Product movement during filling develops a static charge between the liquid surface and the tank shell. The accumulated electrostatic charge can produce an incendiary spark that can lead to accidents. Dissipation of this static charge is the role of anti-static fillers that are added to the body of the storage tank or to the lining coating, and the choice of additive is of critical importance.
Until recently, using a standard anti-static filler – such as conductive mica or carbon black – always involved a compromise that resulted in anti-static properties that were not stable over time and that were affected by weather conditions. Now, however, innovative technologies have enabled graphene nanotubes, also known as single wall carbon nanotubes, to totally reshape the perception of conductive fillers for fiberglass plastics and their coatings.
Tuball graphene nanotubes, produced by OCSiAl, provide ESD protection by dissipating electrostatic charge inside and outside a storage tank. One of the company’s partners is now introducing nanotubes in anti-static fiberglass tanks for storing and transporting easily combustible materials. The previous conductive additive, carbon black, required a loading of 15% but this has now been replaced with just 0.5% of Tuball Matrix 204, a pre-dispersed concentrate of graphene nanotubes.
Permanent and stable volume resistivity of less than 10^6 Ω·cm has been achieved, without “hot spots” and independent of humidity. Moreover, the product colour range has been expanded.
Another of OCSiAl’s partners has launched a Tuball-based lining coating system with an electrostatic dissipation function that is specially designed for storage tanks for highly flammable substances. This manufacturer has replaced 30% of conductive mica, in an epoxy system, with just 0.3% of Tuball MATRIX 201 concentrate. The result is a stable level of volume resistivity of between 10^6 and 10^7 Ω·cm. The prospect of cost cuts resulting from such significant reductions in the overall additive loading is also of great interest to coatings manufacturers.
The application of OCSiAl’s graphene nanotube concentrates simplifies nanotube handling and makes it a standard and clean manufacturing process without the powder or dust usually associated with the utilisation of carbon black. The extraordinary properties of graphene nanotubes have opened the door for storage tank and coatings manufacturers to gain competitivity and provide their clients with advanced solutions in terms of sustainable safety.