Method for producing a large multilayer pipe

Abstract

A method for producing a multilayered large pipe out of an outer pipe which forms a supporting layer, and at least one inner pipe, which forms a lining layer and is bent from a lining sheet and welded along a longitudinal seam or is seamless, including the following sequence of method steps: preparing a wavy inner pipe which is bent from the lining sheet with a continuously rounded wavy contour extending transverse to a longitudinal axis of the large pipe and with wave troughs and wave crests extending continuously over a length of the wavy inner pipe where the maximum outer diameter of the wavy inner pipe is smaller than the inner diameter of the outer pipe; inserting the wavy inner pipe into the outer pipe; and expanding the wavy inner pipe by an expansion force acting in a radially outward direction until it assumes an almost round form and, after removal of the expansion force, is clamped in a nonpositive way in the outer pipe, and subsequent relaxation.

1 . A method for producing a multilayered large pipe out of an outer pipe ( 1 ), which forms a supporting layer and is welded or seamless and thus closed on a casing side, and at least one inner pipe ( 2 ) which forms a lining layer and is bent from a lining sheet and welded along a longitudinal seam or is seamless, including the following sequence of method steps:
 preparing the wavy inner pipe ( 20 ) which is bent from the lining sheet or is seamless and is closed on the casing side, with a continuously rounded, wavy contour ( 22 ) extending transverse to a longitudinal axis of the large pipe and with wave troughs ( 21 ) and wave crests ( 23 ) extending continuously over a length of the wavy inner pipe ( 20 ), where a maximum outer diameter (OD L ) of the wavy inner pipe ( 20 ) is smaller than an inner diameter (ID T ) of the outer pipe ( 1 );   inserting the wavy inner pipe ( 20 ) into the outer pipe ( 1 ); and   expanding the wavy inner pipe ( 20 ) by an expansion force acting in a radially outward direction until it assumes an almost round form and, after removal of the expansion force, is clamped in a nonpositive way in the outer pipe ( 1 ), and subsequent relaxation.   
     
     
         2 . A method for producing a multilayered large pipe out of an outer pipe ( 1 ), which forms a supporting layer, and at least one inner pipe ( 2 ) which forms a lining layer, which is of a lining sheet or a plurality of partial lining sheets that are placed next to one another in a circumference direction, including the following sequence of method steps:
 preparing a supporting sheet which is for the supporting layer and is pre-bent to a predetermined initial bending radius, and at least one lining sheet, which is pre-bent to a predetermined initial bending radius, in which a continuously rounded wavy contour ( 22 ) extending transverse to the longitudinal axis of the large pipe to be produced has been or is formed, with wave troughs ( 21 ) and wave crests ( 23 ) extending continuously over a length of the inner pipe ( 2 ) to be produced;   placing the at least one lining sheet which is pre-bent and has the wavy contour ( 22 ), on an inside of the supporting sheet through positioning and parallel orientation of its longitudinal edges extending in a direction of a longitudinal axis of the large pipe in order to form the supporting layer and at least one wavy lining layer;   integrally joining at least the two longitudinal edges of the at least one lining sheet provided with the wavy contour ( 22 ) to the supporting sheet;   molding the composite of the integrally joined supporting layer and at least one wavy lining layer to produce a slit multilayered large pipe with the outer pipe ( 1 ) and a wavy inner pipe ( 20 );   closing of a gap of the slit large pipe by longitudinal seam welding; and   expanding the wavy inner pipe ( 20 ) by an expansion force acting in a radially outward direction until it assumes an almost round form and, after removal of the expansion force, is clamped in a nonpositive way in the outer pipe ( 1 ), and subsequent relaxation.   
     
     
         3 . The method according to  claim 2 , wherein the wavy contour ( 20 ) is already molded into the lining sheet in the flat initial state. 
     
     
         4 . The method according to  claim 3 , wherein in the unexpanded state before the expansion, an outer circumference length (Li) of the wavy inner pipe ( 20 ) measured in the circumference direction is selected, which is at least a length of a circle with a diameter that exceeds a diameter of the wavy inner pipe ( 20 ) at its wave crests, where Li>π·OD L  and the outer circumference length (Li) is selected to be at least great enough that after expansion and removal of the expansion force, no fold formation occurs in the inner pipe ( 2 ). 
     
     
         5 . The method according to  claim 4 , wherein before the expansion, the outer pipe ( 1 ) and the inner pipe ( 2 ) are closed by a longitudinal seam weld. 
     
     
         6 . The method according to  claim 5 , wherein the length of the lining sheet or of the wavy inner pipe ( 20 ) is selected to be at most as great as a length of the outer pipe ( 1 ) and before the expansion, at first only end sections of the wavy inner pipe ( 20 ) are expanded to the inner circumference surface of the outer pipe ( 1 ) and are integrally joined to the outer pipe ( 1 ) at the ends. 
     
     
         7 . The method according to  claim 6 , wherein with a shorter length of the wavy inner pipe ( 20 ) than the outer pipe ( 1 ), the remaining free section or sections of the inner circumference surface of the outer pipe ( 1 ) each is provided with a lining layer. 
     
