Bulk Carrier - Improving Cargo Safety
N.B. Please refer to the IMO website for the latest information on Bulk Carrier Safety
Code of Safe
Practice for Solid Bulk Cargoes (BC Code)
Improving structural safety
What went wrong?
Measures to improve bulk carrier safety
Enhanced inspections during surveys
The 1997 SOLAS Conference
Formal Safety Assessment
Many different products are carried on ships in bulk. Grains, such as wheat, maize, millet and rye have been transported by sea for centuries - the wheat trade between north Africa and Italy was a major economic feature of the Roman Empire, for example. Since the last century, the grain trade has grown in importance and much of it is carried by sea, often on long trans-Atlantic or trans-Pacific voyages.
According to the International Grains Council, in 2005-2006 total wheat trade amounted to 109 million metric tons.
Originally grain was transported in sacks, but by the middle of the 20th century the normal procedure was to carry it in bulk. It could be stored, loaded and unloaded easily and the time taken to deliver it from producer to customer was greatly reduced, as were the costs involved. However, there were problems.
Grain has a tendency to settle during the course of a voyage, as air is forced out when the individual grains sink (“sinkage”). This leads to a gap developing between the top of the cargo and the hatch cover. This in turn enables the cargo to move from side to side as the ship rolls and pitches. This movement can cause the ship to list and, although initially the ship’s movement will tend to right this, eventually the list can become more severe. In the worst cases, the ship can capsize. This problem was well known and the 1960 SOLAS Convention adopted measures designed to prevent it from occurring. These regulations were more advantageous from an economic point of view than those adopted in SOLAS 1948 (which required a more extensive use of increasingly expensive temporary fittings and/or bagged grain) and many countries quickly put them into effect, even though the Convention itself did not enter into force until 1965.
However, the new regulations still had some deficiencies as far as safety was concerned, for during a period of four years, six ships loaded under the 1960 SOLAS rules were lost at sea. IMO began looking at this problem early in 1963 and asked masters of ships to contribute information to a broad study. Further studies and tests showed that some of the principles on which the 1960 regulations were based were invalid -- in particular, it was shown that the 1960 Convention had underestimated the amount of “sinkage” which occurs in grain cargoes loaded in bulk. This made the basic requirements of the Convention unattainable. As a result, the IMO Assembly in 1969 adopted new grain regulations [resolution A.184 (VI)], which became generally known as the 1969 Equivalent Grain Regulations.
Voyage experience over a three-year period showed that the 1969 Grain Equivalents were not only safer but were also more practical and economical than the 1960 regulations and, with slight amendments, based upon operational experience, they were used as the basis of new international requirements which were subsequently incorporated into the 1974 SOLAS Convention.
grain was the only bulk cargo to be given a special chapter in the 1960 SOLAS
Convention, IMO also developed an international Code of Safe Practice for Solid
Bulk Cargoes (BC Code), which was adopted in 1965. The Code has been
updated at regular intervals since then and is kept under continuous review by
the Sub-Committee on Dangerous Goods, Solid Cargoes and Containers. The
practices contained in the Code are intended as recommendations to Governments,
ship operators and shipmasters. Its aim is to bring to the attention of those
concerned an internationally-accepted method of dealing with the hazards to
safety which may be encountered when carrying cargo in bulk.
that are most relevant to the safety of bulk carriers are the revised BC Code
and a new mandatory International Code for the Safe Carriage of Grain in Bulk
(International Grain Code). Like the original grain rules, the Code is designed
to prevent the particular qualities of grain threatening the stability of ships
when it is carried in bulk. It applies to all ships - including existing ships
and those of less than 500 tgt (tons gross tonnage) - that carry grain in bulk.
Part A contains special requirements and gives guidance on the stowage of grain
and the use of grain fittings. Part B deals with the calculation of heeling
moments and general assumptions.
Code of Safe Practice for Solid Bulk Cargoes (BC Code)
The revised BC Code deals with three basic types of cargo: those which may liquefy; materials which possess chemical hazards; and materials which fall into neither of these categories but may nevertheless pose other dangers. The Code highlights the dangers associated with the shipment of certain types of bulk cargoes; gives guidance on various procedures which should be adopted; lists typical products which are shipped in bulk; gives advice on their properties and how they should be handled; and describes various test procedures which should be employed to determine the characteristic cargo properties.
The Code contains a number of general precautions and it is of fundamental importance that bulk cargoes be properly distributed throughout the ship so that the structure is not overstressed and the ship has an adequate standard of stability. Loaded conditions vary according to the density of the cargo carried. The ratio of cubic capacity to deadweight capacity of a normal ship is around 1.4 to 1.7 cubic metres per tonne and the ratio of volume of cargo to its mass is known as the stowage factor. When high density bulk cargoes with a stowage factor of about 0.56 cubic metres per ton or lower are carried, it is particularly important to pay attention to the distribution of weight in order to avoid excessive stresses on the structure of the ship.
All bulk cargoes when loaded tend to form a cone. The angle formed between the slope of the cone and the bottom of the hold will vary according to the cargo and is known as the angle of repose. Some dense cargoes, such as iron ore, form a steep cone while others - such as grain - have a much shallower angle. Cargoes with a low angle of repose are much more prone to shift during the voyage and special precautions have to be taken to ensure that cargo movement does not affect the ship’s stability. On the other hand, the sheer weight of dense cargoes can affect the structure of the ship.
