Water hammer in steam pipelines

Water hammer occurs due to the presence of liquid in pressure pipes; high-pressure gas causes a sharp change in the velocity of the liquid within the pipes, resulting in vibrations in those pipes. Water hammer poses a serious threat to pipes, and it must be eliminated promptly! Water hammer is mostly caused by the rapid opening of release valves and improper pipeline design.

http://bbs.hcbbs.com/thread-1104847-1-1.html I don’t understand; in this post, it is the condensate that is used to control the heat in the house – so why doesn’t water hammer occur?

This control method is quite reliable; it prevents water hammer effects. Steam enters from the top, and the condensate separates from the high-pressure steam within the shell； If high-pressure steam enters from the bottom, water hammer is likely to occur at the cross-tube section.

Warm the pipe first, drain out the cold liquid, and open the valve slowly to prevent thermal stress.

Before providing a response, it should be noted first that: 1. Under the same operating conditions, the density of condensate is greater than that of steam, and its inertial force is also greater than that of steam； 2. The occurrence of water hammer is actually a phenomenon of uneven force acting on the pipe wall ； Understanding these two points will help explain why water hammer (also known as shock wave) occurs when gas is carried with liquid, liquid is carried with gas, or the valve is closed too quickly.

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Regarding water hammer, it occurs when sudden changes in pressure or temperature inside a pipeline lead to pressure fluctuations. In pressure pipelines, rapid changes in the flow velocity of the liquid result in significant, repeated, and swift variations in pressure; this phenomenon is known as water hammer. 0 ?0 _; B g" E5 o: w The basic cause of water hammer is that when the valves in a pressure pipeline are suddenly closed or opened, or when a water pump stops or starts suddenly, the instantaneous flow rate changes drastically, which leads to a rapid change in the liquid’s momentum and consequently to significant pressure variations. Water hammer can also occur if the check valve on the pipeline fails. In steam pipes, if the pipes are not warmed adequately and water drainage is incomplete, part of the steam delivered will condense into water, causing its volume to shrink suddenly and creating a local vacuum. The surrounding medium will then rush towards this area at high speed, resulting in loud noises and vibrations. When water hammer occurs, the pressure increase can be many times that of normal pressure, subjecting the pipe wall material to high stresses ； Repetitive changes in pressure can cause vibrations in pipes and equipment, and in severe cases, lead to damage to the pipes, pipe fittings, and equipment. The faster the change in temperature or pressure, the more severe the water hammer effect. The larger the pipes, the more noticeable this phenomenon is. As examples: 1. When heating a pipe, if the valve isn’t controlled properly, steam can enter the pipe too quickly, resulting in a sharp change in temperature; this can cause water hammer. 2. When shutting off the steam supply, if the operation is done too quickly and the steam valve is closed all at once, this too can lead to water hammer. The hazards of water hammer: When water hammer occurs, the pressure increase can be many times higher than normal, putting significant stress on the pipe walls ； Repetitive changes in pressure can cause vibrations in pipes and equipment; in severe cases, this can lead to damage to the pipes, pipe fittings, and equipment. The basic methods for eliminating or reducing the effects of water hammer are: (1) opening or closing valves slowly ； (2) Before supplying steam through the steam pipeline, it is necessary to thoroughly warm the pipeline and remove all water from it, and then slowly open the valve to supply the steam. (3) Drain the pipeline