Inlet and outlet piping design of the pump

Cavitation: When the static pressure of the liquid entering the first-class impeller in the pump is lower than or equal to the saturated vapor pressure at this temperature, the liquid vaporizes and produces bubbles. This vaporization and condensation resulting in erosion, vibration, and degradation of pump performance is often referred to as cavitation.

Pump installation sequence: technical preparation→ foundation acceptance→ unpacking inspection→ equipment hoisting in place→ initial leveling and alignment→ paddle filling→ fine leveling and alignment→ secondary grouting → pumps, motor coupling alignment→ process pipeline installation→ alignment and stress review → commissioning preparation, single test run→ load test → delivery acceptance.

Precautions: The inside of the pipe connected to the equipment should be cleaned. The fixed weld should be kept away from the equipment. No additional external force is allowed to be applied to the equipment. The inlet and outlet of the equipment should be added with temporary blind plates, and the pipeline can be removed only after it is cleaned. The flange spacing should be a small distance that can be smoothly put into the gasket. When the pipe is finally connected, its radial displacement should be monitored with a dial gauge on the coupling. At ≤ 6000 rpm, the displacement is ≤ 0. 05mm。 At the rotational speed > 6000rpm, the displacement ≤ 0.02mm. Otherwise, adjust the pipeline.

When the pump inlet pipe system has a reducer, the pipe diameter ≥ DN65 adopts an eccentric reducer to prevent gas accumulation at the reducer. The installation note of the reducer is shown in the figure, that is, when the front elbow of the inlet flange is downward, the top of the reducer is flat; When the elbow is up, the bottom of the reducer is flat.

On-site installation demonstration: media from top to bottom

On-site installation demonstration: media from bottom to top

The suction inlet of the double suction pump should be set up with a straight pipe section not less than 3 times the length of the inlet pipe diameter of the pump, and the large pump should have a straight pipe section with more than 7 times the inlet pipe diameter of the pump, so as to make the liquid enter the pump smoothly and avoid the production of bias flow and rotating flow, causing pump vibration and noise.

When the piping of a double suction pump is for upper suction, it is not necessary to consider the required straight pipe section on the suction inlet. The vertical pipe can be directly connected to the suction nozzle through elbows and reducers, which is required to be as short as possible.

When the suction and discharge outlets of the pump are in the same vertical plane, in order to facilitate the installation of valves, the inlet and outlet can be increased by eccentric reducers or two 45° elbows:

T-Filter:

Y-Filter:

Cone Filter:

The outlet pipeline of the pump should have a certain degree of flexibility, especially under high temperature and high pressure conditions, and must go through stress analysis to determine the geometry of the pipeline according to the magnitude of thermal stress.

Pump outlet and deep protection line design:

The pump outlet should not be directly connected to the elbow. The shut-off valve and check valve at the outlet of the pump are drained with a drain valve. The pump outlet gauge is mounted on a short joint between the pump port and the check valve, and can also be mounted on the outlet reducer. The pressure gauge pipe should have a root valve, and the pressure gauge head should face the operating surface.

Pump protection pipeline - pre-hot line: when the temperature of the conveying medium of the pre-hot wire is greater than 200°C, in order to avoid the sharp influx of high-temperature liquid into the pump to be run when switching pumps. The pump body and impeller are damaged or deformed due to uneven heating, resulting in the stuck part and the rotating part, so it is necessary to set up a pre-hot line to keep the pump in the state of waiting to be started so that it can be switched at any time.

Example of a warm pump line

Pump protection line - small flow line: When the working flow volume of the pump is less than 30% of the rated flow rate of the pump, a force perpendicular to the axial direction is generated - radial thrust. Moreover, because the pump operates under low efficiency, the liquid temperature of the inlet part increases, the vapor pressure increases, and cavitation is prone to occur.

Pump protection pipeline - balance line: for the liquid in the bubble point state of conveying saturated vapor pressure at high dry atmospheric pressure at room temperature, in order to prevent the incoming pump liquid from generating steam or bubbles entering the pump to cause cavitation, it is generally advisable to set up a balance line. The balance line is the gas phase section from the pump inlet to the suction tank (tower).

Pump protection pipeline - bypass line: when starting the high head pump, the outlet valve is unilaterally under excessive pressure, which is not easy to open, and if it is forced to open, there will be a risk of damaging the valve stem and valve seat. A bypass line with a limited flow orifice plate is installed in front of and behind the outlet valve for easy opening. At the same time, the bypass line also has the effect of reducing the vibration and noise of the pipeline.

Pump protection pipeline - anti-condensation line: when transporting liquids with high pour point or high freezing point solidified at room temperature, the backup pump and pipeline should be equipped with anti-condensation line to avoid blockage of the backup pump and pipeline. Generally, there are two pipe diameter DN20 anti-condensation lines. One of them is connected from the pump outlet shut-off valve to the check valve (used when the pump is in standby). The other anti-condensing line is from behind the pump outlet shut-off valve to before the pump inlet shut-off valve (used during standby pump maintenance). Open the corresponding anti-condensation valve to ensure that the fluid in the pipeline is non-condensing.

Pump protection pipeline - safety valve line: for electric reciprocating pumps and rotary pumps, a safety valve should be set on the outlet side, when the outlet pressure exceeds the constant pressure value, the safety valve jumps, and the fluid returns to the inlet side. The pipeline should be arranged as tightly as possible without affecting the operation.

Inlet and outlet piping design of the pump

Inlet and outlet piping design of the pump

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