The Effect of Temperature on the Volume of Liquids in Pipelines in the Case of HSD and Gasoline

In oil and gas facilities, temperature is a crucial factor that affects the quantities of liquids that are either stored or moved, especially high-speed diesel (HSD) and Gasoline (PMG). Fluctuations in temperature can cause these liquids to expand or contract, leading to potential discrepancies during pipeline activities.

This piece explores how temperature impacts the movement of liquids within pipelines, focusing on HSD and Gasoline, and emphasises the importance of managing these changes to ensure efficient operations.

Temperature and Liquid Volume Behavior

As temperatures change, the amount of liquid in storage tanks or pipelines also varies. For instance, when a pipeline that contains a hot liquid, like one at 95°F, is turned off and cools down to 50°F, there will be an initial mismatch when it starts up again.

This occurs because of thermal shrinkage, a process where liquids take up less space when the temperature drops. Once the pipeline is back in operation, the volume of liquid entering will be lower than what is exiting until the empty space created by the shrinkage is filled.

This is especially important for heating HSD and Gasoline, as both are petroleum products that react distinctly to temperature changes.

Keeping an eye on temperature influences is essential for precise measurement and avoiding inconsistencies in inventory.

Non-Linear Temperature Changes in Pipelines

Temperature fluctuations along a pipeline are frequently misinterpreted as following a straight line. In reality, they exhibit a non-linear behavior, particularly when a warm liquid such as gasoline or diesel is introduced into a pipeline that is at lower ground or air temperatures. Instead of cooling down in a simple, direct line, the temperature decreases in an exponential manner.

For instance, when high-speed diesel (HSD) flows into a pipe surrounded by cooler soil and air, it experiences a rapid loss of heat at the beginning of its journey. As time progresses and the temperature difference diminishes, the rate at which heat is lost decreases as well.

This phenomenon is essential for comprehending how pipelines function over extensive distances, ensuring accurate volume measurements are made at both ends of the system.

Temperature Effects

HSD (High-Speed Diesel)

Diesel fuel often shrinks noticeably when exposed to colder temperatures. When a pipeline filled with heated high-speed diesel (HSD) is closed off and permitted to cool, the ensuing thermal contraction can create inconsistencies at the moment of restarting.

This problem becomes more pronounced when HSD is transported over extended distances, as the liquid can dissipate heat to the chilly earth or the surface of the pipes.

Gasoline

Gasoline is significantly influenced by temperature changes; it tends to evaporate more rapidly when it's warm and shrink when it's cool. Within pipelines, the uneven release of heat results in noticeable volume adjustments based on the cooling rate.

Initially, the cooling process occurs swiftly, but as temperatures even out, the rate of heat loss slows down considerably.

Technical Terms

TermDefinitionThermal Shrinkage: The reduction in the volume of a liquid when its temperature decreases.

Non-Linear Temperature Change:Temperature reduction in an exponential decay pattern, rather than in a straight line.

Heat Dissipation: The process where liquid loses its heat to the surrounding environment, usually at a faster rate initially.

References

Hart Energy (Based on a paper presented at the 84th Annual International School of Hydrocarbon Measurement held in Oklahoma City, Oklahoma, May 12-14, 2009.)