In industrial coating projects, it is common to find surfaces that formally meet a specified degree of cleanliness yet still present premature system failures. This situation highlights a key technical reality: a surface can be clean without necessarily being prepared for the coating's performance.
In this context, it is fundamental to understand the relationship between SSPC-SP 10 / NACE No. 2, as an abrasive blast cleaning standard, and AMPP TR21589-2025, as a technical document that expands the analysis toward surface texture characterization. Both documents do not compete; on the contrary, they complement each other to reduce technical uncertainty in demanding applications.
SSPC-SP 10 / NACE No. 2: The Contractual Cleaning Threshold
The SSPC-SP 10 / NACE No. 2 standard, known as Near-White Metal Blast Cleaning, establishes clear and auditable criteria regarding how clean a surface must be after abrasive blasting. Its central requirement allows for the presence of staining, provided it does not exceed 5% per unit area.
SP 10 is not limited to blasting itself. Before the process, it requires the removal of visible contaminants such as oil, grease, and dirt, as well as the treatment of surface imperfections like sharp edges, weld spatter, and geometric defects that could affect coating performance.
From an operational perspective, SP 10 guarantees a contractual minimum of cleanliness, indispensable for ensuring the basic quality of the substrate before the protection system is applied.
AMPP TR21589-2025: When Cleaning Is Not Enough
The AMPP TR21589-2025 is a Technical Report, not a prescriptive standard. Its objective is to organize technical knowledge and available tools to characterize surface roughness beyond the traditional peak-to-valley depth.
Historically, the industry has specified roughness primarily through a single variable: profile depth. However, in severe environments or with surface-sensitive coatings, this approach may be insufficient. TR21589 introduces two critical variables:
- Peak count / Areal peak density.
- Texture angularity: Differentiating sharp surfaces from more rounded ones.
Furthermore, the document clearly distinguishes between 2D (linear) and 3D (areal) metrics. In practical terms, TR21589 does not replace SP 10; it completes the analysis when system performance depends on how the coating anchors to the actual microgeometry.
Profile, Thickness, and Premature Failure Risk
One of the most relevant technical contributions of TR21589 is highlighting the direct relationship between roughness profile and coating thickness. An excessively coarse abrasive can generate a profile so high that a thin coating scheme fails to adequately cover the peaks, increasing the risk of early failures such as rust-through.
This approach forces us to abandon the idea that "more profile is always better" and to consider the coherence between texture, target DFT, and service environment.
Cleaning and Environmental Control During Blasting
SP 10 also emphasizes the control of environmental conditions during dry blasting, recommending maintaining the substrate temperature at least 3 °C (5 °F) above the dew point, in order to minimize the risk of contamination and rust-back before coating application.
A Complementarity Across All Industries
The correct integration of SP 10 and TR21589 is applicable across sectors such as Oil & Gas, mining, infrastructure, marine, energy, water, and industrial plants. The risk lies not only in incorrectly specifying cleanliness but in leaving surface texture to chance.
The technical question is no longer just "what degree of cleanliness do I require?" but also "what texture does my system actually need?".
The Aplika Approach: Reducing Technical Uncertainty
At Aplika Control Corrosión, we are integrating AMPP TR21589-2025 as a reference technical document to improve specifications, acceptance criteria, and inspection plans, complementing the application of standards such as SP 10.
The goal is clear: better surface, less rework, and longer asset life, through better-founded technical decisions starting from surface preparation.
