AMPP CCI-1 cheat sheet

Corrosion is an electrochemical process requiring an anode (oxidation, metal loss), a cathode (reduction), an electrolyte path, and an electron path; removing any one element stops the cell.

Galvanic corrosion occurs when two dissimilar metals contact in an electrolyte; the more active (anodic) metal corrodes, driven by the potential difference between them.

Barrier, inhibitive, and sacrificial (galvanic) are the three primary coating protection mechanisms; most coatings combine barrier with one other mechanism.

Coating permeability to water, oxygen, and ions governs barrier performance; higher crosslink density and higher film build generally reduce permeability.

Adhesion develops through mechanical interlock, chemical bonding, and secondary (van der Waals) forces; loss of adhesion at the interface initiates undercutting and blistering.

Osmotic blistering occurs when soluble salts or contaminants under a coating draw water through the film by osmosis; the driving force is the concentration gradient.

Cathodic disbondment results from hydroxyl ions generated at a cathodically protected surface raising pH beneath the coating and breaking adhesion.

A coating's service life follows the general relationship L = k/m, where m is the number of coating defects or breaks per unit area; fewer defects yield longer life.

NACE No. 1/SSPC-SP 5 (White Metal) leaves no visible residue; NACE No. 2/SSPC-SP 10 (Near-White) permits staining on no more than 5% of each unit area.

NACE No. 3/SSPC-SP 6 (Commercial Blast) permits staining on up to 33% of each unit area; SSPC-SP 7 (Brush-Off Blast) removes loose material only.

Abrasive cleanliness per ISO 11124/11126 and SSPC-AB 1 through AB 4 governs salt, oil, and dust contamination that can transfer to the substrate.

Anchor profile is measured by replica tape (coarse grade for 20-50 micrometres, extra-coarse for 38-115 micrometres) or by stylus profilometers.

Surface salt contamination is commonly assessed by the Bresle patch method (ISO 8502-6) with conductivity measured per ISO 8502-9; thresholds are often specified by the coating manufacturer.

Ambient conditions per ISO 8502-4 require steel temperature at least 3 degrees C above dew point to prevent condensation during preparation and application.

Abrasive blasting nozzles should be sized to the compressor output; a common rule is 3 to 4 cfm per horsepower at the nozzle for efficient cleaning.

Waterjetting standards are graded by SSPC-SP 12/NACE No. 5 and by flash-rust grade (ISO 8501-4); wet abrasive blasting may require inhibitors to prevent flash rusting.

Wet film thickness (WFT) times volume solids fraction equals dry film thickness (DFT); WFT = DFT / %VS, so 100 micrometres DFT at 60% VS requires about 167 micrometres WFT.

Theoretical coverage in square metres per litre = (10 x %VS) / DFT in micrometres; adjust for transfer efficiency and overspray losses.

Holiday (pinhole) detection uses low-voltage wet-sponge testing for thin films and high-voltage spark testing for thicker films; voltage per NACE SP0188 and SP0274.

Adhesion is verified by destructive tests such as ASTM D4541 pull-off or ASTM D3359 cross-cut tape; results are reported as a value or classification.

Environmental readings recorded at each application interval include air and steel temperature, relative humidity, and dew point per ISO 8502-4.

Stripe coats are applied by brush to edges, welds, and back-to-back members before full coat application to build DFT at hard-to-reach areas.

Recoat windows are defined by the manufacturer; exceeding the window may require surface roughening (sweep blast) to restore intercoat adhesion.

DFT is measured with magnetic gauges on steel per SSPC-PA 2, which sets the 80/20 rule: no single reading below 80% of spec, and the average at or above spec.

SSPC-PA 2 governs DFT measurement and defines the 80/20 rule and the number of gauge readings per 10 square metres of coated area.

ISO 12944 classifies corrosivity categories C1 through C5 (plus CX) and defines durability ranges: low up to 7 years, medium 7-15, high 15-25, very high over 25.

NACE SP0188 covers holiday testing of conductive substrates by low-voltage method; NACE SP0274 covers high-voltage spark testing.

A coating specification typically includes surface prep standard, coating system, DFT range, environmental limits, inspection hold points, and acceptance criteria.

Inspection reports should record date, time, ambient and steel temperatures, RH, dew point, surface prep grade, profile, DFT readings, and inspector identity.

Safety data sheets (SDS) per OSHA 1910.1200 provide hazard, PPE, and first-aid information; review before handling any coating or solvent.

Confined-space entry requires atmospheric testing for oxygen, flammables, and toxics, plus a permit and attendant per OSHA 1910.146.

Abrasive blasting requires respiratory protection (Type CE supplied-air for blasting), hearing protection, and eye protection per OSHA 1910.94 and 1910.133.

ASTM D4541 covers pull-off adhesion testing; results are reported in psi or MPa along with the failure mode (adhesive, cohesive, or glue).

ASTM D3359 covers tape adhesion by cross-cut (Method A, X-cut) or lattice pattern (Method B); results are ranked 0B to 5B or 0A to 5A.

ISO 4624 covers pull-off testing of paints and varnishes; ISO 2409 covers cross-cut testing, with classifications 0 through 5.

ISO 8501-1 defines visual rust grades A through D and preparation grades Sa, St, and Fl for previously coated and uncoated steel.

ISO 12944-2 assigns corrosivity categories based on mass loss or penetration rate of standard specimens over one year in a given environment.

Inspection documentation should include a chain of custody for test instruments, calibration records, and signed hold-point release forms.

NACE/AMPP standards are numbered by committee (e.g., SP for standard practice, TM for test method); cite the current revision and year in reports.

OSHA 1926 Subpart D covers construction health and safety, including scaffolding and fall protection relevant to elevated coating work.

A coating specification is a contract document; deviations require written approval from the owner's representative before work proceeds.

Nonconformance reports (NCRs) document deviations from spec, root cause, corrective action, and disposition; they are retained with the project record.

Instrument calibration should be traceable to a national standard (e.g., NIST); record calibration date, due date, and serial number on inspection forms.

Hold points are inspection steps that require sign-off before work continues; witness points are observed but do not stop work.

Environmental and DFT data should be recorded at defined frequencies (e.g., per shift, per area) and signed by the inspector.

Safety data sheets must be accessible at the work site; PPE selection follows the SDS and the employer's hazard assessment.

Confined-space and hot-work permits are required for coating work involving solvents, blasting, or spraying in enclosed spaces.

OSHA 1910.134 covers respiratory protection: fit testing, medical evaluation, and cartridge change schedules are required for spray and blasting operations.