Section
9 Procedures for testing tanks and tight boundaries
9.1 General
9.1.1 The
test procedures detailed in this Section are to be used to confirm
the watertightness of tanks and watertight boundaries, the structural
adequacy of tanks and weathertightness of structures.
9.2 Application
9.2.1 The testing requirements for gravity tanks, defined as tanks subject to a
vapour pressure not greater than 70 kN/m2, and other boundaries required to
be watertight or weathertight, are to be tested in accordance with this Section. Tests
are to be carried out in the presence of a Surveyor at a stage sufficiently close to
completion such that the strength and tightness are not subsequently impaired and prior
to any sealing and cement work being applied over joints see also
Pt 3, Ch 1, 9.8 Application of coating.
9.2.5 The testing of cargo containment systems of liquefied gas carriers are to
be in accordance with the requirements of Ch 4 of the Rules and Regulations for the
Classification of Ships for the Carriage of Liquefied Gases in Bulk.
9.2.6 The
testing of structures not listed in this Section are to be specially
considered.
Table 1.9.1 Testing requirements
Item to
be tested
|
Testing
procedure
|
Testing
requirement
|
Double
bottom tanks, see Note 1
|
Leak and
structural
|
The greater
of:
- head of water up to the top of the overflow
- head of water 2,4 m above top of tank, see Note 2
- head of water up to bulkhead deck
|
Combined double bottom and hopper
side tanks
|
Leak and
structural
|
The greater of:
- head of water up to the top of the overflow
- head of water representing the maximum pressure
experienced in service
|
Double bottom voids,
see Note 3
|
Leak
|
|
Double side tanks
|
Leak and
structural
|
|
Combined double bottom, lower hopper
and topside tanks
|
Leak and
structural
|
The greater of:
- head of water up to the top of the overflow
- head of water 2,4 m above top of tank, see Note 2
- head of water up to bulkhead deck
|
Topside tanks
|
Leak and
structural
|
|
Double side voids
|
Leak
|
|
Deep tanks (other than those listed
elsewhere)
|
Leak and
structural
|
The greater of:
- head of water up to the top of the overflow
- head of water 2,4 m above top of tank, see Note 2
|
Cargo oil tanks, and fuel oil
bunkers
|
Leak and
structural
|
The greater of:
- head of water up to the top of the overflow
- head of water 2,4 m above top of tank, see Note 2
- head of water up to top of tank, see Note 2, plus
setting of fitted pressure-relief valve
|
Scupper and discharge pipes in way of
tanks
|
Leak and
structural
|
|
Ballast hold of bulk carriers
|
Leak and
structural
|
Head of water up to the top of cargo
hatch coaming, see Note 9
|
Holds used for in-port
ballasting
|
Leak and
structural
|
Head of water representing the maximum
loading that will occur in-port as indicated in the Loading Manual.
|
Peak tanks, see Note 4
|
Leak and
structural
|
The greater of:
- head of water up to the top of the overflow
- head of water 2,4 m above top of tank, see Note 2
|
Fore peak spaces with
equipment
|
Leak
|
|
Fore peak
voids
|
Leak
|
|
Aft peak spaces with
equipment
|
Leak
|
|
Aft peak
voids, see Note 4
|
Leak
|
|
Cofferdams
|
Leak
|
|
Watertight
bulkheads
|
Leak
|
See Note 5
|
Superstructure end bulkhead
|
Leak
|
|
Watertight
doors below freeboard or bulkhead deck, and watertight hatches
|
Leak
|
See Notes 6 and 12
|
Double
plate rudder blades
|
Leak
|
|
Shaft tunnel
clear of deep tanks
|
Leak
|
See Note 5
|
Shell doors
when fitted in place
|
Leak
|
See Notes 5 and 7
|
Weathertight doors, hatch covers and closing appliances
|
Leak
|
See Note 5
|
Steel hatch
covers fitted to the cargo oil tanks and cargo holds of ships used for the
alternate carriage of oil cargo and dry bulk cargo
|
Leak
|
See Note 5
|
Chain
locker
|
Leak and
structural
|
Head of
water up to top of chain pipe
|
Independent
edible liquid tanks
|
Leak and
structural
|
The greater
of:
- head of water up to the top of the overflow
- head of water 0,9 m above top of tank, see Note 2
|
L.O. Sump
tanks and other similar tanks/spaces under main engines
|
Leak
|
See
Notes 5 and 11
|
Ballast ducts
|
Leak and
structural
|
The greater
of:
- ballast pump maximum pressure
- setting of pressure-relief valve
|
Chemical tanker cargo tanks
|
Leak and
structural
|
The greater
of:
- head of water 2,4 m above top of tank, see Notes
2 and 8
- head of water up to top of tank, see Notes 2 and
8, plus setting of fitted pressure-relief valve
|
Independent tanks, see Note
13
|
Leak and
structural
|
The greater
of:
- head of water up to the top of the overflow
- head of water 2,4 m above top of tank, see Note 2
|
Note
2. Top of tank is the deck forming the
top of the tank, excluding any hatchways. In holds for liquid cargo or
ballast with large hatch openings, the top of tank is to be taken to
the top of the hatch.
