4. Fabrication and Welding of Hull When building a hull, we will normally divide the hull construction into a number of components, which are termed as blocks or sections, assembled separately and then fabricated into an integral hull on a berth or a slipway. This workmanship mainly includes:

A: Part fabrication-to assemble different kinds of members into a whole part after their processing.

B: Block or section fabricatiom-to assemble different parts into a block or section. C: Berth or slipway fabrication-to assemble a few blocks and sections into an integral hull.

4.1       Division of Sections

Division of sections is of great importance, for not only the strength of hull itself but also the convenience and reasonableness of operation as well as the production procedure, lifting capacity and arrangement of the working site have got to be taken into our account. To make the matter worse, the aforementioned factors are frequently contrary to one another in one way or another. Therefore, it is not rare for us to rack our brains to find ways and means available.

4.2       Fabrication and Welding of Parts

The fabrication and welding of parts, such as frames, beams, girders and seatings, to be performed on a platform in term of the concerned drawings.

4.3       Fabrication and Welding of Blocks and Sections

The fabrication and welding of blocks, such as side, bottom, deck and superstructure, to be conducted on a jig. In respect to sections, two methods for their fabrication and welding are available:

A: Pyramid Method

The practice of this method is as nofollows:

First, lift a bottom block onto a berth or a slipway and take it both as a base and a jig. Then, assemble side blocks and bulkhead blocks. Still then, assemble the deck block. By the pyramid method, all are done bit by bit through welding.

B : Converse Method

This method is good for bow section, stern section, deckhouse and superstructure, the main characteristic of which is to regard the deck block on a berth or a slipway both as a base and a jig. Thus framing blocks, bulkhead blocks and side girders will be erected on the base of a deck block.

5. Tightness Test

Together with the completion of the whole integral hull construction, tightness test is to be carried out so as to check the leakage of welding seams. In addition, water pressure test may be executed for the hull structures that, by virtue of the technical specification, are required to pass through strength test.

Tightness test is to be done only after the X-ray photo check of seams and the completion of fabrication and welding in respect to pipe flanges and cable fixtures and so on, but before the painting process for shell and compartments as well as the laying of insulating materials. Tightness test to be subdivided into kerosene test, watertight test and air-tight test.

6. Ship Launching

It is interesting enough that a ship is to sail at sea but built on land. To move a colossal ship from its building zone to water after the completion of hull construction is referred to as ship launching.

Launching is really a key link to ship building. Should there be any carelessness, a serious accident might take place. No doubt the relevant preparations must get through a strict and thorough examination in order to guarantee a successful launching.

There are now a few launching methods: first, the gravity launching by a longitudinal slipway, which means a ship slips into water by gravity action of the ship itself and overcoming the friction resistance on the slipway taper; then, the floating launching, by which water will be led into a dock and a ship will float by itself; thirdly, the mechanical launching, which is suitable for small or medium ships.

• Securing anchor and chain cable method - 2012-11-16 - 04:00:27
• Securing and stowage of anchor - 2012-11-16 - 03:16:45
• Stabilising systems for ships - 2012-11-15 - 08:12:48
• Small Angle Stability for ships - 2012-11-15 - 05:33:01
• Theory of Hull resistance - 2012-11-15 - 03:34:04
• Theory Hull Stresses for Ships - 2012-11-15 - 02:41:04
• Application of Computers in shipbuilding industry (2) - 2010-01-02 - 10:57:17
• Application of Computers in shipbuilding industry (1) - 2010-01-02 - 10:55:49
• Quality Management in shipbuilding industry (3) - 2010-01-01 - 11:49:49
• Quality Management in shipbuilding industry (2) - 2010-01-01 - 11:48:21

• < Prev
• Next >