Should flexible connections be installed at the inlet and outlet of horizontal centrifugal pumps?

There is no unified standard or specification regarding whether soft connections should be used at the inlet and outlet of horizontal centrifugal pumps. However, in practical applications, in order to reduce pipeline vibration and noise and protect the pump as well as the piping system, soft connections (also known as flexible joints) are usually installed at the pump’s inlet and outlet. Flexible connections can compensate for the thermal expansion of pipes, absorb vibrations, and adjust for minor deviations during installation. For a horizontal single-stage single-suction centrifugal pump with a flow rate of 60 cubic meters per hour and a head of 40 meters, using flexible connections is a good engineering practice. When selecting a flexible connection, factors such as the type of medium, operating pressure, and temperature should be taken into account to choose the appropriate material and model. .

It is only recommended to install flexible connectors at the outlet of pumps with a power of 22KW or higher, to facilitate maintenance and disassembly. Installation in a storage area is not recommended; if cavitation occurs due to water absorption from below, the flexible connections are likely to collapse. Stainless steel flexible hoses can be installed arbitrarily

The head and flow rate are low; it can be installed or not. If it’s not installed, it’s necessary to check the vibration level during actual use. This is also related to factors such as the on-site design and installation structure. For reference.

There are no specific explicit regulations; it is determined based on the operating conditions

Thank you, OP. I hope it goes as you said

This post was last edited by whr73229880 on 2024-1-7 at 21:26. According to the vibration standard Class C for pumps, the maximum value for this pump is 4.5 mm/S. Can this value be achieved only on a testing bench? ?

Currently, pump manufacturers report that the pumps in use experience significant vibration, and they attribute this to the lack of flexible connectors. Is this claim valid?

Currently, pump manufacturers report that the pumps in use experience significant vibration, and they attribute this to the lack of flexible connectors. Is this claim valid?

This post was last edited by SihaiYouxianTian on 2024-1-8 at 07:39. A flexible connection can be used; the hoses connecting the inlet and outlet of the diaphragm pump are there to reduce vibration. Another approach is to use flexible connections at the storage tanks in the tank farm to prevent settlement, and the pump inlet, being the outlet of the storage tank, is also connected via such flexible connections. If the hose connecting to the pump inlet is lined, it needs to be secured with a keel; otherwise, there is a risk of the lining coming off. The layout of the pump inlet and outlet pipelines can refer to SH3012 and GB50275. As for the excessive vibration once the pump is installed, it is necessary to first check how much vibration the pump has during its factory testing, and then determine how much vibration it exhibits during individual testing after it is installed on site. This is because the pump manufacturer will specify requirements regarding the foundation at the installation site; if the vibration level is high already when the pump leaves the factory, it is a problem with the pump itself. If the vibration remains high during individual testing after installation, it may be that the foundation was not constructed in accordance with the manufacturer’s specifications. Once both of these are fine, if the pump operates with significant vibration, then there may be a problem with the process. Generally, the vibration requirements for pumps are clearly specified in API610 and ISO5199. API610 has higher requirements, while ISO5199 has lower requirements. Which standard to use is agreed upon with the manufacturer at the time of selecting the pump.