Thermoplastic Metal-Replacement Valve Set — Metal Plating & Photographic Process Solutions

The family with the cleanest single argument in the whole backfill, and the chart makes it: 316 stainless rates C or F against most plating chemistries while PVC, PP, PVDF, PFA and PTFE all rate E — so plating is precisely where thermoplastic valves beat metal valves on chemistry, not just price. Asahi names electroplating and printing among its industries and names plating solutions, wet chlorine, acidic waste, sulfuric/hydrofluoric/nitric acid, oxidizers, caustics, solvents and halogens as the process chemistries. ISO 5752 short-pattern face-to-face is the commercial mechanism: drop-in when a metal valve corrodes out. All five families carry a 3-year warranty. Photographic solutions group here because they are silver-bearing spent process solutions with the same metals-recovery and discharge-control problem; the chart rates them E across PVC/PP/PVDF/PFA/316SS at 40°C, and sodium thiosulfate (fixer chemistry) E across the board. This is strong evidence.

Materials documented for this service: PVC per ASTM D1784 CC 12454-A, CPVC per ASTM D1784 CC 23567A, PP per ASTM D4101 CC PP0210B67272, PPG bonnet per ASTM D4101 CC PP0110M20A21130, PVDF per ASTM D3222 CC Type II, PTFE disc and seat (Type-55 IS), EPDM / FKM / Nitrile seals, Flowline chart — 316SS is the weak material across this whole family: C on chromic acid at every concentration 10-50% and on stannic chloride; F on plating solutions (nickel), plating solutions (tin), nickel chloride, silver nitrate, zinc sulfate, potassium bichromate; G on copper cyanide, potassium cyanide, nickel sulfate, potassium chromate, sodium bichromate, potassium ferrocyanide, lead acetate. Chemical compatibility depends on exact concentration, temperature, and duty cycle — confirm with a spec review before final specification.

Named chemicals in this documentation: plating solutions (brass, cadmium, copper, gold, nickel, silver, tin), chromic acid 10-50%, photographic solutions, sodium cyanide solution, potassium cyanide, copper cyanide, nickel sulfate, silver nitrate, sodium/potassium bichromate, stannic chloride, wet chlorine, hydrofluoric acid, nitric acid.

Documented examples include Asahi/America Type-57 LIS butterfly (3"-8", PVC body, PVC/CPVC/PP/PVDF disc, EPDM/FKM/Nitrile seat, 316SS/Titanium/Hastelloy C non-wetted stem, 150psi @70°F, Class 6 bubble-tight), Type-55 IS butterfly (2"-12" @150psi, 14"/16" @100psi; ductile cast iron FCD-S powdercoat body with PTFE disc and PTFE/Neoprene-backed seat, 304SS non-wetted stem), Type-14 Flanged Diaphragm Valve (1/2"-4"), Type P Gate Valve (2"-8" standard, three pressure tiers by size), Wafer Check Valve (3"-12", 150psi 3"-8" and 85psi 10"/12", max 120°F).