After dealing with general precautions, the Code then goes on to deal with cargoes having an angle of repose of 35 degrees or less and then with those where the angle of repose is greater than 35 degrees. Cargoes with a low angle of repose are particularly liable to dry-surface movement aboard ship. To overcome this problem, the Code states that such cargoes should be trimmed reasonably level and the spaces in which they are loaded should be filled as fully as is practicable, without resulting in excessive weight on the supporting structure.
Special provisions should be made for stowing dry cargoes that flow very freely, by means of securing arrangements, such as shifting boards or bins. The Code says that the importance of trimming as a means of reducing the possibility of a shift of cargo can never be over-stressed. This is particularly true for smaller ships of less than 100 metres in length. Trimming also helps to cut oxidation by reducing the surface area exposed to the atmosphere. It also helps to eliminate the “funnel” effect, which in certain cargoes, such as direct reduced iron (DRI) and concentrates, can cause spontaneous combustion. This occurs when voids in the cargo enable hot gases to move upwards, at the same time sucking in fresh air.
The Code then gives details of other dangers that may exist. Some cargoes, for example, are liable to oxidation which may result in the reduction of the oxygen supply, the emission of toxic fumes and self-heating. Others may emit toxic fumes without oxidation or when wet. The shipper should inform the master about any chemical hazards that may exist and the Code gives details of precautions that should be taken.
The Code gives details of the various sampling procedures and tests which should be used before transporting concentrates and similar materials and also contains a recommended test procedure to be used by laboratories. There are seven appendices to the Code, giving information about particular cargoes. A list of cargoes which may liquefy is contained in appendix A to the Code, for example while appendix B gives an extensive list of materials possessing chemical hazards. Some of the classified materials listed also appear in the International Maritime Dangerous Goods (IMDG) Code when carried in packaged form, but others become hazardous only when they are carried in bulk - for example, because they might reduce the oxygen content of a cargo space or are prone to self-heating. Examples are woodchips, coal and direct reduced iron (DRI). Appendix C deals with bulk cargoes which are neither liable to liquefy nor possess chemical hazards. More detailed information concerning test procedures, associated apparatus and standards which are referred to in the Code are contained in appendix D. Emergency Schedules for those materials listed in appendix B are contained in appendix E. Recommendations for entering cargo spaces, tanks, pump rooms, fuel tanks and similar enclosed compartments are shown in appendix F. Procedures for gas monitoring of coal cargoes are contained in appendix G.
In 1990 the
IMO issued a circular (MSC/Circ.531) which warned against the risks of shifting
cargo and requested Member Governments to implement revised recommendations for
trimming cargoes which were included in the 1989 edition of the Code and are
intended to minimize sliding failures.
Improving structural safety
taken by IMO undoubtedly helped to solve many of the problems associated with
the carriage of bulk cargoes, such as cargo shift and the consequent loss of
stability. The number of accidents involving bulk carriers dropped during the
1980s and it seemed to many observers that the general problem of bulk carrier
safety had been solved. Then, in 1990 the trend was dramatically reversed: 20
bulk carriers sank with 94 lives lost and in 1991, 24 sank with 154 dead. This
development was so dramatic and so unexpected that alarm bells began to ring
throughout the shipping world. It became increasingly apparent that many of the
bulk carriers lost - often without trace - had suffered from severe structural
damage. In some cases ships had simply broken apart like a snapped pencil.
What had gone wrong? And what could be done to improve matters?
What went wrong?
The analyses of bulk carriers that have been carried out during the last few years have shown that, although there were many different causes, certain conclusions could be drawn.
The importance of age
There is no doubt that there is a clear link between accidents and the age of bulk carriers. All but two of the ships lost in 1990 were over 18 years old. In July 1995 the classification society Lloyd’s Register of Shipping published a table giving details of accidents involving 88 bulk carriers between January 1990 and December 1994. Only three of the ships on the list were less than ten years old and nearly half were over 20. What makes this so worrying is that the average age of bulk carriers had been rising steadily - from under nine years old in 1980 to more than 14 by 1995. The reason for this upward trend is primarily economic. During the 1980s there was a glut of shipbuilding, mainly because the industry greatly over-estimated the way in which trade would develop. This was especially true of tankers, but it was true to some extent of bulk carriers as well and when trade increased much more slowly than had been forecast (and sometimes declined) the result was a fall in the demand for ships. Some older ships were scrapped and others laid up waiting the return of more favourable trading conditions. But throughout the period there has generally been a surplus of unwanted ships and freight rates have usually remained low. This has discouraged the construction of new tonnage and has led shipowners and builders to explore new ways of cutting costs.
This trend is potentially worrying. A survey of bulk carrier safety issued in July 1995 by the classification society Lloyd’s Register (entitled Bulk Carriers - an Update) pointed out that “an historically critical age group for bulk carrier casualties is from 14 to 18 years and that in three or more years’ time a large proportion of bulk carriers in service will be in this age group unless the age distribution is changed by, for example, a substantial scrapping programme.”
For straightforward economic reasons there is little sign of such a mass scrapping taking place. At the turn of the century, the great majority of the world’s bulk carrier fleet have reached the danger point. More than half the world’s bulk carrier fleet is already more than 15 years old and one third is more than 20 years old.
