Pipe freezing on a DN300, PN10 cooling-water line — two butterfly valves replaced, plant kept running, finished in 8 hours.
Plant shutdown is expensive. Draining a cooling-water line is too — and it drags in a cleaning and recommissioning sequence that quickly doubles a planned outage. Pipe freezing removes the whole problem: a precisely positioned ice plug seals the line mechanically while the upstream and downstream medium stays at operating conditions.
The case
Cooling-water line DN300, PN10. Two butterfly valves needed replacement — planned intervention, but no room for a full plant shutdown. Draining would have meant several shifts of cleaning and recommissioning.
What we did
- Measured the positions for two ice plugs, mounted the freezing jackets, set the thermocouple monitoring.
- Connected liquid nitrogen, ran the controlled freeze curve.
- Between the two ice plugs: valve swap including pressure test.
- Controlled thaw, freezing jackets removed, plant continued running.
Result
8 hours total. No draining, no cleaning, no recommissioning. The plant produced throughout. For our customer this means: no production loss, no refilling logistics, no extra safety walk-down.
Where does pipe freezing make sense?
- Valve and butterfly swap under live operation
- Hot taps with the ice plug as second barrier
- Emergency repairs when draining is technically or schedule-wise impossible
- Safety isolation before hot work on pressurised lines
From DN 25 to DN 600, in carbon, stainless, duplex and clad materials — we freeze when draining is not acceptable.