Abstract: In addressing the problem of acoustic source localization within circular pipelines, this paper investigates the similarities and distinctions between the interference structures of acoustic fields in circular pipelines and those in shallow-water environments. A waveguide invariant for pipeline acoustic fields is proposed, and a novel acoustic source ranging method is subsequently developed based on this invariant. The method achieves range estimation of broadband acoustic sources by extracting the slope of interference patterns in the time-frequency domain for specific frequency bands. Importantly, this approach requires only a single receiver to achieve accurate distance estimation. Numerical simulations indicate that the localization error remains below 2.5% when the signal-to-noise ratio (SNR) exceeds 4 dB, while experimental results in a pipe environment demonstrate an error within 4%. These findings confirm the efficacy of the method and noise resilience for accurate acoustic source localization in pipes.