probabilistic damage

LLOYD’S REGISTER EMEACopenhagen Design Support Centre

Presentation of Probabilistic Damage Stability regulations, New SPS Code and MARPOL Regulation 12A

Jens Peter Baltsersen, Senior Surveyor in Charge, Naval ArchitectHenrik Erichsen,Senior Surveyor, Naval Architect


Agenda

• Probabilistic Damage Stability – 45 minBy Jens Peter Baltsersen

• The Special Purpose Code (SPS) – 10 minBy Henrik Erichsen

• MARPOL Regulation 12A – 15 minBy Henrik Erichsen

• Questions / discussions - 5 min


Probabilistic Damage Stability Regulations


Probabilistic Damage Stability Regulations

What Does PROBABILISTIC Damage Stability Mean?

PROBABILISTIC = PROBABILITY!

Probability that a certain compartment in the ship is damaged!


Probabilistic Damage Stability Regulations Short Historical Review

Dry Cargo Ships:• 1992: Damage Stability regulations

for ships > 100 m• 1998: Damage Stability regulations

for ships between 80 m and 100 m included in theexisting regulations

Passenger Ships:• IMO Res. A265 – Probabilistic

Damage Stability regulation (1973)• SOLAS 90 / 98 - Deterministic

Damage Stability regulation• Stockholm Agreement (1998)

Water on Deck

HARMONIZATION!



• Harmonization started in the 1980ties by development of the probabilistic damage stability requirements for dry cargo ships

• Passenger ships should have been included in the probabilistic framework keeping the same level of safety

• 1992-1998: Harmonization process developing probabilistic damage stability regulations for both dry cargo ships and passenger ships

• 2001: EU Project HARDER• ”Back to basic”!• Damage Statistics• Model Tests• Verification• New designs using the new frame work

• 2005: The proposed damage stability regulations was adopted by MSC 20 May 2005 at the 80 session (Resolution MSC.194(80))

SLF42-3Proposal



1st January 2009The new probabilistic damage stability requirements

(revised SOLAS part B-1) will enter into force


Probabilistic Damage Stability RegulationsShort Historical Review


Probabilistic Damage Stability Regulations Requirements (revised SOLAS Part B-1)

Dry Cargo Ships (L>80 m):• Container Ships• RoRo Cargo ships• Car Carriers• General Cargo ships• Bulkcarriers having reduced

freeboard and deck cargo (IACS Unified interpretation no. 65)

• (Cable Laying Vessels)

All Passenger Ships:• Pure Passenger Ships• RoRo Passenger Ships• Cruise Vessels

Which ship types are covered?



• Offshore supply vessels (IMO Resolution MSC.235(82))• Special Purpose Ships (IMO Resolution A.534(13))*• Special Trade Passenger Ships ”Pilgrim Trade” (1971)• High Speed Crafts (HSC Code 2000)• Tankers (MARPOL 73/78)• Ships covered by Reg. 27 of the LL Convention• Ships Carrying Dangerous Chemicals in Bulk (IBC Code)• Ships Carrying Liquefied Gases in Bulk (ICG Code)

* SPS Code currently under revision and will be linked closely to the new SOLAS damage stability requirements

The following ship types are not affected:



A ≥ R

Damage Stability Concept:

Attained Subdivision IndexA = Σ pi si

Required Index R1. Cargo ships L > 100 m2. Cargo Ships L > 80 m (and

below 100 m)3. Passenger ships



Calculation now based on 3 draughts• Deepest Subdivision Draught ds

• Light Service Draught dl

• Partial Subdivision Draught dp

What have changed?

ds

dl

dp60%

Level trim

Level trimService trim

Mean draught dl

100%



Summation of attained index:

A = 0.4As + 0.4Ap + 0.2Al

Assuming that a ship will trade:40% of it’s time at the deepest subdivision draught40% of it’s time at the partial subdivision draught20% of it’s time at the lightest service draught

Minimum attained index on each draught:

Each of the partial indices As , Ap and Al are not to be less than 0.9R for passenger ships and 0.5R for cargo ships!



Trim: If the operational trim range of a vessel exceeds ±0,5% of Ls

then probabilistic damage stability calculations with trim should be supplied

Several GM limit Curves have to be presented !



