A duct comprising: - a pipe for conveying a fluid, extending along an axis and comprising a first portion; - a coupling element fitted to said pipe comprising a second portion fitted to said first portion, which can be connected directly or indirectly to another conveyor pipe of said duct; said first portion and second portion respectively comprising a first corrugation and a second corrugation coupled together so as to axially hold said pipe to said coupling element; said first and second corrugations (15, 16) having an extension axial and thickness radial to said axis; said radial thickness being smaller than said axial extension; each of said first and second corrugations (15, 16) comprising multiple repeated modules, identical to each other and consecutively arranged parallel to said axis; each said module comprising: - a first section arranged at a first radial distance from said axis; and - a second section arranged at a second radial distance from said axis; said second distance being shorter than said first distance; characterised in that it comprises, in addition, a host pipe having a damaged area; said conveyor pipe being fitted coaxially inside said host pipe and cooperating in a fluid-tight manner with the host pipe; said conveyor pipe being inserted, in use, inside said host pipe in the form of an inflatable sheathing; said first section of each module comprising at least one through hole arranged radially to said axis. - a pipe for conveying a fluid, extending along an axis and comprising a first portion; - a coupling element fitted to said pipe comprising a second portion fitted to said first portion, which can be connected directly or indirectly to another conveyor pipe of said duct; said first portion and second portion respectively comprising a first corrugation and a second corrugation coupled together so as to axially hold said pipe to said coupling element; said first and second corrugations (15, 16) having an extension axial and thickness radial to said axis; said radial thickness being smaller than said axial extension; each of said first and second corrugations (15, 16) comprising multiple repeated modules, identical to each other and consecutively arranged parallel to said axis; each said module comprising: - a first section arranged at a first radial distance from said axis; and - a second section arranged at a second radial distance from said axis; said second distance being shorter than said first distance; characterised in that it comprises, in addition, a host pipe having a damaged area; said conveyor pipe being fitted coaxially inside said host pipe and cooperating in a fluid-tight manner with the host pipe; said conveyor pipe being inserted, in use, inside said host pipe in the form of an inflatable sheathing; said first section of each module comprising at least one through hole arranged radially to said axis. said first portion and second portion respectively comprising a first corrugation and a second corrugation coupled together so as to axially hold said pipe to said coupling element; said first and second corrugations (15, 16) having an extension axial and thickness radial to said axis; said radial thickness being smaller than said axial extension; each of said first and second corrugations (15, 16) comprising multiple repeated modules, identical to each other and consecutively arranged parallel to said axis; each said module comprising: - a first section arranged at a first radial distance from said axis; and - a second section arranged at a second radial distance from said axis; - a first section arranged at a first radial distance from said axis; and - a second section arranged at a second radial distance from said axis; said second distance being shorter than said first distance; characterised in that it comprises, in addition, a host pipe having a damaged area; said conveyor pipe being fitted coaxially inside said host pipe and cooperating in a fluid-tight manner with the host pipe; said conveyor pipe being inserted, in use, inside said host pipe in the form of an inflatable sheathing; said first section of each module comprising at least one through hole arranged radially to said axis.