Some surfaces need 800 microns in one pass
Standard liquid epoxies build at 400-500 µm per coat. For severe-service environments — splash zones, tank floors, valve bodies in chemical plants — that's not enough. Multi-coat systems work but stretch the schedule. High-build coatings solve this: two-component epoxy or polyurethane systems engineered to deposit 600-1000 µm of cured film in a single application without sagging.
What you get with high-build
- Single-coat builds up to 1 mm without sag, runs or solvent entrapment
- Same-day return-to-service in most cases (vs 7+ days for multi-coat systems)
- Compatible with most primers — works over zinc-rich epoxy, FBE primers, blasted bare steel
- Holiday-repair grade — same product can patch coating defects on 3LPE / FBE mainline
- Solvent-free formulations for confined-space and potable-water work
Where we deploy high-build
- Valves and fittings — full envelope protection without dimensional creep on sealing faces
- Pipeline field joints — single-coat alternative to HSS where access is limited
- Tank floors and walls — internal lining for crude, water, brines and chemicals
- Holiday and patch repairs — restoring damaged 3LPE, FBE or coal-tar coatings
- Atmospheric service in C5-M zones — coastal industrial steel, jetty piping
- Concrete coatings — secondary containment, splash zones, bunds
Build properties
| Property | Value |
|---|---|
| Single-coat DFT | 600-1000 µm |
| Service temperature | up to 95 °C standard; 120 °C for HT grades |
| Cure @ 25 °C | tack-free 4-8 hours, full cure 7 days |
| Cure @ 60 °C | full cure 90-120 minutes |
| Pot life @ 25 °C | 30-45 minutes |
| Solid content | 95-100% by volume (effectively VOC-free) |
| Pull-off adhesion | ≥ 12 MPa |
| Holiday test | 5 V/µm DC |
Two formulation families
Two-component epoxy high-build. Bisphenol-A or novolac epoxy with polyamine cure. Best for immersion service, chemical resistance, internal tank linings.
Two-component polyurethane high-build. Aliphatic isocyanate with polyol blend. Better for atmospheric service, UV stability, abrasion resistance, decorative finish where required.
Standards
- ISO 12944-5 — protective paint systems (atmospheric, C5)
- AWWA C210 — liquid epoxy lining for water pipes
- NACE SP0188 — discontinuity testing of new protective coatings
- NORSOK M-501 — surface preparation and coating, offshore
- ISO 21809-3 — field-applied liquid coatings for pipelines
Application notes
Surface prep stays critical: Sa 2½ minimum (Sa 3 for immersion). The high-build film masks profile irregularities better than standard liquid epoxy, but it doesn't replace good surface preparation. We airless-spray at controlled pump pressure (200-250 bar typical) with a 0.019" tip — brush/roll application is possible but slower and harder to keep uniform.
Common questions
High-build epoxy vs multi-coat — when does each make sense? High-build wins on schedule and access. Multi-coat wins on absolute long-term performance in severe service. For most pipeline accessory work, high-build is the right call.
Will it sag on vertical surfaces at full thickness? Properly thixotropic formulations sag-resist up to 1 mm at 25 °C. Above that we apply in stacked passes wet-on-wet within the recoat window.
Compatible with cathodic protection? Yes — the cured film is non-conductive and CP-compatible. Holiday detection and adhesion at the substrate determine CP current demand.
