TH Concrete Screw – Atlantis C3-M Coating
The same screw and the same approvals – with a multi-layer organic coating that outperforms hot-dip galvanizing.
Who is the TH Concrete Screw for?
The TH is technically and geometrically identical to the TF concrete screw – the same diameters, the same heads, the same ETA approvals. The only difference is the coating.
The TH is intended for outdoor environments, coastal areas, high humidity and exposed projects – corrosion categories C3 and above. If the anchor sits indoors in a dry environment, TF is enough. If the environment is especially aggressive (pools, food industry, chemicals), move up to TX stainless steel.
Technical Specification
| Characteristics | Direct-fastening concrete screw with the Atlantis C3-M coating |
| Material | Carbon steel, grade 8.8 |
| Coating | Atlantis C3-M – multi-layer organic coating, total thickness > 20 µm |
| Corrosion category | C3 and above – outdoor, coastal, high humidity |
| Technology | Direct fastening |
| Diameters | 5, 6, 8, 10, 12, 14, 16 and 18 mm |
| Cracked concrete | Yes |
| Seismic loads | Yes – C1-C2 |
| Re-usable | Yes |
| Fire standard | Yes – R120 (Efectis) |
| Approvals | ETA1 for cracked and uncracked concrete · ETA6 for hollow-core slabs (Spancrete) |
What Exactly is the Atlantis C3-M Coating?
Atlantis C3-M is a multi-layer organic coating developed specifically for screw anchors in aggressive environments. It is not ordinary hot-dip galvanizing (HDG), and it is not simple zinc plating – it is a system of three layers.
Total thickness: > 20 µm | Curing: 180–200°C for 30–35 minutes
Atlantis C3-M Performance
Atlantis vs. Hot-Dip Galvanizing (45 µm)
Although hot-dip galvanizing is twice as thick, the Atlantis C3-M coating outperforms it in corrosion resistance:
| Test | Atlantis TH | HDG 45 µm |
|---|---|---|
| ASTM-B117 – 1,440 hours in water | Almost no corrosion | Significant corrosion |
| ASTM-G85 – 1,440 hours | Excellent condition | Significant corrosion |
| ISO 9227 – salt spray | > 600 hours | ~400–500 hours |
Why is Atlantis Better than Hot-Dip Galvanizing?
- The epoxy layer forms a sealed physical barrier against water and oxygen – unlike zinc, which works sacrificially.
- No change to hardness or metallurgical structure – the process runs at low temperature, not at 450°C and above as in hot-dip galvanizing.
- No hydrogen embrittlement – a characteristic problem of ordinary electrolytic galvanizing.
- Less galvanic corrosion in contact with other metals.
- Resistant to acids and bases – relevant in damp, high-pH concrete.
- Hexavalent-chromium free – compliant with REACH and RoHS.
Head Range – TH Series
Need a female head? See the TFF female-head concrete screw. Need a different coating? See TF – zinc plated or TX – stainless steel SS316.
Files to Download
- The Atlantis C3-M coating explained
- European Technical Assessment (ETA) – cracked and uncracked concrete
- ETA 6 – prestressed / hollow-core slabs
- Declaration of Performance (DoP)
- AutoCAD files – TH screws
Frequently Asked Questions
What is the difference between TF and TH?
The two are completely identical technically and geometrically – the same diameters, the same heads, the same ETA approvals. The difference is the coating only: TF comes zinc plated (5 µm), and the TH comes with the Atlantis C3-M coating, rated C3 and above.
Is Atlantis the same as hot-dip galvanizing?
No. Atlantis C3-M is a multi-layer organic coating – electrolytic zinc, a chemical conversion layer, and two coats of epoxy. It is thinner than hot-dip galvanizing (over 20 µm against 45), yet it outperforms it in corrosion resistance in the ASTM and ISO tests.
When should I choose TH, and when stainless TX?
The TH suits corrosion categories C3 and above – outdoor, coastal, high humidity. For especially aggressive environments – swimming pools, hospitals, the food industry and chemical conditions – move up to solid SS316 stainless steel (TX).
Is the TH approved for cracked concrete and earthquakes?
Yes. The TH carries exactly the same approvals as the TF – ETA1 for cracked and uncracked concrete, ETA6 for hollow-core slabs, seismic approval C1-C2 and fire resistance R120.
Is there hydrogen embrittlement in the coating?
No. The Atlantis process runs at low temperature and does not create hydrogen embrittlement – a characteristic problem of ordinary electrolytic galvanizing.