In a pressurized water reactor steam pipeline, if condensate is not promptly discharged, it accumulates at the pipe’s bottom. When saturated steam comes into direct contact with this condensate, it gives rise to a phenomenon known as condensation-induced water hammer (CIWH) within the pipeline, posing potential risks to both the steam line’s integrity and personal safety. This paper presents an experimental investigation on the onset and progression of CIWH in steam pipelines, with a particular focus on examining the influence of various condensate volume-related key factors on the CIWH phenomenon. Experimental findings indicate that significant CIWH pressure fluctuations are only observed within a specific range of condensate water volume, corresponding to a ratio of the liquid level at the bottom of the experimental section to the pipe diameter (H/D) between 0.12 and 0.20. Both excessively low and excessively high condensate volumes have notable impacts on the occurrence of CIWH to some degree.