Pi-factor: Probability that only the compartment or group of compartments under consideration may be flooded.

• The parameters used for the determination of pi have been changed in the revised regulations

• Maximum damage length changed from 48 m to 60 m• Damages of B/2 should be assumed (allowing penetration of

longitudinal centre line bulkheads)



Subdivision: There are no rules for the subdividing except that the length Ls defines the extremes for the actual hull. However, it is important to consider a strategy carefully to obtain a good result (large attained index A.)

Z 1

Z 1

Ls

Z4 Z 5 Z 6 Z 7 Z8 Z9 Z10 Z11Z3Z2

Z 2 Z 3



Subdivision:The figure illustrates the possible single and multiple zone damages in a ship with a watertight arrangement suitable for a seven-zone division. The triangles at the bottom line indicate single zone damages and the parallelograms indicate adjacent zones damages.

Ls

Max

dam

age

leng

th

Ls

Z 1 Z 4 Z 5 Z 6 Z 7Z3Z2



Penetration factor r:• Factor r is the probability that a longitudinal bulkhead will not be

breached by the damage. For each longitudinal bulkhead inside the ship’s side, an r-value will be calculated. The sum of all r-values from the shell to the B/2 limit equals unity

• Factor p will be adjusted with factor r to obtain the final joint factor p

Damages of B/2 is now assumed (allowing penetration of longitudinal centre line bulkheads)



Penetration factor r:

• By default, damages should extend to B/2• A limit before B/2 can, however, be set

B/2 line Not included in the index



Penetration factor r:

• Grey + Blue for a zone -> Σr = 1 (until B/2)• Blue for a zone not extending to B/2 -> Σr < 1

B/2 line Not included in the index



Factor v:• The factor v represents the probability that a watertight deck above the

waterline remains intact, or in other words, whether or not the bow of an arbitrary ramming ship will be higher than the deck in question.

The maximum vertical extent of damage above a given waterline have changed from 7 m to 12.5 m!



Factor v:Individual v-factors:• If H – d ≤ 0 → vi = 0• If H – d ≤ 7.8 → vi = 0.8(H - d) / 7.8• If 7.8 < H – d < 12.5 → vi = 0.8 + 0.2((H - d) - 7.8) / 4.7• If H - d ≥ 12.5 → vi = 1

Accumulated v-factors:• v = v1 + (v2 - v1) +…. + (1 - vn)



Survivability Factor si:The value of “si” represents the probability of survival after flooding the zone “i" under consideration, and includes the probability of any horizontal subdivision remaining effective.

Passenger ships:Si = minimum { Sintermediate,I or Sfinal,i·Smom,i }

Cargo ships:Si = Sfinal,i



Intermediate Stages of Flooding:• Sintermediate,i is the probability to survive all intermediate stages of flooding

until the final equilibrium stage• Only applicable to passenger ships!

Sintermediate,i =

Where GZmax is not to be taken as more than 0.05 m and Range as not more than 7°. Sintermediate,i = 0 if the intermediate heel exceeds 15°.

Where cross-flooding fittings are required, the time for equalization shall not exceed 10 min.

4/1max

705.0 ⎥⎦⎤

⎢⎣⎡ ⋅

RangeGZ



Heeling Moments:• Smom,i is the probability to survive heeling moments• Only applicable to passenger ships!

Smom,i = ≤ 1

The heeling moments Mheel is to be calculated as follows:

Mheel = maximum { Mpassenger or Mwind or Msurvivalcraft }

heelMntDisplacemeGZ ⋅− )04.0( max



Openings and evacuation routes:• It is very important to take into account all weathertight and unprotected

openings as they can have a large effect on the attained index!• The margin line definition is no longer in the regulations• Evacuation routes have been included instead

Si is to be taken as zero (no survivability) if:• The lower edge of unprotected or weathertight openings through which

progressive flooding may take place, immerses,• Any part of the bulkhead deck in passenger ship considered a horizontal

evacuation route or any vertical escape hatch will be immersed etc.• Immersion of control for operation of watertight doors, valves etc.



Minor Damages for Passenger Ships (Regulation 8):

In order not to capsize due to a very small damage, a minor damage concept for passenger ships have been introduced in the new regulations.

• Deterministic concept stating that a passenger ship have to survive a given damage extent.