Corrosion and fatigue
The main reason why age is so relevant to shipping casualties is that corrosion and general fatigue increase as ships grow older. This is partly because of the stresses to which the ship is inevitably subjected by routine operations, cargo handling, weather and waves and partly to the effect of seawater on steel. Although any water tends to causes metals such as steel to rust, seawater is much more harmful than fresh water because it contains so much salt. The bulk carriers used in the Great Lakes of North America, for example, frequently survive to 50 or 60 years of age - up to three times as long as the average ocean-going ship.
Corrosion is a serious problem for anything built of metal that is exposed to the elements and for a ship it can be fatal. Corrosion of metallic structure is likely to be more extensive and work more rapidly than on other structures simply because the ship is in continual contact with water, usually seawater. It can also be accelerated by the effects of some cargoes, especially those carried in bulk. The interior of cargo holds can be affected by humidity resulting from the moisture contained in some bulk cargoes. Sulphuric acid can be formed from sulphur residues (which can come from coal) combining with water resulting from condensation.
There are various ways of preventing corrosion - or at least of preventing it from becoming a problem. Tanks can be painted with special coatings and can be carefully washed out. Above all, the condition of the hull and other structures can be continually checked for signs of corrosion or fatigue. This, however, is much easier said than done. There is, in the first place, a great deal of steelwork to be checked. A bulk carrier of 254,000 deadweight tons (representing roughly the amount of cargo it can carry) might be 320 metres long, 54 metres in breadth and 26 metres deep. The total hull area to be examined could thus be in excess of 54,000 square metres and that does not include the interior bulkheads, hopper tanks, brackets and other features. All of this has to be surveyed and inspected - a daunting task that requires the use of special staging, artificial light and a considerable amount of stamina on the part of the surveyor or surveyors involved.
Certainly corrosion seems to have played a significant part in many of the bulk carrier accidents of recent years - especially the most serious losses. An Intercargo analysis of 15 total losses in 1994 showed that 40% were caused by plate failure and subsequent ingress of water. A further 6.7% of losses were never explained because the ships involved disappeared. More than 70% of these losses occurred in heavy weather.
Intercargo found that of 29 fatal accidents involving bulk carriers between 1990 and 1994, 55% were due to plate failure. In terms of lives lost 81% were associated with sinkings and disappearances. In 12 cases adverse weather was a factor and in 67% of the cases, iron ore was the cargo. Not surprisingly, the Intercargo report states: “The inescapable conclusion from this analysis is the fairly obvious one that it is plate failure, taking water and disappearance which cause the majority of fatal accidents. Thus, although during the whole period losses related to human factors account for 33% of all bulker and OBO losses, such accidents comprise only 10% of fatal accidents and involve only 7% of the total fatalities...it is structural failure, aggravated by bad weather and the carriage of iron ore which causes the majority of the really serious accidents involving loss of life.”
The frequent references to iron ore are significant because once laden bulk cargo carriers get into trouble, the consequences can be very sudden. The ships are designed to withstand bad conditions, but not to operate with several holds flooded and the combination of iron ore and a sudden inrush of seawater can result in more weight than the structure can stand. Other investigations came to similar conclusions. The American Bureau of Shipping said in 1991: “The recent spate of casualties on conventional bulk carriers appears to be directly traceable to failure of the cargo hold structure...”
Lloyd’s Register of Shipping concluded that the prime cause of most casualties is the inability of the side structure to withstand the combination of local corrosion, fatigue cracking and operational damage. The evidence of the disastrous consequences of uncontrolled corrosion is overwhelming - but preventing it is not so easy as it sounds, if only because of the size of the ships themselves and the difficulties involved in assessing corrosion and plate thickness.
A report by Lloyd’s Register in the autumn of 1991 stated that the owner of one ten-year old Capesize bulk carrier estimated that the wastage rate of hold frames due to corrosion amounted to 0.5mm per year - and 1mm in some places. Some frames had suffered metal wastage of 20%. During one voyage from South America to Japan a bracket which was in good condition when the ship left became completely detached, leaving a 1.4mm crack. It was not detected because “the rust scale adhering to the surface of the hold structures presented a smooth and regular surface to the eye on visual inspection, making it difficult to detect any cracking.” Since the side plates of a bulk carrier may only be 20mm to 29mm thick the loss of a few millimetres can be disastrous.
Like many of the other studies carried out, the Lloyd’s Register report said that structural failures were due to a combination of factors. Corrosion was important - but so was physical damage suffered during operations. Bulk carriers are designed to withstand heavy seas. The massive structures of the largest ships will bend with the action of the sea. When the centre of the hull is higher than the bow and stern the action is known as “hogging”: the reverse is called “sagging”. But the design assumes that the hull is sound. Corrosion or other damage can lead to weaknesses developing that invalidate the calculations of the naval architect and imperil the whole ship. Loading patterns can make the effect worse. Dense cargoes such as iron ore are often carried in alternate holds in order to raise the ship’s centre of gravity and moderate its roll motions. But this places greater stress on frames and girders and, because holds carrying iron ore are not completely filled, there can be greater side frame deflection. The overall result is increased stress on inner hull components, according to Lloyd’s Register. This might be perfectly acceptable in a new ship - but not in a ship that has suffered from 20 years of hard service and neglect.
Design features originally chosen for operational reasons may also have safety implications. Many bulk carriers are fitted with very large hatch openings to facilitate cargo loading and unloading. Yet these openings may represent points of weakness in the hull since they reduce the torsional resistance of the hull.
