Abstract: A pipe for fluid transportation is made up of a first layer of material with a first desired critical pressure PC1 and a second layer of material with a critical pressure PC2<0.4PC1. Thickness of the first layer is between 0.1% and 25% of total pipe thickness but not less than 0.3 mm and preferably 0.5-1 mm). Surprising it is observed that a pipe made in this manner has a critical pressure CP near the first desired critical pressure PC1 despite the low thickness of the first layer.

Abstract: A pipe for fluid transportation is made up of a first layer of material with a first desired critical pressure PC1 and a second layer of material with a critical pressure PC2<0.4PC1. Thickness of the first layer is between 0.1% and 25% of total pipe thickness but not less than 0.3 mm and preferably 0.5-1 mm). Surprising it is observed that a pipe made in this manner has a critical pressure CP near the first desired critical pressure PC1 despite the low thickness of the first layer.

Abstract: A pipe fitting for pipelines comprises at least one seating (12) for receiving the end of a pipe to be coupled. The seating surface which is intended to come into contact with the surface of the pipe end, is made of a material having a chemical adhesion reaction on reaching of a predetermined temperature and, around the seating (12), the pipe fitting incorporates an electric winding (14) for heating of the material when an electric current passes therethrough in order that said predetermined temperature can be reached. Advantageously, the seating (12) is formed in a sleeve (17) incorporating the electric winding (14) which in turn is incorporated into the pipe fitting body.