• Damage extent depending on the number of passengers.• 2 compartment damages!



Double Bottom Damages (Regulation 9):

A double bottom shall be fitted extending from the collision bulkhead to the aft peak bulkhead.

Any part of a passenger ship or a cargo ship that is not fitted with a double bottom in accordance with the specifications given in Reg. 9 shall be capable of withstanding bottom damages as specified in the regulation 9, paragraph 8 in that part of the ship!



Permeability:

The permeability of a compartment intended for cargo is now depending on the draught!

0.950.950.950.95

0.800.800.900.80

0.700.700.900.70

Dry cargo spacesContainer spacesRo-ro spacesCargo liquids

Permeabilityat draught dl

Permeabilityat draught dp

Permeabilityat draught ds

Spaces


Work currently being carried out atIMO, SLF Committee

• Explanatory Notes for the new probabilistic regulations – draftsubmitted to SLF 50 – to be finalized i 2008

• Passenger Ship Safety- development of criteria for ”safe return to port” either under

own power or under tow- time to flood simulations- requirements for water ingress detection and flood level

monitoring systems• Inclusion of the Special Purpose Ships in the new SOLAS B-1• Revision of IMO Res. A.266 ”Cross-flooding”• MSC/Circ.650 “modification of a major character" • Revision of the Intact Stability Code

• What about the ”Stockholm Agreement” after 2009?


Revision of the SPS CodeCode of Safety for Special Purpose Ships - Resolution A.534(13)


Revision of the SPS Code

Which ships are covered by the SPS Code:• Ships engaged in research, expeditions and survey; • Ships for training of marine personnel; • Whale and fish factory ships not engaged in catching; • Ships processing other living resources of the sea, not engaged in

catching; • Other ships with design features and modes of operation similar

to ships referred above which in the opinion of the Administration may be referred to this group.

Ships with many people onboard !



• “Special personnel” means all persons who are not passengers or members of the crew (or children of under one year of age) and who are carried on board in connection with the special purpose of that ship or because of special work being carried out aboardthat ship.

• Wherever in the SPS Code, the number of special personnel appears as a parameter it should include the number of passengers carried on board which may not exceed 12.

The requirements in the SPS Code depends on how many ”special personnel” are carried!

MANY PERSONS – STRICTER REQUIREMENTS!



The SPS Code, IMO Resolution A.534(13) is currently under revision in IMO.

WHY?

• To update references to current rules and regulations;

• To reflect the new damage stability requirements in SOLAS, Chapter II-1 coming into force 1 January 2009



The draft for the new SPS Code – Damage Stability:

• Based on the probabilistic concept A ≥ R• Based on the revised SOLAS Chapter II-1, Part B-1• Based on the requirements for passenger ships!• Still based on the number of ”special personnel” onboard

1. below [50 special personnel] / [60 persons]2. between [50 and 200 special personnel] / [60 and 240 persons]3. more than [200 special personnel] / [240 persons]



A ≥ R

Damage Stability Concept:

Attained Subdivision Index:A = Σ pi si

Required Index R:1. More than [200 special personnel] [240 persons] – R value as passenger ship2. Less than [50 special personnel] [60 persons] – 0.8R (passenger ship)3. Between [50 but not more than 200 special personnel] [60 but not more than

240 persons], the R value to be determined by linear interpolation



Vessels with more than [200 special personnel] [240 persons]:

Revised SOLAS Chapter II-1, reg. 8 and part B-2, B-3 and B-4 applies as though the ship is a passenger ship and the special personnel are passengers.- Minor damages- Watertight and Weathertight

Subdivision - Stability Management



Vessels with less than [200 special personnel] [240 persons]:

Revised SOLAS Chapter II-1, part B-2, B-3 and B-4 applies as though the ship is a cargo ship and the special personnel are crew.

HOWEVER!

All SPS vessels must comply with the revised SOLAS Chapter II-1, regulation 9, 13, 19, 20, 21 and 35-1 as a passenger ship!


MARPOL Annex IRegulation 12A

Oil fuel tank protection


Regulation 12A - Oil fuel tank protection

• Applies to all vessels delivered on or after 1 August 2010 with an aggregate oil fuel capacity of 600m3 and above:

• Delivered defined as:Building contract placed on or after 1 August 2007 or;If no contract, keels laid on or after 1 February 2008 or;The delivery of which is on or after 1 August 2010.