Cargo handling methods have also been criticized. These have changed considerably in recent years, with the emphasis being to load and unload the ship as quickly as possible so that the berth can be cleared for the next ship. In some loading terminals iron ore can be loaded at up to 16,000 tons an hour by means of conveyor belts often several kilometres long. Stopping the loading process for some reason cannot be done simply by pressing a button - it has to be very carefully planned and can take several minutes to carry out. In these circumstances it is not surprising that bulk carriers can sometimes be overloaded. The International Association of Classification Societies (IACS) says that there is no evidence that high loading rates causes physical damage to the interior of cargo holds (assuming that they are in good condition to begin with) but “high cargo loading rates under an uncontrolled process could result in inadvertent overloading which could cause local or global damage.” Dramatic proof of what can happen if something goes wrong during loading came in 1994 when a bulk carrier broke in half while being loaded at a port in South America.
carried out by IACS members showed that a 5% overload placed in various holds
could increase the
bending moment by up to 15% and the sheer force by up to 5% while a 10% overload
could increase the still water bending moment by up to 40% and the sheer force
by up to 20%. A 10% overload, according to IACS (in reply to questions submitted
by the Nautical Institute) could be caused by a five to eight minute delay in
stopping a conveyor belt with a capacity of 16,000 tons an hour. At the other
end of the voyage, other problems can be waiting. Bulk cargoes are removed from
the hold by means of huge grabs, which can weigh up to 36 tons. The last tons
of cargo, which may be caught up in frame webs and other parts of the hold, are
often removed by bulldozers and hydraulic hammers fitted to the extending arms
of tractors. There is always a danger that the hull - especially if it is
suffering from corrosion or fatigue - may inadvertently be damaged in the
process. Part of the problem is that modern loading and unloading techniques
were developed long after the ships they are intended to load were built. The
need for speed may have compounded the problem in some cases. An article in the
August 1995 edition of the BIMCO Bulletin, the magazine of the Baltic and
International Maritime Council, observed that, “there has been a growing body of
evidence that terminals, which were often owned by the cargo owners or
charterers of the ship, were putting pressure upon the ships to amend their
loading plans or to load cargo to suit them, with little consideration about the
overall safety of the ship.”
A question of attitude
The idea that commercial considerations could threaten safety has been noted by other sectors of the shipping industry. A study by Lloyd’s Register discovered that “operational damage was accepted as the norm by the operators of bulkers and OBOs; second, there was little awareness as to the significance of this damage and its likely consequences on the capability of the ship under adverse operating conditions.” This might be put down to simple thoughtlessness, but that excuse cannot be made for shipowners who purposely move their vessels from one trade to another - to escape increasingly vigilant port State control inspections. That is what happened when Australia, alarmed by a number of accidents involving elderly bulk carriers visiting its ports, tightened its port control procedures.
The result was a rapid switch of tonnage from the Pacific to the Atlantic where inspections were apparently not as rigorous. According to Lloyd’s List “in the first nine months of 1989 there were nine voyages with Capesize vessels aged 20 years or more in the transAtlantic trades. In the corresponding 1993 period that figure had increased to 152.” It is difficult to avoid the conclusion that the owners of at least some of the ships concerned moved them because they knew that the ships were in such bad condition that they would not be allowed to operate in Australia - or even leave port - without being repaired. The owners were presumably quite content to allow the crews to risk their lives on ships which they knew were unseaworthy.
It is not surprising in the circumstances that, when Lloyd’s Register of Shipping began to investigate bulk carrier losses in 1991 it found that “one of the biggest problems facing LR ...is the general attitude of the industry. It is thought by some in the industry that cracking in these structures is inevitable due to the harsh nature of the cargoes and the rigorous operational procedures throughout their service life.”
High tensile steel
Most of the concern about the condition of bulk carriers has focused on old ships, especially those aged more than 20 years. But young ships are not immune to neglect and corrosion and there is also evidence that changes in the steel used on some relatively young bulk carriers could present even more serious problems than those experienced by earlier designs.
The majority of ships operating today are built of mild steel. But since the early-1980s increasing use has been made of high-tensile (HT) steel, especially in the construction of bulk carriers. HT steel has been used in shipbuilding since 1907 but its recent popularity is due to the fact that plates can be thinner without losing any strength. Whereas a normal side plate will be 24-29mm thick, this can be reduced to 20mm by using HT steel. The weight saving - which might amount to several thousand tons - cuts building costs and also enables the ship to carry more cargo. However, for these savings a price has to be paid. One is the simple fact that HT steel corrodes just as quickly as mild steel. Since HT plates are thinner than those of mild steel, corrosion is likely to reach the danger point more quickly. A second problem is that HTS-built ships are more prone to structural problems caused by the way in which load is transmitted through the ships’ structural components and the inter-dependency of the structural response.
IACS observed that the most common example where failure had occurred on HTS-built bulk carriers was at side longitudinal connections to web frames. According to Lloyd’s September 1995 Shipping Economist, HTS-built ships are also prone to a phenomenon known as “springing”: because the ships are flexible and tend to vibrate with short sea waves. The article stated that “classification society rules have always been based on empirical evidence from previous generations of ships, but the increased use of HTS changed the characteristics of vessels and therefore represented a step into the unknown.”
