Standard · Systems, environments and degradation
NACE SP0198
Preventing corrosion under insulation and fireproofing (CUI) with coatings and design.
SP0198 is the standard practice for corrosion under insulation (CUI): steel that corrodes where water is trapped under insulation or fireproofing. The current edition is 2017.
The idea
Water under insulation does not dry out, so the steel lives in conditions close to immersion. SP0198 therefore treats the coating under insulation as an immersion-grade barrier and chooses it by the operating temperature. It also addresses equipment design, choice of insulation, and in-service inspection.
Points exams test
- Carbon steel suffers general corrosion and pitting under wet insulation; austenitic stainless steel suffers external stress corrosion cracking.
- Inorganic zinc alone is not used under insulation in the warm range where CUI is worst: zinc does poorly in a closed wet space and can stop protecting the steel.
- Thermally sprayed aluminium and high-temperature epoxies are among the systems used.
4 practice items in the members area mention NACE SP0198 (CIP 2: 2 · FROSIO written: 2).
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This page describes the subject of NACE SP0198 in our own words; it does not reproduce the standard. For the full text, buy the current edition from AMPP. Checked on 2026-10-14; errors go in the corrections log. CoatMentor is an independent study aid. It is not affiliated with ISO, AMPP, SSPC, NACE International, ASTM or FROSIO.