Welding in Shipbuilding

WELDING IN SHIPBUILDING

In this assignment we are supposed to describe a specific process. I have chosen the welding in shipbuilding simply because I have worked in shipbuilding industry for a while and I am not only describing the process I also understand this process quiet well.

When we speak about shipbuilding industry, welding is very important process. In order to protect the ship structure, the above mentioned process should be performed by the qualified welders and in the end to be controlled by the quality control engineers and Classification Societies (Lloyd's Register, Det Norske Veritas, etc.). All welders should have a certificate and the procedures should be prepared in the shipyards.

As we learned at Production Technology, a good method to create relationship between variables and process behavior is to do it through method of the fishbone diagram.

Below I created a fishbone diagram and I will describe it.

FISHBONE DIAGRAM

METHOD

There are several kinds of welding methods. Some of them we will describe below.

1. In shipbuilding, the most common technique is electric arc welding. Arc welding is one of several fusion processes for joining metals. In arc welding, the intense heat needed to melt metal is produced by an electric arc. The arc is formed between the actual work and an electrode (stick) that is manually or mechanically guided along the joint. A typical manual arc welding set-up we can see below.

2. CO2 Shielded Arc Welding-MAG (Metal Active Gas) welding. It is of hand operation, with the gas and welding wire automatically fed. The primary gases used for this process are helium, argon, or carbon dioxide. This procedure is widely used in the shipbuilding welding. It may be applied to all position fillet welding for warships and one-side welding with a backing. In the drawing below we can see how this type of welding is operating.

3. Another type of welding is ceramic welding (weld back up strips). It is used especially on the shell plating and block connections. This tip of welding provides easiness for the welders and shortens the production period. It was estimated that by using weld back up strips, welding cost is saved approximately by 40-50% and, in the same time, the welding time is saved by approximately 50%. Results of such tip of welding are most of the time 100% radiographic welding

Ceramic materials have the fine property of acid and alkali resistivity. In the process of welding steel pieces, no deformation, physical or chemical reactions occur. In the drawing below we can see how the ceramic plate is used when welding.