• Also applies to vessels which undergo a ‘major conversion’ in accordance with same dates.



• Applies to all oil fuel tanks except small oil fuel tanks, provided that the aggregate capacity of such excluded tanks is not greater than 600m3

• Oil Fuel means any oil used as fuel oil in connection with the propulsion and auxiliary machinery.

• “Small oil fuel tanks” is an oil fuel tank with a maximum individual capacity not greater than 30m3

• Individual oil fuel tanks maximum capacity of 2,500m3



Tanks to be located above the bottom shell plating at a distance of ‘h’where:

h = B/20 m or 2.0 mwhichever is lessMinimum h = 0.76 m.



Tanks to be located inboard of the side shell plating at least distance ‘w’ where:

1. Ships with oil fuel capacity of 600m3 to 5000m3:w = 0.4 + 2.4C / 20,000 m where

C = total oil fuel volume

Minimum w = 1.0 m (except for individual tanks with a capacity < 500m3 minimum w = 0.76m.)

2. Ships with oil fuel capacity of 5000m3 and over:w = 0.5 + C / 20,000 m or,w = 2.0 m whichever is the lesser.

Minimum w = 1.0 m.



• Tanks with oil fuel piping located within ‘h’ and ‘w’ distances from the ship’s bottom and side shell to have special valve arrangements fitted.

• Suction wells in oil fuel tanks may protrude into the double bottom below ‘h’ provided such wells are as small as practicable and that the distance between the well bottom and the bottom shell plating is not less than 0.5h.

ALTERNATIVE to side and bottom protection requirements

• Comply with the accidental oil fuel outflow performance standard in regulation12A



The Accidental Oil Fuel Outflow Performance Standard:

• Probabilistic Concept!

• Mean Oil Outflow Parameter OM

OM ≤ 0.0157 – 1.14E-6C for 600 m3 ≤ C < 5000 m3

OM ≤ 0.010 for C ≥ 5000 m3

C = Total oil fuel volume onboard



Assumptions for the Mean Oil Outflow Calculation:

• Ship assumed loaded to the partial loadline dp

• All oil fuel tanks assumed loaded to 98% of their volumetric capacity

• Nominal density of fuel oil taken as 1000 kg/m3

• For the purpose of the outflow calculations, the permeability of each oil fuel tank shall be taken as 0.99, unless proved otherwise.

• The calculation of the Mean Oil Outflow Parameter is based on a combination of side damages and bottom damages:

OM = (0.4OMS + 0.6OMB)/C

OMS = Mean outflow for side damage [m3]

OMB = Mean outflow for bottom damage [m3]



Mean outflow for side damage OMS:

• OMS =

PS(i) = The probability of penetrating oil fuel tank i from side damage

OS(i) = The outflow, in m3, from side damage to oil fuel tank i, which is assumed equal to the total volume in oil fuel tank i at 98% filling.

i = each oil fuel tank under consideration

n = total number of oil fuel tanks

)()( iS

n

iiS OP∑



Mean outflow for bottom damage OMB:

• OMB = 0.7OMB(0) + 0.3OMB(2.5)

where:

OMB(0) = Mean outflow for 0 m tide condition;

OMB(2.5) = Mean outflow for -2.5 m tide condition.

The mean outflow for bottom damage shall be calculated for each tidel condition as follows:

• OMb(0) = , 0 m tide condition)()()( iDBiB

n

iiB COP∑



Mean outflow for bottom damage OMB:

• OMb(2.5) = , -2.5 m tide condition

where:

PB(i) = The probability of penetrating oil fuel tank i from bottom damage

OB(i) = The outflow, in m3, from bottom damage to oil fuel tank i.

CDB(i) = Factor to account for oil capture in other tanks

i = each oil fuel tank under consideration

n = total number of oil fuel tanks

)()()( iDBiB

n

iiB COP∑



Practical Experience:

• Regulation 12A is a MAJOR design driver for newbuildings as should be taken seriously in the early design fase.

• In some ship types, it is difficult to find enough space for the protected fuel oil tanks.

• Will have a major impact on conversions in the future.

• The probabilistic oil outflow performance standard in Regulation 12A is difficult to fulfil.


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