Wet flue gas condenses on the heater wall, forming an acidic condensate with chlorides and sulfates. Bare 316 attacks quickly. A filled-PTFE cladding seals the tube from the condensate, because the dense film is non-absorbent and the smooth surface sheds the acid.
The material-selection service specifies the wet-stack cladding, with extra film on the condensing zone. At each outage, the film is inspected. The controller holds the wall above the acid-dew point.
Procurement writes the wet-stack spec. The glass filler is inert. The result is a heater that survives the acidic condensate.
Plants that had wet-stack corrosion switched to the cladded heater and stopped the attack. The result is a 316 heater that handles the acidic condensate, because the dense, smooth film blocks the chemistry.
Wet flue-gas condensate is acidic and loaded with chlorides and sulfates, and it condenses on the cooler parts of a heater wall. Bare 316 attacks quickly under that acid film, because the condensate concentrates as it evaporates. A filled-PTFE cladding seals the tube from the condensate, because the dense film is non-absorbent and the smooth surface sheds the acid rather than holding it. The material-selection service specifies the wet-stack cladding with extra film weight on the condensing zone, where the acid is heaviest. At each outage, the film is inspected for blistering, and the controller holds the wall temperature above the acid-dew point so that condensation is minimized in the first place. Procurement writes the wet-stack spec. The glass filler is inert to the acid. Plants that had wet-stack corrosion switched to the cladded heater and stopped the attack. The result is a 316 heater that handles the acidic condensate, because the dense, smooth film blocks the chemistry and the wall-temperature control reduces where the acid can condense.
The controller holds the wall temperature above the acid-dew point, so condensation is minimized. At each outage, the condensing zone is inspected. Procurement writes the wet-stack spec. Plants that had wet-stack corrosion switched to the cladded heater. The result is a heater that handles the acidic condensate, because the dense film blocks it and the temperature control reduces where it forms.
The glass filler is inert to the acid condensate. At each outage, the condensing zone is inspected for wear. The result is a wet-stack heater that lasts, because the dense smooth film sheds the acid and the temperature control limits condensation.
The inspection discipline is what makes the liner work. At each refinery turnaround, the heater is isolated, the liner is holiday-spark-tested over its full length, and any pinhole is repaired before return to wet hydrogen service. The glass-fiber composite is chosen for long-term refinery temperature stability. Sintering density is verified on every batch. Material-selection service also eliminates cathodic over-protection. The result is a heater where the hydrogen-bearing stream stays on the PTFE side of the wall, and the titanium below never absorbs hydrogen.
