The fire pump outlet compensator often deforms
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Dear colleagues from CNOOC: The flexible connectors originally used at the outlet of the fire pumps would often get displaced when the pumps started up. As a result, they were replaced with metal compensators; however, these compensators too can deform when the pumps start operating, and the outlet pipes may become deformed as well. It seems that this is caused by excessive stress on the pipes. Please analyze the reasons for this phenomenon. The fire pump has a head of 110 m, with inlet and outlet pipe diameters of 350/300.
At least a photo or drawing should be provided before discussion can take place. It initially seems to be a problem with the blind plate force, but confirmation can only be made after having the drawings or photos.
Blind plate force – just set up the support properly; f=pA
It is recommended to contact the design institute; based on your description, it seems that a fixing bracket needs to be added downstream of the flexible metal hose. When the pump starts, the valve closes, and there is a hose between the valve and the pump. At the moment of startup, the valve is subjected to force from the pump, and if the flexible metal hose isn’t connected with screws, it is very likely to get torn. Even if screws are used, but no fixing bracket is available downstream, those screws will also be damaged.
It is likely caused by the instantaneous pressure resulting from water hammer when the pump stops; it is recommended to install a check valve downstream of the outlet flexible connection