The battle between which is a better material for fuel tanks continues to this day. Fuel, a combustible material, is stored in tanks either made of plastic or steel. In cars, some manufacturers are opting for plastic fuel tanks partly because they believe this makes the vehicle lighter.
In comparing plastic and steel fuel tanks, there are a number of things to consider:
For the automotive industry, one advantage of plastic fuel tanks is that this material retards the transfer of heat to the fuel. This is because plastic is an insulator. When a fire occurs under the car, the plastic tank will slow down the increase in fuel temperature. Unfortunately, the plastic will also sag as it softens up eventually releasing the fuel.
On the other hand, in the event of an under-car fire, steel tanks will not sag. The temperature of the fuel in a steel tank will definitely rise. This may result in a high increase in pressure causing the fuel to be released via a mechanical fitting.
Another safety issue is the ability of the tank to meet crash requirements. Plastic tanks are seamless and this lack of seams makes it less vulnerable to failures during a major crash. Even if they deform, plastic tanks can rebound back to its initial shape.
Steel tanks deform and absorb energy and are vulnerable at the point where they were welded together. Plus, unlike plastic tanks, steel tanks maybe a source of sparks that can ignite a fire.
In storing tanks in warehouses and factories, some companies have shifted to plastic tanks. However a study has revealed that steel is still the safer option prompting a gradual shift back to steel fuel tanks.
In terms of the actual material used, there are different types of steel tanks. Four of these are terne-coated, electrocoated Zn-Ni and galvanneal, hot-dipped tin and stainless steel. Each kind of steel material has its advantages and disadvantages. But definitely, all these steel materials make for a recyclable tank. Unfortunately, steel is not exactly flexible and in some cases is not effective against corrosion.
With plastics you have HDPE or high-density polyester type and the multilayer and barrier HDPE kind. Plastic is more flexible, corrosion resistant, and lighter but may be more expensive and harder to recycle.
Weight and Design Features
Flexibility is one great advantage of plastic as a material for fuel tanks. Manufacturers do not worry so much about the shape of the gas tank even if the vehicle’s design is more complex because plastic can be molded to fit any shape. A disadvantage to this though is that since plastic tanks have mechanical joints, when the plastic distends due to continuous contact with vapors and liquids, the joints become vulnerable. Some studies have shown that plastic gives the vehicle an advantage in terms of weight. Steel tanks manufacturers however are developing ways to combat the criticism that steel tanks make for heavier cars.
American and European made vehicles favor plastic tanks because they can easily be molded in order to fit spaces as compared to fuel tanks. Japanese cars still opt for steel fuel tanks.
The steel tank manufacturers continue to find ways to develop lighter tanks. While plastic fuel tank manufacturers continue to improve their product to meet the stricter laws and requirements for fuel tanks. This battle is far from over. Expect that both sides will continue to find ways to manufacture fuel tanks that will be better and more environment friendly as compared to their previous counterparts.