In an aviation fuel tank the lining protects more than the steel. It protects the fuel. That inverts the usual logic: in an ordinary tank we worry that the medium will damage the lining; here, that the lining will damage the medium. Everything follows from this — material selection, application requirements and the handover procedure. Step by step below.

Why aviation fuel is a separate case

Kerosene for gas turbine engines — Jet A-1 internationally, TS-1 locally — is not a particularly aggressive substance. In terms of chemical resistance the task is easier than with acids or alkalis. But the requirements for its cleanliness are incomparably stricter than for any other petroleum product.

The Aviation Rules of the Republic of Uzbekistan governing the supply of fuels and lubricants to civil aviation establish multi-stage quality control: incoming control on receipt, acceptance control, storage control, plus sampling and laboratory testing at every stage. Fuel is checked repeatedly and against many parameters before it reaches an aircraft tank.

What matters here is the conclusion, not the procedures themselves. If fuel is controlled that thoroughly, then the tank lining has no right to introduce anything into it — neither particulates nor dissolved substances. The usual requirement that “the coating must resist the product” becomes two-way: resistant to the fuel and harmless to it.

★ To be explicit: the Aviation Rules themselves regulate fuel control, not coating materials — there is no separate local norm stating “what an internal tank lining must be”. In practice the industry falls back on an established approval framework: a coating for aviation fuel tanks is tested at the State Scientific Research Institute of Civil Aviation (GosNII GA), which issues a conclusion on whether the coating affects the operational properties of the fuel. So what is required of the material is not merely a data sheet, but confirmation that it was tested specifically for compatibility with aviation kerosene and does not degrade its quality.

What is required of the lining

From the objective of “do not spoil the fuel” follow five requirements, all of them verifiable.

Documented suitability for aviation fuel. Not “for petroleum products” in general, but specifically for aviation kerosene — with a test conclusion (in industry practice, a GosNII GA conclusion) confirming the coating does not affect the fuel’s properties. This is the first thing to request, and without it the discussion does not proceed.
No leaching. The lining must not release binder components, plasticisers or pigment into the fuel. A fully cured coating does not — but only a fully cured one, see below on timing.
Resistance to bottom water. Water collects at the bottom of kerosene tanks just as in any other, and the bottom zone works under the harshest conditions.
Light colour. Not an aesthetic requirement but a working one: on a light lining an inspection reveals sediment, traces of corrosion and defects in the lining itself. On a dark one nothing is visible.
Continuity with no pores at all. A pore is a point where fuel contacts bare steel and corrosion products enter the product.

On electrostatics — a question to put to the manufacturer

Kerosene is a poor conductor, and at high pumping rates it accumulates static charge. This is a well-known characteristic of handling aviation fuel and it governs loading and discharge procedures.

Exactly how an internal lining affects charge accumulation and dissipation is a question for the manufacturer of the specific material, and it should be put in writing. I deliberately give no numerical requirements or thickness recommendations here: this is a case where general reasoning does harm, and the answer belongs in the material documentation and in the design decisions for the particular tank.

Three zones — the same ones, adjusted for kerosene

Dividing the tank into zones applies here too, only the duties are distributed differently than in a tank holding dark petroleum products.

Bottom and lower shell courses. Bottom water. The harshest zone, and the source from which particulates enter the fuel during discharge.
Shell within the product. Permanent contact with kerosene. The principal requirement is not to leach.
Vapour space and roof. Kerosene vapours and condensation under our daily temperature swings. An underestimated zone, though it often degrades faster than the shell.

Surface preparation

No concessions here. The internal surface of a tank is immersion service, and the cleanliness grade is Sa 2½ as a minimum, Sa 3 for critical duties to ISO 8501-1, with checks on profile, soluble salts and dust.

In addition to the usual sequence: before work begins the tank must not merely be washed but cleaned of residues of any previously stored product. If something else was stored in it, traces of that product in the pores of the old coating and in the welds are a source of contamination for the future fuel.

Application and, above all, curing

The application technique is the same as for any internal lining: control of steel temperature and dew point, a minimum margin of 3 °C above dew point, observance of overcoating intervals, forced ventilation throughout application and curing.

But one point matters more for aviation fuel than anywhere else. The lining must be fully cured before any fuel enters the tank. An under-cured lining releases residual solvent and unreacted components into the product. In a diesel tank that shortens the life of the lining; in an aviation kerosene tank it is fuel contamination, with everything that follows.

Full cure times are stated by the manufacturer and depend on temperature. They cannot be shortened to suit a construction programme — this is the case where you wait exactly as long as the data sheet says.

Handover: what the documentation must contain

Statement of material suitability for aviation fuel — from the manufacturer, before work starts.
Cleanliness grade to ISO 8501-1 with records, profile, soluble salt test, dust — all before the first coat.
Application conditions logged: steel and air temperature, humidity, dew point for each work area.
Dry film thickness over a grid of points.
Holiday detection over the whole surface — mandatory.
Confirmation of full cure before commissioning.
Flushing and a control sample before filling with working fuel — to the client’s procedure.

The absence of any one of these documents means the tank has been accepted as a formality. For aviation fuel that is not bureaucratic pedantry: the fuel quality control chain begins with the vessel the fuel sits in.

In brief

A tank for aviation kerosene differs from an ordinary fuel tank not in the aggressiveness of the medium but in the cost of contamination. Three rules therefore apply. The material is selected only with documented suitability for aviation fuel — by certificate, not by type of binder. The lining is made light in colour and continuous, so that a defect is visible to the eye and to the instrument. And it is allowed to cure fully, however long that takes, before fuel is admitted.

This article concludes the series on corrosion protection. We have covered corrosion and the ways of fighting it, internal protection of tanks holding aggressive media, surface preparation, coating behaviour under our ultraviolet and, finally, the most demanding case of all — aviation fuel storage.

Storage tanks for Jet A-1 and TS-1 aviation fuel