Pipes and steam tracing

There are pipes running all round Fawley Oil Refinery. These pipes carry crude oil, intermediate products and final products. The largest pipes carry crude oil and are a metre in diameter.

Photo of steam tracer
Steam traced pipe on a refinery.

The heavier fractions of crude oil are either solid (bitumen and fuel oil) or thick viscous liquids (lube basestock and heavy gas oil). However, we have to move around the refinery through pipes and pumps. The only way to do this is to keep them hot.

Hot oil is less viscous than cold oil - i.e. it is more runny and flows more easily. When the fractions come out of the distillation column, they are already hot. However, they would soon cool down in normal pipes, clogging up pumps and the pipes themselves. So they have to be kept hot.

We do this using special pipes with steam tracers. The tracer is a pipe that runs alongside the oil pipe. It carries pressurised steam at up to 270°C. The assembly is then wrapped in thick insulation to reduce losses by conduction. This is covered in a shiny, metallic jacket that reduces the radiation (shiny surfaces radiated less than dull, black surfaces).

Different pipes have to be kept at different temperature. A pipe carrying bitumen is kept at 180°C using a steam tracer at 270°C. Sometimes, the tracer pipe runs down the middle of the pipe to keep it at such a high temperature. Other products are kept at more like 80°C using a steam tracer at 180°C.

The steam tracer keeps the product hot rather than heating it. It has already been heated in the furnace before distillation.

Even with all the insulation, the oil and the steam cool down as they run through the pipe. So most steam tracers are only about 150 metres long. One end is connected to the steam main that runs around the site and the other end passes out into the atmosphere where the cooled steam condenses. As one pipe passes out, a new pipe is fed into the lagging with fresh, hot steam.

The steam for the steam main is generated in the COGEN or the SP4 plant on the refinery site.

Graphic of steam tracer
Cross section of steam traced pipe.