Section
5 Special Survey – Hull requirements
5.1 General
5.1.1 The survey is to be of sufficient extent to ensure that the
hull/structure and related piping is in satisfactory condition and is fit for its
intended purpose, subject to proper maintenance and operation and to periodical
surveys being carried out as required by the Regulations.
5.1.2 The examination is to be sufficient to ascertain substantial corrosion,
significant deformation, fractures, damages or other structural deterioration and,
if deemed necessary by the Surveyor, suitable non-destructive examination may be
required.
5.2 Preparation
5.2.1 The unit is to be prepared as necessary for the Surveyors to gain proper
access for the careful inspection and examination of all items listed in this
Section. Voids and closed spaces are to be thoroughly ventilated to ensure adequate
levels of oxygen in the air, fuel tanks, oil storage tanks and other similar spaces
are to be gas freed and cleaned as necessary and paint lining, insulation and other
coatings and coverings are to be removed locally if required by the Surveyors.
5.2.2 In cases where the inner surface of the bottom plating is covered with
cement, asphalt, or other composition, the removal of this covering may be dispensed
with, provided that it is inspected, tested by beating and chipping and found sound
and adhering satisfactorily to the steel.
5.2.3
Ship units and other surface type units. The requirements of Pt 1, Ch 3, 5.2 Preparation of the Rules for Ships are to be complied with,
as applicable.
5.3 Examination and testing
5.3.1 All spaces within the hull/structure and superstructure are to be subject
to an overall survey and examination.
5.3.2 Watertight integrity of tanks, bulkheads, hull, decks and other
compartments is to be verified by visual inspection.
5.3.4
Ship units and other surface type units. The requirements of Pt 1, Ch 3, 5.3 Examination and testing of the Rules and Regulations for the Classification of Ships, July 2022 are to
be complied with, as applicable. Testing of crude oil storage tanks is to be carried
out as deemed necessary by the attending Surveyor. For units assigned an ESP
notation, the requirements of Pt 1, Ch 3, 7.5 Testing of the Rules and Regulations for the Classification of Ships, July 2022 are to
be complied with as applicable, see also
Pt 1, Ch 3, 5.3 Examination and testing 5.3.16.
5.3.6 In spaces used for salt-water ballast, excluding double bottom tanks,
where a protective coating is found in POOR condition, as defined in Pt 1, Ch 3, 1.5 Definitions, and it has not been repaired, where a soft or
semi-hard coating has been applied or where a protective coating was not applied
from the time of construction, maintenance of class will be subject to the space in
question being internally examined and gauged as necessary at Annual Surveys.
5.3.7 For independent salt-water double bottom tanks where a protective
coating is found to be in POOR condition, as defined in Pt 1, Ch 3, 1.5 Definitions, and it has not been repaired, where a soft or
semi-hard coating has been applied or where a protective coating was not applied
from the time of construction, maintenance of class may, at the discretion of the
Classification Committee, be subject to the spaces in question being examined and
gauged as necessary at Annual Surveys.
5.3.8 Double bottom, deep, ballast, peak and other tanks, including cargo
holds assigned also for the carriage of salt-water ballast, are to be tested with a
head of liquid to the top of air pipes or to the top of hatches for ballast/cargo
holds. Boundaries of fuel oil, lubricating oil and fresh water tanks are to be
tested with a head of liquid to the maximum filling level of the tank. Tank testing
of fuel oil, lubricating oil and fresh water tanks may be specially considered,
based upon a satisfactory external examination of the tank boundaries, and a
confirmation from the Master stating that the pressure testing has been carried out
according to the requirements with satisfactory results.
5.3.9 Where repairs are effected to the shell plating or bulkheads, any tanks
in way are to be tested to the Surveyor's satisfaction on completion of these
repairs.
5.3.10 In units with crude oil storage tanks, all piping systems on deck and
within the storage tanks and adjacent spaces are to be examined to ensure that
tightness and condition remain satisfactory. Special attention is to be given to
ballast piping in storage tanks and crude oil storage piping in ballast tanks,
pump-rooms, pipe tunnels and void spaces.
