Continuous pressure pulses will result in fatigue failure of the plates. Start cold circuit first, then the steam side. Ensure that the steam trap is correctly sized to allow full condensate discharge - this prevents water clogging inside the exchanger. Water hammer occurs when a flowing liquid is suddenly halted. Pressure waves then travel along the pipes creating a hammering effect as they bounce off any restrictions within the pathway.
Thermal shock occurs when the bulk temperature of the exchanger is suddenly raised or lowered.
The resulting expansion or contraction of the unit can result in leakage - sometimes quite severe from the plate pack. Switch off hot circuit pump. Switch off the cold circuit pump. Close all isolating valves. Lubricate tie bolts.