5 Regulations of Annex I:
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Statutory Documents - IMO Publications and Documents - Circulars - Marine Environment Protection Committee - MEPC/Circular.167 – Carriage of High Vapour Pressure Oil Products in Gas Carriers – (Adopted on 3 June 1986)Submitted by Norway - Notification of Equivalency - 5 Regulations of Annex I:

5 Regulations of Annex I:

  Regulation 13 — Segregated Ballast Tanks, Dedicated Clean Ballast Tanks and Crude Oil Washing.

 Since Regulation 13(1) has been developed for oil tankers and gas carriers have performed satisfactorily with the present segregated ballast capacity standards, this Regulation will not be formally applied to gas carriers.

  Regulation 13E — Protective Location of Segregated Ballast Spaces.

The vessels will be required to comply.

Regulations 15 — Retention of Oil onboard

As water cleaning and ballasting of cargo tanks are prohibited, this Regulation is not applicable. No arrangements for supply of water to cargo tanks will be accepted.

Regulation 18 — Pumping, Piping and Discharge Arrangements of Oil Tankers

This regulation is not applicable.

Regulation 20 — Oil Record Book

The Oil Record Book requirements for oil tankers will be applied.

Regulation 22 — Damage Assumptions

The vessels will be required to comply.

Regulation 23 — Hypothetical Outflow of Oil

The vessels will be required to comply.

Regulation 24 — Limitation of Size and Arrangements of Cargo Tanks

Paragraphs (2) and (3) will be fully applied as required by paragraph (1).

The different sectional arrangements listed in paragraph 4 only deal with typical oil tanker arrangements. Accordingly, these formulas are not considered applicable for gas carriers with independent tanks. Length of cargo tanks will be limited because of the requirements in Regulation 25. Although there is no possibility of referring to any actual calculation, it is assumed that the maximum length will not exceed 0.2 x L to any considerable degree. Furthermore, the Norwegian Administration refers to Det norske Veritas Report No. 83-0402 "Assessment of the risk for outflow of cargo in the event of collisions and groundings — comparison of gas carriers and oil tankers” dated 21 April 1983 (copies were made available during the nineteenth session of MEPC) containing:

  • .1 available statistical data regarding cargo outflow resulting from penetration of cargo tanks of oil tankers and gas carriers;

and

  • .2 a comparison of oil tankers and LPG tankers regarding critical speeds for penetration of cargo tanks.

 This report was produced at the request of the Norwegian Maritime Directorate.

  • "Item 6. Discussions and conclusions:

    The statistical data for oil tankers (Table 1) indicate that 15 to 30 per cent of all collisions, groundings and similar events result in hull penetrations in the cargo area with outflow of cargo.

 For a larger oil tanker (Table 2) the percentage of hull penetrations is lower, around 15 per cent. For gas carriers the statistical data (Table 3 and 4) show that of a total number of 57 accidents none has resulted in penetration of the cargo tanks.

Of course one should not draw too firm conclusions from such statistical data, but the difference is so significant it must be concluded that the risk of penetrating the cargo tank of a conventional oil tanker in the event of a collision or grounding is much higher than that of a gas carrier. The main reason for this difference is assumed to be the inherent difference in design of the two categories of vessels, in particular the fact that the cargo tanks in gas carriers are separate. This assumption is clearly supported by calculations carried out for two LPG-carriers and for conventional tankers of corresponding displacements for determining the required minimum speed of a striking vessel at which penetration of cargo tanks occurs. The results (summarized in Table 6) show a factor in the range of 2 to 3 in favour of the LPG-carriers.

According to the requirements of MARPOL 73/78 new crude oil tankers above 20,000 DWT and product carriers above 30,000 DWT should have segregated ballast tanks protectively located, i.e. a portion of the bottom and side area of the cargo tank is to be shielded by these tanks. The protected portion should be a minimum of 45 per cent for tankers of 20,000 DWT, decreasing proportionally to 30 per cent for tankers of 200,000 DWT and above.

This will to some extent reduce the advantage of the LPG-vessels with regard to risk of penetration of cargo tanks. The above indicated figure of 15 per cent probability of penetrating the cargo tanks of an oil-tanker in the event of collision/grounding will hence be reduced, and a figure at around 10 per cent may be anticipated.

However, LPG-carriers will still have a very significant advantage over oil tankers with respect to risk of cargo outflow due to penetration of cargo tanks.

It is therefore concluded that although compliance with Regulation 24(4) is not required equivalence is achieved from a pollution point of view.”

Regulation 25 — Subdivision and Stability

The vessels will be required to comply.

Parent topic: Notification of Equivalency
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