Inert Gas requirements - · PDF fileInert Gas requirements A summary of the current...

Inert Gas requirements

A summary of the current requirements

INTERTANKO Tanker Event at Istanbul 2008Otto Nyquist, Det Norske Veritas (MTPNO880)2008-04-21

© Det Norske Veritas AS. All rights reserved Slide 222 April 2008

Are the present IG requirements complicated?

Above table gives DNV’s understanding of present IG requirements in SOLAS


Why do we have IG requirements?

T/T ”KONG HAAKON VII”


Keep in mind:

IG requirements relate only to low flash-point cargoes

IG requirements are given in 2 different statutory instruments:

Chem Code

SOLAS


Chem Code IG requirements

Applies when ”Inert” is given in Ch. 17 column ”h” of the IBC Chem Code

Applies for this product irrespectively of ship age, ship size, tank size, etc.

Operational requirement only; (no specific technical requirements are given):

- Pre-purging with IG supplied from shore before loading is OK- Bottles with N2 for topping up during voyage- Supply from shore during unloading, (if required)

IG used is normally N2


SOLAS IG requirements

Requirements given in Ch. II-2 Reg. 4, item 5.5

Applicable to tankers of 20 000 DWT and above

Full cycle required:- Pre-purging- Topping up during voyage- Filling during unloading- Topping up during tank cleaning- Purging until less than 2% hydrocarbons

Both detailed equipment requirements and detailed operational requirements



The requirements are given in SOLAS Ch. II-2 Reg. 4, item 5.5 with detail requirements in:

- FSS Code- MSC Circulars- Res. A 567(14) (modified requirements for tankers holding Chem Code

Certificate of Fitness)- IACS UR F20

Oil tankers:- must have IG capacity not less than 125% of unloading rate- must have deck water seal

Tankers with Chem Code CoF:- must limit the unloading rate to max 80% of IG capacity- may have double block-and-bleed arrangement in lieu of deck water seal



Historical development

Original SOLAS 74 text included IG requirements for oil tankers above 100 000 DWT and combination carriers above 50 000 DWT

TSPP 78 SOLAS Protocol requires IG for “new” oil tankers on or above 20 000 DWT and gives time scheme for upgrading “existing” tankers above on or above 20 000 DWT

SOLAS 81-Amendments make reference to Res. A 473(XII) with some relaxations for combined oil/chemical tankers when carrying oil cargoes;(IG not required for low-flash chemicals)

SOLAS 83-Amendments make IBC Code mandatory under SOLAS(IG still not required for chemicals)



Historical development (continued)

SOLAS 89-Amendments clarified that:- Chemical tankers keel-laid before 1986-07-01 need not use IG for Ch. 17 and

Ch. 18 products- Chemical tankers keel-laid on or after 1986-07-01 must use IG for low FP Ch.

17 and 18 products- when tanks are 3 000 m3 or above or- when tank cleaning machines exceed 17.5 m3/h pr. nozzle or 110 m3/h

totally



Background for present requirements

Tank size limitations because water washing in larger tanks was taken to cause possibility for electrostatic charges causing ignition

Relaxations for chemicals because gas from IG generator will cause contamination of cargo; (N2 generators not available when the requirements were established)


DNV understanding of SOLAS IG requirements


http://www.dnv.com/

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