English to French Tech/Engineering Engineering: Industrial Gland steam documentation - steam cooler

Hi,

I am translating the documentation of a cooler with an injection pipe (steam cooler) and I was wondering if you could help me understand and translate into French "cooling at stepdown stations" in the following sentence:

"Both the inlet part and the outlet part (in some cases a conical diffuser is not executed on the outlet, for example cooling at stepdown stations) of the cooler body are fluently shaped (...)."

I understand the inlet and outlet parts as "pièce d'entrée et de sortie du corps de refroidissement". I imagine that sometimes, the diffuser is not "installed" or something on this "pièce de sortie", but I must say I am getting lost!

Could you help me please?

Thanks a lot!