5.3.11 Where substantial corrosion, as defined in Pt 1, Ch 3, 1.5 Definitions, is identified in crude oil storage tanks and is
not rectified, this will be subject to re-examination at Annual and Intermediate
Surveys and is to be gauged as necessary.
5.3.12 At the first Special Survey and at subsequent Special Surveys,
representative tanks are to be examined by a Close-up Survey. The extent of the
survey is to be agreed with LR in advance of the survey. For all units over 10 years
of age, all salt-water ballast tanks and free-flooding areas where accessible are to
be examined.
5.3.13 The attachment to the structure and condition of anodes in all tanks is
to be examined.
5.3.14 In addition to the requirements of 5.3.1, columnstabilised units and
tension-leg units are to have a complete bracing Close-up Survey consisting of a
detailed dry examination of all bracings and their structural connections to columns
and decks. The connections of columns to lower hulls, pontoons and upper hulls are
to be examined. All critical regions defined in 2.2.3 are to be examined by approved
methods of NDE, see also
Pt 1, Ch 2, 3.5 Existing installations – Periodical Surveys 3.5.11 . Primary structure of the upper hull or
platform which form 'Box' or 'I' type supporting structure and their end connections
are to be examined. All free-flooding areas and sponsons are to be examined.
5.3.15 In addition to the requirements of 5.3.1, self-elevating units are to
have a complete survey of all legs, footings and mats. Particular attention is to be
given to the leg structure in way of the waterline. Tubular or similar type legs are
to be examined externally and internally, including stiffeners and pin holes. All
critical regions defined in Pt 1, Ch 3, 2.2 Structure and equipment 2.2.4 are to be examined by approved methods of NDE,
including the leg connections to footings or mats, see also
Pt 1, Ch 2, 3.5 Existing installations – Periodical Surveys 3.5.11. Jetting piping systems or other external
piping, particularly where penetrating footings or mats, are to be examined. Where
the spud cans or mat are partly or entirely obscured below the mud line where the
Special Survey is otherwise being completed, consideration may be given to
postponement of the examinations until the next Rig move.
5.3.16 In addition to the requirements of 5.3.1, surface type units are to have
a Close-up Survey carried out in accordance with an agreed programme, see
also
Pt 1, Ch 3, 1.6 Planned survey programme 1.6.1. The programme should identify all critical areas of
primary structure components and connections within compartments to be surveyed.
Special attention is to be given to underdeck structure supporting topside
equipment, flare stack and cranes, etc. The Surveyor may extend the Close-up Survey
if deemed necessary, taking into account the maintenance of the tanks under survey
and the condition of the corrosion prevention system. For areas in tanks where
coatings are found to be in GOOD condition, as defined in Pt 1, Ch 3, 1.5 Definitions 1.5.14, the extent of Close-up Survey may be specially
considered.
5.3.17 In addition to the requirements of 5.3.1, structural appendages and ducts
for positioning units, sponsons and positioning spuds on surface type units are to
be examined.
5.3.18 On all units, careful examination is to be made of those parts of the
structure particularly liable to excessive corrosion, or to deterioration or damage
from causes such as chafing, lying on the sea bed or handling of drilling equipment,
stores, etc., and due to water collection in corners of bulkheads and on weather
decks, and in other exposed areas.
5.3.19 All decks including helidecks and their supporting structure,
deck-houses, casings and superstructures are to be examined. Where aluminium alloy
is used in the structure, bimetallic joints are to be examined as far as
practicable. Lifeboat and winch platforms and their supporting structures are to be
examined.
5.3.20 Wood decks and sheathing are to be examined. If decay or rot is found or
the wood is excessively worn, the wood is to be renewed. Attention is to be given to
the condition of the plating under wood decks, sheathing or other deck covering. If
it is found that such coverings are broken, or are not adhering closely to the
plating, sections are to be removed as necessary to ascertain the condition of the
plating, see also
Pt 1, Ch 3, 1.2 Surveys for damage or alterations 1.2.1.
5.3.21 Primary bulkheads in the upper hull of column stabilised units and in
the hull of self-elevating units are to be examined. Particular attention is to be
given to the structure below and derrick sub-structures and supports under process
plant, drilling derricks and other heavy equipment. Bulkheads adjacent to leg wells,
turrets and moonpools are to be examined. Bulkhead penetrations in way of doors and
other openings are to be examined.
