What should be done if the pipe surface is heavily rusted before repairs?

When dealing with a heavily rusted pipe surface before undertaking repairs, it is essential to remove the rust using a wire brush or sandblaster. This step is crucial because rust can significantly compromise the integrity of the pipe and the effectiveness of the repair materials applied.

Rust creates a weak bond between the existing surface and the repair materials, leading to potential failure of the repair over time. By thoroughly cleaning the surface of rust, you not only ensure better adhesion of the repair materials but also help prevent further corrosion from occurring under the repair, which could cause leaks or structural failures later.

Other options, like applying repair materials directly or ignoring the rust, would not address the underlying issues associated with the rust. Similarly, applying a coat of paint before repairs would not solve the problem, as the paint would not adhere well to a rusted surface, potentially leading to similar failures. Therefore, properly removing the rust is the most effective way to prepare the pipe for a durable and successful repair.