Tanker safety - preventing accidental pollution

IMO's major function is to make shipping of all types safer, including tankers.  The measures incorporated in the numerous safety conventions and recommendations apply to these as well as other ships - and the safer a ship is, the less likely it is to be involved in an accident.

In this section:
SOLAS
Inert gas systems
Equipment duplication
Mandatory towing arrangements
MARPOL 73/78  - Reducing the consequences of accidents
Protective location, segregated ballast tanks
Double hulls

Single-hull phase-out timetable
Condition Assessment Scheme (CAS)

Carriage of heavy grade oil

Revision of Annex I of MARPOL

Enhanced inspections
Mandatory ship reporting systems
COLREGS
STCW Convention
ISM Code
The Erika incident
The Prestige incident

Further information

SOLAS
The International Convention for the Safety of Life at Sea  (SOLAS), 1974 includes special requirements for tankers.  Fire safety provisions, for example, are much more stringent for tankers than ordinary dry cargo ships, since the danger of fire on board ships carrying oil and refined products is much greater.

Inert gas systems
It is not just fire which is dangerous - in certain circumstances a single spark can cause a disaster, for even tanks which contain no oil are filled with flammable gas which can explode unless proper procedures are followed.

The normal method is to fill these tanks with inert (non-explosive) gas from the ship's boiler flue: it is cleaned and then pumped into the empty tanks, or into the spaces left above the oil in loaded tanks.  An inert gas system is required on all new tankers and most existing tankers of 20,000 dwt and above.

Equipment duplication
IMO has introduced several measures over the years which are designed to ensure that, in the event of mechanical failure, the ship can still be controlled. SOLAS makes it necessary for essential parts of the steering gear of tankers to be duplicated.

As with other ships, much of the navigational equipment of tankers must also be duplicated.

Mandatory towing arrangements
Since 1 January 1996 all new tankers of 20,000 dwt and above have had to be fitted with an emergency towing arrangement fitted at either end of the ship. Existing ships had to be fitted with such an arrangement not later than 1 January 1999.

MARPOL 73/78  - Reducing the consequences of accidents
The International Convention for the Prevention of Pollution by Ships (MARPOL 73/78) includes regulations regarding subdivision and stability which are designed to ensure that, in any loading conditions, the ship can survive after being involved in a collision or stranding.

Protective location of segregated ballast tanks
The 1978 MARPOL Protocol introduced the concept known as protective location of segregated ballast tanks.  This means that the ballast tanks (which are empty on the cargo-carrying leg of the voyage and only loaded with water ballast for the return leg) are positioned where the impact of a collision or grounding is likely to be greatest.  In this way the amount of cargo spilled after such an accident will be greatly reduced.

The 1983 MARPOL amendments ban the carriage of oil in the forepeak tank - the ship's most vulnerable point in the event of a collision.

Double hulls
In 1992 MARPOL was amended to make it mandatory for tankers of 5,000 dwt and more ordered after 6 July 1993 to be fitted with double hulls, or an alternative design approved by IMO (Regulation 13F (regulation 19 in the revised Annex I which entered into force on 1 January 2007) in Annex I of MARPOL 73/78). 

The requirement for double hulls that applies to new tankers has also been applied to existing ships under a programme that began in 1995 (Regulation 13G (regulation 20 in the revised Annex I which entered into force on 1 January 2007) in Annex I of MARPOL 73/78).  All tankers would have to be converted (or taken out of service) when they reached a certain age (up to 30 years old). This measure was adopted to be phased in over a number of years because shipyard capacity is limited and it would not be possible to convert all single hulled tankers to double hulls without causing immense disruption to world trade and industry.

Although the double hull requirement was adopted in 1992, following the Erika incident off the coast of France in December 1999, IMO Member States discussed proposals for accelerating the phase-out of single hull tankers. As a result, in April 2001, IMO adopted a revised phase-out schedule for single hull tankers, which entered into force on 1 September 2003 (the 2001 amendments to MARPOL 73/78). The new revised MARPOL regulation 13G set out a stricter timetable for the phasing-out of single-hull tankers.

In December 2003, further revisions to 13G (regulation 20 in the revised Annex I which entered into force on 1 January 2007) were made, accelerating further the phase-out schedule. These amendments entered into force on 5 April 2005. A new Regulation on the prevention of oil pollution from oil tankers when carrying heavy grade oil (HGO) banned the carriage of HGO in single-hull tankers of 5,000 tons dwt and above after the date of entry into force of the regulation (5 April 2005), and in single-hull oil tankers of 600 tons dwt and above but less than 5,000 tons dwt, not later than the anniversary of their delivery date in 2008.

