Abstract <p>Deviation from the nominal wall thickness of a pipe—both during manufacturing and in operation—is a critical factor affecting the durability of equipment. This study proposes a model of acoustic wave propagation across a pipe cross section with eccentricity. The model forms the theoretical basis for a method of integral assessment of wall thickness nonuniformity in small-diameter pipes. The method is implemented using a specialized flexible piezoelectric transducer based on polyvinylidene fluoride (PVDF) on several samples of seamless pipes with varying thickness and validated by the results of local ultrasonic thickness gaging.</p>