Valve Maintenance in Refinery Crude Distillation Units

Crude distillation units (CDUs) expose valves to highly variable service conditions—from ambient temperature crude at the preheat train inlet to >380 °C atmospheric bottoms streams. Valve reliability directly affects crude throughput and product slate.

Preheat Train Valves

Heat exchanger inlet and outlet isolation valves handle crude at 50–200 °C. Gate and ball valves are typical. Scale and rust particles from crude storage tanks can cause seat damage—upstream strainers and periodic valve exercising are recommended.

Crude Furnace Charge Valves

Valves on furnace charge and pass control loops handle crude at 200–350 °C. Control valves with hardened trim resist erosion from sand and catalyst fines carried in crude. High-temperature packing (graphite) and high-temperature actuator springs are required.

Confirm Cv and trim class for erosive crude at the design flow rateSpecify anti-cavitation trim if flashing can occur on pressure let-downUse extended bonnet actuators where flange temperatures exceed 200 °CSchedule globe valve trim inspection at each turnaround

Atmospheric Tower Valves

Tower draw-off control valves handle LGO, HGO, and AGO streams at temperatures up to 360 °C. Overhead condenser isolation valves may see HCl-induced corrosion—alloy trim or plastic-lined valves may be specified for overhead streams.

Atmospheric Bottoms (Residue) Valves

Vacuum residue and atmospheric bottoms valves handle highly viscous, high-temperature (>350 °C) streams that can solidify on cooling. Steam-traced or jacketed valve bodies prevent solidification during outages. Gate valves with full-bore openings are preferred.

Install steam tracing on residue valves and confirm trace operation before startupHydraulically flush valve body before opening after any extended shutdownInspect valve internals for coking deposits at each turnaroundDocument any change in valve position required to maintain target flow