Acid Proof Bricks for Chemical Plants

Acid-proof bricks are dense, vitrified ceramic bricks formulated to resist acidic chemical attack. They are used to line acid-storage tanks, process vessels, neutralisation pits, fertiliser plant floors, pickling tanks, electrolyte cells, and chemical-plant trenches and drains. They withstand most mineral and organic acids, except hydrofluoric acid (HF).

Acid-proof bricks resist sulphuric, hydrochloric, nitric, phosphoric, acetic, citric, lactic and most other mineral and organic acids at all concentrations. They do NOT resist hydrofluoric acid (HF), strong alkalis, or molten salts, for those, switch to carbon brick or fluoropolymer linings. Always specify the chemical environment when ordering.

IS 4860 is the Indian Standard for acid-resistant bricks. We supply Class I, the higher class: water absorption 2% max, compressive strength 700 kg/cm² (about 69 MPa) min, flexural strength 100 kg/cm² (about 9.8 MPa) min, and 1.5% max weight loss in the standard acid test. Test values for each supply are available on request.

Three families: silicate-based cement (cheapest, used for sulphuric/HCl service), furan resin mortar (best chemical resistance, used for organic acid and alkali service), and polymer mortar (epoxy, vinyl-ester for severe duty). Joint material must be matched to the chemical environment; wrong jointing is the most common failure mode of acid-proof linings.

Surface preparation: clean concrete or steel substrate, primer coat. Membrane: bituminous or rubber sheet to seal the substrate. Bedding: chemical-resistant mortar at 6–10 mm thickness. Brick-laying: stretcher bond, joints 3–6 mm wide, fully filled. Cure: 24–72 hours before chemical exposure. Skilled installation is essential, bad workmanship will fail in months.

Properly installed acid-proof brick linings in pickling tanks and acid storage typically last 8–15 years before requiring full relining, with localised joint repairs every 2–3 years. Life is limited by joint deterioration, mechanical impact, and thermal cycling. Linings exposed to dilute acid usually last longer than concentrated, due to slower joint attack.