Method of thermally insulating coaxial pipes with a particulate insulating material

A method of thermally insulating the annular space in an element of an assembly of two coaxial pipes, in which a spacing is provided, the insulation being provided by a porous, thermally-insulating material that is confined under small absolute gas pressure, the method being characterized by:

• a) placing said element at an inclination, said annular space being closed at each end by a closure piece, the closure piece at the top end including a filler orifice that is closable;
• and
• b) substantially completely filling the annular space with said insulating material in the form of particles in bulk, by pouring the material into said filler orifice of the closure piece at the higher end of said inclined pipe elements, said annular space being maintained under a high vacuum throughout filling;
• wherein in step b) said insulating material is poured from a first reservoir in which a high vacuum is established by evacuating through an orifice of said reservoir that is provided with a first leaktight isolation valve, and said particles of insulating material are conveyed via a first flexible hose between said first reservoir and said filler orifice of a closure piece for closing the annular space at the top end of the inclined pipe elements, and before said annular space is filled and while said annular space is being filled, said annular space is itself evacuated via an orifice provided with a second leaktight isolation valve communicating with said first flexible hose.

A method of thermally insulating the annular space in an element of an assembly of two coaxial pipes, in which spacing is preferably provided by centralizer elements, the insulation being provided by a porous, thermally-insulating material that is confined under small absolute gas pressure, the method being characterized by:

• a) placing said element of an assembly of two coaxial pipes at an inclination said annular space being closed at each end by a closure piece, the closure piece at the top end including a filler orifice that is closable;
• and
• b) substantially completely filling the annular space with said insulating material in the form of particles in bulk, by pouring the material into said filler orifice of the closure piece at the higher end of said inclined pipe elements, said annular space being maintained under a high vacuum throughout filling;
• wherein said particles of insulating material are shaken at least intermittently while the annular space is being filled by causing said pipe element to vibrate, and/or by causing it to pivot in angular rocking about its longitudinal axis XX′ in order to compact said insulating material;
• and
• wherein pivoting is performed in back-and-forth angular rocking through an amplitude 2β, corresponding to turning through an angle of ±β of 5° to 45° relative to the vertical axial plane of the pipe element.