Hatch Cover

Maintenance

SHIPS
Hatch Cover Maintenance
CONTENTS even new-builds are not exempt from hatch cover problems
and can give rise to the largest individual claims.
Introduction................................................................................................... 01
Cost Versus Consequence...................................................................... 01 What is Weathertightness?
What is Weathertightness?.................................................................... 01 We always refer to hatch covers needing to be ‘weathertight’,
Testing for Weathertightness............................................................... 01 but what does this actually mean?
Hose Testing.................................................................................................. 01
The statutory requirement contained in Regulation 3(12) of the
Ultrasonic Testing....................................................................................... 02
International Convention on Load Lines 1966, states:
Testing is only part of the process...................................................... 02
Top Ten Hatch Cover Defects................................................................ 02 ‘“weathertight” in relation to any part of a ship other than a
Preventative and Planned Maintenance.......................................... 03 door in a bulkhead means that the part is such that water will
Use of Sealing tape.................................................................................... 04 not penetrate it and so enter the hull of the ship in the worst
Inspection check list.................................................................................. 05 sea and weather conditions likely to be encountered by the ship
Acknowledgements...................................................................................06 in service’.

Testing for Weathertightness

The Club may periodically require a ship’s hatch covers to be
tested for weathertightness for example as part of a condition
survey or steel preload survey. Similar surveys are also often
required by classification societies, and representatives of
cargo shippers, particularly where the cargo is sensitive to
water. These surveys may be performed by the traditional hose
test or by using the preferred and more modern method of
ultrasonic leak detection.

Hose Testing
There are some practical limitations with the traditional hose
test and examples of these are as follows:
The surveyor has to enter the cargo hold in order to identify
Introduction any leaks, whilst the exact source of the leak is often difficult
Cargo wet damage claims due to water ingress through hatch to pin point.
covers are common and can be very costly. Variations in water pressure, angle of jet, distance from the
hatch coaming and speed of travel can and often does lead
This briefing aims to raise awareness amongst Members and
to inconsistencies.
ship’s staff of the common causes of ingress claims and how
these causes can be avoided through best practice Many port authorities do not allow hose testing due to local
anti-pollution legislation.
Cost Versus Consequence A hose test cannot be carried out in sub-zero temperatures.
The mention of cost of improvement is pertinent because the A hose test cannot be carried out with cargo loaded on
disparity between this and the cost of failure to maintain board.
weathertight integrity can be enormous. For example, we
A hose test requires a minimum of two surveyors, one inside
typically encounter a number of claims each year costing over
the cargo hold and one on deck monitoring the operation.
$500,000 for wet-damaged cargoes resulting from hatch cover
defects, not to mention numerous smaller claims. A hose test can only be carried out when holds are empty.

In general, the cost of preventing these losses can usually be

measured in a few thousand dollars or less, such as replacing
defective rubber seals, minor steelwork repairs or sometimes
quite simply cleaning the coamings and sealing surfaces before
closing the hatch covers. We will aim to show just how easy it
can be to prevent costly failures.
It is commonly thought that most problems are experienced by
older ships and smaller ships. But larger ships, newer ships and

For more information, please visit www.nepia.com

Copyright © 2019 The North of England P&I Association Limited

01 Ships / Hatch Cover Maintenance

Hatch Cover Maintenance (cont.)
Ultrasonic Testing 1) Seal rubber beyond the point of replacement
Ultrasonic leakage detection equipment was introduced to 2) Seal rubber worn/torn, displaced or missing (including the
overcome difficulties associated with the hose test. An cross joints)
ultrasound transmitter is placed in the empty hold or on top of 3) Temporary seal ‘fixes’
the cargo stow, with the hatch covers and accesses closed and
4) Wastage of steel support pads or coaming side plates
secured.
(causes over-compression of seal and subsequent damage)
5) Blocked drain holes in hatch covers and coaming corners
6) Wasted cross joint drain channels
7) Cross-joint cleating or alignment faulty
8) Cleats and support stools wasted or missing
9) Holes in the steel plating caused by corrosion, possibly
localised
10) Wear on the centreline wedge devices on side-rolling
covers, which causes the cross-joint to open when the ship
is at sea

