Section
3 Refrigerating machinery and refrigerant storage compartment arrangements
3.1 General
3.1.1 Refrigerating
machinery is to be installed in a well ventilated compartment. In
general, the arrangements are to be such that all components of the
refrigerating machinery can be readily opened up for inspection or
replacement. Space is to be provided for the withdrawal and renewal
of the tubes in ‘shell-and-tube’ type evaporators (secondary
refrigerant coolers) and condensers. Proposals for alternative arrangements
are to be submitted to LR for consideration.
3.1.2 Refrigerating
machinery using toxic and/or flammable refrigerants is to be located
outside the main machinery space in a separate gastight compartment.
3.1.3 Where
the refrigerating machinery is located in a separate gastight compartment,
outside the main machinery space, this compartment is to be equipped
with effective mechanical ventilation to provide 30 air changes per
hour based upon the total volume of the space. The mechanical ventilation
system is to have two methods of control, one of which is to be operable
from outside the compartment.
3.1.4 Openings
for pipes, electrical cables and other fittings in bulkheads and decks
are to be fitted with gastight seals.
3.2 Gas storage compartments
3.2.1 Portable
steel cylinders containing reserve supplies of refrigerant are to
be stored in a well ventilated compartment reserved solely for this
purpose.
3.2.2 The
storage compartment is to be provided with a mechanical ventilation
system providing 10 air changes per hour.
3.2.4 The
storage compartment is to be provided with suitable water drainage
arrangements not connected with the main machinery spaces.
3.2.5 Steel
storage cylinders are to be of an approved type and are to be filled
to a level suitable for an ambient temperature of plus 46°C.
3.2.6 The
storage compartment is to be provided with racks to facilitate secure
stowage of the cylinders.
3.3 Pressure testing at manufacturers’ works
3.3.1 Components
intended for use with a primary refrigerant are to be subject to pressure
testing procedures as detailed in Table 15.3.1 Test pressure.
Table 15.3.1 Test pressure
| Component
|
Test
pressure, (MPa)
|
| Pressure test
|
Tightness test
|
| (1)
|
Pressure vessels
|
See
Pt 5, Ch 11 Other Pressure Vessels
|
1,0p
|
| (2)
|
Compressor
cylinders/crankcase/casing
|
1,5p
|
1,0p
|
| (3)
|
Valves and fittings
|
2,0p
|
1,0p
|
| (4)
|
Pressure piping, fabricated.
headers, air coolers, etc.
|
1,5p
|
1,0p
|
|
|
3.3.2 Component
pressure tests are to be hydraulic or where suitable safety measures
are taken, may be pneumatic. The latter is to be carried out with
a suitable dry inert gas.
3.3.3 Component
tightness tests are to be carried out only after completion of satisfactory
pressure tests. Pneumatic pressure is to be applied using a suitable
dry inert gas.
3.3.4 Components for use with a secondary refrigerant or cooling water are to be
hydraulically tested to 1,5 times the design pressure which, in no case is to be less
than 0,35 MPa.
3.4 Pressure test after installation on board ship
3.4.1 For
primary refrigerant piping welded in place, pressure tests of the
welds are to be carried out at a test pressure of 1,5p.
This will normally take the form of a pneumatic test (see
Pt 7, Ch 15, 3.4 Pressure test after installation on board ship 3.4.2) since hydraulic testing
media such as water are not acceptable due to their incompatibility
with the primary refrigerants and the difficulty of removing all traces
from a completed system.
3.4.2 Pneumatic
pressure tests are to be carried out using a suitable inert gas.
Note Where pneumatic testing is used, adequate safety precautions
recognising the hazards involved should be observed to prevent danger
to personnel and to minimise risk to property.
3.4.5 Secondary refrigerant piping welded in place is to be hydraulically tested
to 1,5 times the design pressure which, in no case is to be less than 0,35 MPa.
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