Crude oil and gas condensates contain varying amounts of wax or paraffin.
When oil is at 60 to 70°c, the wax is dissolved, but as the temperature drops below 35–40°C, wax solidifies onto the walls of the pipe, causing roughness and turbulent flow and diameter restriction, reducing the flow. The wax can become extremely hard on the wall of the pipe through time, especially with static flow and temperature changes during maintenance shutdowns.
Using a regular pigging maintenance program, deposits aren’t allowed to form, flow is maximized and energy costs reduced.
It is very easy to remove too much wax at once, using incorrect methods and pigs. We have designed special cleaning pigs that will remove the wax, but keep it entrained in the flow ahead of the pig. On a recent project, the pigs used had on board intelligence to monitor the environment in the pipeline. As the line had a number of check valves, the impact on the clapper was recorded by the pig to ensure there was no significant force to damage the valve.