NACE 1/2/3/4 Blast Cleaning Standards Explained with Visual References
The four NACE blast cleaning grades — used widely in pipeline, offshore, and petrochemical specifications — explained with visual criteria, joint NACE/SSPC mapping, and guidance on when NACE is cited rather than SSPC.
The NACE Standards in Context
NACE International (now part of AMPP — Association for Materials Protection and Performance) developed its own numbered system for blast cleaning grades that runs parallel to SSPC. The two were jointly published for many years as combined documents (e.g., SSPC-SP 10/NACE No. 2).
Pipeline contractors, offshore platform operators, and petrochemical engineering firms tend to cite NACE; structural steel fabricators, shipyards, and architectural projects tend to cite SSPC. Both are correct and describe the same cleanliness criteria. The full standards landscape is in our pillar guide on sand blasted surface specification.
NACE No. 1 — White Metal Blast
Equivalent to SSPC SP 5 and ISO 8501-1 Sa 3. The visual criterion: all visible oil, grease, dirt, mill scale, rust, oxide, paint, and other foreign matter removed, presenting as uniformly bright metal.
Typical NACE-specifying contexts where NACE No. 1 is cited:
- Internal coating of large oil and gas storage tanks
- Pipe internal coatings for crude transmission
- FRP-lined vessels for chemical service
- Critical immersion service in petrochemical facilities
NACE 1 / SP 5 is the most expensive cleanliness grade. Pipeline contractors typically default to NACE 2 unless internal immersion coatings are involved.
NACE No. 2 — Near-White Blast
Equivalent to SSPC SP 10 and ISO 8501-1 Sa 2½. The dominant standard in pipeline, offshore, and petrochemical work. The visual criterion permits very light staining or shadowing on no more than 5% of each unit area.
NACE 2 is the cleanliness standard underlying virtually all modern external pipeline coatings (fusion-bonded epoxy, three-layer polyethylene), offshore structural coatings, and petrochemical equipment. The complete external pipeline coating workflow rests on this cleanliness followed by appropriate profile depth — see our guide on anchor pattern specifications: how to match profile depth to coating DFT.
NACE No. 3 — Commercial Blast
Equivalent to SSPC SP 6 and ISO 8501-1 Sa 2. At least 66% of each unit area free of all visible contaminants; tightly adherent material may remain on up to 33%.
NACE 3 sees use in:
- Atmospheric pipeline service (above-ground sections in mild environments)
- Tank exteriors with thick high-build coatings
- Structural members in petrochemical plants where corrosion exposure is moderate
- Maintenance painting over previously coated steel
NACE No. 4 — Brush-off Blast
Equivalent to SSPC SP 7 and ISO 8501-1 Sa 1. The lightest blast cleanliness grade — only loose mill scale, loose rust, and loose coatings must be removed.
NACE 4 is used for:
- Maintenance touch-up over existing pipeline coatings
- Pre-cleaning before thick mastic or polyurea overlay
- Field repair work where full re-blast is economically prohibitive
Joint SSPC/NACE Documents
From the 1990s through 2021, SSPC and NACE published the four primary blast cleaning standards as joint documents:
- SSPC-SP 5/NACE No. 1 — White metal blast cleaning
- SSPC-SP 10/NACE No. 2 — Near-white metal blast cleaning
- SSPC-SP 6/NACE No. 3 — Commercial blast cleaning
- SSPC-SP 7/NACE No. 4 — Brush-off blast cleaning
Following the 2021 merger of NACE and SSPC into AMPP, the joint structure continues. When you see only the NACE number, the SSPC equivalent is automatically implied. The complete SSPC standards family is mapped in our SSPC vs ISO Sa complete cross-reference.
Preguntas frecuentes
Is NACE 2 the same as SSPC SP 10?
Yes. NACE No. 2 and SSPC SP 10 are equivalent designations for near-white metal blast cleaning. The two organizations published joint standards for many years, and the standards are now consolidated under AMPP.
Which standards system do pipeline projects use?
Pipeline, offshore, and petrochemical projects predominantly cite NACE designations. Structural steel fabricators and architectural projects more commonly cite SSPC. Both reference identical cleanliness criteria.
What replaced NACE after the AMPP merger?
NACE merged with SSPC in 2021 to form AMPP. The NACE designations remain in active use; new standards are published under AMPP with backward compatibility to both NACE and SSPC numbering.
Is there a NACE standard for wet abrasive blasting?
Yes. SSPC-SP 16/NACE WAB-6 covers wet abrasive blasting to a near-white finish, and additional WAB-designated standards address wet abrasive variants at other cleanliness levels.
What is NACE No. 5?
There is no NACE No. 5 in the blast cleaning series. The numbered series for abrasive blast cleaning includes NACE 1, 2, 3, 4, and 8 (industrial blast).
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