Sulfuric Acid Tank Material By Concentration

sulfuric acid, h2so4, 93% sulfuric, 96% sulfuric, 98% sulfuric, concentrated sulfuric acid, concentrated acid tank, 11/15 rule, snyder 880046, houston polytank sulfuric acid, heap leach acid storage

Corrects a working assumption that concentrated sulfuric acid always requires exotic alloys. Two independent vendors (General Industries Inc., ProTank) state in their own published literature that carbon steel PASSIVATES at 93-98% H2SO4 — forms a protective coating that makes concentrated acid LESS corrosive to carbon steel than dilute acid — making carbon steel the standard, economical bulk-storage tank material at this specific concentration band, not a fallback. ProTank additionally states FRP tops out around 80% and XLPE fails within 6 months at 98% — both unsuitable for storage at the 93-98% band. This does NOT extend to pumps/valves, where turbulent flow, velocity, and lower-concentration excursions still require Alloy 20/PTFE-lined/one-piece-flanged construction per the existing sulfuric-acid-98plus-material-selection rule (Griffco source, SO3 contaminant attacks PVDF/Noryl). Carver Pump's own case study and G2C/G2S Series tech spec PDF independently confirm Alloy 20 (ASTM A744 Grade CN-7M) as a real wetted-parts material for sulfuric acid pump service, consistent with the existing rule's pump-side recommendation. IMPORTANT NUANCE: Alloy 20 is NOT one of Carver's standard catalog material codes (their standard options are A/cast iron, B/316SS-fitted, C/all-316SS, X/Special) — in the standard Key Component Materials table, Alloy 20 appears only for the slinger. A full Alloy-20-wetted-parts build (as used in the real case study, replacing a failing self-priming PVDF pump with a G2S vertical sump pump, 22 ft submergence, 2,500 GPM) is a special/custom order under code X, not an off-the-shelf SKU — factor real lead time into any quote calling for full Alloy 20 wetted parts. Treat tank material and pump/valve material as governed by different mechanisms for this chemical — do not apply one rule's material choice to the other equipment category. REAL UNRESOLVED CONFLICT, added after cross-checking Poly Processing's own Tank_Specs.pdf: Poly Processing's own compatibility table lists sulfuric acid as XLPE-compatible up to 98% with no stated service-life caveat, directly contradicting ProTank's published claim that XLPE fails within 6 months of service at 98% concentration. Do not spec an XLPE tank for 98% sulfuric acid off either vendor's claim alone — this is the same category of disagreement as the sodium-hypochlorite HDLPE-vs-XLPE conflict documented in sodium-hypochlorite-epdm-rating; present both positions in comparison content, and verify with a vendor-specific warranty/service-life statement at the exact concentration before a real spec decision. RECONCILIATION ADDED 2026-09-10/11 (mining/hydrometallurgical duty-class research): the ProTank-vs-Poly-Processing conflict above is narrower than it first appears once each vendor's actual named spec is read. ProTank's objection is specifically to XLPE (crosslinked polyethylene) failing at 98%. Three roster vendors each publish a distinct, engineered concentrated-acid tank spec using three different base materials: Poly Processing uses XLPE + OR-1000(TM) antioxidant inner surface, and its own published "11/15 rule" states verbatim that any Poly Processing tank under 11,000 gallons and under 15 feet tall is fine for sulfuric acid storage (SAFE-Tank if no secondary containment exists, IMFO if it does). Snyder Industries' sulfuric acid resin #880046 is HDLPE — linear, NOT crosslinked — a genuinely different polymer, so Snyder's spec and ProTank's XLPE warning are not actually in conflict; they describe different materials. Houston PolyTank sidesteps the argument a third way, via extrusion-winding (no molded-in stresses, the actual failure mechanism) plus wall thickness up to 6 inches, engineered to DVS 2205. Practical rule: never quote a generic catalog PE tank at 93-98% H2SO4; quote a vendor's NAMED concentrated-acid product (Snyder #880046, Poly Processing XLPE+OR-1000 within the 11/15 size limit, or Houston PolyTank extrusion-wound) or carbon steel — all four are defensible, a commercial-grade rotomolded tank is not. This does not fully resolve the original conflict (Poly Processing's own Tank_Specs.pdf still shows no service-life caveat at 98% the way ProTank's warning implies), but it narrows it from 'XLPE vs. everything' to 'XLPE specifically, within a stated size ceiling, using the OR-1000 antioxidant system.'

General Industries Inc. / ProTank Carbon steel storage tanks (Tank)