Page 135 - Ship Construction.DJ Eyres 6Ed

Ch13-H8070.fm Page 124 Wednesday, October 18, 2006 6:56 AM

13
Plate and Section Preparation and Machining

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This chapter deals with the working processes which a plate or section
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
undergoes from the time it is received into the shipyard until it is in its final
shape ready to be welded into a unit of the ship structure. In recent years
many changes have occurred in this sphere of shipyard activity, and sub-
stantial economies can be achieved by obtaining an even flow of production
at this stage.

Plate and Section Preparation

Initial preparation of material is essential for its efficiency in the completed
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ship structure and its marshalling on arrival is essential to the efficiency of
the shipbuilding process.

STOCKYARD On arrival at the shipyard, plates and sections are tempo-
rarily stored in the stockyard. As a rule the stockyard is an uncovered space
having sufficient area to provide storage for enough plates and sections
required for the working of the yard some months ahead. In the United
Kingdom the amount stored might be about three months’ stock, but ship-
yards in countries which are not substantial steel producers may find it nec-
essary to carry much larger stocks of material. In contrast a Japanese yard
closely associated with a steel manufacturer claims to carry as little as one
month’s stock, and in some cases less.
When the plates and sections are ordered the steel mills are provided
with details of the identification code for each item so that they may be
marked. On arrival in the stockyard, since the coding is generally in terms of
the unit structure for which each item is intended, it is convenient to store the
plates and sections in their respective ship and ship unit areas. In other words
the material for each ship is allotted an area of the stockyard, this area being
subdivided into plots for those items intended for a major structural fabrica-
tion block of the ship.
Material delivery and storage is controlled in accordance with production
engineering practices to suit the ships construction programme.
As a rule the plates are now stacked horizontally in piles as required.
Originally it was common practice to store the plates vertically in racks,