5.3.22 A Close-up Survey of structure around external and internal turrets is to
be held as per an agreed planned survey programme. Thickness measurements are to be
made as per the agreed planned survey programme, see
Pt 1, Ch 2, 3.5 Existing installations – Periodical Surveys 3.5.11. Turret bearings are to be examined in
accordance with the manufacturers’ recommendations and agreed survey programme.
Records of analyses of turret and swivel bearing seals and lubricants are to be
examined by the Surveyors for compliance to manufacturers’ standards and/or
recommendations.
5.3.23 Mooring buoys, mooring arms and yokes, mooring towers, and other similar
special features of the installation are to be specially examined in accordance with
an agreed planned survey programme.
5.3.24 For deep draught caisson units having combined oil/ballast tanks which
for operational requirements are always full, the periodic survey programme is to be
agreed to at the design stage. Owners may consider installing suitable steel coupon
plates in these tanks, where practicable, to monitor corrosion. Where coupon plates
are fitted, their position will be specially considered and they are to be
electrically insulated from the unit. Weight and thickness of the coupon plates are
to be recorded and reported at each special survey.
5.3.25 For tension-leg units, a Close-up Survey of the structure in way of
tethers is to be carried out.
5.3.26 For units having a DRILL notation, the drilling derrick,
including bolting arrangements is to be examined. Other structural components and
supports forming part of the drilling plant are to be examined and tested as
necessary, see also
Pt 1, Ch 3, 2.7 Drilling units.
5.3.29 Crane pedestals and similar supporting structures to access gangways and
flare booms, masts and standing rigging are to be examined.
5.3.30 At the second Special Survey and subsequent Special Surveys, chain
lockers are to be cleaned and examined internally.
5.3.31 For disconnectable units and mobile offshore units assigned the
character figure (1), anchors are to be examined. Anchors are to be partially
lowered and raised by the windlass or winch as applicable. The chain cables and wire
rope cables are to be examined as far as practicable. If any length of chain cable
is found to be reduced in mean diameter at its most worn part by 12 per cent or more
from its nominal diameter, it is to be renewed. The anchor windlass or winch is to
be examined. For equipment forming part of a positional mooring system, see
Pt 1, Ch 3, 5.5 Positional mooring systems.
5.3.32 The hand pumps, suctions, watertight doors, air and sounding pipes are to
be examined. In addition, the Surveyor is to examine internally air pipe heads in
accordance with the requirements of Table 3.1.
5.3.33 The Surveyor is to be satisfied as to the efficient condition of the
helm indicator, protection of aft steering wheel and gear on self-propelled
units.
5.3.34 Foundations and supporting headers, brackets and stiffeners for
drilling-related apparatus, where attached to hull, deck, substructure or
deck-house, are to be examined.
5.3.35 Foundations of machinery are to be examined.
Table 3.5.1 Air pipe head internal
examination requirements (applicable for automatic air pipe heads installed on
exposed decks of all units)
| Special Survey I
Age ≤ 5
|
Special Survey II
5 < Age ≤ 10
|
Special Survey III and subsequent
Age > 10
|
| (1) Two air pipe
heads (one port and one starboard) on exposed decks in the forward
0,25L. See Notes 1 to 5
|
(1)
All air pipe heads on exposed decks in the forward 0,25L. See Notes
1 to 5
|
All air pipe heads on exposed decks. See Notes 1 to 6
|
| (2) Two air pipe
heads (one port and one starboard) on the exposed decks, serving
spaces aft of 0,25L See Notes 1 to 5
|
(2)
At least 20% of air pipe heads on exposed decks, serving spaces aft
of 0,25L. See Notes 1 to 5
|
| NOTES
|
| 1. Air pipe heads serving ballast tanks are to be selected where
available.
|
| 2.
The Surveyor is to select which air pipe heads are to be
examined.
|
| 3.
