Jet Fuel Pipelines And Storage Require Special Operation, Maintenance Considerations

Jet fuel pipelines and bulk storage tanks require special operating and maintenance considerations. Jet fuels, specifically Jet A-1 and JP-8, are kerosene-type fuels used to power aircraft engines.

These fuels are subject to stringent quality requirements necessitating special equipment and engineering. Along the distribution chain, from the refinery to the airport, jet fuels are stored in bulk oil storage terminals and transported via pipelines, marine vessels and road tankers. It should be ensured that the fuel quality has not deteriorated to unacceptable levels along the distribution chain. Jet fuels have a flash point of 38oC and are combustible liquids. Measures to mitigate fire hazards should be in place for safe storage and handling.

Dedicated carbon steel pipelines are used to transport jet fuels to airport depots. In addition to their external coating and cathodic protection systems, the fuel pipelines have an internal coating applied to mitigate corrosion and fuel contamination. The pipelines should be piggable so that the capability for periodic cleaning and inspection is ensured. Pigs should be designed so as to not damage the internal coating.

Flow rate in pipelines is limited on the lower side by the self scouring velocity, typically 1.5 to 2 m/s and on the higher side by erosional velocity, typically 4 m/s or static electricity consideration which is 3 m/s.

Horizontal centrifugal pumps are used to provide the source pressure for pipeline transport. At terminals, jet fuels are passed through micronic filters to remove particulate matter and filter/separator systems to remove free water. If the pressure rating of the piping system and components is high, due to the need for high-source pressure for long-distance transportation, it is economical to use pressure-reducing valves at the downstream terminal and associated filtration units of a lower pressure rating.

At jointly operated facilities such as marine berths, where dedicated jet fuel piping is not available, jet fuels should be imported/exported via white oil lines reserved for middle distillates such as kerosene and gas oil. With multi-product pipelines, jet fuels are prone to higher contamination due to commingling of batches, surfactants which cling to the pipeline wall, free water and particulate matter. Leading and trailing grade interfaces must be diverted to slop tanks or non-aviation fuel storage tanks. Recertification is generally mandatory with multi-product pipeline transport. Batch planning and tracking is of particular importance to avoid jet fuels failing the quality tests.

Static Electricity
Jet fuel has a typical conductivity value ranging from 0.2-50 pS/m and is classified as a static accumulator. Military jet fuels and commercial Jet A-1 require the use of a static dissipator additive to increase the electrical conductivity of the fuel to a range of 50-300 pS/m, thereby turning the fuel into a static non-accumulator. However, the effectiveness of the additive diminishes with time and one cannot be sure if the conductivity is above 50 pS/m. Therefore, for long-distance pipelines and intermediate storage facilities, it is recommended that jet fuel be presumed to be a static accumulator.

If the fuel is a static accumulator it is recommended that its velocity in pipelines and long-distance piping be limited to 3 m/s to minimize charge generation. Short lengths of loading lines, such as marine loading arms, are sized with a velocity limit of 7 m/s.