Exam Question

### (a) Reasons Why Oil in Boiler Water is Serious
The presence of oil, even in small quantities, in boiler water is considered a very serious condition due to the following chemical and physical consequences:
1. **Overheating and Tube Failure:** Oil has a much lower thermal conductivity than water. It deposits on boiler heating surfaces (furnace walls, tubes) as a thin, insulating film. To maintain the same steam generation rate, the furnace temperature must be increased, causing the tube metal temperature to rise significantly. This leads to overheating, reduced tensile strength, bulging (plastic deformation), and ultimately, catastrophic rupture of the pressure part, posing a severe risk to personnel and equipment.
2. **Foaming and Priming:** Oil contamination reduces the surface tension of the boiler water, promoting the formation of a stable foam on the water surface. This condition is known as foaming. This foam can be carried over with the steam into the steam lines, a phenomenon called priming. Consequences of priming include: