Method of Making an Udersea Pipe, the Method Including Peening Assembly Welds Inside the Pipe

Abstract

A method of making undersea steel pipes, by assembling unit pipe elements together end-to-end by welding, the steel or metal alloy weld beads of said welds being disposed on the outside of the pipe, wherein localized peening is performed on the inside of the pipe to increase the compression of the steel or metal in the vicinity of the welds and over the adjacent peripheral inside surface of the pipe on either side of the weld so as to create a swath of surface that has been peened over a limited distance L in the axial longitudinal direction of said pipe. The peening is preferably performed using a wheeled carriage fitted with a peening tool.

1 - 21 . (canceled) 
   
   
       22 . A method of making steel undersea pipes, the method comprising end-to-end assembly by welding of unit pipe elements with welds having steel or metal alloy weld beads, the steel or metal alloy weld beads of said welds being located on the outside of the pipe, wherein localized peening is performed inside the pipe to increase the compression of the steel or metal in said welds and over the adjacent peripheral inside surface of the pipe on either side of the weld so as to create a surface swath that is peened over a limited distance L in the axial longitudinal direction XX of said pipe, preferably over a distance L that is not less than the width of the weld, on the inside of the pipe, plus a width of 1 mm to 10 mm on either side thereof. 
   
   
       23 . The method according to  claim 22 , wherein the weld comprises a main weld bead at the outside of the pipe and an inside projection or seam of smaller thickness standing proud of the inside of the pipe. 
   
   
       24 . The method according to  claim 22 , wherein said ends of unit pipe elements for welding together present, in longitudinal axial section, a straight end on the inside of the pipe forming a root face preferably occupying at least one-fourth of the thickness of the main portion of the pipe, and extended towards the outside of the pipe by a sloping chamfer. 
   
   
       25 . The method according to  claim 22 , wherein material is removed by machining, preferably by grinding or by milling, from the inside surface of the pipe and from the weld bead over the surface that is to be peened, prior to said peening. 
   
   
       26 . The method according to  claim 22 , wherein said peening is performed at least in the transition region between the inside surface of the weld bead and the adjacent inside surface of the pipe. 
   
   
       27 . The method according to  claim 22 , wherein said peening is performed in such a manner as to establish compression or to increase compression over a thickness of 0.2 mm to 2 mm of said inside surface of the pipe and of said weld. 
   
   
       28 . The method according to  claim 22 , wherein the limited distance L represents one to three times the thickness of the pipe. 
   
   
       29 . The method according to  claim 22 , wherein peening is performed in such a manner as to obtain compression stress that is greater than 5 MPa, preferably greater than 50 MPa, over the entire peened surface. 
   
   
       30 . The method according to  claim 22 , wherein said peening is performed with a peening device that is moved inside said pipe in translation and in rotation in the vicinity of said weld, the peening device comprising:
 at least one peening tool mounted on a first motor-driven carriage;   said first carriage being suitable for moving inside said pipe in translation in the axial longitudinal direction XX of said pipe;   said first carriage supporting means for moving said peening tool in radial translation YY relative to said first carriage, enabling said peening tool to be applied against the inside surface of the pipe, or enabling the peening tool to be set back away from said inside surface of the pipe; and   means for moving said peening tool in rotation about said axial longitudinal axis XX of the pipe, enabling said peening to be performed over the entire circumference of the inside surface of said pipe one said rotation of the peening tool.   
   
   
       31 . The method according to  claim 30 , wherein said peening tool comprises a vibratory surface that preferably extends over said limited distance L in the axial longitudinal direction XX, and a plurality of projectiles of rounded or pointed type suitable for being projected towards the inside surface for treatment by said vibrating surface in order to create a plurality of impacts. 
   
   
       32 . The method according to  claim 30 , wherein said first carriage includes means for moving said peening tool in translation relative to said first carriage in said longitudinal axial direction XX. 
   
   
       33 . The method according to  claim 30 , wherein:
 said first carriage is moved in translation inside said pipe in said axial direction XX, such that said peening tool is substantially positioned so that it can perform peening in said weld region and on either side thereof over a said distance L for peening, in said longitudinal axial direction XX and astride said weld; then   said peening tool is moved against or close to the inside surface of the pipe by moving   said peening tool in radial translation YY; then   said peening tool is then moved in rotation about said axial longitudinal axis XX over the circumference of the inside surface of the pipe; and then where appropriate, the peening tool is moved in translation in the axial longitudinal direction XX relative to said first carriage so as to perform the peening and compression over the entire peened surface, in particular for a peening tool including a plurality of said projectiles of pointed or rounded type that are spaced about from one another.   
   
   
       34 . The method according to  claim 30 , wherein:
 said first motor-driven carriage supports a first shaft placed in said axial longitudinal direction XX; and   said first shaft supports a transverse guide support suitable for guiding the movement of a second carriage in radial translation in a transverse direction perpendicular to said axial longitudinal direction XX, and comprising means suitable for keeping said peening tool in position facing the inside surface of said pipe; and   said first shaft comprises means for driving it in controlled rotation about its said axial longitudinal axis XX, so as to enable said peening tool to be moved over the circumference of the inside surface of the pipe in controlled rotation about its axis; and   said first shaft is preferably suitable for being driven in translation relative to said first carriage in said axial longitudinal direction XX, over at least a said limited distance L.   
   
   
       35 . The method according to  claim 30 , wherein said peening tool comprises a plurality of projectiles that are projected against said surface for peening from a vibrating surface of said peening tool. 
   
   
       36 . The method according to  claim 35 , wherein said peening tool is mounted to pivot relative to said second carriage thus enabling the angle of inclination β of the projection direction Y 1 Y 1  of said projectiles to be varied relative to said direction YY of movement in radial translation of said second carriage. 
   
   
       37 . The method according to  claim 30 , wherein prior grinding is performed of the surface for peening with a grinder tool having a rotary grindwheel mounted in the place of or together with a said peening tool on a said first carriage. 
   
   
       38 . The method according to  claim 22 , wherein said welding is performed using carbon steel, stainless steel, or a corrosion-resisting alloy of the Inconel type having high elasticity, and good fatigue resistance, and preferably Inconel of grade 625 or 825. 
   
   
       39 . The method according to  claim 22 , comprising the following successive steps:
 1) in a workshop on land, assembling the respective ends of at least two unit pipe elements together end-to-end by said welding in order to form pipe strings; and   2) at sea, on board a laying ship fitted with a J-lay tower, assembling respective ends of said strings together by said welding to form a pipe.   
   
   
       40 . An undersea bottom-surface connection pipe including at least a portion having regions of said welds assembling together unit pipe elements, the welds being put into uniform compression by the method according to  claim 22 . 
   
   
       41 . An undersea bottom-surface connection pipe according to claim  19 , wherein it acts as an SCR catenary pipe having at least a portion that includes a region in contact with the bottom that extends above the bottom over at least 100 m, and preferably 200 m, said portion being assembled using a method according to  claim 22 . 
   
   
       42 . A peening device suitable for use in a method according to  claim 30 , the device including at least one said peening tool mounted on a said first carriage suitable for moving in translation inside a pipe, the device comprising a said peening tool suitable for moving in longitudinal translation XX relative to said first carriage and in rotation about said axial longitudinal axis XX of the pipe in the vicinity of said welds, as defined in  claim 30 .