The requirements of this section apply to the storage of aviation fuel, and also of components such as straight run, wet treated, hydroprocessed and synthetic kerosines, or Avgas component streams before they are blended in finished product tanks. Although such component tanks mainly exist at refineries, they also occur at terminals that blend synthetic with conventional jet fuel.
9.3.1 Number and size
The number and size of tanks should be sufficient for the location volume turnover to provide adequate working capacity and to allow for settling, testing and tank cleaning requirements.
9.3.2 Preventing dirt and water ingress
Tanks shall be designed to avoid ingress of water and dirt.
9.3.3 Vent requi rements
Free vent devices should be installed for jet fuel storage tanks, unless otherwise specified by local legislation. Where the expected operating temperature range will be close to or exceed the flash point of jet fuel, an internal floating roof should be fitted. Pressure/vacuum relief valves shall be installed for above-ground tanks storing Avgas. Free vent devices may be used for buried Avgas tanks. Screens to prevent the ingress of foreign bodies should have a coarse mesh with minimum 5 mm (0,25 in.) holes. Note: Local legislation may also require the use of flame arresters.
9.3.4 Roof type
New tanks, or tanks brought into aviation fuel service, shall have fixed roofs.
It should be noted that existing tanks may have open floating roofs, which are much more prone to rainwater ingress and fine rust and dirt particle generation via abrasion in the rim seal area.
If there is a requirement for open floating roof tanks to stay in use, appropriate facilities and/or procedures shall be in place, e.g. the use of triple rim seals, to ensure that rainwater and dirt entering the system do not get transferred with the product, or have an impact on product quality. In the longer term, floating roof tanks should be converted or replaced.
9.3.5 Tank water, sedim ent and sampl ing management sys tem
Tanks shall have a means for effective removal of water and sediment. Tanks should have slope down bottoms to a centre sump with a fixed water draw-off line. Horizontal tanks should be installed with a continuous slope of 1:50 minimum, and vertical tanks should have a cone-down bottom with a continuous slope of 1:30 minimum to a centre sump.
It is recognised that optimum designs for large diameter tanks may include a cone-up tank bottom with a minimum of three radial sump drain points. Irrespective of tank design, dip hatches shall be positioned above each drain point to enable water measurement.
It is recognized that existing storage tanks may have different bottom types such as flat, cone up or sloped to one side. These tank bottom types make complete water removal much more difficult, as often undrainable areas of water exist and therefore significantly increase the risk of microbiological contamination.
In case of flat, cone up or sloping to one side bottom types, appropriate equipment and procedures shall be in place to provide effective water draining. Examples of how this could be achieved include ring draining lines, additional draining lines into identified low points after bottom level scaling, or large volume flushing at high flowrates. The effectiveness of the draining procedures could be determined by taking true bottom samples with a bottom dip sampler from opposite sides of the draining line.
The drain line shall be fitted with a suitable, preferably self-closing (spring-loaded or equivalent) valve for the draining of water and sediment. The line shall be of a diameter appropriate for the size of the tank.
Tank draining systems shall allow safe and efficient fast-flush water draining of the storage tank through the sump. The fast-flush line shall also incorporate a sample point to enable a flowing sample to be taken. To allow recovery of the drained product, and for water to be drawn off at high flow rates, tank drain lines should lead into large capacity receiving vessels. This enables the site to over-flush without product loss, as the product can be returned via an appropriate return system. Vessels should be designed with cone down bottoms and a drain valve to enable the removal of water before returning the product to the tank. An example of a suitable design is shown in Figure 7.
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DRAFT EI/JIG 1530 FOR STAKEHOLDER REVIEW. Copyright © EI & JIG 2012 EI12/059 Please submit any comments to [email protected] by 4 January 2013
9.3.6 Lining
At least the bottom and first metre of the walls of all new tanks, tanks classified as delivering directly to airports, and tanks that are brought into jet fuel service (converted from other products) shall be coated internally. Full lining is considered best practice. A light-coloured epoxy material, confirmed as being compatible with aviation fuels in accordance with EI 1541 Performance requirements for protective coating systems used in aviation fuel storage tanks and piping shall be used. Zinc rich coatings shall not be used.
Where existing tanks that are classified as direct delivery are not lined, a plan shall be developed to line them (at least the bottom and first metre of the walls) as soon as practicable.
For existing indirect delivery tanks, consideration should be given to the benefits of lining.
Fully lining a tank facilitates the maintenance of product quality/cleanliness and protects against corrosion. Note: Dirt and water are less likely to adhere to lined tank walls and bottoms, settle out more easily, and can then be removed during tank draining. With lined tanks, the risk of microbiological growth is reduced, tank cleaning is less time consuming and possibly less frequent and downstream filter life is likely to be longer. The requirements of 9.3.6 are shown schematically in Table 9.
Table 9 – EI/JIG 1530 requirements for internal lining of storage tanks
9.3.6 Lining
At least the bottom and first metre of the walls of all new tanks, tanks classified as delivering directly to airports, and tanks that are brought into jet fuel service (converted from other products) shall be coated internally. Full lining is considered best practice. A light-coloured epoxy material, confirmed as being compatible with aviation fuels in accordance with EI 1541 Performance requirements for protective coating systems used in aviation fuel storage tanks and piping shall be used. Zinc rich coatings shall not be used.
Where existing tanks that are classified as direct delivery are not lined, a plan shall be developed to line them (at least the bottom and first metre of the walls) as soon as practicable.
