Storage vessels, also known as storage tanks, are more important than most people realize. They are used to store a wide variety of products. It's safe to say that storage vessels are an unsung hero in today's world. But how is one made?
There is a lot of engineering that goes into fabricating storage tanks. How many gallons or liters and the total density/weight of the product are to be factored in before fabrication. It's during the engineering or costing stage that the overall size of the vessel would be determined. But for all intents and purposes, let's focus on the fabrication process rather than the engineering.
The first stage, materials for fabrication can only be purchased as large, flat, sheets of iron. The two common measurements being 4 feet by 8 feet and 6 feet by 20 feet. It is necessary for the iron sheets to be stored in a dry place. Moisture is an untreated tank's worst enemy, as corrosion is immediate and can compromise the integrity of the entire structure. Any leak, no matter how minute, can be extremely dangerous.
The second stage of fabrication is the "layout". In this stage, experienced personnel will calculate exactly how much of each sheet will be used in fabrication. The remaining will be cut from the sheet by means of extreme heat using either oxyacetylene cutting or, more preferably, plasma arc cutting. Once the correct measurements have been made and the sheets have been trimmed to the exact size, the sheets will then be welded together end-to-end.
At the third stage, the now welded flat sheets must be rolled into a circle. This procedure is carried out by a precision rolling machine, which uses hydraulic pressure and a chain pulley system to perfectly rolling the sheets without causing any creases or cracks in the sheet. Once the sheets are rolled and the opposite ends of the sheet are touching, its now time to weld them together.
The next stage is "fit-up". In this stage you fit up all the rolled sheets and weld them together, creating a tube-like structure. When the tubular portion of the tank is complete, the ends must be welded into place. The ends are normally flat or have a slight bowl-like shape.
At this stage, the welding has been completed, with the inclusion of an access panel and several fittings which are used for ventilation, loading, and unloading of the stored product. The storage vessel must now undergo a series of tests to ensure airtightness and stability.
Once the tank has passed quality control, it can now be treated with a rust inhibitor. A coat of primer and a top coat of paint will also be applied for further protection and aesthetics.
So the next time you see a storage vessel, take a closer look. There's a lot more going on there than most people think.
