Step by Step process for the high finish Painting of Tanks, Radiators & fans of Transformers. скачать в хорошем качестве

Step by Step process for the high finish Painting of Tanks, Radiators & fans of Transformers.

1. Surface prep Abrasive blast to Sa 2½; profile 40–75 µm for epoxy systems. Where blasting isn’t feasible thin fins, hard-to-reach, do mechanical cleaning to St 3 + chemical pretreatment see Radiators section. 2. Salt check optional but ideal: Bresle test; if 20–30 mg/m², wash & re-blast. 3. Dust removal: Blow-off + vacuum + tack-rag. 4. Stripe coat edges, welds, fasteners, sharp corners with primer before full coat. 5. Coating application Maintain gun distance 300–450 mm, 50% overlap, cross-passes for uniformity. 6. Flash & cure Respect recoat windows; if exceeded, light sweep-blast/scuff P240–P320 before next coat. 7. DFT & QC after each coat details at the end. 3) Tanks Main Tank / Body External surfaces 1. Blast Sa 2½, profile 50–75 µm. 2. Primer Epoxy zinc phosphate or zinc-rich epoxy in harsh/coastal sites DFT:60–80 µm 3. Stripe coat on edges, welds, nozzle collars, lifting lugs. 4. Intermediate High-build epoxy or MIO epoxy for barrier + abrasion resistance DFT:100–150 µm 5. Topcoat Aliphatic PU, desired color & gloss DFT: 40–60 µm Total DFT:200–290 µm C4 or 240–320 µm C5 with zinc-rich primer Internal surfaces oil-contact zones Follow OEM/spec: often Oil-resistant epoxy / epoxy-phenolic or left uncoated if design allows. If coating required: 1. Blast Sa 2½, clean thoroughly. 2. Oil-resistant epoxy single or double coat DFT:120–200 µm total 3. Holiday test spark per spec before closing. 4) Conservators External Same as Tank external. Pay attention to seam welds, suspension lugs, and sight-glass areas masking + neat cut lines. Total DFT:200–290 µm as above Internal oil contact Typically oil-resistant epoxy or bare per OEM spec. If coated: 120–160 µm total + holiday test. 5) Radiators Panel Radiators / Finned Banks Radiators need corrosion protection plus a smooth, run-free finish without bridging between fins. Option A – Wet paint common at assembly plants: 1. Prep Degrease thoroughly radiators often oily, hot alkaline wash if possible. Mechanical prep St 3 on accessible flats. Avoid aggressive blasting that deforms fins. If available, a 7-tank phosphating line is excellent: 1. Alkaline Degrease → 2) Rinse → 3) Derust/Pickle → 4) Rinse → 5) Zinc Phosphate → 6) Rinse → 7) Passivation → Dry. 2. Primer Epoxy zinc phosphate thin passes to avoid runs between fins DFT:40–60 µm 3. Intermediate High-build epoxy – optional for C3; recommended for C4/C5 DFT: 60–100 µm apply in two light coats, allow flash-off 4. Topcoat PU DFT: 30–40 µm two light coats for flow & gloss Total DFT:130–200 µm C3 or 160–240 µm C4/C5 6) Fans Impellers, Guards, Hubs Key concern: balance & bearing protection. 1. Masking: Bearing seats, bores, threads, balancing drill marks. 2. Prep: Degrease → Light blast Sa 2–2½ or sweep blast on thin blades. 3. Primer: Epoxy zinc phosphate 30–40 µm thin, even. 4. Topcoat:PU 25–35 µm usually no intermediate to keep mass uniform. 5. Cure fully → Remove masking → Check dynamic balance re-trim if needed. Total DFT:55–75 µm thin to preserve balance and airflow. 7) Flash-off, Curing & Handling Typical flash between coats: 10–30 min touch-dry, no stringing. Recoat windows: Follow TDS; epoxies commonly 6–24 h @ 25–30 °C. Full cure: Epoxy 5–7 days; PU 5–7 days faster with warm, ventilated booth. Handling: Use padded slings; avoid stacking within 24 h; no packing until tack-free and at least 48 h cure at 25–30 °C. 8) Quality Control each batch Surface cleanliness: Visual to Sa 2½ / St 3; dust rating ≤2 ISO 8502-3.Profile: 40–75 µm replica tape/comb. WFT/DFT: Comb & gauge after each coat; record at ≥5 locations/side. Adhesion:ASTM D3359 cross-hatch ≥4B or pull-off if specified. Gloss & shade: As per spec e.g., 60° gloss per ASTM D523. Cure: MEK double rubs ASTM D4752 where applicable. Holiday test: Internals/oil-contact coatings as specified. Defects check: runs, sags, pinholes, dry spray, orange peel—mark & repair.