single pass loading case study
TRANSCRIPT
Single Pour - High Speed Loading
Case Study 176k Capesize
22Sunday, April 9, 2023 Technical Forum - Singapore
Case Study: Single Pour - High Speed Loading
Main ParticularsLbp = 277.94 m
Bml = 45.00 m
D = 24.80 m
Tsc = 18.30 m
Typical design with 9 cargo holds & 9 associated ballast tanks in the double bottom
To examine the effects of single pour – high speed loading on ship’s strength
Study performed for the: Examination of the vessel’s longitudinal strength
Shear forces
Bending moments
Examination of the vessel’s local strength
Bottom structure examined with permissible mass curves
Tank top plating with impact study
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High speed & single pour/single pass loading
Alternate loading condition, holds loaded in a single pour – Step 0
Ballast condition – arrival
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High speed & single pour/single pass loading
Alternate loading condition, holds loaded in a single pour – Step 1
100% 88%
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High speed & single pour/single pass loading
102% 82%
Alternate loading condition, holds loaded in a single pour – Step 2
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124% 106%
107% 88%
High speed & single pour/single pass loading
Alternate loading condition, holds loaded in a single pour – Step 3
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High speed & single pour/single pass loading
126% 103%
Alternate loading condition, holds loaded in a single pour – Step 4
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High speed & single pour/single pass loading
Alternate loading condition, holds loaded in a single pour – Step 5
Alternate condition - Departure
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High speed & single pour/single pass loading
For this particular case study:
Shear force problems remain even after shear force correction
Special consideration should be given during the initial design of the ship
Maximum allowable bending moments are within allowable limits but higher than typical loading sequences
Local strength of bottom is within allowable limits (checked with vessel’s allowable mass curves) but closer to the limit than typical loading sequences, especially during the first steps of the loading procedure due to low draft.
It has been assumed that the de-ballasting rate is high enough as to provide synchronization with the loading rate
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High speed & single pour/single pass loading
118% 105%Amplified SF & BM
Local strength problem – insufficient draft for given weight
Effect of de-ballasting rate
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Local Strength of Inner Bottom
Z
V
inner bottom
26 m
iron ore (16,000 t/h)
Impact load of bulk cargo dropping with high velocity on the inner bottom
Possible damage?
BV case study:
Iron ore loaded at 16,000 t/h on the inner bottom of a capesize bulk carrier
Representative drop height of 26 m above the inner bottom
Model falling cargo as incompressible liquid jet diverted on a perpendicular surface (inner bottom)
Dynamic amplification included Results: inner bottom plating and stiffeners have sufficient margin in their strength compared to class required scantlings (taking relevant loading conditions, sea pressures and accelerations)
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BV – SINGLE PASS NOTATION
Introduction of additional class notation SINGLEPASSLOADING
Applicable to ships with service notation ore carrier which are specially designed to be loaded from empty (ballast) condition up to fully loaded condition by filling each cargo hold in a single pour
Following requests of major owners/operators of ore carriers
Focus on single pour/single pass loading as key technical issue
Notation may be completed by design loading rate in tons per hour Example: SINGLEPASSLOADING [16,000 t/h]
The vessel is to be examined for Longitudinal strength (against maximum
allowable BM & SF)
Local strength of double bottom (with the use of the hold mass curves)
Sufficient de-ballasting rate to cope with the Increased loading rate