Using an ultrasound detector, operated by the surveyor, the

outer sides and cross-joints of the cover as well as any other
accesses and openings are scanned to locate any leaks.
Any leaks detected by ultrasound testing equipment should
not exceed 10% of the “open hatch value” (OHV), which is a
control reading determined at the start of the test. This 10%
OHV is an industry standard measure. Readings in excess of
10% may require any associated defects to be properly rectified
before the vessel sails if the ship’s operators are to be able to
demonstrate that they have exercised due diligence to make
the ship seaworthy at the commencement of the voyage.
For further detailed information on hatch cover testing, North
has produced a Loss Prevention briefing on the topic, which is
freely accessible on our website at:
www.nepia.com/latest/publications

Testing is only part of the process

Neither the hose nor ultrasound tests can replicate the
conditions experienced when a ship is rolling and pitching in a
seaway with water cascading over decks and hatches – which is
Carrying Out Onboard Repairs
why testing is only part of the loss-prevention process. The question arises: what do we do if, as a result of careful
checking of the hatch covers, we find a problem?
Well-maintained seals, cleats, supports, drains and other hatch
cover components are the key to achieving weathertightness. In practice ship’s crew face real challenges carrying out repairs
during the limited time available in port and with limited
Top Ten Hatch Cover Defects resources of people and materials.
The top ten hatch cover defects giving rise to claims for water Often a temporary repair can be carried out that will alleviate
damage are shown below. These are based on experience of the problem until more permanent repairs are possible. As long
many hatch cover surveys and damage claims. In most cases, as the repair is such that it remains effective during the
significant claims could have been avoided with low cost remaining voyage, then there is nothing wrong with this in
preventative remedial work. principle.

