Preheat the pump and rotate it manually with the high-pressure feed pump

The front turning disc should be preheated first and properly aligned; it cannot be turned while being preheated

Preheating requires shaft rotation, as this helps to achieve a more even preheating effect and prevents a large temperature difference between the upper and lower sections of the pump. Some pumps have startup conditions that require a temperature difference within the cylinder to be no more than 30 degrees.

For the preheating of our high-temperature pumps, it is necessary to rotate the shaft to prevent excessive temperature differences from causing the shaft to bend or deform. What are the reasons behind your company’s requirement not to perform a crank test?

OP, the truth is this: indeed, with ordinary pumps, it’s necessary to rotate the pump shaft during preheating. Doing so helps ensure a more even preheating effect and prevents too large a temperature difference between the upper and lower sections of the pump. Some pumps have startup conditions that require a temperature difference within the cylinder to be no more than 30 degrees. However, when preheating a high-pressure feed pump, it is necessary to control the preheating rate first; the preheating process must not be too rapid. If the pump is rotated during preheating, this will cause the temperature of the pump cylinder to rise, and if this increase in temperature exceeds the pump’s allowable preheating rate, it can damage the mechanical components inside the pump, thereby preventing effective preheating. The preheating of the hot oil pump should occur at a rate of 50°C/h. The hazards of excessive preheating include the following: ① It has a significant impact on the pump’s service life ； ②Uneven preheating of the pump’s components leads to damage or malfunction ； ③End face seal leakage, flange and cover leakage.

I’ve really never dealt with preheating high-pressure feed pumps before; it’s such an interesting topic to learn about!

Dear sea friends, I asked the equipment manufacturer for the reason, and the summary is as follows: During the preheating phase, turning the rotor can easily cause the moving and stationary parts to engage with each other. Due to the small gap between these parts, as well as the static deflection of the rotor, and the large temperature difference between the upper and lower casings, uneven heating leads to deformation; therefore, it’s easy for the rotor to lock up at this time. Turning the rotor should be done only after preheating is complete, and during preheating, the temperature difference across various points of the pump body should not exceed 30 degrees℃

There are two opinions now: some factories require turning the shaft while using a hot oil pump for preheating, while others do not. Apparently, it depends on the standards provided by the equipment manufacturer

There is no strict requirement against turning the pump; during the pump’s preheating process, the preheating line remains active, which means that there is flow at the inlet and outlet as well as a pressure difference. If the pump is turned at this time, it might reverse due to inertia. Therefore, the preheating line should not be set to a too high level. During inspections, it is necessary to check for any reversal of the pump’s rotation; if such a situation is detected, the preheating line should be turned off immediately. Once the pump has stopped rotating, the preheating line can be turned up slightly again