Types of Welding in Shipbuilding Industry

Welding is a process used in a diverse range of industries, be it aerospace, automotive, railroad, or our household products industry. One such industry that highly relies on the perfection of welding processes is the shipbuilding industry. Welding is by far the most effective method used by professionals to build these incredibly huge structures.

Years of experience and research along with the advancements in welding technology have enabled us to build perfectly watertight and oil-tight ship structures. It is impossible for these structures to function efficiently and more importantly, safely without the proper use of welding materials and techniques.

While a welder can replace the process of welding joints in a ship by riveting them, the latter process causes expenses in the initial stage and also requires timely maintenance. On the other hand, welded joints have shown to reduce steel weight and require minimal to absolutely no maintenance. 

Now that we know welding is better than the rest when it comes to the building of ships, let us understand how it can be incorporated into the ship’s design. Depending on the structure of the ship, the process of welding is selected. The versatility that welding allows to reduce the excessive use of welding materials and provides a cost and time-effective solution. The commonly used techniques in shipyards are: shielded metal arc welding which is done by welding electrodes or welding rods, gas metal arc welding and resistance welding.

Shielded metal arc welding is used in the fabrication of panels, grillages, tank units, etc. This method’s positional flexibility makes it the only process used to weld the underside of overhead deck plates. Gas metal arc welding is used to weld comparatively light structures. The entire structure of the ship is built with a combination of these welding techniques.

As a whole, welding practices are used for two purposes at the primary stage in the shipbuilding industry: 

A. Multiple passes welding- This is used to fill the gaps between two welded plates of high thicknesses (usually more than 5mm to 6mm). A number of welding passes are required between two plates to achieve complete penetration.

B. Tack welding- To prevent plates from opening apart due to heat gradients during the main welding pass, the tack welding method is used. Tack welding is done at regular intervals along the length of the weld joint to keep the plates in position.

With welding hidden in every corner of the ship, it’s obvious that it is one of the integral processes of shipbuilding. Not surprisingly, researchers are on a constant hunt to improve weld quality and predict the nature of weld distortions. You’d wonder why the researchers are investing their time in studying distortions. Well, by predicting this, their aim is to introduce such welding materials and methods that eliminate the need to rectify welding induced stresses on structures. This shows that there is indeed a vast scope of research which makes welding quite an interesting topic in shipbuilding. Even Classification Societies have laid down in-depth norms on not only the methods of welding to be used but also on the standard of electrodes to be used for each type of joint.

We hope with this, the next time you step on a ship you are aware of the hundreds of joints that have been welded together to build it, and that would mean we have served our purpose here!