For more information, please visit www.nepia.com

Copyright © 2019 The North of England P&I Association Limited

02 Ships / Hatch Cover Maintenance

Hatch Cover Maintenance (cont.)
Note: All repairs whether temporary or permanent should be 2) The surface smoothness and correct profile of trackways of
carried out employing the hatch cover patentees methods rolling covers, compression bars and other steel work
and materials. bearing on seals or friction pads are to be preserved to
reduce wear rates on these components.
Regular inspections of the hatch covers and regular
maintenance according to the hatch cover supplier’s operating Corroded or damaged trackways affect the movement of
and maintenance manual should help to avoid surprises and hatch covers and may lead to misalignment. Trackways are
the need for emergency temporary repairs. But when an therefore to be kept clean and in a good painted condition.
unexpected defect is found, there are some basic rules to be An effective seal can only be obtained if the compression
observed. bar is straight, undamaged and non -corroded. If this is not
the case, the compression bar must be repaired or
If an area of the rubber seal is found to be damaged or
replaced.
defective, then it can be repaired by cutting out and replacing
the defective length. The hatch cover supplier’s manual Any debris left over from the last cargo operation will
should give detailed instructions as to the size and type of accelerate the wear rate of resting pads.
seal, the type of glue, the cutting and fitting instructions and 3) The hydraulic or mechanically powered opening, closing,
so on. In general, the minimum length which should be securing or cleating systems are to be maintained in
inserted is 500mm as shorter lengths are very unlikely to be accordance with the manufacturer’s recommendations.
satisfactory. All parts that move when operating the covers are to be
Inserting rubber pieces to pack out defective areas will not kept in good condition. The play of hatch cover hinges and
provide a reliable seal. Once the ship is at sea, with relative wheels is to be verified to be within the tolerances.
movement occurring between the hatch covers and the Otherwise this will cause the slewing of panels. Besides
coaming, then leaks are inevitable. other movable parts, the wheel spindles, hinge pins, racks,
If possible complete lengths of seal should be replaced to pinions and hydraulic cylinder bearings are to be regularly
avoid steps in the seal level. greased.
If end pieces of seal or special nosings of solid rubber are The hydraulic system’s oil stowage tank level is to be
needed, experience suggests that ‘do-it-yourself’ inserts will monitored regularly. This is to ensure that the hydraulic
never be satisfactory – the manufacturer’s specified items cylinder valves are balanced to prevent the hatch cover
such as pre-formed sections should be used. panels from twisting. Oil samples should be taken
frequently to verify the condition and, if necessary, the oil is
The use of temporary steel packers to build up wasted
to be changed.
supports or wedges can be effective as a temporary
measure, but such work should not be undertaken without While the hydraulic oil might last for approx. five years, the
taking into account the whole hatch cover system. oil filters are to be changed more frequently as stated in the
Sometimes what seems like a helpful remedial measure can manufacturer’s instructions.
bring into play some other unrecognised defects. 4) Where it has been identified that resting pads, compression
bars, seals, etc., are to be replaced due to significant
Try to avoid ‘quick fixes’ by spotting trouble early. If repairs
wastage, wear or loss of adjustment capability, the
become necessary for any reason, then the ideal solution is to
adjustment of manual cleats is to be maintained.
call in a service engineer familiar with hatch cover repairs. If this
option is not available, then repairs can be carried out by The function of the cleats is to keep the hatch covers in
onboard personnel following the information available in the position and maintain the seal’s design compression. The
supplier’s operating and maintenance manual. This is, of excessive trimming of cleats will not improve
course, dependent on an adequate supply of spares onboard. weathertightness but will lead to the accelerated wear of
seals.
Preventative and Planned Maintenance 5) Seals and other wear components are to be replaced in
DNV GL provide the following guidance on preventative and accordance with the manufacturer’s recommendations.
planned maintenance. This requires a sufficient number of spare parts of the
correct specification to be carried on board or obtained,
1) The overall structural strength is to be preserved by
keeping in mind that seals are designed for a particular
protecting the exposed surfaces of the hatch cover plating
degree of compression, hardness and chemical and wear
and stiffeners.
resistance.
It is essential that the protective coating of the hatch cover
The lifetime of hatch cover seals is in the range of four to
structure is maintained in order to sustain the overall
five years given normal operations and maintenance. This
strength and avoid expensive repairs. Particularly single skin
period fits perfectly with the special survey interval and
folding type covers are quite challenging in this respect as
allows sufficient replacement time. Otherwise, due to the
accessibility is difficult.

For more information, please visit www.nepia.com

Copyright © 2019 The North of England P&I Association Limited

03 Ships / Hatch Cover Maintenance

Hatch Cover Maintenance (cont.)
wear on steel -to-steel work or misalignment of hatch Tape or other material should not be used between
covers, the seals might have to be replaced earlier compression bars and rubber seals as an alternative to proper
depending on the permanent set of the seals. In general, repairs. Similarly, high-expansion foam is often used as a ‘belt
the manufacturer should state the permissible permanent and braces’ measure to achieve reliable weathertightness. This
set but a well recognised standard is to allow for 50% of the type of foam is hard to control in practice and can block drain
initial design compression which is stated in the hatch cover holes and drain channels, such that water leaking in can find its
operating and maintenance manual. way to the cargo rather than draining out as the system
In general, it is advisable to change the entire length of the designers intended.
respective seal at the first opportunity.
If resting pads are worn out, they have to be repaired in North’s policy is that: “the use of such tape or foam is
accordance with their original dimension. Although the acceptable as an additional precaution on well-maintained
relative movement of hatch covers is small on typical bulk weathertight hatch covers, but is not acceptable as an
carriers compared to on open hatch vessel with a higher alternative to proper permanent repairs”.
torsional flexibility, it is advisable to use replaceable and
adjustable low friction pads.
6) All hatch cover drains and their non -return valves, where
fitted, are to be kept in working order, noting that any drains
fitted to the inboard side of seal lines will have non-return
valves to prevent water ingress to holds in the event of
boarding seas.
It should go without saying that, after each cargo operation,
the coaming tops and cross-joint channels are to be
cleaned by removing any loose scale or cargo residue. The
same applies to the coaming drain holes and the non
-return valves, which are to be checked to ensure they
function, e.g. is the rubber ball moving freely.

