Last year I got an email from an EHS manager at a university chemistry lab in the Middle East. Their steel acid cabinet was less than 3 years old. The hinges had rusted shut. The bottom panel had perforated from hydrochloric acid vapor. One shelf had collapsed. He asked a simple question: keep replacing steel, or try PP? If you’re weighing PP vs steel acid cabinet for long-term lab storage, this post gives you a real 5-year comparison. Not spec-sheet theory. What actually happens in a working lab, month by month. What happens to a steel acid cabinet after 5 years Steel cabinets aren’t useless. For non-corrosive chemicals, they do the job fine. But store hydrochloric, sulfuric, nitric acid, or sodium hydroxide — the strong stuff — and the lifespan drops fast. Year 1: Looks perfect. The epoxy coating keeps metal off the acid. But one dent that exposes bare steel starts the clock. Corrosion begins the day the coating breaks. Year 2: Hinges go first. Metal hinges oxidize in acid vapor. Doors start squeaking, then jam. Rust spots show up at the weld seams on the bottom panel. Year 3: Bottom perforates. HCl and H2SO4 vapor is heavier than air. It sinks and pools…