AMPP S-CAT cheat sheet

Wet film thickness (WFT) = dry film thickness (DFT) ÷ volume solids fraction; a 70% VS coating sprayed to 10 mils DFT needs about 14.3 mils WFT.

Theoretical coverage (ft²/gal) = 1604 × volume solids fraction ÷ DFT in mils; multiply by (1 − transfer efficiency) to get practical coverage.

Conventional air spray transfer efficiency is typically 25–40%; airless 40–60%; air-assisted airless and HVLP 55–75%; the balance is overspray loss.

Airless tip orifice size controls flow: doubling orifice area roughly quadruples flow at constant pressure, since flow rises with the square of orifice diameter.

Fluid pressure in airless spraying is set by pump ratio × air motor pressure; a 30:1 pump at 60 psi air delivers about 1800 psi fluid.

HVLP is defined by atomizing air pressure at the cap of 10 psi or less, reducing bounce-back and overspray.

Pot life starts when components are mixed; a coating with a 4-hour pot life that gels must be discarded, not thinned back into service.

Stripe coats are applied first at edges, welds, and back-cut areas to build thickness the broad spray pass cannot reach.

NACE/SSPC abrasive blast cleanliness grades: SSPC-SP 5 / NACE No. 1 (white metal), SP 10 / NACE No. 2 (near-white), SP 6 / NACE No. 3 (commercial), SP 7 / NACE No. 4 (brush-off).

Abrasive blast profile is specified as a range; typical angular grit profiles are 1.5–3.5 mils, and profile depth must fall within the coating maker's stated range.

ISO 8501-1 rust grades: A (intact mill scale), B (mill scale beginning to rust), C (mill scale gone, pitting), D (general pitting).

Surface preparation to SP 10 permits staining on no more than 5% of each unit area; SP 5 permits no visible residue.

Soluble salt contamination is commonly limited to 3 µg/cm² chloride for immersion service and higher for atmospheric exposure; test per ISO 8502-6/9.

Ambient conditions for blasting and coating usually require steel temperature at least 3°C (5°F) above dew point and relative humidity below 85%.

Anchor profile is measured by replica tape (press-o-film) or a profilometer; coarse-grade tape reads 20–50 µm range, X-coarse 38–115 µm.

Power tool cleaning grades: SSPC-SP 3 (power tool), SP 11 (power tool to bare metal), SP 2 and SP 15 for hand tool equivalents.

Air-supplied respirators for blast/coat require Grade D breathing air: 19.5–23.5% oxygen, CO below 10 ppm, no oil mist or particulate above limits.

Confined space entry requires atmospheric testing for oxygen, flammability, and toxicity before entry and continuous monitoring during work.

Coating DFT is measured with magnetic gauges on steel; Type 1 gauges are least accurate, Type 2 better; take multiple readings per area and average.

SSPC-PA 2 defines DFT acceptance: each gauge reading must be at least 80% of specified thickness, and the average must meet or exceed specification.

Holiday (pinhole) detection uses low-voltage wet sponge for thin films and high-voltage spark testers for thicker films; voltage is set per film thickness.

Adhesion is verified by cross-cut or pull-off testing; pull-off results are reported in psi or MPa and compared to the specified minimum.

Solvent and coating vapors are flammable; bonding and grounding of equipment and containers prevents static ignition during transfer.

Inspection records should capture ambient conditions (temperature, RH, dew point), surface profile, DFT readings, and cure verification for each lot.