9.2.1 Steelwork
and fittings are to be clean and dry, and suitably coated to prevent
corrosion, before insulation is applied.
9.2.2
In
situ insulation and insulating panels are to be of a type that
has been approved by LR and accordingly, whenever practicable, be
selected from the List of Type Approved Products published
by LR. A copy of the Procedure for LR Type Approval System will
be supplied on application. Prefabricated panels, with an organic
foam core and metal or similar cladding both sides, are also to be
manufactured under survey at a works approved by LR. Organic foam
materials are to be certified as self-extinguishing. All materials
are to be free from odour likely to cause taint.
9.2.3 The
thickness of insulation over all surfaces and the manner in which
it is supported are to be in accordance with the approved specification
and plan.
9.2.4 The
insulation is to be efficiently packed and, where it is of slab form,
the joints are to be butted closely together and staggered. Where
it is intended to use a foamed in situ type of insulation,
full details of the process are to be submitted for approval before
the work commences and pre-production testing on site is to be carried
out to the satisfaction of the Surveyor, using a `mock-up' representative
of the system to be employed. Prefabricated panels are to be of a
design such that, when erected, continuity of the insulation envelope
is maintained without any gaps. Gaps between panels or insulation
slabs are to be filled with insulating material to the satisfaction
of the Surveyor.
9.2.5 The
inner surfaces of insulation envelopes are to be clad with a suitable
lining, such as marine grade aluminium or plywood, or equivalent material
which is:
- impermeable;
- able to withstand wear and tear and the flexing of the ship's
structure without fracture at the notation temperatures;
- non-corrosive, non-rotting; and
- free from odour likely to cause taint.
Where prefabricated panels are employed the outer surfaces are
also to be clad with a suitable lining.
9.2.6 Insulation
linings are to be constructed and fitted so that they are airtight
and provide an effective vapour barrier. The means of joining prefabricated
panels are to have sufficient mechanical strength to maintain a vapour
barrier on the inner and outer faces. All joints, including corner,
deck, deckhead and tank top intersections are to be sealed with a
suitable flexible, water vapour resistant sealant or gasket. Special
care is necessary where air ducts are embedded in the insulation,
and where refrigeration pipes, air refreshing ducts, fan supports,
fixtures, etc. protrude through the linings.
9.2.7 Hatch
covers and plugs, access doors, manhole plugs, bilge limbers and plugs
forming part of the insulated envelope are to be constructed of, or
covered with, a suitable lining material.
9.2.8 Insulation
linings and air screens, together with supports, are to be strong
enough to withstand the loads imposed by either refrigerated or general
cargo.
9.2.9 Successive
coatings impervious to oil are to be applied before insulating the
exposed plating of tank tops and bulkheads protecting tanks containing
oil. The total thickness of the required coating will depend on the
construction of the tank, the composition of the coating used and
the method of application.
9.2.10 If
the cargo to be loaded on the tank top insulation could cause damage
to the lining, then additional protection is to be provided in way
of the hatch and 0,6 m beyond. The protection may be of either a permanent
or temporary nature.
9.2.11 Where
the insulation is to support fork lift trucks, the strength of the
lining and its supports is to be demonstrated. A sample of the insulation,
approximately 4 m × 4 m, is to be prepared and tested by a fully
loaded fork lift truck with a gross weight of 6,5 tons on one axle
with a wheel pitch of 1450 mm, having single wheeled pneumatic tyres.
The truck is to be driven and manoeuvred over the sample to the satisfaction
of the Surveyors.
9.2.12 Prefabricated
panel systems are to be fitted with suitable pressure equalising devices
to prevent damage which may be caused by under or over pressure resulting
from the defrosting of coolers, rapid changes in pressure on the inner
and outer faces of the panels or rapid cooling of the chamber.
9.2.13 The
pressure equalising devices are to be so designed as to allow the
passage of air in either direction, but remain effectively closed
until the pressure differential reaches a value of 10 mm water column.
Heating is to be provided to protect the mechanism from freezing.