Accelerated phase-out for single-hull tankers
Under the revised regulation 13G (regulation 20 in the revised Annex I which entered into force on 1 January 2007) of Annex I of MARPOL, the final phasing-out date for Category 1 tankers (pre-MARPOL tankers) was 2005. The final phasing-out date for category 2 and 3 tankers (MARPOL tankers and smaller tankers) was brought forward to 2010, from 2015.

The full timetable for the phasing out of single-hull tankers is as follows:

Condition Assessment Scheme (CAS)
Under the revised regulation, the Condition Assessment Scheme (CAS) is applicable to all single-hull tankers of 15 years, or older.

The revised regulation allows the Administration (flag State) to permit continued operation of category 2 or 3 tankers beyond 2010 subject to satisfactory results from the CAS, but the continued operation must not go beyond the anniversary of the date of delivery of the ship in 2015 or the date on which the ship reaches 25 years of age after the date of its delivery, whichever is earlier.

In the case of certain Category 2 or 3 oil tankers fitted with only double bottoms or double sides not used for the carriage of oil and extending to the entire cargo tank length or double hull spaces, not meeting the minimum distance protection requirements, which are not used for the carriage of oil and extend to the entire cargo tank length, the Administration may allow continued operation beyond 2010, provided that the ship was in service on 1 July 2001, the Administration is satisfied by verification of the official records that the ship complied with the conditions specified and that those conditions remain unchanged. Again, such continued operation must not go beyond the date on which the ship reaches 25 years of age after the date of its delivery.

Carriage of heavy grade oil
A new MARPOL regulation 13G (regulation 21 in the revised Annex I which entered into force on 1 January 2007) on the prevention of oil pollution from oil tankers when carrying heavy grade oil (HGO) bans the carriage of HGO in single-hull tankers of 5,000 tons dwt and above after the date of entry into force of the regulation (5 April 2005), and in single-hull oil tankers of 600 tons dwt and above but less than 5,000 tons dwt, not later than the anniversary of their delivery date in 2008.

Under the new regulation, HGO means any of the following:

In the case of certain Category 2 or 3 tankers carrying heavy grade oil as cargo, fitted only with double bottoms or double sides, not used for the carriage of oil and extending to the entire cargo tank length, or double hull spaces not meeting the minimum distance protection requirements which are not used for the carriage of oil and extend to the entire cargo tank length, the Administration may allow continued operation of such ships beyond 5 April 2005 until the date on which the ship reaches 25 years of age after the date of its delivery.

Regulation 13G (regulation 21 in the revised Annex I which entered into force on 1 January 2007) also allows for continued operation of oil tankers of 5,000 tons dwt and above, carrying crude oil with a density at 15ºC higher than 900 kg/ m3 but lower than 945 kg/ m3, if satisfactory results of the Condition Assessment Scheme warrant that, in the opinion of the Administration, the ship is fit to continue such operation, having regard to the size, age, operational area and structural conditions of the ship and provided that the continued operation shall not go beyond the date on which the ship reaches 25 years after the date of its delivery.

The Administration may allow continued operation of a single hull oil tanker of 600 tons deadweight and above but less than 5,000 tons deadweight, carrying heavy grade oil as cargo, if, in the opinion of the Administration, the ship is fit to continue such operation, having regard to the size, age, operational area and structural conditions of the ship, provided that the operation shall not go beyond the date on which the ship reaches 25 years after the date of its delivery.

The Administration of a Party to the present Convention may exempt an oil tanker of 600 tons deadweight and above carrying heavy grade oil as cargo if the ship is either engaged in voyages exclusively within an area under the Party's jurisdiction, or is engaged in voyages exclusively within an area under the jurisdiction of another Party, provided the Party within whose jurisdiction the ship will be operating agrees. The same applies to vessels operating as floating storage units of heavy grade oil.

A Party to MARPOL 73/78 shall be entitled to deny entry of single hull tankers carrying heavy grade oil which have been allowed to continue operation under the exemptions mentioned above, into the ports or offshore terminals under its jurisdiction, or deny ship-to-ship transfer of heavy grade oil in areas under its jurisdiction except when this is necessary for the purpose of securing the safety of a ship or saving life at sea.

