Here's how common LPG tanks are made from sheets of metal

These pieces are stored and sorted ready for use.

To start the process, disks of steel are placed in a 500-ton special press and molded into shape to form the hemispherical ends of the tanks. This is done by a skilled worker who manipulates the sheets, operates the press, and checks each piece to ensure it has been pressed correctly.

Once pressed into a donut shape, the parts are then stored ready for the next part of the process. The next part of the process is to mount the end caps into another special machine to trim them down. 

This machine works similar to a large can opener with a sharp metal disk that trims off a strip of the tank part as it spins. 

For more cylindrical tanks sheet metal is passed through a series of presses and rollers to make bands of metal into which valve pieces are set. Valves are also included within the rings to allow LPG to be filled and drawn from the tanks once complete. 

These are welded into place, as needed. 

Where needed, information plates are also welded into place on parts as required. 

Step 2: Welding the tanks together

With the main parts of the LPG tanks ready, the next step is to join them together. Each half of the tank is placed in yet another machine and then the spot-welded top holds the two parts together. 

Once done, the press then joins the inner portion of the tank together to ensure that it is airtight. With that done, each ring tank is removed from the machine and all joins are then welded by hand. 

Once the welds are fused, a skilled worker then hammers and grinds the weld smooth. With that done, the tanks are then moved to another lathe-like welding machine for further welding. 

This machine operates autonomously and creates a very strong weld between the two halves of the tank. 

This machine is very versatile, can be used to weld different shapes and sizes of tanks. At all stages of the welding, a skilled worker is present to monitor the process and intervene or correct should their experience deem it necessary. 

Step 3: Coating the tanks

With the main tanks now more or less complete, the next step is to coat the tanks. The tanks are suspended from hooks and placed in a large coating machine ready and heated/cleaned for a period of time. 

Once complete, the tanks are removed from the machine and left to cool/cure.

With that, the LPG tanks are now basically ready to be shipped out to their final destinations. 

If you enjoyed this little look behind the scenes of how LPG tanks are made from scratch, you might enjoy watching another industrial process in action? How about, for example seeing how hair dye products are made?