Abstract: Apparatus for simulating corrosion activity of a process stream on equipment and transport lines. The apparatus includes a series of modular canisters coupled to a process stream source and a process stream discharge point. A cooling coil is positioned within each canister and the cooling coils are interconnected in series. The first cooling coil is coupled to a coolant source and the last cooling coil is connected to a coolant discharge. The process stream flows thorough the series of canisters and the coolant flows through the coils in counterflow to the process stream to cool and partially condense the process stream. Corrosion activity and temperature within the canister are monitored using corrosion probes and/or coupons. Modular construction of the canisters permits disassembly and reassembly to adapt the simulator to different simulation applications.