Revision of Annex I of MARPOL

The revised MARPOL Annex I Regulations for the prevention of pollution by oil was adopted in October 2004 and entered into force on 1 January 2007. It incorporates the various amendments adopted since MARPOL entered into force in 1983, including the amended regulation 13G (regulation 20 in the revised Annex) and regulation 13H (regulation 21 in the revised annex) on the phasing-in of double hull requirements for oil tankers. It also separates, in different chapters, the construction and equipment provisions from the operational requirements and makes clear the distinctions between the requirements for new ships and those for existing ships. The revision provides a more user-friendly, simplified Annex I.

Following the entry into force, on 1 January 2007, of the Revised Annex I to MARPOL 73/78, references to regulations regaarding double hulls must be updated taking into account the new numbering system in the revised Annex I according to the following table:

For a comprehensive cross-reference table between "old" and "new" regulation numbers in MARPOL Annex I, please refer to MEPC/Circ.421 (also included in the Additional Information section of the 2006 consolidated edition of MARPOL (IMO sales No.IC520E))

Enhanced inspections
Since 1995 all tankers and bulk carriers aged five years and over have been subject to a specially enhanced inspection programme which is intended to ensure that any deficiencies - such as corrosion or wear and tear resulting from age or neglect - are detected.

Guidelines on enhanced surveys on tankers and bulk carriers are contained in Assembly resolution A. 744 (18), adopted in November 1993, as amended. 

Mandatory ship reporting
Since 1 January 1996, Governments have been able to propose to IMO the introduction of mandatory ship reporting systems in areas where there are special environmental or navigational concerns.

Mandatory reporting systems require ships to report in to shore authorities when they reach a designated routeing system and give the ship's name, cargo and other information. This enables the ship to be identified on radar and its course plotted throughout the system.

In December 2000, IMO adopted mandatory requirements for  the carriage of automatic identification systems (AISs) capable of providing information about the ship to other ships and to coastal authorities automatically. The regulation in SOLAS chapter V – Safety of Navigation, requires AIS to be fitted aboard all ships of 300 gross tonnage and upwards engaged on international voyages, cargo ships of 500 gross tonnage and upwards not engaged on international voyages and passenger ships irrespective of size built on or after 1 July 2002.

Existing tankers (those constructed before 1 July 2002), had to fit AIS not later than the first survey for safety equipment on or after 1 July 2003.

COLREGS
The International Regulations for the Prevention of Collisions at Sea, 1972 (COLREGS) contains special provisions for ships such as tankers which, by virtue of their draught, have a reduced ability to manoeuvre.

STCW Convention
The International Convention on Standards of Training, Certification and Watchkeeping for Seafarers, 1978, as amended in 1995 (STCW) includes several requirements aimed specifically at those working on tankers.

ISM Code
The International Safety Management (ISM) Code was adopted in 1994 and became mandatory for tankers in 1998. The ISM Code imposes strict standards on shipping companies.

The Erika incident
The sinking of the Erika off the coast of France in December 1999 led to a new, accelerated phase-out schedule for single-hull tankers - the revision of regulation 13G (regulation 20 in the revised Annex I which entered into force on 1 January 2007) of MARPOL 73/78.

The investigations into the Erika incident carried out by the French government and the Maltese maritime authority concluded that age, corrosion, insufficient maintenance and inadequate surveys were all strong contributing factors to the structural failure of the ship.

There was a wide consensus that the Erika and other the recent accidents involving oil tankers pointed to a need for additional international measures to eradicate substandard vessels, particularly substandard oil tankers given the catastrophic impact such ships may have on the marine environment in the case of an accident.

Besides the revised phase-out scheme for single-hull tankers, IMO also adopted other measures in response to the incident:

The Prestige incident
The Prestige incident of November 2002 led to further calls for amendments to the phase-out schedule for single hull tankers.

The MEPC at its 49th session in July 2003 agreed to an extra session of the Committee, to be convened in December 2003, to consider the adoption of proposals for an accelerated phase-out scheme for single hull tankers, along with other measures including an extended application of the Condition Assessment Scheme (CAS) for tankers.

Further Information
Please see latest summary reports of the Marine Environment Protection Committee (MEPC) and Maritime Safety Committee (MSC).

Information Resources on current topics

Information Resources on double hull/single hull ship design and related topics

Information Resources on the Prestige

Information Resources on the Erika incident and the revision of Regulation 13G (regulation 20 in the revised Annex I which entered into force on 1 January 2007) of MARPOL 73/78

Tanker safety - preventing accidental pollution

Responding to oil spills

MARPOL 73/78