It is clear
from the above that HTS ships need at least as much care and maintenance as
those build of mild steel, especially as they too are frequently subject to
greater stresses in cargo loading and unloading than was originally envisaged.
Many shipping experts believe that whereas mild steel bulk carriers usually
begin to experience major problems at the age of 20, those built of HTS will do
so much earlier. Since most of those built in the early 1980s are already in
their late-teens, the danger is that there could be another rise in bulk carrier
casualties, unless action is taken to prevent it.
Measures to improve bulk carrier safety
The sudden increase in bulk carrier losses in 1990 and 1991 caused considerable alarm in the shipping industry. In response, the IMO Assembly adopted Resolution A.713(17) (“Safety of Ships Carrying Solid Bulk Cargoes”) which contains interim measures designed to improve the safety of ships carrying solid bulk cargoes. The preamble expressed concern at the continuing loss of bulk cargo carriers and the heavy loss of life incurred. The resolution noted that the nature of cargo and ballast operations can subject bulk carriers to severe patterns of bending and sheer forces and also to significant wear. It referred to the dangers posed by some bulk cargoes through their high density and tendency to shift.
The importance of not overstressing the ship’s structure during cargo operations was emphasized and governments were advised to pay particular attention to the structural integrity and seaworthiness of ships when port State control procedures are carried out under SOLAS.
Shipowners were encouraged to fit vessels with equipment to monitor the stresses on the ship’s structure during the voyage and during cargo operations. They were also encouraged to install equipment required by the Global Maritime Distress and Safety System (GMDSS), which entered into force on 1 February 1992 but which did not become mandatory for most existing ships until 1999.
of this resolution and action initiated by major classification societies was
immediately beneficial. The number of bulk carrier losses dropped to just two
within the next year. What is most significant about this improvement is that
the resolution did not introduce any new measures but simply stressed the
importance of implementing existing standards. From this it is possible to
conclude that at least some of the casualties that occurred in 1990 and 1991
were due not to defects in the regulations covering bulk carrier safety but to
the ineffective way in which they were implemented.
Poor implementation of regulations is a problem that concerns all forms of shipping and is one that IMO has been treating with even greater urgency. Successful implementation depends upon a number of factors, but to be really effective it requires everybody involved doing their job efficiently and with the necessary commitment and dedication.
Those involved in implementation are:
flag States - the Governments which have ratified conventions and thereby promised to put them into force
port States - which have authority under conventions to check that foreign ships visiting their ports comply with IMO requirements
shipowners - who own the ships and have the greatest responsibility - and opportunity - for ensuring that they are maintained in good condition.
seafarers - whose training and skill are vital to shipping safety and who stand to suffer most if something goes wrong.
Actions taken by IMO to improve implementation have been particularly important such as:
established a Sub-Committee on Flag State Implementation, which spotlights some of the problems Governments have in enforcing IMO conventions and provides guidance in overcoming them;
encouraged the establishment of regional port State control systems. Regional systems are especially useful in improving port State control because ships normally visit more than one country in a particular region. Regional co-operation in inspecting and surveying ships ensures that few sub-standard ships avoid the net - and that ships in good condition are not inspected unnecessarily;
adopted guidelines on management for the safe operation of ships and for pollution prevention. These were replaced by an International Safety Management Code (ISM Code) which became mandatory in 1998 through a new chapter IX of SOLAS; and complete revision of the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW) in 1995 which became effective in February 1997. The Convention introduces strict new controls which will enable IMO to validate the training and certification procedures of Parties to the Convention.
IMO's Sub-committee on Ship Design and Equipment (DE) began work on measures to do with constructional safety, especially the hull integrity of large ships and installation of a monitoring system that would provide information to the master of the ship while the ship was under way and during loading and unloading operations. Such a system might prevent the accident from happening in the first place. The recommendation was subsequently issued as MSC/Circ.646. The Circular contains guidance on the fitting of hull stress monitoring systems (HTMS) and recommends that they be fitted to bulk carriers of 20,000 dwt and above. Governments were asked to provide IMO with information on experience gained.
Sub-Committee also considered ways of combating corrosion of seawater ballast
tanks, a problem shared by both bulk carriers and oil tankers. It included the
regulation 14-1 in Chapter II-1 of SOLAS, which requires all dedicated seawater
ballast tanks to be provided with an efficient corrosion prevention system, and
the relevant guidelines. These guidelines were adopted by the IMO Assembly in
1995 by resolution A.798(19). The regulation itself was included in amendments
to SOLAS adopted by the 66th session of the MSC in 1995 which entered into force
in 1998, and was
replaced by regulation II-1/3-2, applying to oil tankers and bulk carriers
constructed on or after 1 July 1998.
Enhanced inspections during surveys
Resolution A.713(17) emphasized the importance of regular inspections of bulk carriers, especially of older ships, and in 1993 guidelines on an enhanced programme of inspections during surveys of bulk carriers and oil tankers were adopted by the 18th Assembly by resolution A.744(18). It was originally intended that the guidelines would apply to tankers but because of concern about the loss of bulk carriers they were extended to them as well. The guidelines were regarded as so important to safety that amendments to SOLAS to make them mandatory were adopted in May 1994 and entered into force on 1 January 1996.
