The effects of vibration in crystalising and making brittle steel or copper petrol pipes is well known, and on racing cars and aeroplanes the use of flexible piping is almost universal. Petrol-flex tubing, which is marketed by S. Smith & Sons (M.A.), Ltd., of Cricklewood Works, London, N.W. 2, has proved particularly successful in this connection, while the initial cost is small. The tubing is built up with two walls, the inner one, which is treated to withstand the action of petrol, benzol and other hydrocarbons, being in one piece ; the outer wall is specially treated canvas wound on in spiral formation. An internal spiral of wire is formed integral with the core lining and also serves as a key for the screwed unions which fit
at each end of the pipe, while a further external armouring protects the tube from chafing and other external damage.
The unions are easily fitted, but in the case of many well-known cars, the pipes may be obtained cut to lengths with the unions in place. For the “P ” type Midget, for instance, two pipes are required and each costs 4s.