Note
4. Testing of the aft peak is to be
carried out after the sterntube has been fitted.
Note
7. For shell doors providing watertight
closure, watertightness is to be demonstrated through prototype
testing before installation. The testing procedure is to be agreed
with LR prior to testing.
Note 8. Where a cargo tank
is designed for the carriage of cargoes with a specific gravity greater
than 1,0, an appropriate additional head is to be considered.
Note 9. Where air vents are
fitted below the top of the coaming, adequate blanking off of these vents
may be required prior to the commencement of the test.
Note 11. Where L.O. sump tanks and other similar spaces under main engines
intended to hold liquid form part of the watertight subdivision of the
ship, they are to be tested in accordance with the requirements for deep
tanks (other than those listed elsewhere).
Note 12. All watertight
doors and hatches are to be hose tested after installation. Hose testing
is to be carried out from each side of a door or hatch unless, for a
specific application, flooding is anticipated from only one side. Where a
hose test is not practicable because of possible damage to machinery,
electrical equipment insulation or outfitting items, it may be replaced
by an ultrasonic leak test or an equivalent test.
Note 13. Independent tanks not confirmed watertight by a prototype test are
to be subject to a hydrostatic test. A leak test is to be carried out
after installation on board.
|
9.3 Test types
9.3.1 The
types of test specified in this Section are:
-
Structural
test: which is to be conducted to verify the tightness and
structural adequacy of the construction of tanks. This may be a hydrostatic
test or, where the situation warrants, a hydropneumatic test.
-
Leak test:
which is to be used to verify the tightness of a boundary. Unless
a specific test is indicated, this may be a hydrostatic, hydropneumatic
test, air or other medium test.
9.4 Structural test procedures for SOLAS
ships
9.4.1 Tanks which are intended to hold liquids, and which form part of the watertight
subdivision of the ship, shall be tested for tightness and structural strength as
indicated in Table 1.9.1 Testing requirements.
9.4.3 Where a structural test is specified in Table 1.9.1 Testing requirements, unless specified otherwise, a hydrostatic
test is to be carried out in accordance with Pt 3, Ch 1, 9.7 Definitions and details of tests 9.7.1. Where practical limitations prevent a hydrostatic test
being carried out, a hydropneumatic test in accordance with Pt 3, Ch 1, 9.7 Definitions and details of tests 9.7.2 is to be conducted. All external boundaries of the tested
space are to be examined for structural distortion, bulging, buckling, or other related
damage and/or leaks.
9.4.4 A hydrostatic test or hydropneumatic test may be carried out afloat to
confirm the structural adequacy of tanks, provided that a leak test is carried out and
the results are confirmed as satisfactory before the vessel is afloat.
9.4.5 Consideration is to be given to the selection of tanks to be structurally
tested. Selected tanks are to be chosen so that all representative structural members
are tested for the expected tension and compression. Tank boundaries are to be tested
from at least one side.
