Glass-reinforced plastic (otherwise known as fiberglass or GRP) is a fibre reinforced polymer made of a plastic matrix reinforced by fine fibres of glass. It is an inexpensive, lightweight, extremely strong, robust material and can be easily formed using moulding processes. This is the reason that more and more traditional water tanks are being replaced by GRP tanks. But why has Tank Reline been commissioned to repair GRP tanks of late?

An individual structural glass fibre is both stiff and strong in tension and compression—that is, along its axis. Although it might be assumed that the fibre is weak in compression, it is actually only the long aspect ratio of the fibre which makes it seem so; i.e., because a typical fibre is long and narrow, it buckles easily. On the other hand, the glass fibre is unstiff and unstrong in shear—that is, across its axis. Therefore if a collection of fibres can be arranged permanently in a preferred direction within a material, and if the fibres can be prevented from buckling in compression, then that material will become preferentially strong in that direction.
Sounds great, and this is why so many companies are opting to replace old water tanks with GRP tanks. However, the majority of our reline jobs have been on GRP tanks and we want to share the reasons why.

Mastic Erosion

Mastic erosion occurs when the joints and steel bolts holding the panels together begin to corrode and subsequently provide a safe harbour for bacterial growth. Osmotic blistering of the GRP substrate due to water permeation, can also lead to deterioration of the gel coat and, subsequently, a surface which is highly likely to harbour and promote the growth of micro-aquatic organisms. This can be a very serious position to be in, this is because, if ignored, such internal water osmotic blisters will eventually burst putting their contents into the potable water. These chemicals not only have a very unpleasant taste but are also dangerous if they come into contact with humans.

Fungi & Mould

Black spore fungi is often found in run down GRP tanks which need repairing. It can be extremlely difficult to remove if not treated in the appropriate time, which is why regular audit checks on your water tanks are recommended. Black spore fungi, like all moulds and fungi are very common in Britian because it is often cold and wet which is the perfect breeding ground – a lot like a water tank. Mould is a health hazard and should be handled appropriately

If you are unsure about how to approach your tank reline please read our advice page for GRP tanks and contact us with any questions you may have.