What Is an Alloy Reactor? Grades, Design & Applications Answering the core question: What is an alloy reactor, and why are specialty alloys chosen over 304 or 316 stainless? An alloy reactor is fabricated from engineered nickel, duplex, or super-austenitic grades whose chromium, molybdenum, and nitrogen content deliver PREN values from 25 (316L) up to 65 (Hastelloy C-276). This resists chloride stress-corrosion cracking, high-temperature sulfidation, and reducing acids that