Where considered necessary by the Surveyor as a result of the
examinations, the extent of examinations may be extended to include
other air pipe heads on exposed decks.
|
| 4. Where the inner parts of an air pipe head cannot be properly
examined due to its design, it is to be removed in order to allow an
internal examination.
|
| 5. Particular attention is to be given to the condition of the zinc
coating in heads constructed from galvanised steel.
|
| 6.
Exemption may be considered for air pipe heads where there is
documented evidence of their replacement within the previous five
years.
|
5.4 Thickness measurement
5.4.2 In addition to the thickness measurements required by 5.4.1 to ascertain
local wastage, thickness measurement is to be carried out on units with crude oil
bulk storage tanks at the first Special Survey and at subsequent Special Surveys, in
accordance with the requirements of Pt 1, Ch 3, 5.6 Thickness measurement and Pt 1, Ch 3, 7.7 Thickness measurement of the Rules for Ships, as applicable.
5.4.4 Where the protective coating is in GOOD condition, then the extent of thickness
measurements of internals may be specially considered, but not dispensed with in its
entirety, at the discretion of the Surveyor.
5.4.5 On all other unit types, thickness measurement is required at the second
Special Survey and at subsequent Special Surveys. Thickness measurement of the
primary hull structure is to include the shell plating of hulls, pontoons, columns,
bracings, main strength decks, bulkheads, legs, footings, mats and the structure of
representative salt-water ballast and pre-load tanks and other tanks and critical
areas as required by the Surveyor, to determine the amount of any general diminution
in thickness. The extent and location of such measurements are to be agreed by LR
prior to each survey, see also
Pt 1, Ch 3, 1.6 Planned survey programme 1.6.1.
Table 3.5.2 Minimum Requirements for
Thickness Measurements for Self-Elevating Units at Special Survey
| Special Survey I
Age ≤
5
|
Special Survey II
5< Age ≤ 10
|
Special Survey III
10
< Age ≤ 15
|
Special Survey IV and subsequent
15 < Age
|
| (1) Suspect areas throughout the unit (particular
attention to be paid to the legs in way of the Splash Zone).
|
(1) Suspect areas throughout the unit.
|
(1) Suspect areas throughout the unit.
|
(1) Suspect areas throughout the unit.
|
|
|
(2) Legs in way of Splash Zone.
|
(2) Legs in way of Splash Zone.
|
(2) Legs in way of Splash Zone.
|
|
|
(3) Primary application structures where wastage is
evident.
|
(3) Representative gaugings, throughout, of special
and primary application structures.
|
(3) Comprehensive gaugings, throughout, of special
and primary application structures.
|
|
|
(4) Representative gaugings of upper hull deck and
bottom plating and internals of one preload tank.
|
(4) Leg well structure.
|
(4) Leg well structure.
|
|
|
|
(5) Representative gaugings of deck, bottom, and
side shell plating of hull and mat.
|
(5) Representative gaugings of deck, bottom, and
side shell plating of hull and mat.
|
|
|
|
(6) Representative gaugings of upper hull deck and
bottom plating and internals of at least two preload tanks.
|
(6) Substructure of derrick as deemed
necessary.
|
|
|
|
|
(7) Representative gaugings of internals of all
preload tanks.
|
|
Note 1. Structural
application designation (Special, Primary, Secondary) are
defined in IACS Recommendation No. 11
|
Table 3.5.3 Minimum Requirements for
Thickness Measurements for Column-Stabilized Units at Special Survey
| Special Survey I
Age ≤
5
|
Special Survey II
5
> Age ≤ 10
|
Special Survey III
10
> Age ≤ 15
|
Special Survey IV and subsequent
15 > Age
|
| (1) Suspect areas throughout the unit.
|
(1) Suspect areas throughout the unit.
|
(1) Suspect areas throughout the unit.
|
(1) Suspect areas throughout the unit.
|
| (2) Columns and bracings where wastage is evident in
Splash Zone.
|
(2) Representative gaugings of columns and bracings
in Splash Zone together with internals in way as deemed
necessary.
|
(2) Representative gaugings, throughout, of special
and primary application structures.
|
(2) Comprehensive gaugings, throughout, of special
and primary application structures.
|
|
|
(3) Special and primary application structure where
wastage is evident.
|
(3) One Transverse Section (Girth Belt) of each of 2
columns and 2 bracings in Splash Zone together with internals in way
as deemed necessary.
