Polypropylene (PP) is just one of the many types of plastics from which storage tanks can be made. However, the attributes of this particular polymer include advantages such as excellent chemical and corrosion resistance, as well as a very high melting point of 320ºF.
Polypropylene is a light, durable thermoplastic that is denser, stiffer, and stronger than polyethylene and also has a high melting point. Due to its high rigidity, and good structural strength, polypropylene can be easily fabricated into tanks by means of various welding processes using hot air, extrusion, and fusion equipment.
As a result of the many beneficial characteristics of polypropylene, tanks fabricated from this material are ideal for a variety of electroplating applications and are increasingly being used in the demanding environment of steel processing plants. Additional applications of polypropylene tanks include the storage of potable drinking water and a wide variety of mild to aggressive chemicals including hydrogen sulfide, oleic acid, photographic solutions, potassium carbonate, magnesium hydroxide and many more.
Polypropylene is less commonly used than polyethylene for tanks, although it is much stronger than polyethylene and has a much higher melting point. In addition, the crystalline structure of polypropylene falls in between that of low density polyethylene (LDPE) and high density polyethylene (HDPE). Polypropylene tanks have several advantages over traditional metal tanks such as steel, stainless steel and titanium.
These advantages include a seamless construction that provides them with greater impact strength and superior resistance to rust, corrosion, chemicals, and fuel additives. In addition, these virtually indestructible tanks also have a longer lifespan than metal tanks, which are apt to fracture and leak. Polypropylene tanks can easily be molded to fit tank compartments, unlike metal tanks, and are simple to install. One common method of fabricating polypropylene tanks is through the injection molding process.
In this process, melted pellets of polypropylene are injected into an open mold cavity, which is then clamped shut. Next, the heated polypropylene is cooled by means of water or other fluids that are circulated through the cooling system of the mold and thus used to extract the heat. The polypropylene tank is then held in the mold under high pressure until it solidifies and can be ejected from the mold.