Wish to share about water hammer phenomenon with all my energy sector professionals which was one of the query point raised by my audiences in a technical workshop.
Water hammer phenomenon occurs whenever water mass is accelerated by steam pressure or a low-pressure void and is suddenly stopped by impact on a valve or fitting, such as bend or tee joint, or on a pipe inner surface. As a result of this, Initial water velocities which can be much higher than the normal steam velocity in the pipe, especially when the water hammer is occurring at start-up. They are sometimes called dynamic pressure changes or pressure transients ( unsteady flow condition). The main causes of transient flow conditions (water hammer condition) are:• In a steam-flow-driven water hammer phenomenon a slug of rapidly moving water strikes a stationary object. The exchange of momentum creates a pressure of perhaps a few hundred psi in the impact area.
• In a condensate-induced water hammer phenomenon there is a rapid condensation when a steam pocket, being totally surrounded by colder condensate, collapses into a liquid state at water -steam interface. Depending on the pressures and temperatures involved, the reduction in volume may be by a factor of several hundred to well over a thousand, and the resulting low-pressure void allows the pressurized surrounding condensate to rush in, resulting in a tremendous collision. This can be a very dangerous HSE incident. In mild cases, there is noise and perhaps movement of the pipe. More severe cases lead to fracture of the pipe or fittings with almost explosive effect and consequent escape of live steam at the fracture. Fracturing of pipes or steam system components can propel fragments that can cause injury or loss of life.
• Sudden Closing or opening of shut-off valves in the piping system
• poorly designed or malfunctions of Steam traps
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