|
(3) One Transverse Section (Girth Belt) of each of
one-half of the columns and bracings in Splash Zone and internals in
way as deemed necessary (i.e., gauge half of the unit’s columns and
bracings in Splash Zone).
|
|
|
|
(4) Lower hulls in way of mooring lines where wastage
is evident.
|
(4) Lower hulls in way of mooring lines where wastage
is evident.
|
|
|
|
(5) One Transverse Section (Girth Belt) of each lower
hull between one set of columns.
|
(5) One Transverse Section (Girth Belt) of each lower
hull between one set of columns.
|
|
|
|
|
(6) Representative gaugings of substructure of
drilling derrick.
|
|
Note Structural
application designation (Special, Primary, Secondary) are
defined in IACS Recommendation No. 11
|
Table 3.5.4 Minimum Requirements for Thickness Measurements for CALM Buoys
| Special Survey I
Age ≤ 5
|
Special
Survey II
5 < Age ≤ 10
|
Special
Survey III
10 < Age ≤ 15
|
pecial
Survey IV and subsequent
Age > 15
|
| (1) Suspect
areas throughout the unit.
|
(1) Suspect
areas throughout the unit.
|
(1) Suspect
areas throughout the unit.
|
(1) Suspect
areas throughout the unit.
|
|
|
(2) External
watertight envelope of the buoy where wastage is evident.
|
(2) External
watertight envelope of the buoy.
|
(2) External
watertight envelope of the buoy.
|
|
|
|
(3) Structural
appendages where wastage is evident.
|
(3) Structural
appendages where wastage is evident.
|
|
|
|
(4) Internal
watertight divisions – plating and stiffeners.
|
(4) Internal
watertight divisions – plating and stiffeners.
|
Table 3.5.5 Requirements for Additional
Thickness Measurements in way of Substantial Corrosion
| Structural
Member
|
Extent Of
Measurement
|
Pattern Of
Measurement
|
| Plating
|
Suspect area and adjacent
plates.
|
5 point pattern over 1 square
meter.
|
| Stiffeners
|
Suspect area.
|
3 measurements each in line
across web and flange.
|
5.4.6 A report is to be prepared by the qualified firm carrying out the
thickness measurements. The report is to give the location of measurement and the
thickness measured as well as the corresponding original thickness. The report is to
give the date when measurement was carried out, the type of measuring equipment,
names of personnel and their qualifications and is to be signed by the Operator.
5.4.7 The thickness measurement report is to be verified and signed by the
Surveyor and countersigned by an Authorising Surveyor.
5.5 Positional mooring systems
5.5.2 Where practicable, mooring cables, chains and anchors are to be lifted
to the surface for detailed inspection in accordance with 5.5.3 and 5.5.4 at each
Special Survey. Alternatively, in situ inspection, using acceptable techniques, will
be considered by LR when requested. See also
Pt 3, Ch 20 Guidelines on the Inspection of Positional Mooring Systems for guidance notes on the inspection of
positional mooring systems.
5.5.3 As far as practicable, the Surveyor is to determine the general
condition of the mooring system, including cables, chains, fibre ropes, fittings,
fairleads, connections and equipment. Particular attention is to be given to the
following:
- Cable or chain in contact with fairleads, etc.
- Cable or chain in way of winches and stoppers.
- Cable or chain in way of the splash zone.
- Cable or chain in the contact zone of the sea bed.
- Damage to mooring system.
- Extent of marine growth.
- Condition and performance of corrosion protection.
5.5.4 Anchors of mobile offshore units are to be cleaned and examined. Wire
rope anchor cables are to be examined. If cables are found to contain broken, badly
corroded or bird caging wires, they are to be renewed. Chain cables are to be ranged
and examined. Maximum acceptable diminution of anchor chain in service will normally
be limited to a two per cent reduction from basic chain diameter (basic chain
diameter can be taken as the diameter, excluding any design corrosion allowance,
which satisfies the Rule requirement for minimum factors of safety).
5.5.5 The windlasses or winches are to be examined.
5.5.6 Structure in way of anchor racks and anchor cable fairleads is to be
examined.
|