FRP tank under repair.

The Ultimate Fiberglass Repair Guide

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Fiberglass tanks have long been used for storage purposes across an extensive range of industries. Due to their watertight nature and leak-free performance, these tanks are particularly popular for water storage. Although fiberglass is highly durable and rarely needs repairs, the tank can occasionally deal with minor composite damage.

Here’s all you need to know about the repair process.

Primary and secondary structure

The repair process is different from how the original piece was initially constructed. When a composite part is manufactured for the first time, the resin bonds the reinforcement fabrics, both chemically and physically. Irrespective of the number of plies of fabric, the reinforcement results in a single strong unit. This is known as the primary structure.

However, when a composite part is repaired, the process differs. In this case, the resin used to repair must be just as strong as the resin used to fabricate the part in the first place. At this point, all repairs become secondary bonds and are attached to the primary structure. This is why the resin’s ability to attach the repaired part to the original structure has an important role to play.

Types of composite damage

There are four main types of composite damage that your repair may involve:

  1. Tear: This happens when the tensile strength of the composite part has exceeded its limit or has failed. Tears are more common if the fracture extends through the substrate completely.
  2. Puncture: This type of damage is limited to the fiberglass surface and results from an impact or cutting. 
  3. Delamination: Unlike puncture, damage from delamination is caused by impact across the layers. In this case, damage affects the layers of material separating from one another.
  4. Crushed core: This type of damage takes place when the composite skin of the laminate either deflects but doesn’t fail. As a result, the sandwich core material collapses.
The interior view of an FRP tank

Important considerations

Before starting the repair process, your FRP tank repair service will always look for the root cause. They must check whether something inside the tank has broken loose or has something hit the tank. You can’t evaluate the extent of the damage by looking at the tank’s outer structure. At times, fiberglass might look slightly damaged on the impact side, but you’ll find many broken fibers on the backside. Make sure your repair service takes a detailed look at the tank before quoting a price.

It’s also imperative that the technicians accurately “map” the surface before applying the fairing compound. They should invest their time in finding the high and low spots on the tank surface. This will help them even out the thickness of the final product and use less sanding. They must also have different sanding tools to repair the bridges in a detailed and flat area.

If you’re on the lookout of a Fiberglass tank inspection and repair service, Hudson Fiberglass is your best bet. We’re an FRP tank installation, repairs, and tank inspection services based in Watertown, FL. Drop us a message for details.

Learn more about fiberglass surface coating here.