and how various challenges and unpredicted difficulties were resolved successfully through numerous brainstorming sessions and implementing new ideas.