Operation and Maintenance of Centrifugal Pumps After Shutdown

In industrial process systems, the shutdown of a centrifugal pump does not mean the end of maintenance work—on the contrary, correct operation and maintenance after shutdown are often the key to ensuring the long-term stable operation of the equipment. Whether it is planned maintenance, seasonal shutdown, or emergency shutdown due to failure, neglecting the post-shutdown processing steps can easily lead to serious problems such as corrosion, crystallization blockage, shaft bending, seal failure, and even pump body freezing and cracking.

Why is standardized operation still required after shutdown?

Many on-site personnel mistakenly believe that "the pump is safe once it stops", but actual cases show that more than 60% of secondary failures of centrifugal pumps are caused by improper handling during shutdown. Residual liquid may corrode metal components, easily crystallizable media can block flow channels, and special protection is required under high or low temperature operating conditions. Therefore, shutdown is not the end, but a new starting point for maintenance.

Standard Operation Procedures for Centrifugal Pumps After Shutdown

1. Close valves and cut off power to ensure safe isolation

Immediately close the inlet valve after the pump stops running to prevent backflow or siphonage.
After the pump body cools down naturally, close the outlet valve of the auxiliary system and other process valves in sequence.
At the same time, cut off the motor power supply and implement the Lockout-Tagout (LOTO) procedure to ensure personnel safety.

✅ Tip: Do not forcefully close all valves when the pump body is at a high temperature, as this may cause abnormal pressure rise inside.

2. High-temperature pumps: Strictly implement turning and cooling procedures

After the shutdown of a high-temperature centrifugal pump, the shutdown procedure must be implemented in accordance with the equipment technical documentation.
Generally required: Manually turn the pump half a turn every 20–30 minutes until the pump body temperature drops below 50℃.
Turning the pump can prevent the rotor from bending due to thermal deformation, avoiding excessive vibration or jamming during the next startup.

3. Low-temperature pumps: Maintain primed state and seal system pressure

Unless otherwise specified, the low-temperature pump should remain filled with liquid after shutdown to prevent vaporization or dry running.
The suction valve and discharge valve should be kept open to maintain system pressure balance.
For low-temperature pumps with double mechanical seals, ensure that the liquid level controller is working normally, and the pressure of the sealing fluid in the seal chamber is not lower than the priming pressure of the pump to prevent air intrusion and seal failure.

4. Pumps for special media: Rinse in time to prevent blockage

For centrifugal pumps transporting easily crystallizable, easily solidifiable, or easily precipitable media (such as lime milk, syrup, sludge, high-concentration salt solutions, etc.), anti-blocking measures must be taken immediately after shutdown.
It is recommended to quickly backwash the pump body and pipelines with clean water or other compatible flushing fluids after shutdown to thoroughly remove residues and avoid difficult cleaning after deposition and hardening.

5. Drain accumulated liquid to prevent corrosion and freezing cracking

For pumps not in low-temperature conditions or without liquid retention requirements, open the drain valve at the bottom of the pump body to completely drain the accumulated liquid.
This can effectively prevent:

Internal corrosion (especially for carbon steel pump casings)
Freezing cracking in winter (when the ambient temperature is below 0℃)
Microbial growth or chemical deposition

❗ Note: Before draining, be sure to confirm the nature of the medium—highly corrosive or toxic liquids must be recycled and treated in accordance with environmental protection and safety regulations, and shall not be discharged directly.

Warning of Common Operational Mistakes

Mistakes	Correct Practices
"No need to handle short-term shutdown"	Even for a shutdown of a few hours, easily precipitable media may cause impeller blockage
"Low-temperature pumps can be drained"	Most low-temperature pumps need to operate with liquid retention; draining will lead to seal failure or cavitation
"Turning the pump is too troublesome; skipping once is okay"	Lack of turning for high-temperature pumps is one of the main causes of rotor bending

Conclusion: Details Determine Equipment Life

The operation and maintenance of centrifugal pumps after shutdown may seem like finishing work, but they are actually the core of preventive maintenance. To obtain more detailed industry-customized shutdown maintenance plans or to select high-reliability centrifugal pump systems for your working conditions, please visit the Omron Tech Pumps official website.

At Omron Tech Pumps, we focus on intelligent fluid transportation technology and provide one-stop solutions from design, selection to full-life cycle services, helping industrial customers achieve safe, energy-saving, and low-maintenance operational goals.

📞 Want to consult more centrifugal pump shutdown maintenance skills or technical support? Contact us immediately—the Omron Tech Pumps engineer team is ready to serve you at any time.