9.4.6 For watertight boundaries of spaces other than tanks, excluding ballast
holds, chain lockers and cargo holds which are intended to be used for in-port
ballasting, structural testing may be exempted completely, provided that the
watertightness in all boundaries of exempted spaces are verified by leak tests and
thorough inspection. The testing of ballast holds, chain lockers and cargo holds which
are intended to be used for in-port ballasting, are to comply with the requirements of
Pt 3, Ch 1, 9.4 Structural test procedures for SOLAS ships 9.4.3 to Pt 3, Ch 1, 9.4 Structural test procedures for SOLAS ships 9.4.5.
9.4.7 Tanks which do not form part of the watertight subdivision of the ship, need not be
structurally tested providing that the watertightness of all boundaries of these spaces
is verified by leak tests and thorough inspection.
9.5 Structural test procedures for non-SOLAS ships and SOLAS exempt/equivalent ships
9.5.2 For tanks of the same structural design, configuration and the same general
workmanship, as determined by the attending Surveyor, a structural test need only be
carried out on one tank, provided that all subsequent tanks are tested for leaks by
an air test. The relaxation to accept leak testing using an air test instead of a
structural test does not apply to cargo space boundaries adjacent to other
compartments in tankers and combination carriers or to the boundaries of tanks for
segregated cargoes or pollutant cargoes in other types of ship.
9.5.3 Where the structural adequacy of a tank has been verified by structural testing on a
previous vessel in a series, tanks of structural similarity on subsequent vessels
within that series (which are built at the same shipyard) need not be structurally
tested, provided that the watertightness of all exempt tanks is verified by leak
tests and thorough inspection. However, structural testing is to be carried out for
at least one tank of each type of tank on every vessel in the series. The relaxation
to accept leak testing and thorough inspections instead of a structural test on
subsequent vessels in a series does not apply to cargo space boundaries adjacent to
other compartments in tankers and combination carriers or to the boundaries of tanks
for segregated cargoes or pollutant cargoes in other types of ship.
9.6 Leak test procedures
9.6.1 Where a leak test is specified in Table 1.9.1 Testing requirements, unless specified otherwise, a tank air test,
compressed air fillet weld test, or vacuum box test is to be carried out in accordance
with the applicable requirements of Pt 3, Ch 1, 9.7 Definitions and details of tests 9.7.4 to Pt 3, Ch 1, 9.7 Definitions and details of tests 9.7.6. A hydrostatic or hydropneumatic test conducted in
accordance with the applicable requirements of Pt 3, Ch 1, 9.7 Definitions and details of tests 9.7.1 and Pt 3, Ch 1, 9.7 Definitions and details of tests 9.7.2 will be accepted as a leak test on the condition that
safe access to all joints being examined is provided, see
Pt 3, Ch 1, 9.9 Safe access to joints 9.9.1. Where a hydrostatic or hydropneumatic test is applied
as a leak test, the external boundaries are to be free of any liquid residue prior to
the commencement of the test.
9.6.3 Air
tests of joints may be conducted at any stage during construction
provided that all work that might affect the tightness of the joint
is completed before the test is carried out.
9.6.4 Where acceptable to the attending Surveyor, provided that careful visual inspections
show a continuous uniform weld profile shape, free from repairs, and the results of
selected NDE testing show no significant defects, the leak testing of automatic butt
welds and semi-automatic (flux core arc welding) butt welds may be omitted.
9.7 Definitions and details of tests
9.7.1
Hydrostatic
test is a test conducted by filling a space with a liquid to
a specified head. Unless another liquid is approved, the hydrostatic
test is to consist of filling a space with either fresh or sea-water,
whichever is appropriate for the space being tested, to the level
specified in Table 1.9.1 Testing requirements.
For tanks intended to carry cargoes of a higher density than the test
liquid, the head of the liquid is to be specially considered.
9.7.2
Hydropneumatic
test is a combination of a hydrostatic test and a tank air
test, consisting of partially filling a tank with water and conducting
a tank air test on the unfilled portion of the tank. A hydropneumatic
test, where approved, is to be such that the test condition in conjunction
with the approved liquid level and air pressure will simulate the
actual loading as far as practicable. The requirements for tank air
testing shown in Pt 3, Ch 1, 9.7 Definitions and details of tests 9.7.4 are
to be adhered to.