The guidelines apply to existing tankers and bulk carriers of five years of age and over which means that the vast majority of the world tankers and bulk carriers are affected. The enhanced surveys must be carried out during the periodical, intermediate and annual surveys prescribed by the SOLAS Convention. The guidelines pay special attention to corrosion. Coatings and tank corrosion prevention systems must be thoroughly checked and measurements must also be carried out to check the thickness of plates. These measurements become more extensive as the ship ages. The guidelines go into considerable detail to explain the extra checks that should be carried out during enhanced surveys. One section deals with preparations for surveys and another with the documentation which should be kept on board each ship and be readily available to surveyors. This should record full reports of all surveys carried out on the ship.
Annexes to the guidelines go into still more detail and are intended to assist implementation. They specify the structural members that should be examined, for example, in areas of extensive corrosion; outline procedures for certification of companies engaged in thickness measurement of hull structures; recommend procedures for thickness measurements and close-up surveys; and give guidance on preparing the documentation required.
Guidance on planning the enhanced programme of inspections was adopted by the MSC in May 1994 and issued by means of MSC/Circ.655.
The guidelines were
amended on several occasions and now also include provisions for double hull oil
IMO's Sub-Committee on Dangerous Goods, Solid Cargoes and Containers (DSC) considered ways of improving the safety of loading and unloading operations. One aim was to amend Chapter VI of SOLAS so that ship masters would be provided with sufficient information on cargoes to be able to assess stress limitations. A questionnaire, issued as MSC/Circ.611 deals with the loading and unloading of bulk cargoes based on a model plan prepared by the Nautical Institute and the International Federation of Shipmasters’ Associations (IFSMA). Other organizations were also working to improve bulk carrier safety, including the leading classification societies, most of whom are members of the International Association of Classification Societies (IACS).
circulars were issued in December 1994. MSC/Circ. 665 is concerned with the
duties of Chief Mate and Officer of the Watch at bulk cargo loading and
discharge ports. It contains checklists which are designed to ensure that
loading and unloading is carried out safely. The circular was superseded in
June 1995 by MSC/Circ. 690, which contains an improved model ship/shore safety
checklist. MSC/Circ. 666 contains a cargo operation form, which is intended to
ensure proper planning and calculation prior to the commencement of cargo
operations. MSC/Circ. 667 contains general advice on bulk carrier safety. It
stresses, for example, the importance of reducing corrosion within holds and
ballast tanks by maintaining paint coatings and gives guidance on where
corrosion is most likely to occur.
The 1997 SOLAS Conference
A new chapter XII to SOLAS - Additional Safety Measures for Bulk Carriers, adopted by the November 1997 SOLAS Conference entered into force on 1 July 1999. It covers survivability and structural requirements to prevent bulk carriers from sinking if water enters the ship for any reason. Existing ships which do not comply with the appropriate requirements will have to be reinforced - or they may have to limit either the loading pattern of the cargoes they carry or move to carrying lighter cargoes, such as grain or timber.
The regulations stipulate that all new bulk carriers 150 metres or more in length (built after 1 July 1999) carrying cargoes with a density of 1,000 kg/m3 and above should have sufficient strength to withstand flooding of any one cargo hold, taking into account dynamic effects resulting from presence of water in the hold and taking into account recommendations adopted by IMO.
For existing ships (built before 1 July 1999) carrying bulk cargoes with a density of 1,780 kg/m3 and above, the transverse watertight bulkhead between the two foremost cargo holds and the double bottom of the foremost cargo hold should have sufficient strength to withstand flooding and the related dynamic effects in the foremost cargo hold.
Cargoes with a density of 1,780 kg/m3 and above include iron ore, pig iron, steel, bauxite and cement. Less dense cargoes, but with a density of more than 1,000 kg/m3, include grains such as wheat and rice, and timber.
Chapter XII allows surveyors to take into account restrictions on the cargo carried when considering the need for, and the extent of, strengthening of the transverse watertight bulkhead or double bottom. When restrictions on cargoes are imposed, the bulk carrier should be permanently marked with a solid triangle on its side shell. The date of application of Chapter XII to existing bulk carriers depends on their age. Bulk carriers which are 20 years old and over on 1 July 1999 have to comply by the date of the first intermediate or periodical survey after that date, whichever is sooner. Bulk carriers aged 15-20 years must comply by the first periodical survey after 1 July 1999, but not later than 1 July 2002. Bulk carriers less than 15 years old must comply by the date of the first periodical survey after the ship reaches 15 years of age, but not later than the date on which the ship reaches 17 years of age.
The SOLAS Conference also adopted a number of Resolutions, including:
Recommendation on Compliance with SOLAS Regulation XII/5.
The Resolution refers to the new requirement for bulk carriers built on or after 1 July 1999 and notes Unified Requirements issued by IACS regarding longitudinal strength, evaluation of scantlings and evaluation of allowable hold loading for single side-skin bulk carriers. The Resolution urges Governments to ensure that all bulk carriers of single side-skin construction, whether or not they are classed with classification societies which are members of IACS, to comply with the IACS Unified Requirements.
Standards for the evaluation of scantlings of the bulkhead between the two foremost cargo holds and standards for the evaluation of allowable hold loading of the foremost cargo hold. The Resolution sets out the standards, which are mandatory under Regulation 6 of the new Chapter XII. The technical standards provide formulae for calculating when steel renewal is necessary on scantlings, and for calculating the allowable hold for a bulk carrier, taking into account loads and the shear capacity of the double bottom.
Recommendation on loading instruments.
