There have been a number of 18 inch torpedoes in service with the United States. These have been used on ships and submarines of the US Navy. American "18 inch" torpedoes were actually 17.7 inches (45 cm) in diameter, beginning with the "Fiume" Whitehead torpedo of 1890.
Ship classes that carried 18 inch torpedoes include:
Length:360 cm (140 in)
Weight:383 kg (845 lb)
High:74 km/h (40 kn)
Range:910 m (1,000 yd)