     
         8 . The method according to  claim 7 , wherein the large pipe has a corrosion protection on an outside through heat treatment, before or after the expansion procedure. 
     
     
         9 . The method according to  claim 8 , wherein the expansion force for the expansion procedure is exerted by a mechanical or a hydraulic expansion device. 
     
     
         10 . The method according to  claim 9 , wherein before the expansion, the cavity between the wavy inner pipe ( 20 ) and the outer pipe ( 1 ) is evacuated by a vacuum pump. 
     
     
         11 . The method according to  claim 10 , wherein before expansion an adhesive layer is applied to a part or all of an area of the wavy inner pipe ( 20 ) and/or the outer pipe ( 1 ) on sides oriented toward each other and the adhesive layer is hardened during or after the expansion. 
     
     
         12 . The method according to  claim 2 , wherein in the unexpanded state before the expansion, an outer circumference length (Li) of the wavy inner pipe ( 20 ) measured in the circumference direction is selected, which is at least a length of a circle with a diameter that exceeds a diameter of the wavy inner pipe ( 20 ) at its wave crests, where Li>π·OD L  and the outer circumference length (Li) is selected to be at least great enough that after expansion and removal of the expansion force, no fold formation occurs in the inner pipe ( 2 ). 
     
     
         13 . The method according to  claim 2 , wherein before the expansion, the outer pipe ( 1 ) and the inner pipe ( 2 ) are closed by a longitudinal seam weld. 
     
     
         14 . The method according to  claim 2 , wherein the length of the lining sheet or of the wavy inner pipe ( 20 ) is selected to be at most as great as a length of the outer pipe ( 1 ) and before the expansion, at first only end sections of the wavy inner pipe ( 20 ) are expanded to the inner circumference surface of the outer pipe ( 1 ) and are integrally joined to the outer pipe ( 1 ) at the ends. 
     
     
         15 . The method according to  claim 2 , wherein with a shorter length of the wavy inner pipe ( 20 ) than the outer pipe ( 1 ), the remaining free section or sections of the inner circumference surface of the outer pipe ( 1 ) each is provided with a lining layer. 
     
     
         16 . The method according to  claim 2 , wherein the large pipe has a corrosion protection on an outside through heat treatment, before or after the expansion procedure. 
     
     
         17 . The method according to  claim 2 , wherein the expansion force for the expansion procedure is exerted by a mechanical or a hydraulic expansion device. 
     
     
         18 . The method according to  claim 2 , wherein before the expansion, the cavity between the wavy inner pipe ( 20 ) and the outer pipe ( 1 ) is evacuated by a vacuum pump. 
     
     
         19 . The method according to  claim 2 , wherein before expansion an adhesive layer is applied to a part or all of an area of the wavy inner pipe ( 20 ) and/or the outer pipe ( 1 ) on sides oriented toward each other and the adhesive layer is hardened during or after the expansion. 
     
     
         20 . The method according to  claim 1 , wherein the wavy contour ( 20 ) is already molded into the lining sheet in the flat initial state. 
     
     
         21 . The method according to  claim 1 , wherein in the unexpanded state before the expansion, an outer circumference length (Li) of the wavy inner pipe ( 20 ) measured in the circumference direction is selected, which is at least a length of a circle with a diameter that exceeds a diameter of the wavy inner pipe ( 20 ) at its wave crests, where Li>π·OD L , and the outer circumference length (Li) is selected to be at least great enough that after expansion and removal of the expansion force, no fold formation occurs in the inner pipe ( 2 ). 
     
     
         22 . The method according to  claim 1 , wherein before the expansion, the outer pipe ( 1 ) and the inner pipe ( 2 ) are closed by a longitudinal seam weld. 
     
     
         23 . The method according to  claim 1 , wherein the length of the lining sheet or of the wavy inner pipe ( 20 ) is selected to be at most as great as a length of the outer pipe ( 1 ) and before the expansion, at first only end sections of the wavy inner pipe ( 20 ) are expanded to the inner circumference surface of the outer pipe ( 1 ) and are integrally joined to the outer pipe ( 1 ) at the ends. 
     
     
         24 . The method according to  claim 1 , wherein with a shorter length of the wavy inner pipe ( 20 ) than the outer pipe ( 1 ), the remaining free section or sections of the inner circumference surface of the outer pipe ( 1 ) each is provided with a lining layer. 
     
     
         25 . The method according to  claim 1 , wherein the large pipe has a corrosion protection on an outside through heat treatment, before or after the expansion procedure. 
     
     
         26 . The method according to  claim 1 , wherein the expansion force for the expansion procedure is exerted by a mechanical or a hydraulic expansion device. 
     
     
         27 . The method according to  claim 1 , wherein before the expansion, the cavity between the wavy inner pipe ( 20 ) and the outer pipe ( 1 ) is evacuated by a vacuum pump. 
     
     
         28 . The method according to  claim 1 , wherein before expansion an adhesive layer is applied to a part or all of an area of the wavy inner pipe ( 20 ) and/or the outer pipe ( 1 ) on sides oriented toward each other and the adhesive layer is hardened during or after the expansion.