Single Pass Loading Case Study

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


High speed & single pour/single pass loading

Alternate loading condition, holds loaded in a single pour – Step 0

Ballast condition – arrival




100% 88%



102% 82%



124% 106%

107% 88%





126% 103%





Alternate condition - Departure



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



118% 105%Amplified SF & BM

Local strength problem – insufficient draft for given weight

Effect of de-ballasting rate


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)


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

Single Pass Loading Case Study

Documents

Transcript of Single Pass Loading Case Study