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Bulk Structural 5

 

Transverse web and top side wing tank in bulk hold

Side structure

The upper and lower parts of the shell form the walls of the side tank and the hopper tank and have a longitudinal structure, and the central part has a transverse structure formed by the side transverse allowing cargo to flow down naturally.

A transverse rib structure is adopted to allow cargo to flow naturally.

Conventionally, a large special was built at the location of the hopper transverse to support the weight of ballast or oil in the side tank, but each classification society usually recommends uniformly increasing the section modulus.


Double bottom structure

It has a double hull structure between the bottom shell and inner bottom plates, and the girders and floors are orthogonal to each other in a lattice structure. 

The upper and lower inner bottom plates and bottom shell plates have a longitudinal rib structure to withstand the load or water pressure of the cargo hold and contribute to the longitudinal strength of the hull.

Conventionally, a large special frame was built at the location of the hopper transverse to support the weight of ballast or oil in the side tank, but each classification society usually recommends increasing the section modulus of the frame evenly.


The detailed types are as follows.

Girder: Vertical plate arranged along the length of the ship within a double bottom.

Centerline girder: Centerline girder placed on the centerline of the central section.

Duct girder: Forms the wall of a duct or a double bottom tank.

Hopper girder: Constructs the wall of the hopper tank

Side girder: common girder

Docking girder: Girder installed where half timber is placed.

Floors: Vertical plates arranged in the width direction of the ship within the double bottom, forming a lattice structure with girders to withstand the load of the cargo hold, the pressure of sea water due to large drafts when fully loaded, and the water pressure when used as a ballast tank. 


Hopper structure


It consists of 45-degree inclined plates attached to both corners of the cargo hold floor, and the inclination angle is adjusted considering the type of cargo and the cargo capacity of the cargo hold.~


Lastly, let’s look at the stool~

There are two types of stools. Up and down~

Lower stool: It serves to reduce the distance (span) between points of the bulkhead plate and is arranged in a box shape on the double bottom. Diaphragm plates to maintain the box shape inside are placed at intervals between girders within the double bottom, and reinforcement members in the longitudinal direction of the ship are installed at intervals between longitudinal ribs to provide adequate rigidity to withstand lateral loads.

Lower stool

And the upper stool: It has the effect of reducing the distance between the points of the corrugated plate, maintains the box-shaped structure between the windows, and provides rigidity against deformation of the form.~

Upper stool

This is a very brief look at the basics of bulk carriers. They said it would be explained in a very easy way, focusing on people working in the field, but I'm not sure.



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