General

FRP tanks shall be designed, manufactured and tested in accordance with a quality assurance
programme recognized by the competent authority; in particular, lamination work and welding of
thermoplastic liners shall only be carried out by qualified personnel in accordance with a procedure
recognized by the competent authority.

For the design and testing of FRP tanks, the provisions of 6.8.2.1.1, 6.8.2.1.7, 6.8.2.1.13, 6.8.2.1.14
(a) and (b), 6.8.2.1.25, 6.8.2.1.27, 6.8.2.1.28 and 6.8.2.2.3 shall also apply.

Heating elements shall not be used for FRP tanks.

For the stability of tank-vehicles, the requirements of 9.7.5.1 shall apply.

Construction

Shells shall be made of suitable materials, which shall be compatible with the substances to be carried
in a service temperature range of between -40°C and +50°C, unless temperature ranges are specified
for specific climatic conditions by the competent authority of the country where the transport
operation is performed.

Shells shall consist of the following three elements :
- internal liner,
- structural layer,
- external layer.

The internal liner is the inner shell wall zone designed as the primary barrier to provide for the longterm
chemical resistance in relation to the substances to be carried, to prevent any dangerous reaction
with the contents or the formation of dangerous compounds and any substantial weakening of the
structural layer owing to the diffusion of products through the internal liner.
The internal liner may either be a FRP liner or a thermoplastic liner.

FRP liners shall consist of:
(a) surface layer ("gel-coat"): adequate resin rich surface layer, reinforced with a veil, compatible
with the resin and contents. This layer shall have a fibre mass content of not more than 30%
and have a thickness between 0.25 and 0.60 mm;
(b) strengthening layer(s): layer or several layers with a minimum thickness of 2 mm, containing a
minimum of 900 g/m² of glass mat or chopped fibres with a mass content in glass of not less
than 30% unless equivalent safety is demonstrated for a lower glass content.

Thermoplastic liners shall consist of thermoplastic sheet material as referred to in 6.9.2.3.4, welded
together in the required shape, to which the structural layers are bonded. Durable bonding between
liners and the structural layer shall be achieved by the use of an appropriate adhesive.
NOTE: For the carriage of flammable liquids the internal layer may require additional measures in
accordance with 6.9.2.14, in order to prevent the accumulation of electrical charges.

The structural layer of the shell is the zone specially designed according to 6.9.2.4 to 6.9.2.6 to
withstand the mechanical stresses. This part normally consists of several fibre reinforced layers in
determined orientations.

The external layer is the part of the shell which is directly exposed to the atmosphere. It shall consist
of a resin rich layer with a thickness of at least 0.2 mm. For a thickness larger than 0.5 mm, a mat
shall be used. This layer shall have a mass content in glass of less than 30% and shall be capable of
withstanding exterior conditions, in particular the occasional contact with the substance to be carried.
The resin shall contain fillers or additives to provide protection against deterioration of the structural
layer of the shell by ultra-violet radiation.

Raw materials

All materials used for the manufacture of FRP tanks shall be of known origin and specifications.

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