AMPP Bridge Coatings cheat sheet

SSPC-SP 5/NACE No. 1 white metal blast removes all visible rust, mill scale, coating, and foreign matter; the finished steel has a uniform gray color.

SSPC-SP 10/NACE No. 2 near-white blast permits only slight streaks or stains on at most 5% of each unit area; at least 95% must be clean.

SSPC-SP 6/NACE No. 3 commercial blast removes visible residues but allows tightly adherent material; about two-thirds of the surface must be free of visible residues.

SSPC-SP 2 hand-tool and SSPC-SP 3 power-tool cleaning are used where blast cleaning is not permitted or practical; they do not create a deep anchor profile.

Surface profile is measured with ASTM D4417 methods; nozzle pressure, abrasive type and size, angle, and standoff distance control anchor-pattern depth.

ISO 8502-6 Bresle extraction with ISO 8502-9 conductivity conversion quantifies soluble salts; acceptance limits are project-specific and commonly reported in micrograms per square centimeter.

A common environmental rule is steel temperature at least 3 degrees Celsius, about 5 degrees Fahrenheit, above dew point; condensation after cleaning or before coating can cause adhesion failure.

Blasting abrasive must be dry and free of oil, grease, and salts; ASTM D4940 conductivity testing checks soluble ionic contamination.

Wet film thickness equals dry film thickness times 100 divided by percent volume solids; this calculation sets spray-pass coverage and verifies wet-film checks.

Theoretical coverage in square feet per gallon equals 1604 times the volume-solids fraction divided by dry-film thickness in mils; actual coverage is lower because of overspray, loss, and surface roughness.

Volume solids and volatile organic compound content come from product data and test methods such as ASTM D2697 and EPA Method 24.

Inorganic zinc silicate primers provide galvanic protection to steel; they usually need humidity to cure and require a compatible tie coat before topcoating.

Aliphatic polyurethane topcoats resist ultraviolet degradation and retain gloss and color; epoxy topcoats chalk and yellow when exposed to sunlight.

ISO 12944 corrosivity categories C1 through C5 and expected service life drive coating-system selection for bridge environments.

A recoat window is product-specific; exceeding the maximum interval usually requires abrasion, cleaning, and sometimes a tie coat to restore adhesion.

Specifications should state surface preparation grade, profile, primer, intermediate, topcoat, dry-film thickness ranges, stripe coats, recoat limits, color, volatile organic compound limits, and acceptance tests.

Before application, verify product data limits for air and steel temperature, relative humidity, dew point, recoat time, and pot life; record readings.

Airless spray atomization depends on tip orifice, fan angle, fluid pressure, and coating viscosity; a test spray pattern identifies tip wear or clogging.

Two-component coatings must be mixed at the specified volume ratio; some products require an induction time before spray application.

Pot life is counted from mixing; material that gels, skins, or exceeds pot life is discarded rather than thinned for use.

Stripe coats are applied by brush or roller to welds, edges, fasteners, cutouts, and back-to-back angles before full spray coats.

Each spray pass typically overlaps the previous pass by about 50%; this reduces thin streaks and missed areas on large bridge surfaces.

If the maximum recoat window is exceeded, the surface is abraded and cleaned, and the manufacturer's repair procedure is followed.

Ventilation and dehumidification control solvent concentration, humidity, and cure; forced cure must remain within product data limits.

An inspection and test plan lists hold points, witness points, acceptance criteria, sampling frequency, and records for each coating operation.

SSPC-PA 2 dry-film thickness measurement commonly uses five spot measurements per 100 square feet, with each spot the average of three gauge readings.

Dry-film gauges are verified on the actual substrate and on shims; measurements near edges, corners, and welds are treated separately.

Wet-film thickness is checked with ASTM D4414 comb gauges during application and converted to predicted dry-film thickness.

Adhesion is assessed by ASTM D3359 cross-cut tape testing for thin films or ASTM D4541 pull-off testing for thicker systems.

Holiday detection uses ASTM D5162 low-voltage wet-sponge testing for thin films and high-voltage spark testing for thicker films, at specified voltages.

Visual surface preparation is compared with SSPC-VIS 1 or ISO 8501-1 reference photographs; the specified blast grade must be documented.

Nonconformance reports record location, description, disposition, corrective action, and closure verification for out-of-specification work.

OSHA 29 CFR 1926.62 regulates construction lead exposure and requires exposure assessment, respiratory protection, hygiene facilities, blood-lead monitoring, and training.

OSHA 29 CFR 1926.1153 limits respirable crystalline silica; abrasive blasting controls include containment, ventilation, wet methods where feasible, and respirators.

Permit-required confined spaces require atmospheric testing, ventilation, an attendant, rescue arrangements, and entry authorization under OSHA 29 CFR 1910.146.

Respiratory protection requires medical clearance, fit testing, training, and cartridge or supplied-air selection based on contaminant and exposure level.

EPA Method 24 measures volatile organic compound content; project specifications and local air permits set volatile organic compound and solvent-handling limits.

Spent abrasive, paint waste, solvents, and contaminated containment are characterized and managed under RCRA and project waste plans.

Safety data sheets have sixteen sections and provide hazard, handling, personal protective equipment, first-aid, storage, and disposal information for each coating product.

Project records include daily logs, environmental readings, inspection reports, nonconformance reports, material certificates, and as-built coating documentation.