Tercoo® vs Needle Gun on Marathon 550 Epoxy

Marathon 550 is a two-component, surface-tolerant epoxy coating developed for highly corrosive environments. It provides high abrasion and impact resistance and is suitable for demanding applications such as offshore structures, splash and tidal zones, industrial plants and immersed steel.

These properties protect the substrate during service, but they also make the coating difficult to remove when maintenance or repair becomes necessary.

For the Actemium demonstration, the objective was straightforward: compare a conventional needle gun with Tercoo® while removing the same hard coating system.

How the tools performed

The needle gun and Tercoo® use impact to attack the coating, but they transfer that impact to the surface in very different ways.

A needle gun works through a bundle of individual needles. Their repeated point impacts can break coating and corrosion locally, particularly around edges and irregular details. Across a larger coated area, however, the operator must make many overlapping passes.

Tercoo® uses flexible rotating discs fitted with tungsten-carbide pins. As the disc rotates, the pins strike the surface in a controlled pendulum motion. This produces an aggressive removal action across a wider working track.

The difference was clear during the demonstration:

• Tercoo® completed the coating removal three times faster.

• The needle gun was unable to remove the primer.

• Tercoo® produced a visibly cleaner surface.

• No loose abrasive media or blast equipment was required.

These results apply to the coating, equipment and conditions used during this demonstration. Working speed on another project will depend on factors such as coating type and thickness, substrate condition, access, operator technique and the required final surface standard.

Why the needle gun stopped at the primer

The individual needles concentrate their energy on small points. This can fracture the upper coating, but it does not necessarily remove every layer consistently across the complete surface.

On the Marathon 550 test area, the needle gun removed part of the coating system but could not remove the primer. Continuing with the same method would have required more passes without guaranteeing a uniformly prepared surface.

Tercoo® applies repeated impacts across a broader path. Its tungsten-carbide pins are designed for the bulk removal of thick paint, epoxy, bitumen, heavy rust and layered contamination. On this test plate, that action allowed the tool to continue through the coating system and expose a much cleaner substrate.

Why surface cleanliness matters

Removing most of an old coating is not the same as preparing steel for a new one. Primer residues and contamination can remain even when the surface appears partly clean.

This distinction matters in offshore maintenance. The replacement coating depends on the condition of the substrate beneath it. Incomplete removal or an unsuitable surface profile can affect adhesion and shorten the life of the repair.

Tercoo® is the heavy-removal step in the MontiPower method. It strips the thick coating and exposes the substrate. Where the coating specification requires a defined anchor profile, the next step is to use the Bristle Blaster® to clean and profile the steel before inspection and recoating.

An important limit of the demonstration

The Actemium test compared Tercoo® with a needle gun. A separate Bristle Blaster®-only area was not prepared on the same plate under identical conditions.

The demonstration therefore supports a direct comparison between Tercoo® and the needle gun for Marathon 550 removal. It should not be presented as a three-way productivity comparison involving the Bristle Blaster®.

The Bristle Blaster® has a different role in the process. Tercoo® performs the aggressive bulk removal, while the Bristle Blaster® creates the controlled anchoring surface required for the next coating.

Relevant to offshore maintenance

The Petrobras teams watching the demonstration manage maintenance work on offshore platforms and from supporting head offices. In these environments, mobilising abrasive-blasting equipment can require considerable preparation, containment and cleanup.

A portable mechanical system offers another option for local repairs and maintenance areas. Tercoo® removes the heavy coating without loose abrasive media. The same compatible drive unit can then be configured for Bristle Blasting when the exposed steel needs further cleaning and profiling.

The Actemium demonstration made the practical difference visible. On the hard Marathon 550 system used for the test, Tercoo® worked three times faster than the needle gun, removed material the needle gun left behind and produced the cleaner surface.

Start with the coating and the required result

Tool selection should begin with the coating system, substrate and required final surface condition.

A needle gun remains useful for local scaling and difficult details. When the task involves removing a hard, abrasion-resistant coating across a larger repair area, the Actemium demonstration showed the advantage of using a purpose-built heavy-removal tool.

After removal, the exposed surface must still be checked against the coating specification. Where a defined anchor profile is required, complete the process with the Bristle Blaster® and verify the surface before recoating.

Discuss your coating-removal project

Working with a hard epoxy coating or planning maintenance where abrasive blasting is difficult to deploy? Tell us the existing coating, substrate, required surface standard and working environment. A MontiPower® specialist can help define the correct removal, profiling and inspection steps.