The Resolution urges Governments to apply IACS Recommendation No. 48 on loading instruments when approving loading instruments as required by Regulation 11 of the new Chapter XII, and to ensure that loading instruments already fitted have been approved in accordance with the standards of recognized organizations.
Interpretation of the definition of “bulk carrier” as given in Chapter IX of SOLAS 1974, as amended in 1994.
The Resolution is aimed at clarifying the definition of “bulk carrier” in Chapter IX of SOLAS, which makes mandatory the application of the International Safety Management (ISM) Code.
Enhanced surveys carried out prior to entry into force of the amendments.
The Resolution allows Governments to permit bulk carriers to carry heavy cargoes (with a density above 1,780 kg/m3) if they have been subject to an enhanced survey in compliance with SOLAS regulation XI/2 before 1 January 1996.
Further work on the safety of bulk carriers.
The Resolution calls on the Maritime Safety Committee of IMO, as a matter of urgency, to consider further the safety of bulk carriers not already covered by the new Chapter XII (for example, those under 150 metres in length) and to develop a definition of single side-skin construction for bulk carriers.
Implementation of the International Safety Management (ISM) Code.
The Resolution notes that a significant number of shipping companies operating bulk carriers have not yet obtained ISM certification, according to information received by IMO, and urges Governments to redouble efforts to ensure timely and effective implementation of the ISM Code on bulk carriers.
Chapter XII to SOLAS on the safety of bulk carriers represented the culmination
of a lengthy process involving Governments, shipowners and classification
societies in looking at all aspects of bulk carriers, from operational issues to
their design and structure.
The IMO Assembly also considered the questions of bulk carrier safety and adopted two important resolutions, namely:
A.862(20) Code of Practice for the Safe Loading and Unloading of Bulk Carriers. The Code of Practice, referred to as the BLU code, notes that a number of accidents involving bulk carriers have occurred as a result of inadequate loading and unloading and that safe practices could prevent such accidents in future. The Code contains recommendations to shipowners, masters, shippers, and operators of bulk carriers, charterers and terminal operators for the safe handling, loading and unloading of solid bulk cargoes. It includes a Ship/Shore Safety Checklist to help ship and terminal personnel recognize potential problems by taking both parties step by step through procedures and requirements, from confirming whether the depth of water at the berth is adequate to checking whether the terminal has been advised of the time required for the ship to prepare for sea on completion of cargo work.
A.866(20) Guidance to ships’ crews and terminal personnel for bulk carrier
The Resolution highlights the principal areas on bulk carriers that are likely to be susceptible to corrosion or damage, in the form of a simple guide aimed at ships’ crew and terminal operators. The Guidance notes that severe structural damage may occur to bulk carriers due to loading/unloading operations, including major damage, which could endanger the ship’s safety, or minor cracks which could develop into serious defects prior to the ship’s next scheduled Enhanced Survey. The Guidance therefore recommends that terminal operators and members of the ship’s crew themselves regularly inspect cargo holds, ballast tanks and hatch covers to detect damage and defects at an early stage.
Formal Safety Assessment
Following the publication of the report on the 1980 sinking of the bulk carrier Derbyshire in the South China Sea with the loss of all on board, a formal safety assessment (FSA) study of bulk carriers by the United Kingdom to aid future IMO decision-making on bulk carrier safety.
FSA is a process for assessing the risks associated with any sphere of activity, and for evaluating the costs and benefits of different options for reducing those risks. It therefore enables, in its potential application to the rule making process, an objective assessment to be made of the need for, and content of, safety regulations. The FSA consists of five steps: identification of hazards (a list of all relevant accident scenarios with potential causes and outcomes); assessment of risks (evaluation of risk factors); risk control options (devising regulatory measures to control and reduce the identified risks); cost benefit assessment (determining cost effectiveness of each risk control option); and recommendations for decision-making (information about the hazards, their associated risks and the cost effectiveness of alternative risk control options is provided).
More information on FSA on the IMO website
SOLAS Chapter XII - Additional Safety Measures for Bulk Carriers
The new chapter XII to SOLAS was adopted by a conference held in November 1997 and it entered into force on : 1 July 1999.
The Conference adopted a new Chapter XII to the Convention entitled Additional Safety Measures for Bulk Carriers.
The regulations state that all new bulk carriers 150 metres or more in length (built after 1 July 1999) carrying cargoes with a density of 1,000 kg/m3 and above should have sufficient strength to withstand flooding of any one cargo hold, taking into account dynamic effects resulting from presence of water in the hold and taking into account the recommendations adopted by IMO.
For existing ships (built before 1 July 1999) carrying bulk cargoes with a density of 1,780 kg/m3 and above, the transverse watertight bulkhead between the two foremost cargo holds and the double bottom of the foremost cargo hold should have sufficient strength to withstand flooding and the related dynamic effects in the foremost cargo hold.
Cargoes with a density of 1,780 kg/m3 and above (heavy cargoes) include iron ore, pig iron, steel, bauxite and cement. Lighter cargoes, but with a density of more than 1,000 kg/m3, include grains such as wheat and rice, and timber.
The amendments take into account a study into bulk carrier survivability carried out by the International Association of Classification Societies (IACS) at the request of IMO. IACS found that if a ship is flooded in the forward hold, the bulkhead between the two foremost holds may not be able to withstand the pressure that results from the sloshing mixture of cargo and water, especially if the ship is loaded in alternate holds with high density cargoes (such as iron ore). If the bulkhead between one hold and the next collapses, progressive flooding could rapidly occur throughout the length of the ship and the vessel would sink in a matter of minutes.
