Dive Tank Steel Vs. Aluminum

Scuba tanks worldwide are made from either steel or aluminum. The choice of which tanks to have is affected what weight and strength the diver would like the tank to be, corrosion and care issues and how buoyancy will be affected by the tank. There is also the issue of reaction to heat and total cost of the tanks. Aluminum cylinders are the most popular cylinder around the world and are used in most resort diving operations; however, a large number of experienced divers still prefer steel tanks.

  1. Strength

    • Steel is stronger than aluminum, and therefore less steel is used in the construction of a tank compared with how much aluminum is used in one of the same air capacity. This means that a steel tank with the same gas capacity as the equivalent aluminum one will be lighter, yet have better buoyancy characteristics. Steel tanks are also more durable, being less susceptible to dents and damage than aluminum tanks.

    Corrosion and Service Life

    • Both steel and aluminum corrode in the presence of seawater. Aluminum produces aluminum oxide and steel produces iron oxide, or rust. The issue of corrosion is not as much of an issue if the tanks are properly cared for and serviced. However, for tanks that are not properly looked after, corrosion is a major issue, although this is not particularly affected by the type of metal. With regard to servicing, though, steel cylinders are regarded to have a 40-year life span when cared for correctly. This is opposed to aluminum cylinders, which many dive shops will refuse to fill after around 15 years.

    Heat Damage

    • Aluminum tanks during the manufacturing process are strengthened using a heating and cooling process. They are then, particularly susceptible to heat damage when heated beyond 350 degrees Fahrenheit, with the tank walls losing their strength. Steel tanks, on the other hand, can handle higher temperatures. This becomes an issue, for example, when cylinders are being recoated with paint or chrome using heat.

    Buoyancy

    • Aluminum tanks change their buoyancy during a dive as more air is used. They shift from negative to positive buoyancy. This becomes an issue with the diver having to be over-weighted at the start of a dive in order to be properly weighted when the diver has consumed much of the air in the tank. Steel tanks shift from negative to neutral buoyancy and are preferred by experienced divers.

    Price

    • The initial price of a steel tank compared with an similarly sized aluminum one is considerably more. Some argue that over time this cost is counteracted by service life, although it does mean that many dive operations opt for the cheaper aluminum when they choose their tanks.