Experimental tests are reported on steel pipelines that have been struck by a relatively large rigid wedge-shaped mass travelling up to 10.4 m/s. A pipeline is supported across a span, is fully clamped at both ends and is struck at the mid-span and at the one quarter span positions. Most of the pipelines are pressurised with a nitrogen gas. The initial impact energy produces large inelastic ductile deformations of the pipeline and, in some cases, failure. The experimental results are compared with previous data obtained on larger diameter pipelines and observations are offered on the accuracy of the geometrically similar scaling of the final deformations. The results are also compared with several empirical equations and comments are made on their accuracy.