Material Compatibility Quick Reference

★ Flowtech Featured Materials

Composite Material COMPOSEAL XP1600 / XP1620

XP1600 / XP1620 are our flagship composite valve body materials (see the composite control valve product page). Compared with metals and common plastics, they reach the Excellent class across all of the following typical media — including aluminum fluoride, dry-gas hydrochloric acid, mercuric chloride, >40% phosphoric acid, sodium hypochlorite, sodium sulfide and 75–100% concentrated sulfuric acid, all of which are severe-corrosion no-go zones for 316 stainless steel. In a word: what stainless steel cannot stand is exactly where the composite excels.

Legend: Excellent　Good　Fair　Severe corrosion　N.A.　·　Data source: Emerson COMPOSEAL public brochure; typical values — confirm final selection against actual service conditions.

Hydrofluoric Acid (HF)

Typical applications: Hydrofluoric acid, fluoride-containing cleaning solutions, fluorine chemistry, PV etching

Selection notes: Hydrofluoric acid specifically attacks silicon-containing materials (glass, enamel and ceramics dissolve completely) and titanium; stainless steel fails as well — this is the medium with the most material-selection no-go zones. Non-metallic lining is the mainstream solution; Monel 400 works only in oxygen-free dilute acid, and corrosion accelerates significantly once oxygen is present.

Hydrochloric Acid (HCl)

Typical applications: HCl cleaning, regeneration systems, chloride service

Selection notes: Hydrochloric acid is a typical reducing acid and stainless steel is ruled out across the board. With oxygen or Fe³⁺ impurities the corrosion rate multiplies — in that case C-276 outperforms the B family; for pure hydrochloric acid the B family is more economical. The corrosion rate doubles for every 10 °C rise in temperature.

Sulfuric Acid (H₂SO₄)

Typical applications: Dilute acid circulation, concentrated acid storage & transport, lithium-battery pickling

Selection notes: Sulfuric acid selection must be zoned by concentration: carbon steel works in 93–98% concentrated acid at room temperature, but fails as soon as flow velocity rises or temperature climbs; dilute acid (<10%) is a severe-corrosion zone for carbon steel — go with non-metallic lining or Alloy 20. For operation across concentration zones, select materials for the most severe range.

Phosphoric Acid (H₃PO₄)

Typical applications: Thermal/wet-process phosphoric acid, lithium iron phosphate precursor, phosphating lines

Selection notes: What matters is where the phosphoric acid comes from: thermal-process phosphoric acid is pure and 316L suffices; wet-process phosphoric acid carries fluorides and chloride ions, pushing the corrosion class up a notch — titanium, on the contrary, is ruled out by fluorides. Lithium-battery precursor service must also control metal ion leaching; lining solutions are preferred.

Sodium Hydroxide (NaOH)

Typical applications: Caustic soda, wastewater neutralization, MVR alkaline liquor

Selection notes: Caustic soda is friendly to carbon steel — one of the few media where carbon steel takes the lead. Titanium suffers crevice corrosion and stress corrosion cracking in hot concentrated caustic, a textbook no-go zone. Chlorate impurities in the liquor additionally accelerate corrosion and must be assessed together.

Seawater / Brine (incl. MVR Concentrated Brine)

Typical applications: Seawater intake, brine refining, MVR evaporation & concentration, sodium chloride / calcium chloride service

Selection notes: Chloride pitting corrosion and crevice corrosion are the main enemies. 316L is acceptable in dilute brine at room temperature, but under MVR hot concentrated brine (>80 °C, Cl⁻ enriched) 316L will pit without fail — go straight to titanium or 254SMO. In structural design, crevices, dead zones and the edges under gaskets are where corrosion starts, deserving more attention than material selection itself.

Ammonia / Urea

Typical applications: Ammonia storage & transport, denitrification, urea solution, synthesis service

Selection notes: Ammonia is a fatal stress corrosion cracking source for copper alloys — even copper-containing instrument parts must be avoided. Urea service relies on continuous oxygen injection to maintain the passive film; once the oxygen stops, conditions turn active. Ammonium carbamate liquor is extremely corrosive to ordinary stainless steel; high-pressure synthesis requires dedicated urea-grade steel.

Nitric Acid (HNO₃)

Typical applications: Nitric acid storage & transport, pickling, nitration service

Selection notes: Nitric acid is an oxidizing acid and the selection logic is the reverse of reducing acids such as hydrochloric acid: stainless steel and titanium passivate well, while champions against reducing acids such as Monel and Hastelloy B actually perform poorly. Aluminum passivates well in concentrated nitric acid but not in dilute — do not mix them up.

Organic Acids (Oxalic / Citric / Formic / Acetic Acid)

Typical applications: Lithium-battery oxalic acid purification, precursor washing, equipment pickling & passivation, acetic acid storage & transport

Selection notes: Organic acids are milder than inorganic acids overall, but oxalic acid is the biggest exception — the strong chelation of oxalate strips off the passive film, and hot concentrated oxalic acid severely corrodes stainless steel. Since it is often used to remove aluminum and iron from precursors, metal ion leaching requirements rule out carbon steel and ordinary stainless steel completely. Acetic acid gets "the purer, the fiercer": concentrated acetic acid corrodes more than dilute — do not assume dilute-acid behavior.

Lithium-Battery Slurry (Cathode / Ternary Precursor)

Typical applications: NMP cathode slurry, ternary precursor slurry, grinding & dispersion, slurry transfer and metering

Selection notes: Slurry service has two major enemies: wear and metal ion contamination. Ternary precursors are extremely sensitive to Fe, Ni, Cr and Cu leaching — the wear-induced leaching of ordinary stainless steel is enough to spoil a whole batch. Slurries are viscous with hard solids, so prefer smooth linings for valve internals to prevent buildup and scaling; fit elbows and throttling orifices with wear-resistant materials separately. The NMP solvent itself is mild — all the trouble lies in the solids.

Lithium Salt Solutions (Lithium Hydroxide / Lithium Carbonate / Lithium Chloride)

Typical applications: Lithium hydroxide batching, lithium carbonate slurring, lithium chloride concentration, electrolyte raw materials

Selection notes: The three lithium salts behave completely differently: lithium hydroxide is a strong base — copy the caustic soda selection logic and aluminum/zinc are no-go zones; lithium carbonate solution is mild but particle wear during slurring must be considered as well; lithium chloride is a chloride ion source and concentration service equals brine — select for pitting and crevice corrosion. All three salts require battery-grade control of Fe, Cr, Ni, Cu and Zn leaching — keep contact surfaces inert throughout, make lining the main line, the XP1600/XP1620 composite solution is the most worry-free, and do not overlook fasteners and gaskets as exposed metal points.