IACS concluded that the most vulnerable areas are the bulkhead between numbers one and two holds at the forward end of the vessel and the double bottom of the ship at this location. During special surveys of ships, particular attention should be paid to these areas and, where necessary, reinforcements should be carried out.
The criteria and formulae used to assess whether a ship currently meets the new requirements, for example in terms of the thickness of the steel used for bulkhead structures, or whether reinforcement is necessary, are laid out in IMO standards adopted by the 1997 Conference.
Under Chapter XII, surveyors can take into account restrictions on the cargo carried in considering the need for, and the extent of, strengthening of the transverse watertight bulkhead or double bottom. When restrictions on cargoes are imposed, the bulk carrier should be permanently marked with a solid triangle on its side shell. The date of application of the new Chapter to existing bulk carriers depends on their age. Bulk carriers which are 20 years old and over on 1 July 1999 have to comply by the date of the first intermediate or periodic survey after that date, whichever is sooner. Bulk carriers aged 15-20 years must comply by the first periodical survey after 1 July 1999, but not later than 1 July 2002. Bulk carriers less than 15 years old must comply by the date of the first periodical survey after the ship reaches 15 years of age, but not later than the date on which the ship reaches 17 years of age.
2002 SOLAS amendments relating to bulk carrier safety
The MSC at its 76th session in December 2002 adopted amendments to chapter XII (Additional Safety Measures for Bulk Carriers) of the International Convention for the Safety of Life at Sea (SOLAS), 1974, as amended to require the fitting of high level alarms and level monitoring systems on all bulk carriers, in order to detect water ingress.
The recommendation for the fitting of such alarms was first highlighted during the meeting of the Working Group on Bulk Carrier Safety held during the MSC's 74th session in December 2001, following on from recommendations of the United Kingdom Report of the re-opened formal investigation into the loss of the Derbyshire.
The new regulation XII/12 on Hold, ballast and dry space water level detectors will require the fitting of such alarms on all bulk carriers regardless of their date of construction. The requirement is expected to enter into force on 1 July 2004, under the tacit acceptance procedure.
In addition, a new regulation XII/13 on Availability of pumping systems would require the means for draining and pumping dry space bilges and ballast tanks any part of which is located forward of the collision bulkhead to be capable of being brought into operation from a readily accessible enclosed space.
A further regulation affecting bulk carriers was also adopted: Access to spaces in cargo areas of oil tankers and bulk carriers. The new regulation II-1/3-6 in SOLAS chapter II-1 (Construction - structure, subdivision and stability, machinery and electrical installations), Part B (Subdivision and stability), is intended to ensure that vessels can be properly inspected throughout their lifespan, by designing and building the ship to provide suitable means for access. Associated Technical provisions for means of access for inspections, also adopted, are mandatory under the new regulation.
December 2004 - revised SOLAS chapter XII adopted
The MSC at its 79th session in December 2004 adopted a new text for SOLAS chapter XII (Additional safety measures for bulk carriers), incorporating revisions to some regulations and new requirements relating to double-side skin bulk carriers. The amendments are expected to enter into force on 1 July 2006.
The amendments include the addition of a new regulation 14 on restrictions from sailing with any hold empty and requirements for double-side skin construction as an optional alternative to single-side skin construction. The option of double-side skin construction will apply to new bulk carriers of 150m in length and over, carrying solid bulk cargoes having a density of 1,000 kg/m3 and above.
The MSC also adopted standards and criteria for side structures of bulk carriers of single-side skin construction and standards for owners' inspections and maintenance of bulk carrier hatch covers.
Free-fall lifeboats on bulk carriers
The MSC at its 79th session in December 2004 also adopted an amendment to regulation 31 in SOLAS chapter III (Life-saving appliances and arrangements) to make mandatory the carriage of free-fall lifeboats on bulk carriers.
Information resources on bulk carrier safety
UK study Formal Safety Assessment study on bulk carrier safety
Focus on IMO - IMO and the safety of bulk carriers -
This paper reviews the specific safety issues relating to bulk carriers and the background to the adoption of SOLAS chapter XII.
Bulk carrier graphic
Code, 1998 Edition
CODE OF PRACTICE FOR THE SAFE LOADING AND UNLOADING OF BULK CARRIERS (BLU CODE), 1998 Edition
Being concerned about the continued loss of ships carrying solid bulk cargoes, sometimes without a trace, and the heavy loss of life incurred, and recognizing that a number of accidents have occurred as a result of improper loading and unloading of bulk carriers, the Sub-Committee on Dangerous Goods, Solid Cargoes and Containers (DSC) at its first session (February 1996) developed a draft code of practice for the safe loading and unloading of bulk carriers, with the aim of preventing such accidents.
The resulting Code of Practice for the Safe Loading and Unloading of Bulk Carriers (BLU Code) was approved by the MSC at its 68th session (June 1997) and adopted by the Assembly at its 20th session (November 1997) by resolution A.862(20).
The BLU Code, which provides guidance to masters of bulk carriers, terminal operators and other parties concerned with the safe handling, loading and unloading of solid bulk cargoes, is also linked to regulation VI/7 of the 1974 SOLAS Convention, as amended by resolution MSC.47(66).
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Website: International Maritime Organisation (IMO)