Use of Sealing tape

The use of sealing tapes at the cross-joints of hatch covers is
common, and is sometimes expressly called for by the shipper
or charterer. On the face of it, this seems like a sensible Rubber seals on well-maintained hatch covers can normally be
additional precaution to enhance weathertightness. However, expected to last several years in normal service. However, if the
there are negative aspects to using hatch cover sealing tape, seal is over-compressed due to deterioration of the hatch cover
which include: steel work, bearing pad wear or misalignment of the hatch
cover panels, the seal will undoubtedly become damaged. This
It can lead to a false sense of security
damage may be tearing of the rubber seal or detachment of
The tape can wash off in heavy seas the seal from its retaining channel, whereby it is easy to see
The tape can obstruct drain holes, trapping water in the that an immediate repair is required.
cross-joint
More commonly, the over-compression causes the elasticity of
Complete sealing by means of tape is difficult due to the the seal to be lost resulting in a deep groove in the rubber
presence of cross-joint cleats or other fittings known as ‘permanent set’ (see photograph). It is quite easy to
The tape can cause accelerated corrosion of the steelwork measure the depth of the permanent set using a ruler or a
due to the deterioration of coatings upon its removal. gauge. This should then be compared to the designed
compression of the seal, found in the onboard hatch cover
operating and maintenance manual).
The simple rule for replacement of the seal is:

Manufacturers state that: “when permanent set reaches

half the design compression – replace the seal”.

For more information, please visit www.nepia.com

Copyright © 2019 The North of England P&I Association Limited

04 Ships / Hatch Cover Maintenance

Hatch Cover Maintenance (cont.)
There may be a temptation to continue service with the seals in Are quick-acting cleats all in place and in good, free working
poor condition, on the basis of cost saving. This is a false condition? Are the under-coaming consoles in strong
economy, as the relatively modest cost of seal replacement is condition? Are the rubber washers pliable and free from paint?
dwarfed by the value of claims for damaged cargoes.
Additionally, the presence of permanent set may be a If the hatch panel side and end plates are in steel-to-steel
symptom of other more serious problems with the hatch contact with the coaming tops when closed, are the coaming
covers, particularly wastage of the steel or misalignment, tops free from grooving or wear?
which will require further attention.
If the hatch covers are supported by bearing pads, chocks or
Inspection check list
support blocks, are they free from wear or damage?
When a ship undertakes to safely carry a cargo it is taking on an
onerous responsibility. The ship’s personnel and
Are the coamings free of corrosion and are the coaming
superintendent are at the end of the chain of that responsibility
brackets fully connected?
– and their influence in preventing, identifying and rectifying
problems cannot be over-stated. The task is not easy, largely Panels
because of the physical scale. For example, a typical Panamax Are the side and cross-joints seals in good condition? (Record
bulk carrier will have hatch covers with a total surface area permanent deflection at about 1 metre intervals and record
greater than a football pitch, hundreds of cleats and trackway width of existing rubber. Renewal of seals is recommended if
wheels, several hundred metres of hydraulic piping and, permanent deflection in excess of half the design
crucially, about half a kilometre of rubber sealing material. compression.)
Of huge importance is the regular and thorough inspection of
the coamings, hatch covers and in particular the sealing Is the permanent deflection in the centre of the rubber and not
arrangements. Attention should be given as to the condition of to one side? (Non-central permanent set may indicate
these arrangements when the covers are being opened or misalignment of panel)
closed. This continuous monitoring can alert crew at the onset
of problems and prevent more serious damage occurring.
Are the rubber seals free from deformation or tipping to one
Close inspection need not take too much time or effort; it may side?
simply be the process of making observations and recording
them accordingly. A check list is the ideal way to systemise
Are corner pads, joints and end pieces intact and in correct
these observations. The checklist given here is in three
position? Are they properly glued?
sections: coamings, panels and closure/sealing.

