Sulfuric Acid Storage — Tank, Resin & System Selection
Sulfuric Acid Storage — Tank, Resin & System Selection
OEM-verified materials of construction for 93% and 98% sulfuric acid storage in rotomolded polyethylene tanks.
Overview
Sulfuric acid (H2SO4) is the industrial world's most-produced chemical. At concentrations above 70% it is a powerful dehydrating agent; at 93% and 98% it becomes oleum-adjacent and attacks many otherwise-serviceable plastics. Polyethylene tank selection for sulfuric acid is NOT a matter of picking any HDPE — only specific high-density linear polyethylene resins qualify, and only with a narrow window of fittings, gaskets, and bolting hardware. Get any one of these wrong and you get a release. This page documents what actually works, per the OEM recommendations of Snyder Industries and Enduraplas (Equistar resin data).
Why 1.9 ASTM Specific Gravity Is Mandatory
At 98% the specific gravity of sulfuric acid is 1.84 g/mL, and at 93% it is 1.83 g/mL. For rotomolded polyethylene tank design, hoop stress scales directly with stored-fluid SG. A tank rated for 1.5 ASTM fluid SG will fail when you put 1.83 SG sulfuric in it — the tank wall simply isn't thick enough. Both Snyder's 880046 resin and any tank you commission for this service MUST be ordered at 1.9 ASTM specific gravity. This is non-negotiable. A 1.9 ASTM tank has visibly thicker walls than a 1.5 ASTM tank of the same nominal volume.
Why Resin #880046 — And Not Generic HDPE
Snyder's 880046 HDLPE is a specific linear polyethylene resin formulation chosen for sulfuric-acid service. Generic crosslinked polyethylene (XLPE) is NOT approved for sulfuric at any concentration — oxidizing sulfuric breaks the crosslinks. Linear polyethylene of the 880046 grade retains wall integrity at 98% at ambient temperature but will discolor (the asterisk on Snyder's chart). Discoloration is cosmetic, not failure; the tank is still rated. Do not substitute a generic HDPE resin without documented sulfuric-acid service history — Snyder's warranty is tied to the specific resin lot.
System-of-Construction Table (Snyder Industries)
This is the exact specification Snyder Industries publishes for sulfuric-acid service. Every column is required; changing any of them voids the service rating.
| Concentration | Resin | Specific Gravity | Fitting | Gasket | Bolt |
|---|---|---|---|---|---|
| 98% | HDLPE #880046* | 1.9/ASTM | CPVC | Viton | Hastelloy |
| 93% | HDLPE #880046* | 1.9/ASTM | CPVC | Viton | Hastelloy |
Concentration-Band Compatibility (Enduraplas / Equistar Data)
Polyethylene chemical resistance for sulfuric acid by concentration band and service temperature. Satisfactory (S) means long-term service. Limited (O) means occasional short-term use only. Unsatisfactory (U) means do not use.
| Concentration | LDPE/MDPE @ 70°F | LDPE/MDPE @ 140°F | HDPE @ 70°F | HDPE @ 140°F |
|---|---|---|---|---|
| 0-50% | Satisfactory | Satisfactory | Satisfactory | Satisfactory |
| 70% | Satisfactory | Limited | Satisfactory | Limited |
| 80% | Satisfactory | Unsatisfactory | Satisfactory | Unsatisfactory |
| 96% | Limited | Unsatisfactory | Limited | Unsatisfactory |
Frequently Asked Questions
- What tank material do I use for 98% sulfuric acid?
- Snyder Industries specifies HDLPE resin #880046 at 1.9 ASTM specific gravity. Generic crosslinked polyethylene (XLPE) is not approved. Expect cosmetic discoloration of the tank wall; it is not a failure.
- Can I use EPDM gaskets on my sulfuric storage tank?
- No. EPDM swells and cracks in sulfuric acid service. Viton (FKM) is required for any wetted gasket, including the manway, bulkhead fittings, and any flanged connections.
- Why does the specific gravity matter?
- Sulfuric at 93% has an SG of 1.83 and at 98% has an SG of 1.84. Tank wall hoop stress scales directly with stored-fluid SG. A 1.5 ASTM tank will over-stress and fail. Order the tank at 1.9 ASTM — non-negotiable.
- What about hardware?
- Hastelloy C-276 or higher for all bolted connections. 316SS pits in sulfuric vapor even where it doesn't touch the liquid. CPVC for the fitting body (not PVC, which softens above 130°F).
- Does Tank-Depot or Plastic-Mart sell a sulfuric-rated tank?
- Every major reseller carries tanks that CAN be commissioned for sulfuric service if spec'd correctly with Snyder. What differs is who will verify the MOC stack with you before shipment. OneSource checks the full system — resin, SG, fittings, gaskets, bolts — every time you order for sulfuric service.
Source Citations
- Snyder Industries — Chemical Resistance Recommendations (current edition)
- Enduraplas / Equistar Technical Tip — Chemical Resistance of Polyethylene (12-page reference)
- Field service bulletins on 880046 resin tank discoloration and continued service integrity
Chemical-Service Tanks
These HDPE vertical chemical-storage tanks from Snyder Industries ship pre-engineered for industrial chemistry service at 1.9 ASTM design specific gravity. When you order for sulfuric acid service, our team verifies the full materials-of-construction stack (resin grade, fittings, gaskets, bolts) against the OEM recommendations above before shipment — no surprises at commissioning.
Need your state's septic or tank regulations?
Chemical service tanks are spec'd at the manufacturer level, but the installation still has to comply with your state and county rules — setbacks, containment, permitting, and in some states, construction-authorization review. Our State Regulation Guides cite actual statutes, not generic lore.