In order to reduce the size of a tubular rail for a high-pressure fluid, the rail is obtained from a hollow body with an external diameter and an internal diameter, and has two terminal portions, each provided with an external milling to favour gripping thereof. The millings have an external diameter such as to ensure, together with a cylindrical portion of a coaxial element, a radial strength at least equal to that of the hollow body. Made between the hollow body and each cylindrical portion is a front connection. For this purpose, the cylindrical portion has a plane front surface, whilst each terminal portion has an internal milling with an internal diameter greater than the internal diameter of the hollow body so as to house the cylindrical portion and so as to form an annular shoulder. A washer of softer material is set between the annular shoulder and the front surface.