Coamings
Are the hatch panel tops in corrosion-free condition and well
Are the compression bars in good condition, undamaged by coated? Are they free from pitting and wastage?
corrosion, pitting, grab or wire damage and with uniform height
and thickness? (Record height and width in mm)
Are the undersides and internal structure of the hatch panels in
corrosion-free condition and well coated?
Is the coaming-top water channel between the compression
bar and the vertical coaming plate clean and free from
corrosion? Are the sides of the panels in way of the rubber seal retaining
channel and edges in good condition and free from distortion?
Is the extension of coaming plate forming one side of the water
channel in good condition without thinning, not bent from grab Are seal retaining channels in good, corrosion free condition?
contact and a uniform height all around? (Record height -
minimum guideline is 20mm)
Are the cross-joint seal retaining channels straight and
corrosion-free and channel supports and brackets in good
Are the inboard coaming faces free from any vertical rust
condition?
staining which would indicate water leakage, especially at the
cross-joints or split-joints?
Are the cross-joint compression bars in good scale-free
Are drains free from previous cargo residues and are there condition, undamaged, straight and with uniform width?
efficient means of closing, such as non-return valves? Are these
in place and working?

For more information, please visit www.nepia.com

Copyright © 2019 The North of England P&I Association Limited

05 Ships / Hatch Cover Maintenance

Hatch Cover Maintenance (cont.)
Are secondary drainage channels in scale-free condition, of Acknowledgements
adequate depth and drain freely into the coaming top water The Association is very grateful to David Byrne for providing
channel? information for this briefing.
Are the covers free of any deficiencies such as:
The second edition of North’s comprehensive loss-prevention
worn wheels/bearings or track-way guide entitled Hatch Cover Maintenance and Operation: A
hatch cover end distortion Guide to Good Practice, also written by David Byrne, is available
link pin wear, arm pin wear, pontoon cover locating guide from the Associations’ Loss Prevention Department.
wear The Association is grateful to DNV GL for their contribution to
hydraulic oil leaks or worn/damaged hoses the Preventative and Planned Maintenance section.
Chain wear or elongation

Closure
Are the adjacent hatch cover panels in alignment, without one
higher or lower than the next, or skewed relative to each other?

Is the necessary steel-to-steel contact or support correct?

Are the cleats correctly applied, that is applying an even holding

down force?

Are the anti-lift bolts properly engaged and in sound condition,

if fitted?

Are cross-joint wedges (where fitted) in place, operational and

effective?

Are cross-joint wedge bridges strong?

Disclaimer
The purpose of this publication is to provide a source of information which is
Are cross-joint wedge support areas on panel tops in good additional to that available to the maritime industry from regulatory, advisory,
condition, with end panel supports corrosion-free? and consultative organisations. Whilst care is taken to ensure the accuracy
of any information made available no warranty of accuracy is given and users
of that information are to be responsible for satisfying themselves that the
Do hatch panel sides form good steel-to-steel contact, with information is relevant and suitable for the purposes to which it is applied.
In no circumstances whatsoever shall North be liable to any person whatsoever
coaming tops without gaps?
for any loss or damage whensoever or howsoever arising out of or in
connection with the supply (including negligent supply) or use of information.
Are sufficient spares onboard, such as cleats, preformed corner Unless the contrary is indicated, all articles are written with reference to
rubber sections, linear rubber? English Law. However it should be noted that the content of this publication
does not constitute legal advice and should not be construed as such.
Members should contact North for specific advice on particular matters.
Have closed and secured hatch cover panels been subjected to
Published May 2015.
and proved weathertight by
a) Ultrasonic testing
b)Hose testing using water pressure of about 2 bar pressure,
through 15-18mm nozzle, aimed not more than 1 metre from
and directly at, every part of the peripheral, cross-joint or
split-joint seals?

For more information, please visit www.nepia.com

Copyright © 2019 The North of England P&I Association Limited

06 Ships / Hatch Cover Maintenance

Hatch Cover Maintenance (cont.)

For more information, please visit www.nepia.com

Copyright © 2019 The North of England P&I Association Limited

08 Ships / Hatch Cover Maintenance