For existing indirect delivery tanks, consideration should be given to the benefits of lining.
Fully lining a tank facilitates the maintenance of product quality/cleanliness and protects against corrosion. Note: Dirt and water are less likely to adhere to lined tank walls and bottoms, settle out more easily, and can then be removed during tank draining. With lined tanks, the risk of microbiological growth is reduced, tank cleaning is less time consuming and possibly less frequent and downstream filter life is likely to be longer. The requirements of 9.3.6 are shown schematically in Table 9.
Table 9 – EI/JIG 1530 requirements for internal lining of storage tanks
Tank scenario Internal lining requirement
Newly constructed tank Lining of the bottom and first 1 metre of walls Existing tanks that deliver directly
to airports
Lining of the bottom and first 1 metre of walls. If not currently the case, upgrade as soon as practicable Tanks brought into jet fuel service Lining of the bottom and first 1 metre of walls
Existing tanks that do not deliver directly to airports
No lining requirement, but consider the benefits of lining
9.3.7 Separate inl et and outlet tank lin es
All tanks shall be fitted with separate inlet and outlet pipe work systems. This is to ensure that only fully batched/certified product is delivered.
Where existing tanks have a common inlet/outlet line, a plan shall be developed to upgrade.
Until the upgrade is completed, procedures shall be in place to ensure that the line is flushed clear of unbatched product before delivery and to ensure that the line is filled only with certified product. All line clearings shall be downgraded or diverted to product tankage and shall be rebatched and recertified before release.
The accumulation of water in inlet or outlet tank line low points is not acceptable. Where this occurs, it will either require draining from the low point or high velocity flushing on a regular basis. The frequency of flushing should be determined by documented experience.
9.3.8 Posit ive segregati on
The operation of valves on tanks shall provide assurance that inlet and outlet valves are counter-locked or interlocked so that the inlet cannot be open (even slightly) or reopen once the outlet valve is opened. Examples of how this can be achieved are preferably IT control of motor-operated valves (MOVs), physical blocking with chains or Castell or similar locks, or
DRAFT EI/JIG 1530 FOR STAKEHOLDER REVIEW. Copyright © EI & JIG 2012 EI12/059 Please submit any comments to [email protected] by 4 January 2013
manual control check sheets.
This control system shall additionally provide the tank status information, e.g. the position of the valves, when valves are opened or closed after production, awaiting certification and when put on delivery (change of internal ownership) including the identification of the releasing person.
In refineries that do not deliver directly to an airport storage depot, it is acceptable to segregate certified and uncertified aviation fuel at the batching tanks with single valve isolation provided that systems and procedures are in place to assure that valves are not by-passing and that unit rundown property controls exist. The unit rundown tests need to provide assurance that only controlled components run into tankage and the risk of any contamination with incidental material via the single valve segregation is eliminated.
Where aviation fuel is received or exported through non-dedicated systems such as ships, multi-product pipelines, rail or road, the more stringent requirements of positive segregation shall apply to isolate the tank from non-aviation products. A single sealing arrangement is not acceptable.
Positive segregation shall be achieved by:
− a double block and bleed (DBB) valve arrangement. This can either be a single DBB valve with two independent seals and a cavity between them or two valves with a drain arrangement in a pipe spool between them. (when the valves are in a closed position the cavity or drain spool shall be checked to confirm no product is passing, see 9.5.1.6); or
− spectacle blinds, spades or equivalent; or
− removable distance pieces like spools or flanges.
Thermal relief valve (TRV) lines for aviation fuel systems shall not be interconnected with TRV lines for any other fuel grade.
TRVs on tank inlet-lines shall not by-pass to storage tanks (e.g. Inlet line TRVs should be connected to a tank-side fast flush tank or product recovery unit). TRVs on tank outlet lines may by-pass to storage tanks provided that they are fitted with a non-return valve to prevent reverse flow.
9.3.9 Floating sucti on / tank outlet
A means shall be provided to minimise dirt/water contamination uptake during delivery from storage tanks. This may be achieved by the use of either a floating suction arm or an upturned or slotted suction pipe.
The minimum requirement in all cases is that product cannot be drawn from less than 40 cm (16 in.) above the tank floor in vertical tanks, or 15 cm (6 in.) above the tank bottom in horizontal tanks (at high end of tank). A floating suction shall include a means to support the inlet to meet this requirement.
Where there is a risk of high levels of airborne particulates, upturned or slotted suction pipes are preferred for tanks without internal floating roofs.
In cases where internal floating roofs/covers are installed, it is necessary to ensure that the floating suction will not interfere with the operation of the floating cover.
9.3.10 Markings
Tanks and pipelines shall be clearly numbered and marked with the grade stored in accordance with EI 1542 Identification markings for dedicated aviation fuel manufacturing and distribution facilities, airport storage and mobile fuelling equipment and, show the date of the most recent internal inspection and cleaning. If IT systems provide sufficient detailed monitoring of these intervals, labelling on tanks is not required. Flow directional arrows shall be indicated on all pipe work.
Tanks that contain or have contained leaded products in the past shall be labelled accordingly on the tank access chamber(s).
9.3.11 Access/entry point
A means of tank entry for personnel shall be provided to enable gas freeing and cleaning operations.
9.3.12 Gauge hatches
Gauge hatches shall be provided to enable sampling and tank dipping.
9.4 FILTRATION AND FUEL CLEANLINESS