9.7.3
Hose test is a test used to verify the tightness of joints with a jet of water.
The jet of water is to be directed perpendicular to the joint. It is to be carried out
with the pressure in the hose nozzle maintained at not less than 0,2 MPa during the
test. The hose nozzle is to have a minimum inside diameter of 12 mm and is to be
situated no further than 1,5 m from the joint. Where a hose test is not practical
because of possible damage to machinery, electrical equipment insulation or outfitting
items, it may be replaced by a careful visual examination of welded connections,
supported by an ultrasonic or penetration leak test, or an equivalent, see SOLAS
Regulation 11 - Initial testing of watertight bulkheads, etc.
9.7.4
Tank air test is to be used to verify the tightness of a compartment by means of
an air pressure differential and leak indicator solution. An efficient indicating
solution (e.g. soapy water) is to be applied to the weld or penetration being tested and
is to be examined whilst an air pressure differential of not less than 0,015 MPa is
applied by pumping air into the compartment. Arrangements are to be made to ensure that
any increase in air pressure does not exceed 0,03 MPa. A U-tube with a height sufficient
to hold a head of water corresponding to the required test pressure is to be used for
verification and to avoid overpressure. The cross-sectional area of the U-tube is not to
be less than that of the pipe supplying air to the tank. Alternatively, two calibrated
pressure gauges may be considered acceptable. All boundary welds, including pipe
connections in the compartment are to be examined twice. The first is to be examined
immediately upon applying the leak indication solution; the second approximately five
minutes afterwards.
9.7.5
Compressed air fillet weld test. This test consists of compressed air being
injected into one end of a fillet welded joint and the pressure verified at the other
end of the joint by a pressure gauge. Pressure gauges are to be arranged so that an air
pressure of at least 0,015 MPa above atmospheric pressure can be verified at each end of
all passages within the portion being tested. A leak indicator solution is to be applied
and the weld line examined for leaks. A compressed air test may be carried out for
partial penetration welds where the root face is greater than 6 mm.
9.7.6
Vacuum box test is a test used to verify the tightness of joints by means of a
localised air pressure differential and leak indicator solution. The test is to be
conducted with the use of a box with air connections, gauges and an inspection window
that is to be placed over the joint being tested with a leak indicator solution applied.
The air within the box is to be removed by an ejector to create a vacuum i.e. a pressure
differential of 0,02 to 0,026 MPa inside the box.
9.7.7
Ultrasonic test may be used where a hose test is not practical to verify the
tightness of a boundary, see
Pt 3, Ch 1, 9.7 Definitions and details of tests 9.7.3. An arrangement of ultrasonic echo transmitters is to be placed
inside a compartment and a receiver outside. The receiver is to be used to detect any
leaks in the compartment.
9.7.8
Penetration test may be used where a hose test is not practical to assess butt
welds, see
Pt 3, Ch 1, 9.7 Definitions and details of tests 9.7.3, by applying a low surface tension liquid to one side of a
compartment boundary. When no liquid is detected on the opposite side of the boundary
after expiration of a defined period of time, the verification of tightness of the
compartment’s boundary may be assumed. A developer solution may be applied on the other
side of the weld to aid leak detection.
9.7.9 Other
methods of testing may be considered and are to be agreed by LR prior
to commencement of testing.
9.8 Application of coating
9.8.1 A final
coating may be applied over automatic butt welds before the completion
of a leak test, provided that careful visual inspections show continuous
uniform weld profile shape, free from repairs, and the results of
selected NDE testing show no significant defects. For all other joints,
the final coating is to be applied after the completion of a leak
test. The Surveyor reserves the right to require a leak test prior
to the application of the final coating over automatic erection butt
welds.
9.8.2 Any
temporary coating which may conceal defects or leaks is to be applied
at a time as specified for the final coating, see
Pt 3, Ch 1, 9.8 Application of coating 9.8.1. This requirement does not
apply to shop primer.
9.9 Safe access to joints
9.9.1 For
leak tests, safe access to all joints under examination is to be provided.
|