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Construction Requirements for Oil Tankers


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 19 in Annex I of MARPOL).
 
The requirement for double hulls that applies to new tankers has also been applied to existing ships under a programme that began in 1995 (under old regulation 13G (now regulation 20 in Annex I of MARPOL).  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). The revised requirements set out a stricter timetable for the phasing-out of single-hull tankers.
 
In December 2003, further revisions to the requirements 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.
 

Single-hull oil tanker phase out

 
What happened on 5 April 2005?

On 5 April 2005, amendments to Annex I of MARPOL, adopted by IMO's Marine Environment Protection Committee (MEPC) by resolution MEPC.111(50) in December 2003, entered into force for all Parties to the MARPOL Convention.
 
How many flag States does this affect?

To date, MARPOL (Annexes I and II) has been ratified by 150 countries representing over 99 per cent of world merchant shipping tonnage. See status of Conventions
 
What are the amendments exactly?

The amendments revised the existing regulation 13G (now regulation 20) on Prevention of accidental oil pollution - Measures for existing oil tankers of Annex I of MARPOL  and added a new regulation 13H (now regulation 21) on Prevention of oil pollution from oil tankers carrying heavy grade oil as cargo. Consequential amendments to the Condition Assessment Scheme (CAS) for oil tankers were also adopted.
 
What does regulation 20 say?

The revised regulation brought forward the phase-out schedule that was first established in 1992, and revised in 2001 for existing single-hull tankers. It says that tankers which are single hull should be phased out or converted to a "double hull" by the dates set out in the revised regulation.
 
Can any single hull tankers operate beyond the dates set?

Regulation 20 allows the Administration (flag State) to permit continued operation of category 2 or 3 tankers beyond its phase-out date in accordance with the schedule 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 tankers fitted with 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 its phase-out date in accordance with the schedule, 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.
 
A Party to MARPOL can deny entry of single hull tankers which have been allowed to continue operation under the exemptions mentioned above, into the ports or offshore terminals under its jurisdiction.
 
Which Administrations have communicated information on their implementation of the regulations?
 
Parties to MARPOL applying the provisions allowing for extended operation of category 2 or 3 tankers and Parties which will deny entry to those tankers must communicate this information to IMO. Please see circulars under the section oil tankers – regulations 20/21 implementation.
 
What about tankers which have been converted, how do you determine the date of delivery?
 
IMO's MEPC, at its 52nd session in October 2004, adopted a unified interpretation to regulation 13G(4) (now 20.4) of MARPOL Annex I on Major Conversion, which clarified the situation.
 
It states that "For the purpose of determining the application date for the requirements of regulation 13G(4) of MARPOL Annex I, where an oil tanker has undergone a major conversion, as defined in regulation 1 of MARPOL Annex I, that has resulted in the replacement of the fore-body, including the entire cargo carrying section, the major conversion completion date of the oil tanker shall be deemed to be the date of delivery of the ship referred to in regulation 13G(4) of MARPOL Annex I, provided that:

- the oil tanker conversion was completed before 6 July 1996;
 
-
the conversion included the replacement of the entire cargo section and fore-body and the tanker complies with all the relevant provisions of MARPOL Annex I applicable at the date of completion of the major conversion; and
-​ ​the original delivery date of the oil tanker will apply when considering the 15 years of age threshold relating to the first CAS survey to be completed in accordance with regulation 13G(6) of MARPOL Annex I.
 

Condition Assessment Scheme (CAS)

Under the regulation, the Condition Assessment Scheme (CAS) is applicable to all single-hull tankers of 15 years, or older.
 
The Regulation 20 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

MARPOL regulation 21 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 deadweight (DWT) and above after the date of entry into force of the regulation (5 April 2005), and in single-hull oil tankers of 600 DWT and above but less than 5,000 tons DWT, not later than the anniversary of their delivery date in 2008.
 
Under regulation 21, HGO means any of the following:
 
- crude oils having a density at 15ºC higher than 900 kg/m3;
 

-

oils, other than crude oils, having either a density at 15ºC higher than 900 kg/ m3 or a kinematic viscosity at 50ºC higher than 180 mm2/s; and
-​ ​bitumen, tar and their emulsions.

In the case of certain Category 2 or 3 tankers carrying HGO 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 tankers fitted with 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, under certain conditions, 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 21 also allows for continued operation of oil tankers of 5,000 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 DWT and above but less than 5,000 DWT, carrying HGO 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 may exempt an oil tanker of 600 DWT and above carrying HGO 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 HGO.
 
A Party to MARPOL can deny entry of single hull tankers carrying HGO 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.

 

Industry sources (external websites for which IMO is not responsible)

International Tanker Owners Pollution Federation Limited (ITOPF) www.itopf.com
International Association of Independent Tanker Owners (INTERTANKO) www.intertanko.com
International Chamber of Shipping www.marisec.org
Ship brokers and shipping consultancies - try www.wsdonline.com
 
Other NGOS

 
 

 

 

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