Flexible joint on suction and discharge pipe

[Lan123]

Under what conditions should flexible joints(Eg. Bellow type) be provided on suction and discharge piping? I have a low lift 30 hp sewage pump application and I am curious to find out whether these are really required as I hardly see these on most of the pump applications I come across.

Thanks in advance

 

[Artisi]

There is considerable discussion already in this forum on this subject, suggest you do some research.
However, wouldn't you think by not seeing many would suggest something.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)